Explain The Three Phases Of Actin Polymerisation

Explain The Three Phases Of Actin Polymerisation
The three phases of actin polymerisation are the nucleation phase, the elongation phase and the
equilibrium phase. A in the curve is the nucleation phase. A few G–actin subunits combine to form
short oligomers. However these are unstable and readily dissociate. When three subunits bind
together and transition to form a more stable oligomer with many subunit–subunit interactions, this
can then act as a seed for actin polymerisation (often called the nucleus). The phase is sometimes
referred to as the lagging phase, this is due to a delay in the time taken for G–actin to form these
stable oligomers. This was proven in experiment when some preformed stable filaments were added
in vitro at the beginning of polymerisation the lag was eliminated. This is followed by the
elongation phase which is B on the curve. The elongation phase is more rapid, actin monomers are
being added to both ends of the nucleus to form the actin filament, F–actin. As the F–actin filament
grows G–actin monomer concentration is decreasing. In equilibrium or steady state phase C on the
curve, a balance is reached between the F–actin filament ends and G–actin concentration.
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Explain The Sliding Filament Theory Of Muscle Action
The sliding filament theory of a muscle action has five phases. The first phase is resting. In this
phase there is no calcium available to bind the myosin to the actin. This is the normal state of the
muscle until activated by the excitatory phase. During this second phase, the sarcoplasmic reticulum
becomes stimulated. This releases calcium ions and binds with troponin. This is a protein that is
strung along the actin filaments. Tropomyosin runs along the actin filaments. The actin is pulled
closer to the sarcomere. The contraction phase is when it gets interesting. ATP is broken down into
ADP in order to create energy for the contraction. To return to the normal state of the muscle, ATP
replaces ADP and aids in detachment of the myosin cross

Motor Recruitment Theory
1. Ok so the sliding filament theory is basically the contraction of the sacromere. Calcium released
from an ion channel bind to troponin which lies on the thick filament known as the actin. This then
causes the tropomyosin to reveal on the actin. The myosin head then releases a phosphate from an
ATP which causes then forms a cross bridge attaching both thick and thin filament. Causing one
muscle contraction.
2. The motor recruitment theory explains the use of multiple muscle fibers such as type 1, type 2,
and type 2 b muscle fibers during different physical activities. Each person has all three of the fibers
but, they may be more versatile in one then the others. For example, I have more type 2 b (known as
fast twitch glycolytic fibers)

Muscle Contraction Lab Report
First, before this assignment I had no idea of the levels involved in a muscle contraction. We can
directly control or regulate the activity of our skeletal muscles. Striated muscle movement, produced
by the interaction of filaments containing the proteins myosin and actin, is regulated by the proteins
tropomyosin and troponin on the actin filaments. When an electrical signal passes down the motor
nerve to a muscle it triggers a depolarization of the muscle membrane (sarcolemma). In results,
triggers the sarcoplasmic reticulum to release calcium ions into the muscle interior where they bind
to troponin, which causes tropomyosin to shift the actin filament to which myosin heads need to
bind to produce contraction. During relaxation calcium is pumped back into the sarcoplasmic
reticulum, troponin loses its calcium and tropomyosin reverts. When this action occurs it blocks
mechanism of muscle regulation. ... Show more content on Helpwriting.net ...
Calcium ions exposes the binding sites on the actin filaments. Calcium ions binds to the troponin
molecule causing tropomyosin to expose positions on the actin filament for the attachment of
myosin heads. Cross bridges between myosin heads and actin filaments form. When attachment sites
on the actin are exposed, the myosin heads bind to actin to form cross bridges. ADP and Pi are
released, and sliding motion of actin results. The attachment of cross bridges between myosin and
actin causes the release of ADP and Pi. This, in turn, causes a change in shape of the myosin head,
which generates a sliding movement of the actin toward the center of the sacromere. This pulls the
two Z discs together, effectively contracting the muscle fiber to produce a power stroke. ATP causes
the cross bridges to unbind. When a new ATP molecule attaches to the myosin head, the cross bridge
between the actin and myosin breaks, returning the myosin head to its unattached

How Does Adhesion Site Assembly Occurs While Nader Et Al
Constructing a picture or model for the particular situation (or modify one you find in one of the
papers or a review article).
Signaling pathways that result in cell migration are often useful in understanding how cancer cells
metastasize. The researchers of Swaminathan et al., 2016 examine how adhesion site assembly
occurs while Nader et al., 2016 focuses primarily on the adhesion turnover both are fundamental
processes in cell migration. Integrins play a dominant role in nascent integrin–mediated adhesions
(NAs) which are important in lamellipodium protrusion and generating traction at focal adhesion
points involved in cell motility. Integrins have been extensively studied and are linked to wound
healing as well as metastasis in cancer cells (Lawson et al., 2012). When extracellular signals, either
chemical or physical, contact the cell surface it triggers a response that induces movement. If the
signaling molecule is a growth factor (ex. Epidermal Growth Factor) it could activate a GTPase
protein coupled receptor (GPCR). The next is a signal cascade often led by Rabs or Ras (small G–
proteins) proteins that are powered by GTPase hydrolysis, which often recruits and activates
Wiskott–Aldrich Syndrome protein (WASP) or Scar. Previous studies identified cancer cell that use
Rab–coupling to control cell motility by regulating B–intgrins trafficking (Nader et al., 2016).
WASP recruits Actin related protein 2 and 3 (Arp2/3) complex to the cell membrane and activates it

Sliding Filament Thory, with Ref to Upper Arm.
Norah Carr
Co–ordination and movement
Lo3.
March 2012.
3:1 eplain the sliding filament theory of muscle contraction with reference to the antagonistic
muscles of the upper arm.
3:2. Draw and label a diagram of a synovial joint, explaining the functions of each structure.
3:3. Distinguish between a hinge, pivot and a ball and socket joint with reference to named
examples, shapes of bones and the ranges of movement possible.
To understand the sliding filament theory, one should first look at the muscles. All movement
through the body is created and stopped by muscles. Muscles work in antagonistic pairs, that means
that when one muscle relaxes, it antagonistic pair will contract and vice versa. Muscle fibres are
found in ... Show more content on Helpwriting.net ...
The binding of ATP allows myosin to detach from actin. While detached, ATP hydrolysis occurs
"recharging" the myosin head, (Or resetting the myosin head) If the actin binding sites are still
available, myosin can bind actin again.
The collective bending of numerous myosin heads (all in the same direction), combine to move the
actin filament relative to the myosin filament. This results in muscle contraction in the upper arm.
In the presence of the biochemical adenosine triphosphate (ATP), the myosin and actin fibres would
slide past each other, effectively shortening the muscle. (Huxley).
Summary
Scientists have come a long way in the research relating to muscle contraction. In the past several
decades information has been added along the way and will certainly continue into the future. It is
fascinating to learn how the body moves. It relates to every one of us in every part of our day. As a
student I sit in amazement at the processes that are required in every small movement we can so
easily take for granted.
(Muscle contraction 2011).
3:3

Ball and socket joint – the rounded head of one bone sits within the cup of another, such as the hip
joint or shoulder joint. Movement in all directions is allowed. The ball and socket joint allows a
greater range of movement than the pivot joint at the neck.
(joints) In a hinge joint, the rounded–end portion of one bone fits into the

