This presentation gives an overview of Lipid Rafts, how it was discovered, its importance and the future research in this area,Feel free to comment and ask any questions
The structure of the cell membrane, the phospholipid layer distinguished to the break down of protein and the lipid layer. Their structural components and the molecular basis of it.
This presentation gives an overview of Lipid Rafts, how it was discovered, its importance and the future research in this area,Feel free to comment and ask any questions
The structure of the cell membrane, the phospholipid layer distinguished to the break down of protein and the lipid layer. Their structural components and the molecular basis of it.
This presentation contains the introduction to the structure of plasma membrane. This gives an insight into the biochemistry of the plasma membrane and the singer and nicholsan model.
Describes the plasma membrane in detail, explains the each major component with its functions.
Transport mechanism across the cell is covered with detailed explanation with examples.
by Dr. N.Sivaranjani, MD
Basic Cell cycle regulation suitable for undergraduate students.
This presentation has been started from the basics to enable easy understanding. It covers all the details of cell cycle regulation in yeast as well as higher eukaryotes.
. Introduction
2. Cell / Plasma membrane
3. Transport across membrane
Passive transport
a.Osmosis
b. Simple diffusion
c. Facilitated diffusion
Active transport
a. Primary active transport
b. Secondary active transport
Example-
1. Na+/K+ ATPase
2. Ca+ ATPase
3. Proton pump
4. Transport of large molecule by plasma membrane
Endocytosis
Exocytosis
5. Transport of nutrients by membraneprotiens
Channel protein
Carrier proteins
6. Role of membrane Transport
7. Conclusion
8. Reference
The cell membrane (also known as the plasma membrane or cytoplasmic membrane) is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells.The basic function of the cell membrane is to protect the cell from its surroundings. It consists of the phospholipid bilayer with embedded proteins. Cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall, glycocalyx, and intracellular cytoskeleton.
This presentation contains the introduction to the structure of plasma membrane. This gives an insight into the biochemistry of the plasma membrane and the singer and nicholsan model.
Describes the plasma membrane in detail, explains the each major component with its functions.
Transport mechanism across the cell is covered with detailed explanation with examples.
by Dr. N.Sivaranjani, MD
Basic Cell cycle regulation suitable for undergraduate students.
This presentation has been started from the basics to enable easy understanding. It covers all the details of cell cycle regulation in yeast as well as higher eukaryotes.
. Introduction
2. Cell / Plasma membrane
3. Transport across membrane
Passive transport
a.Osmosis
b. Simple diffusion
c. Facilitated diffusion
Active transport
a. Primary active transport
b. Secondary active transport
Example-
1. Na+/K+ ATPase
2. Ca+ ATPase
3. Proton pump
4. Transport of large molecule by plasma membrane
Endocytosis
Exocytosis
5. Transport of nutrients by membraneprotiens
Channel protein
Carrier proteins
6. Role of membrane Transport
7. Conclusion
8. Reference
The cell membrane (also known as the plasma membrane or cytoplasmic membrane) is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells.The basic function of the cell membrane is to protect the cell from its surroundings. It consists of the phospholipid bilayer with embedded proteins. Cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity and cell signalling and serve as the attachment surface for several extracellular structures, including the cell wall, glycocalyx, and intracellular cytoskeleton.
Transport across cell membrane, CELL MEMBRANERajshri Ghogare
Transport across cell membrane, Active transport, Active transport,
Types of passive transport-Diffusion, Filtration, Osmosis, Facilitated diffusion , Types of active transport antiport and symport
Cell Membrane Transport/Factors/Transport of SubstancesPharmacy Universe
The gradient consists of two parts, the electrical potential and a difference in the chemical concentration across a membrane.
In biological processes, the direction an ion moves by diffusion or active transport across a membrane is determined by the electrochemical gradient.
Generally compound moves from an area of high concentration to low concentration (or concentration gradient). All compounds permeable to the phospholipid bilayer will move this way.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
2. Introduction
2
• All communication between cell and extracellular
medium is mediated through cell membrane.
• In this sense PM has dual functions:
• A. It must retain dissolved material inside the cell
• B. It must allow necessary exchange of material in and
out of the cell.
• Through cell membrane substances may diffuse
• Cell permeability determine which substances can
enter the cell, many of which may be necessary to
maintain its vital processes and the synthesis of living
substances.
3. It is a double layer of phospholipids –
lipid bilayer.
It is an elastic (7.5-10 nm)
It contains almost proteins called
membrane proteins
4.
5. 1.Structure of cell membrane
Lipid Bilayer -2 layers of
phospholipids (Gorter &
Grendel (1925)
a.Phosphate head is polar
(water loving)
b.Fatty acid tails non-polar
(water fearing)
c.Proteins embedded in
membrane
Phospholipid
Lipid Bilayer
6. • 1. Cell membranes have pores (holes) in it
a.Selectively permeable: Allows some molecules
in and keeps other molecules out
b.The structure helps it be selective!
Pores
7. • Ions, hydrophilic molecules larger than water, and large
molecules such as proteins do not move through the membrane on
their own.
• Membrane is impermeable to large & polar-molecules (ions,
proteins & polysaccharides)
• Membrane is permeable to Nonpolar & hydrophobic molecules like
lipid and small molecules (O2, CO2, N2, NO etc)
• Thus, permeability depends on solubility, charge or solute size.
Semipermeable nature of Membrane
9. Transport – What it means?
Its highly selective filter, permits nutrients
and
leaves the waste products from the cell.
Maintain Homeostasis.
Play an important role in cell to cell
communication.
Its detects Chemical messengers arriving at
the cell surface.
14. • Distance -
– The shorter the distance, the more quickly concentration