Skeletal Muscle Vs Muscle
In producing movement bones, "support the body, and provide leverage for the skeletal muscles of
the body" (Sailey, pg. 113). The muscles, "skeletal muscles work together, a system of pairs when
one contracts (shorter) the other relaxes (longer) and causes joints to move" (Sailey, pg. 113). The
nerves, signals are sent to the brian and then to the synapses to muscles.
The sliding filament theory of muscle contraction is basically saying the myosin thick filaments
slide past actin thin filaments during muscle contraction. I believe the sarcomere would be an
example of this occurring.
Both skeletal and cardiac muscle are striated, however skeletal muscle is voluntary and controls
movement. While cardiac muscle is involuntary.
The skeletal

Muscles: Troponin Interaction Between Myosin And T
In the gastrocnemius muscle of the B. Marinus used, there are two types of myofilaments that are
inside the muscle fibres. These myofilaments are thick filament protein called myosin, and a thin
filament containing three different proteins; actin, tropomyosin and troponin. These myofilaments
are arranged in myofibrils in a structure known as a sarcomere (Hopkins. M, P. 2006). The muscle in
this experiment was stretched and forced to contract through an ATP–driven interaction between
myosin and action called crossbridge cycling. In this process, the head of the myosin molecule
extends laterally and binds with an actin molecule to form what is known as the crossbridge. The
contraction of the muscle in this experiment occurs through a process called a power stroke
(Hopkins. ... Show more content on Helpwriting.net ...
2006). Essentially, the head of the myosin bends inward towards the centre of the sarcomere and
pulls the actin until the cross bridge breaks – this process repeats over and over and causes
contraction of muscles. However, this entire process can only occur until specific conditions.
Calcium must be present in order to cause troponin to reposition tropomyosin to expose the myosin
binding sites and cause the cross bridge cycle to occur; if calcium is absent, troponin cannot
reposition tropomyosin to open myosin binding sites (Hopkins. M, P. 2006). The sarcomere is what
provides force in a muscle through its myofilaments. In this experiment, the sarcomere is being
stretched involuntarily and the power stroke is being observed. When the action potential runs down
the axon and calcium is released into the cytosol, the peak contractile force can now

Myosin Skeletal Muscle Contraction
Myosin is a conventional term used to reference a group of molecular motors that translocate actin
filaments or translocate vesicles on fixed actin filaments in living organisms[1]. The human genome
also contains 24 unconventional Myosins divided into 11 distinct classes including some nonmuscle
Myosins[2]. This poster will cover in particular Myosin II which is responsible for skeletal muscle
contraction[1]
Myosin II has a molecular weight of 520 kDa contains two heavy chains, each roughly 2000 amino
acids in length[3]. Each of these heavy chains are comprised of an N–terminal head domain and C–
terminal tails that together take on a coiled–coil morphology holding the two heavy chains
together[4]. Apart from the 2 heads and heavy chains Myosin ... Show more content on
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Myosin can hydrolyze a single ATP in 30 seconds which is slow when compared to the 5–10 ATP
hydrolyzed every second when combined with Actin[7]. One Myosin head binds to one Actin
filament to hydrolyze ATP, this occurs due to the polarity of the Actin molecule[7][Img2]. After
completion of the hydrolyzation process and release of the products the usually weak bond between
Myosin and Actin is strengthened due to the release of Phosphate[6]. This change is referred to as
the "Power Stroke"' as it pulls the Actin filament down the line, ADP is released and the Myosin
head detaches once a new ATP is secured so the process can repeat[1][Img2].
Rigor Mortis is a stiffening of the body caused in part by the lack of aerobic respiration[8]. In death
the body releases Calcium ions which interact with Actin and Myosin to contract muscles
throughout the body[8]. Due to the cessation of respiration the body is unable to efficiently produce
ATP[9]. This causes a shortage that denies Myosin and Actin the ability to disconnect, Calcium ions
are unable to be pumped back out of the muscle cell so the muscles remain tense and the body

Structural Protein
Functions of Proteins in Living Organisms
Proteins are an essential part of a healthy diet in the human body which help to stimulate growth and
maintenance. They are made up of amino acids, which the body uses to make new protein for a huge
variety of functions. Proteins work as a power source which is said to be the bodies tissue building
blocks. Protein is needed to form blood cells. Protein assists in shaping the hair, nails and muscles
which are the structural features of the body.
Structural Protein
Structural proteins produce in the cells are use to shape component in the body, for example,
collagen. Collagen is a fibrous structural protein which is made up of three polypeptide chains
surrounding each other like a twisted rope. Collagen provides a mechanical durability in most
regions of the cell. Blood that is being pumped from the heart at great force has been stopped from
bursting the walls of arteries by a layer of collagen. Tendons connect skeletal muscles to ... Show
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One of this filament is called myosin. Myosin exists as a filament inside of the eukaryotic cells
which are a motor molecule responsible for a number of interactions, such as contractions muscles
and movement. The head and the tail domain are mostly composed of myosin molecules and
converts ATP (adenosine triphosphate), a molecule that cells use in order to work and live, into
mechanical energy (energy of work). This will then create force and movement. The filamentous
actin is bound by the head domain and uses ATP hydrolysis to "walk" along the filament and to
create force and towards the end. The tail domain generally mediates interaction with other myosin
subunits and/or cargo molecules. This will result in an expansion and contraction movement. It
works closely with a globular protein called actin that polymerises to create actin

Muscle Contraction Lab Report
Muscles contract through an action potential moving along a motor neuron toward the skeletal
muscle and they connect to a neuromuscular junction  acetylcholine vesicles being released 
binding on the sarcolemma  causes Na+ influx in the muscle fiber generating an action potential
within the muscle fiber  action potential moves through the T–tubules Calcium channels open
calcium is released into the cytoplasm  actin–myosin binding sites and cross–bridges are
activated by calcium ions between the actin/ myosin heads  ATP is hydrolyzed to flex myosin head
 this flexion makes the actin filaments move close to the middle of the sarcomere  The length of
the sarcomere becomes shorter  contraction. I would like to define a few terms discussed within
this ... Show more content on Helpwriting.net ...
A twitch is a contraction caused by one action potential. HYPOTHESIS!!!!!!!!!!!!!!!! In experiment
2, we measured muscular twitch in the thumb by using a finger pulse transducer and attaching a
stimulus electrode to send shock through the ulnar nerve in the wrist. In experiment 3, we observed
summation and tetanus by opening a new chart window, and placing the bar stimulus on the left
wrist to send impulses to. In experiment 4, we measured the electrical activity of the median nerve
stimulation by using the Bio Amp and the bar stimulus to stimulate the median nerve in the wrist
and elbow. In experiment 5, we measures the nerve conduction velocity by opening a new window
and placing extra pressure on the nerve in the elbow and increasing the amplitude to 15–20 mA. In
experiment 2 the lowest stimulus that had a response was 7.5 mA with a response of 0.013 v/s, and
the highest was 17.5 mA with a response of .147 v/s. In experiment 3 we found two responses up
until the frequency of 10 Hz, we measured summation (.05s, .171 mV) and tetanus (.05s, .353 mV)
at 20 Hz. In experiment 5 we measured latency and distances between the wrist and

Myo1c
Myo1c, a non–processive actin motor protein in the myosin family, has been localized in cell as part
of the intercellular transport system. Specifically this protein has been found trafficking cargo on
actin filaments, although their role is not fully understood or researched. Myosin–1 proteins have
single heads and they are used to help interactions with actin and the membrane system of the cell.
Some examples of their jobs in the cell is "to recycle lipid raft cargos, and final glucose transport."
Many scientists believe myo1c is a tethering protein, or it is a slow transporter. Myo1c has a major
role in kinesin–1 and TM2 interactions in–vitro cell cultures. Studying the Myo1c interactions
would provide scientists with a better understanding ... Show more content on Helpwriting.net ...
The in vitro cell cultures were used first to determine the role in Myo1c in the start and ending for
kinesin–1 transport on the actin filament and microtubule intersection. By tagging the kinesin–1
with fluorescences and placing the protein attached in environments with or without Myo1c, there
could be an investigation on how the protein moves a synthesized cargo around the cell. From these
results, it is noticed that Myo1c is helpful in the initiation of kinesin–1 runs on microtubules. The
cargo docking at the AF intersections were shown to be specific to Myo1c. By using α–actinin to
stop cargo at the same point as Myo1c, there was a distinct difference in the efficiency of pause in
transport. This results of the α–actinin caused stops were shorter and less frequent than the Myo1c
caused stops supporting the thought that these distinct stops are unique to Myo1c motor proteins. In
order to test the effect non–muscle tropomyosins have on the Myo1c motor proteins experiments
looking at the interaction between full length Tm2 and Myo1c, and how this interaction changes the
AF/MT intersection were performed. Testing the Tm2–actin gliding inhibited how in the presence of
Tm2, the Myo1c was prevented from pausing the cargo as it approached the Tm2–AF/MT

Eukaryotic Cell Functions
All eukaryotic cells have microtubules, which are hollow rods assembled from a globular protein
called tubulin. Microtubules grow in length by adding tubulin dimers. Those dimers can also be
disassembled, which would allow the tubulin to build microtubules elsewhere in the cell. The two
opposite ends of of a microtubule are actually pretty unique. One end can can accumulate or release
tubulin dimers at a much higher rate which allows it to grow or shrink during cellular activities
(Campbell, pg.114). The microtubules and the motor proteins of a cell are closely related, which is
why I must introduce some of there functions. Cell motility generally requires interaction if the
cytoskeleton with motor proteins. They work together with plasma ... Show more content on
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Now we are presented with microtubules again and this time I shall describe to you why this is part
of the correct choice. As microtubules structure actually serves as tracks, which organelles that are
equipped with motor proteins can use to move. That seems like one of the two functions we were
looking for that contribute to movement within a cell. Microtubules are often handled with the task
of guiding vesicles from the ER to the Golgi apparatus (Campbell, pg. 114). The next part of choice
B is motor proteins, which are often compared to as feet or how the cell walks to their destination.
They use the tracks provided by the cytoskeleton. The motor protein kind work with the
cytoskeleton and the plasma membrane molecules, which allow whole cells to move along fibers on
the exterior portion of the cell (Campbell, pg.113). Choice B is correct.
Choice C. I don't want to repeat myself and sound repetitive so I tried to give a detailed response to
choice A as to why actin filaments is incorrect. Actin filaments is more of a structural component of
the cell aiding it in bearing tension (Campbell, pg. 114) Motor proteins I tried to give a detailed
description in choice B as to why it is correct. Motor proteins work with various parts of the cell to
allow whole portions of a cell to move along fibers outside the cell (Campbell, pg.113). Choice C is

Skeletal muscle is necessary for locomotion and the...
Skeletal muscle is necessary for locomotion and the maintenance of posture. Without skeletal
muscle, which operates under voluntary control, humans would lack the ability to do the most basic
of tasks such as or standing or walking. A muscle is comprised of numerous muscle fascicles, which
consist of muscle fibers. These muscle fibers are composed of muscle fascicles, which The basic
unit of skeletal muscle is the sarcomere, which is comprised of myofibrillar proteins myosin (thick
filament) and actin (thin filament) which consists of Troponin and Tropomyosin, two important
proteins necessary for muscle contraction.1 Skeletal muscle contraction occurs as a result of
excitation–contraction coupling. Upon the arrival of a nerve ... Show more content on
Helpwriting.net ...
A greater cross–sectional area of the muscle will allow the muscle to produce more force when
activated.
An increase in cross–sectional area of a muscle is primarily due to muscle hypertrophy. Muscle
hypertrophy can be defined as an increase in myofibril size, and can be . Satellite cells can be
thought of as the stem cells of the muscle and play an essential role in exercise–induced muscle
damage repair.3 Satellite cells are located between the sarcolemma and basement membrane of
skeletal muscle fibers,4 and lay dormant in a mitotically quiescent state until the muscle any form of
trauma or injury due to overload.5 Within several hours of muscle damage, satellite cells are
activated as evidenced by increased cellular levels of MyoD and myogenin, two important
transcription factors involved in myogenesis.5 Satellite cell activation is Hepatocyte growth factor
(HGF)
Whether or not muscle fiber hyperplasia occurs in humans remains a controversial topic in exercise
physiology. Hyperplasia refers to a net increase in the number of muscle fibers in an individual
muscle. Numerous studies have shown that muscle fiber hyperplasia does occur in animals under
particular training protocol ( insert citation, and biefly decribe 2 of the studies) Although the
evidence supporting muscle hyperplasia in animals is vast,very

Cilia Are Tiny Hairs Of The Respiratory Tract By Capturing...
What are cilia?
Cilia are tiny hairs, which protect parts of the respiratory tract by capturing particles, which has
entered the body by using a sweeping movement to keep the particles such as dust and debris out of
the lungs. The cilia are found attached to the apical surface of the cell. For example, dust that has
been breathed in through the nose would be captured to stop it going even further. There are roughly
200 to 300 tiny hairs on the cell.
Non–ciliated simple columnar epithelial tissue
Non–ciliated simple columnar epithelial tissue is found on the lining digestive tract, which is the
stomach, gall bladder and the excretory ducts of some glands. It is a tube, which transfers food to
the digestive organs. It also contains a nucleus at its base, has a single layer of cells however are not
ciliated; they do not contain tiny hairs. It also has microvilli to increase the surface area and to make
the absorption more effective, the microvilli can also be referred to as the brush border due to its
hairy appearance.
Pseudostratified columnar epithelial tissue
The Pseudostratified columnar epithelium tissue that lines the trachea and upper respiratory tract
contains many goblet cells. They are unevenly shaped due to the nucleus that is positioned in
different places within the cells; it is this that makes the cells look as if it has many layers, however
it only has one layer that stretches between the apical surface and basement membrane. It secretes
mucus and can

Listeria monocytogenes Essay
Listeria monocytogenes
Introduction
Listeria monocytogenes, a motile, gram–positive rod, is an opportunistic food–borne pathogen
capable of causing listeriosis in humans. Listeriosis includes manifestations of septicemia,
meningitis, pneumonia, and encephalitis. L. monocytogenes is also implicated in miscarriages,
stillbirth, and premature birth for pregnant women. L. monocytogenes is a tough bacterium resistant
to freezing, drying, and heat; most strains have been shown to be pathogenic. It is hypothesized that
1–10% of humans are intestinal carriers of L. monocytogenes. Over 37 mammalian species,
including wild and domestic animals, are capable of L. monocytogenes infection and transmission.
Extensive environmental reservoirs for L. ... Show more content on Helpwriting.net ...
Pathogenic L. monocytogenes go through an intracellular life cycle involving early escape from the
phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin–based motility,
and direct spread to neighboring cells, in which they reinitiate the cycle. The bacterium is first
phagocytosed by these cells and secretes a pore–forming toxin called listeriolysin, which allows the
bacterium to escape from the phagosome. All virulent strains of L. monocytogenes synthesize and
secrete listeriolysin. Phospholipase A and B are other virulence factors that facilitate escape of L.
monocytogenes from the phagosome. Once out of the phagosome L. monocytogenes is capable of
rapid division in the cytoplasm, evading the immune response and moving throughout the cytoplasm
from cell to cell. L. monocytogenes is well known for its ability to propel itself like a rocket through
the cell cytoplasm. This is the result of the bacterium's ability to polymerize actin filaments at its tail
end. Actin is arranged in subunits to form microfilaments that are capable of directing cell
movement. L. monocytogenes accomplishes cell motility through a virulence factor called ActA that
takes advantage of normal actin polymerization going on in the cell. The ActA protein shares
sequence homology with a protein called WASP that is found in virtually all eukaryotic cells. WASP
is responsible for recognizing and

Skeletal Muscle Analysis
The skeletal muscles of vertebrates are responsible for all voluntary movements, as well as many
involuntary actions. They are made up of many bundles of skeletal muscle cells, called muscle
fibers. Within the muscle fibers are bundles of the proteins actin and myosin, which control
contraction; these bundles are known as myofibrils. Within a myofibril, repeating units of
overlapping actin and myosin filaments make up the sarcomeres. Actin filaments with the
sarcomeres are wrapped with tropomyosin, another protein, which has troponin protein molecules
attached to it. At end points of the myosin filaments are globular heads which are capable of binding
to sites on the actin and moving the actin. The movement of actin by the myosin is referred to as the
power stroke. The sarcomeres shorten during contraction (Sedava et al, 2014). Skeletal muscle
contraction follows the sliding filament model. When an action potential is delivered to a muscle
fiber, Ca2+ ions are released from the sarcoplasmic reticulum and diffused into the sarcoplasm. The
Ca2+ ions bind to the troponin, exposing myosin–binding ... Show more content on Helpwriting.net
...
In order to stimulate all muscle fibers in an area, the stimulus must have a high voltage. However,
there are a limited number of muscle fibers within each muscle, so there is a limit on how great the
force of the contraction can be (Sedava et al, 2014). I hypothesized that if the stimulus applied to the
muscle increases in voltage, then the force of the contraction will increase in strength until it reaches
its maximal force where all individual muscle fibers will be recruited. This hypothesis was tested by
delivering stimuli of increasing voltages to the muscle and recording the corresponding contraction
forces (Holbrook et al, 2017). Through observation of the contraction and graphing the recorded
values, it was possible to determine whether the results followed the

Statistical Analysis On The Rate Of Cytoplasmic Streaming
Statistical analysis of variations in the rate of cytoplasmic streaming in Nitella pseudoflabellata due
to differences in cell width and treatment with mechanism–inhibitory cytochalasins C and D
observed using light microscopy
Introduction
Cytoplasmic streaming is the organised flow of the cytoplasm and its constituents within a living
cell (Shimmen et al., 2004). Organelles and important molecules move through the cytosol along the
structure of the cytoskeleton (actin filaments and microtubules) with the aid of myosin I, an actin–
binding motor protein that plays a part in various cell functions including cell motility and
endocytosis (Flavell et al., 2008). Actin microfilaments (F–actin) are the thinnest filaments of the
cytoskeleton, ... Show more content on Helpwriting.net ...
As suggested by Seagull et al. (1980), while the rate of cytoplasmic streaming does not vary with
the size of the motile particle (organelle, cargo molecule, etc.) or the size of the cell itself, larger
cells with increased surface area may absorb these mechanism–inhibitory substances more readily
and may therefore have slower rates of cytoplasmic streaming as less F–actin is available to the
myosin complex at any one time.
Cytochalasins are a group of small organic fungal metabolites which are capable of permeating cell
membranes
Nitella pseudoflabellata is
Aims
1. To measure the rate of cytoplasmic streaming in Nitella pseudoflabellata cells in pond water
2. Correlate the rate of cytoplasmic streaming with the width of the cell
3. Determine the mechanism behind cytoplasmic streaming in Nitella pseudoflabellata by observing
variations in cytoplasmic streaming following treatment with cytochalasins C or D
Materials and Methods
Materials and methods were followed from (Keszei, 2014) with a few exceptions: o Only 50 µL of
each cytochalasin C and cytochalasin D were provided o Cytoplasmic streaming was measured 4
times after flushing the cells with pond water, at 5 minute intervals
Results
Table 1 – Rate of cytoplasmic streaming in Nitella cells in pond water
Cell # Cell width (μm) Time to

Myosin And Myosin Function And Its Effect On A Huge Number...
Abstract:
The actin–myosin interaction is most commonly known for its role in sliding filament theory, where
myosin II bundles interact with actin filaments to shorten muscle sarcomeres and ultimately contract
the muscle. However the myosin superfamily is huge, numbering 17 different proteins to date, and
encompassing many different roles. The interaction of myosin and actin in non–muscle cells is thus
a huge topic, but in understanding the structure, function and regulation of this part of the
cytoskeleton, it is possible to find new drug targets and design new treatments to a huge number of
diseases. One such target is the Rho–associated protein kinases (ROCKs), which are responsible for
the regulation of the actin myosin cytoskeleton. This report aims to briefly cover the basic role of
the actin–myosin cytoskeleton in non–muscle cells, how it is regulated by the ROCK family of
serine/threonine kinases, and how ROCK inhibitors have could have huge therapeutic potential.
Introduction:
The cell cytoskeleton in an immensely complex system of protein filaments and motors, which is
responsible for maintaining the rigidity and architecture of the eukaryotic cell, while transporting
vesicles and organelles throughout the cell and assisting in cell movement. There are 3 types of
protein filaments in the cytoskeleton – actin filaments, intermediate filaments, and microtubules –
and 3 associated motor proteins – myosin, dynein, and kinesin. Of particular interest, and the focus
of

Why Actin Is A Protein Of Any Cell
Actin
Introduction:
Proteins are the primary functionary macromolecules of any cell due to their vast variety in function,
which is a result of their amount of varying forms, and they are polymers composed of amino acids.
These functions include transportation, structural support, motility, gene regulation, signal carrying
and receiving, storage, and catalyzing reactions; these functions are determined by the form of the
protein. It follows then that the many functions of proteins come from their multitude of forms and
their multiple levels of structure which are as follows: primary, secondary, tertiary, and quaternary.
The primary structure is most basic chain or sequence of amino acids that accumulate into the alpha
helices and beta sheets which compose the secondary structure of a protein. The tertiary structure is
a complete and three–dimensional polypeptide chain containing the secondary structures, folds,
coils, loops, and such that form a globular form. Quaternary structure is a single protein formed by
multiple polypeptide chains or multiple tertiary structures.
General Information on Actin:
Actin is a protein of moderate size that was discovered in an extraction of rabbit muscle tissue by
Bruno Ferenc Straub. Actin is the component of actin filaments which are a major component in the
cytoskeleton. This actin cytoskeleton that structurally supports the cell membrane is quite important
to the morphology of a cell due to its spread, abundance, and general size; it can

Factors That Affect The Growth Of Cells And Their Cellular...
Significance
Age is a universal time–dependent deterioration factor that affects all organisms and their cellular
functions, thus, determining their lifespan. Actin organization and function declines with age in
many cells, tissues and organs. For example, age–associated declines in myosin and actomyosin
ATPase activities, changes in myosin structural state, and oxidative damage to actomyosin occur and
may contribute to sarcopenia [1]. Similarly, the age–associated deficit in the motility of fibroblasts,
which contributes to impaired wound healing, has been linked to a progressive decline in actin
organization [2]. There is an age–associated decline in immunological synapse formation between
CD4+ T cells and the antigen presenting cells (APC) in which actin cytoskeletal structure and
dynamics are critical for this formation and activation of T cells (6 and 14 – CS). Defects in T cell
activation are shown to be a result of defects in recruiting actin binding protein talin, which is
critical for reorganization of the actin cytoskeleton, and development of lamellipodia, which is
responsible for increasing the communication surface area between CD4+ T cell and APC at the
immunological synapses (6 and 14 – CS). Finally, actin cytoskeleton integrity declines in
Alzheimer's patients affecting the integrity of dendritic spines by disrupting its morphology and
impinging memory and learning (20n21 – CS). In Alzheimer's patients there is a disproportionate
expression of cofilin,

Protein Phosphatase Receptor Analysis
Its function is regulated by dopaminergic and glutaminergic receptors. When stimulated by
dopaminergic receptors it is a potent inhibitor of PP1α (Hemmings, 1984). In contrast, when
stimulated by glutaminergic receptors, the inhibitory activity of DARPP–32 against PP1 is reduced
(Halpain, 1990). DARPP–32 is regulated by brain–derived neurotropic factor as well as the Akt
pathway and CDK5/p35 pathway (Stroppolo, 2001) (Bogush, 2007).
Protein Phosphatase Inhibitor 2 Protein Phosphatase Inhibitor 2 (I–2) I–2 is a heat stable protein that
can inhibit the catalytic subunits of PP1 (Huang, 1976). When unphosphorylated I–2 is inhibitory to
PP1c however, phosphorylation of I–2 can induce PP1c activity (Cohen 2002). It has been shown to
be important in cell cycle regulation and is found at the centrosomes during interphase (Eto, 2002).
The consensus as to the purpose of I–2 is to act as a regulator of PP1 to control the kinase/PP1
balance and activate different cellular events. It has also been shown to play a role in tubulin
acetylation in the cilium of retinal epithelial cells. Wang and Brautigan showed that I–2 localizes to
the cilium of human retinal epithelial cells with PP1. RNAi knockdown of I–2 showed ... Show
In order to answer the question from the introduction "How do such a small number of phosphatases
regulate the phosphorylation of thousands of proteins while also allowing each protein to be
regulated independently?" PP1 has evolved mechanisms to bind numerous different subunits in
order to function the way it needs. There are many more regulatory subunits than discussed above.
The subunits discussed above are the major subunits involved in PP1 dynamics. It is a near certainty
that more regulatory subunits will be discovered. If PP1 could only form a complex with one
subunit at a time there are ~42 different holoenzyme structures possible with the subunits discussed

Sliding Filament Theory
How Do We Move?
Many of us go through our daily lives and activities without much thought on how
or why we move our bodies. Walking, jogging, lifting weights or even getting ourselves
out of bed in the morning requires an intricate pattern of processes that allow us to
move and access our enviroment. Our bodies move through a lever and pulley system
made up of our muscles bones and tendons acting on each other through muscle
contraction and relaxation. (1,3) To understand how a muscle contracts you must first
look at the anatomy of skeletal muscles.
Anatomy of Skeletal Muscle
Figure 1 shows the components of a cross section of muscle. Each muscle belly
is made up of thousands to tens of ... Show more content on Helpwriting.net ...
The
sarcomeres are divided to show
how the sections move during a contraction. The Z line is in the middle of the I bands
and notes the separation of each sarcomere. The I band is light colored because it only
contains the thin filaments actin. The A band contains overlapping actin and myosin,
and the H zone only has myosin filaments. The M line is in the middle of the sarcomere
and is where the myosin filament is free of cross bridges.

Sliding Filament Theory
The sliding filament theory was first introduced over 50 years ago. Hugh Huxley
and Allan Huxley conducted two independent studies and published them in May 1954.
The theory has been added to, but remains relatively the same to this day.
Before the sliding filament theory, it was widely accepted by most academics that
the protein myosin contracted with the presence of calcium ions. The actin proteins roll
had not yet been realized. The 1954 theory states that the filaments containing the proteins myosin
and
actin "slid" past each other and neither filament changed in length. In 1957 Allan Huxley
added that the myosin has a cross bridge structure that binds, rotates and detaches
from the actin. He also states when energy is released from the conversion of ATP to
ADP it creates a power stroke that moves the filaments past each other. (6)
How the Filaments "Slide"
Movement begins when an action potential (electrical

How Do Proteins Help Body Repair Cells
Living organisms need proteins in their diet to help the body repair cells and make new ones. The
basic structure of protein is a chain of amino acids. When two amino acids join together a dipeptide
is formed but when more than two amino acids are joined together a polypeptide is formed. Proteins
are made up of one or more polypeptides. Proteins are large molecules made up of the elements
hydrogen, oxygen, nitrogen and carbon. Types of proteins include, structural proteins, contractile
proteins, hormones, enzymes, antibodies and transport proteins. Some functions of proteins are
movement in muscles, tendons and ligaments. Enzymes make biological reactions possible and
hormones regulate metabolism. The protein shape determines its function.Proteins ... Show more
content on Helpwriting.net ...
They include keratin found in hair and nails, and collagen found in connective tissue. Collagen
under a microscope look like long fibres that are woven together to create extra strength, it is a
fibrous protein. Collagen is made up of three polypeptide chains wound around each other.
Hydrogen bonds forms between the chains and this gives the structure strength.The collagen account
for around a quarter of all proteins in the body. The function of collagen is to give mechanical
strength. In the walls of arteries, a layer of collagen prevents blood that is being pumped from the
heart at high pressure from bursting the walls. Tendons connect skeletal muscles to the bones.
Tendons are mostly collagen and form a strong connection that allows muscles to pull bones for
movement. Collagen is also responsible for the elasticity of the skin, which is why the skin becomes
wrinkled when it lacks collagen . It also makes the skin waterproof. The functions of collagen in the
connective tissue include nutrient transport and inflammation. Hormones are also a type of proteins
and functions as chemical signaling molecules . These proteins are secreted by endocrine cells that
act to control or regulate specific physiological processes which include growth development,
metabolism, and reproduction. Insulin is a protein hormone secreted by the beta cells of the pancreas
and helps to regulate blood glucose levels. In response to insulin, muscle cells, red blood cells and
fat cells take glucose in from the blood which ultimately lowers high blood glucose levels back to
the normal

Myosin And Muscle Contraction Research Paper
These muscles requires actin filaments and myosin filaments interacting with each other in–order
for movement. [1] The myosin are aligned between the actin and muscle contraction is brought
through the sliding of the two filaments. The myosin head can tightly bind to the place on the actin
molecule but generally there are other proteins which prevent the binding called tropomyosin (form
a filament which semi curve around the myosin where the actin would possibly bind) and troponin
(variety of different proteins).[2] Naturally ATP has bounded to the myosin head and when this
happens the energy is slit into ADP and phosphate, however both would still remain attached to
myosin. The tropomyosin is coving the binding place for myosin to attach to ... Show more content
on Helpwriting.net ...
This happens very quickly before the pain is apparent.[1] There is no control over this occurrence
and also there is no negative or positive feedback control system. [1]The body is able to still be in a
upright position due to signals begin sent to the muscles in the opposite leg, where the leg stiffen to
take the extra weight. This happens when the range of excitatory impulse up and down the spinal
cord to stimulate more motor neurons called irradiation of stimulus and as a result recruitment. [2,3]
As This requires an increase drive to the extensor muscles as there is also a decrease drive to the
flexors muscles. [2] This is also known as the crossed extensor reflex. There are other movements
which adjust the body position to shift the centre of gravity and enable standing on leg, hence,
throwing the body in to an unbalanced state, i.e. hopping on one leg is a method that the body uses
when trying to remain balanced while the pained foot is

Skeletal Muscle Contraction And Relaxation Is Vital For
Skeletal muscle contraction and relaxation is vital for voluntary body movements to occur. Skeletal
muscles contract when myofibrils composed of actin and myosin slide past each other, which
contracts the muscle by altering its length. The gastrocnemius muscle in Rana pipiens, which is
attached to the sciatic nerve, can be stimulated to find threshold and maximal stimulus voltage.
Once threshold is reached, contraction amplitude increases with stimulus voltage until the maximal
voltage is reached, at which point it levels off. Altering the interstimulus interval can induce twitch
summation in the gastrocnemius, leading to one combined contraction with a high amplitude.
Increased stimulus frequency can be used to induce a tetanic ... Show more content on
Helpwriting.net ...
Twitches are the resulting contraction from the firing of an AP in muscles. Twitches are much longer
than the APs themselves. Twitch recruitment uses external stimuli to determine the threshold and
maximal voltages of nerves and muscles. Stimuli below the threshold voltage, or the minimum
stimulus strength required to elicit an action potential, will not cause a muscle to twitch. Once
threshold potential is determined, increased stimulus voltage will increase the contraction amplitude
of the twitch until the maximal stimulus is reached. The twitch will not significantly increase in
strength for any voltage above maximal. This is because at maximal stimulus voltage all motor units
have already been recruited to contract. The gastrocnemius muscle has a far higher threshold and
maximal voltage that the sciatic nerve due to its size and the number of motor units present in the
gastrocnemius. Along with increasing stimulus voltage, contraction amplitude can also be increased
through twitch summation. Twitch summation occurs when a muscle is stimulated twice in quick
succession, so that the second twitch occurs before the first twitch has relaxed. The twitches then
combine to form a stronger muscle contraction. This process is made possible by the temporal
relationship between a muscle's AP and the resulting twitch, which is far longer in duration than the
1 ms AP that causes it. Due to the nature of skeletal muscle contraction, the length–tension
relationship in

Genetic Analysis : The Nature Of The Smyd1b Gene
Use of Genetic analysis to study the nature of the Smyd1b gene in Cardiac and Skeletal
Muscular Systems of Zebra Fish
Prajwal Keranahalli
Poolesville High School
Institution: Institute of Marine and Environmental Technologies/ University of Maryland
Baltimore Campus
Mentor: Dr. Shaojun Du
Research Project Teachers: Mr. Mark Curran, Dr. Patricia Miller
Summer 2014
Abstract:
One of every 5600 to 7700 males below 30 suffer from genetic muscular dystrophy.
Muscular dystrophy is a group of genetic diseases, with no known cure, in which muscle fibers are
unusually susceptible to damage and weakening until the person dies. Our goal was to use genetic
analysis to study the role of the Smyd1b gene in the skeletal and cardiac muscular systems in the
model organism zebra fish. When this gene in knocked down, the organism 's muscles become
dysfunctional and it eventually dies. Four sets of fish from two genetic lines, with a GFP tagged
SMYD 1b promoter sequence transgene, were observed in whole mounts through a fluorescence
microscope during an eight day period. The gene was found around skeletal and cardiac muscles
thus supporting the idea that it is linked to muscle organization. The proposed Smyd1b physiology is
that it is a methyltransferase, which modifies in this case other sarcomeric proteins. We believe that
the Smyd1b TV1 strain is co–localized with the M–Line protein myomesin; the imaging software
ImageJ was used to systematically measure and compare distances between

Myosin Temperature Lab Report
All proteins have their own optimal temperature at which they function best at. But when
requirements such as these are not meet it can be detrimental to the protein. The protein can begin to
denature or degrade. Thus losing its ability to function. At times this reversible. Therefore they have
different solidification temperatures. Figure 1 shows the expected results
The myosin heads, troponin, tropomyosin are responsible for the muscle shortening on a
microscopic level. In this experiment for the frog the solidification temperatures for myosin is 40°C
.Tropomyosin is 47°and the highest is troponin at 56°C.Muscle shortening is also known as heat
rigor which is due to the coagulation of the muscle proteins. At 60°C the muscle could not contract
any futher. Therefore the ... Show more content on Helpwriting.net ...
Even though the muscle had shortened. This shows that the muscle proteins where denatured but
there but no activitiy was recorded. The muscle has thin and thick filaments. The thick filament
which was myosin, is an unstable molecule when in a solution (Pelletier and Ouellet, 1961).
Therefore as the expected results show in myosin would have been denatured first at round 40 °C.
This because when the myosin is heats up the first thing that is destroyed at the ATPase activity. The
heavy–meromyosin fragment of the myosin would be destroyed (Stossel and Hartwig,1975).Thus
meaning no enzymatic activity would not be able to take place and ATP will not be able attach and
hydrolyzed .This would have the myosin be left attached to the actin. The higher the temperature the
more the individual myosin heads produce a powerful power stroke thus increasing the contraction
(Woledge et al, 1985). Because the number of heads that are attached myosin heads does not change
with increasing temperature. The exertion per head is a part of the whole force with the sliding
distance covered while in contact with the actin ( Woledge et al,

Myoblast Fusion Research Paper
Abstract:
The formation of multinucleated muscle cells through cell–cell fusion is a conserved process from
fruit flies to humans. Numerous studies have shown the importance of Arp2/3, its regulators, and
branched actin for the formation of an actin structure, the F–actin focus, at the fusion site. This F–
actin focus forms the core of an invasive podosome–like structure that is required for myoblast
fusion. In this study, we find that the formin Diaphanous (Dia), which nucleates and facilitates the
elongation of actin filaments, is essential for Drosophila myoblast fusion. Following cell recognition
and adhesion, Dia is enriched at the myoblast fusion site, concomitant with, and having the same
dynamics as, the F–actin focus. Using different ... Show more content on Helpwriting.net ...
While Arp2/3 can nucleate F–actin filaments de novo, it does this slowly [32]. The presence of pre–
existing filaments accelerates Arp2/3's ability to form branched F–actin [33]. Formins, another
group of actin regulators, complement the activity of Arp2/3 by generating linear actin filaments.
Studies have revealed both collaborative and antagonistic relationships between members of the
WAVE regulatory complex, Arp2/3, and formins. As examples, Abi, a member of the WAVE
complex, has been shown to interact with the formin mDia1 to positively regulate cell–cell adhesion
in tissue culture cells [34]. In contrast, mDia2, WAVE, and Arp2/3 have been shown to form a
multimeric complex, which inhibits mDia2–dependent filopodium formation in cultured cells [35].
Arp 2/3 and formins often act together in different in vivo contexts, including pseudocleavage
furrow formation, cytokinesis, and filopodia formation in Drosophila primary neurons [36,37].
Particularly relevant for our studies in myoblast fusion are the findings that, in cancer cells and
macrophages, Arp2/3 and formins are required for the formation of podosomes, which resemble the
invasive structure at the myoblast fusion site [21,38,39]. How Arp2/3 and formins interact to
regulate actin dynamics in different in vivo contexts, particularly myoblast fusion, remains to be

A Experiment On Actin And Myosin
Abstract
Research was conducted on Actin and Myosin protein; chains of amino acid residue responsible for
muscle contraction in muscle cells. Through phosphorylation, which causes changes in enzyme
activity as result of an alteration in protein conformation, the Myosin Light Chain ½ stimulates and
subsequently contracts the smooth muscle. Concentrations of the protein were determined and
analyzed among Catfish, Atlantic Salmon, Sockeye Salmon, Shrimp, Red Tuna, Red Snapper,
Tilapia, and Wild Cod. Electrophoresis provided a method of visualization of the samples, where
Immunodection was then used to identify Actin/Myosin Light Chain ½ proteins. Wild Cod
expressed the most Myosin LC ½ protein, whereas Shrimp expressed the least. Furthermore, both
Wild Cod and Shrimp differed considerably in comparison to the determined volume intensity of the
other seafood samples, which were closer in expression levels with one another. Animal behavior
and habitat are factors that have overtime resulted in the overall amount and subsequent use of
muscle. Thus analyzing the variance in Actin/Myosin ½ light chain protein expression serves as a
tool in understanding adaptation and evolution among species.
Introduction Actin and Myosin proteins serve the primary role of producing muscle contraction.
Myosin molecules will create pressure in the skeletal muscle, where ATP hydrolysis causes Myosin
to bind to Actin. A conformational change of the molecule then result in Myosin being

Myosin Light Chain
All organisms, from humans to simple bacteria, have a necessity to move in order to adapt to
changes in their external or internal environment, navigate towards food, and avoid dangers. Even
cells are teeming with motion as they reorganize organelles, nucleic acids, and proteins. At the
molecular level, two types of elements assist in the control movements of the cell and the organism
as a whole: molecular–motor proteins and intricate complexes of protein filaments that make up the
cytoskeleton of the cell (Vale and Milligan, 2000). Myosin is a family of motor protein that act as
enzymes in the hydrolysis of adenosine triphosphate (ATP) to form adenosine diphosphate (ADP)
and inorganic phosphate (Pi), The energy released by this reaction to drive the movement of
molecules and contraction of muscle fibers (Grigorenko et al., 2007). A remarkable part of evolution
is that the same mechanisms that control of contraction of muscles by myosin, are also used to
propel ... Show more content on Helpwriting.net ...
In the N–terminal region, the heavy chain forms a motor domain that is globular in structure. The
motor domain has an α–helix that extends from the C–terminus, which becomes part of the light
chain binding domain. At this binding domain, the essential and regulatory light chains wrap around
the α–helix to thicken and support its structure. The motor domains can be divided into three
domains: the actin–binding site, the nucleotide binding site (P–loop NTPase domain core as an ATP
catalytic site), and the converter domain. A converter domain is present at the junction between the
ATP catalytic site of the motor domain and the light chain binding domain. The converter domain
and the light chain binding domain compose the "lever arm", which has a significant role in
producing the mechanical force needed to generate movement during muscle

The Structure And Function Of Myocytes. Ian Pittwood....
The Structure and Function of Myocytes
Ian Pittwood
Missouri University of Science and Technology Introduction Even some of the most basic of
organisms can move. In multicellular organisms, there can exist cells that alter their size and shape
to promote this movement. These cells are then grouped into muscle tissue that can work together to
create motion in the organism. One of these cells, the myocyte from skeletal muscle, will be covered
in this paper. I chose this cell as I am an avid weightlifter and would like to investigate more into
how muscle cells are structured and how they function. I believe that this knowledge could make me
more effective in the gym.
Structure
Myocytes when first discovered had such an unusual structure ... Show more content on
Helpwriting.net ...
The membrane for myocytes is stretched into a longer form with fibers at the end that combines
with surrounding muscle cells. The sarcolemma also has pores on its surface that extend into T–
tubules that wrap muscle fibers and can transfer an action potential from motor neurons to the fibers.
(Saladin, 2012) Unlike many other cells, muscle cells only appear strung together in fibers. The
nucleus or nuclei of a fiber is pushed up against the edge of the membrane to make room for
myofibrils within the cell. Myofibrils within the cell are part of the cytoskeleton and contain
filaments of actin and myosin that work to move the muscle. These myofibrils have repeating
patterns that appear as bands on muscle fibers. Each of these repeating sections is known as a
sarcomere. These fibers cause the overall shape of the myocyte to be long and tubular. (Liner, 2017)
Figure 1 and 2 above display a confocal image of muscle fibers with a motor neuron and a diagram
of a muscle fiber. On Figure 1 the green neurons can easily be can the yellow/orange nuclei for the
muscle cell. Figure 1 displays how randomly placed the nuclear as well as the sheer size of the
muscle fibers. It also displays how neurons are linked into the T–tubules of the cell. Unfortunately
figure 1 does not yield much information about the detailed internal structure of the myocyte. The
diagram in Figure 2 creates a much more detailed figure that shows not only the nuclei bordering

For My Final Clone Report, I Choose To Write About...
For my Final Clone Report, I choose to write about T6DL4.17. Below is the sequence of my clone:
... Show more content on Helpwriting.net ...
Comparing the BLASTx and BLASTp search results, allowed me to determine if I chose the correct
ORF in the Toolbox which I believe I did as the proteins found in the BLASTp search were the same
as the proteins found in the BLASTx search. The E–values for the same protein found by both the
BLASTx and BLASTp searches were also the same but only the start and stop positions of the
BLASTx and BLASTp alignments were different for the same protein. Overall, I determined the 5'
UTR to be G1–A28 and the ORF to be A29–G1051. What is your gene similar to? What is the ORF
sequence name of the C. elegans homolog (i.e. ZC101.2)? If there is a gene name (i.e. unc–52), what
is it? The name of the homolog of my gene in C. elegans is act–3 and its gene id is 179533. It is
similar to ACT–1, ACT–2, and ACT–4. Its locus is T04C12.4 and it is also known as ACTin family
member (act–3). What does the protein encoded by your gene do? What does it interact with? What
biochemical pathway is it in? What biological function does

Muscle Contraction Lab
This lab was conducted to test the muscle reaction to three different solutions and observe the
muscle contraction in the presence of each solution. We predicted that ATP solution in distilled
water might cause muscle contraction since ATP alone binds to myosin to break the cross–bridge
and enable the myosin to rebind to actin at the next muscle contraction. ("ATP and Muscle
Contraction." Boundless Biology) All three groups were given a 2cm length of psoas muscle, which
was placed on a microscope slide with a small drop of glycerol. First, we measured each fiber, and
then added 2 drops of one of the solutions, Solution A; .25% & ATP in distilled water, Solution B;
.25% ATP solution in water, .05M KCI, .001 M MgC12 in distilled water, and Solution C; .05 M
KC1, .001 M MgC12 in distilled water. We waited 30 seconds after adding the solution and we
measured the fiber again to see if there was any muscle concentration after adding the solution. Our
hypothesis was not supported, because the fiber size did not change.
Purpose:
The purpose of this lab was to learn if any of the three solutions used for the experiment would
cause the fiber to have a muscle contraction and if there wasn't any muscle contraction, understand
why the solution didn't cause a muscle contraction.
Introduction:
Muscle contractions are a reduction in size of muscle ... Show more content on Helpwriting.net ...
(Table 1) ATP alone causes myosin to break the cross–bridge and allow the myosin to reattach to the
actin causing a muscle contraction, since the solution we used had ATP; I believed that that was
enough to cause the fiber contraction. I thought that we had done our experiment in correctly
because there was no muscle contraction. I believed that it was due to the amount of solution we
added to the fiber. We re did the experiment and added four drops of the solution but there was no
muscle contraction as

Muscle Moment Lab Report
The purpose of the experiment in lab 5 was to see how force and EMG of the muscles would be
affected when the wrist angles were changed. In order to determine how much the myosin and actin
were interacting and how many times the muscle cell was stimulated we had to measure the force.
When the wrist was fully flexed at 90–degrees the muscle was more contracted. Therefore, causing
the sarcomere to be pushed closer together and the zone of overlap to be larger. This causes the
myosin and actin to be on top of each other making it more difficult to have a quality cross bridge
formation. This makes it harder to stimulate the muscle. As we continued to squeeze at different
angles the force would get greater as the angle became more flat. We had the

The Membrane And Its Effects On Human Development
It is generally accepted that resting CaMKIIβ bundles and stabilizes actin cytoskeleton. Transient
activation of CaMKIIβ relaxes cytoskeleton, promotes actin polymerization and CaMKIIβ
recruitment, and favors cytoskeleton growth. This model has been shown in both synaptogenesis
(Okamoto et al., 2007) and OL maturation (Waggener et al., 2013). Based on this theory, we
proposed that prolonged CaMKIIβ activation by NMDA–R–mediated Ca2+ influx leads to
destabilization of actin cytoskeleton and membrane disintegration in mature OLs. Although our
experiments unambiguously showed that NMDA–R activation results in CaMKIIβ activation, direct
proof that links CaMKIIβ activation and membrane reduction are lacking. All the existing CaMKIIβ
inhibitors ... Show more content on Helpwriting.net ...
As mentioned in chapter 5, a repeated measure experiment using OLs from CaMKIIβA303R mice
will be the best way to investigate this question. The CaMKIIβA303R mutant retains its ability to
bundle F–actin, but loses its Ca2+/CaM binding capacity. Based on our proposed model, Tat–
induced [Ca2+]i increase should have no effect on OL membrane area since Ca2+/CaM can not bind
and activate CaMKIIβA303R, and promotes its release from actin cytoskeleton.
Most of our experiments are done in mice cells. Since HIV is a human disease, we used an hBrnAgg
model to try to verify our finding in human cells. We thought that the hBrnAgg model serves our
experiments best because 1) it mimics the in vivo environment with the presence of all major CNS
cell types, 2) myelination has been observed in the model by other investigators, thus fulfill the
needs of studying effect of HIV/Tat on both OLs and myelin, and 3) the hBrnAgg model can be
maintained for a long period of time (up to 60 days), made it a good model to study long–term effect
of HIV/Tat.
Our immunostaining experiments suggested that there are far less OLs in the aggregates than we
expected. Under EM, plenty of synaptic structures, both symmetric and asymmetric, were observed
in the hBrnAgg. However, cells with typical mature OL characteristics, including dark cytoplasm
and nucleus, elongated, thin strands of endoplasmic reticulum; numerous mitochondria, and stacks
of Golgi apparatus, were rarely

Similarities and Differences between Seletal, Cardiac, and...
SIMILARITIES AND DIFFERENCES BETWEEN SELETAL, CARDIAC, AND SMOOTH
MUSCLE:
Skeletal Muscle Structure: skeletal muscles cells are like long fiber structures, That contain many
nuclei and are subdivided into smaller structures that are called "myofibrils". The "Myofibrils" are
created of two kinds of "myofilaments". Thin filaments are made of two strands of the protein–actin
and one strand of a regulatory protein coiled with each other. Thick filaments are staggered arrays of
"myosin molecules". * Organization Units of skeletal muscle. Filaments are organized into
structures called the "sarcomeres". "Sarcomeres" are created in the following manners: * The Z lines
are at the border of the "sarcomere". They align in adjacent "myofibrils". *The I bands are areas that
are near the edges of the "sarcomere" containing only thin filament. * The A bands are regions
where thick and thin filaments overlap each other and correspond to the length of the thick
filament.* The H zones are the areas in the center of the A bands containing only thick filament. In
vertebrates Cardiac Muscles: are only found in the heart. Muscles cells are branched, and the
junctions between the cells contain intercalated discs that electrically connect all heart muscle cells
with each other, allowing the co–ordinated actions. These cells can also create their own action
potentials. In Smooth Muscles: There are no striations and contain less myosin; the myosin is not
associated with specific actin strand.

Skeletal Muscle Research Paper
Every system of the human body is important, but the systems are all accounted for different
functions. The movement of the body is one of the main responsibilities a muscular system has.
However, without the basic unit of muscle structure called sarcomere, the muscles would not be able
to contract or become relaxed. Sarcomeres are structural components of myofibril that are in striated
muscle tissues, which consist of three called the skeletal muscle, cardiac muscle, and the smooth
muscle. Sacromeres are what is found in the interaction between myosin and actin filaments.
Furthermore, without the formation of the muscular tissue called myogenesis then there would be no
muscles or contractions of the body system. These next few paragraphs ... Show more content on
Helpwriting.net ...
However, there are slight changes in the process of contractions. Calcium is an important factor in
muscle contractions. The nerve impulse spreads from the cell membrane right into the transverse
tubule. The difference in the process is the calcium that will enter the cell from the extracellular
fluid. This step does not apply to the skeletal muscle. Two important factors that help contract and
relax the muscles are the troponin and tropomyosin, which binds with calcium. The importance of
these two muscle regulatory proteins is the relaxation and contractions they send to the human body.
As calcium and troponin combines with one another, it allows the tropomyosin to move way from
the myosin and actin bind, which will form a crossway bridge between the actin and myosin,
causing a contraction. The higher the calcium is, the more the tropomyosin moves out the way and
the calcium then binds with troponin. Without calcium, the tropomyosin is blocking the myosin in
attaching itself to the actin and causes the muscle to relax. Without cardiac muscle tissue
contractions, the heart wouldn't push blood through the blood

Muscle Contraction Research Paper
Most accepted model of muscle contraction
The explanation for how muscles contract to produce force
Structures that are involved: Myofibril, Sarcomere, Actin, Myosin, Tropomyosin, and Troponin
Myofibril: cylindrical organelle running the length of the muscle fiber, containing Actin and Myosin
filaments
Sarcomere: functional unit of the Myofibril, divided to I, A and H bands
Actin: thin contractile protein filament, containing active or binding sites
Myosin: thick contractile protein filament,
Tropomyosin: actin–binding protein which regulates muscle contraction
Troponin: complex of three proteins, attached to tropomyosin
Myosin head attaches to Actin Myofilament:
Formation of a new cross bridge leads to the release of Pi
The Myosin head enters it's high–energy configuration and binds to the Actin Myofilament. ... Show
Before this the ADP and Pi are still bound to the Myosin head
After binding to the Actin Filament the Pi detaches from the Myosin head
Pi release triggers the "Power Stroke"
Change in Myosin head moves the Actin and Myosin filaments relative to each other
"Power Stroke" = "Working Stroke"
The Myosin undergoes another conformational change c
Myosin head pivots and moves the thin filament closer to the M line (center structure of the H zone)
proteins as the thick filament slides past
The Z lines/Z disc ('z' like formation) of the sarcomere move closer together, the entire contractile
unit shortens
ATP binds to the Myosin
The cross bridge between the two fibers breaks as the Myosin head dissociates from the Actin
Myofilament
Myosin heads act as a molecular motor, attaches to Actin molecules to create a cross bridge between
the Sarcomere
Then ATP binds to the Myosin head, separating it from the Actin

Explain The Three Phases Of Actin Polymerisation

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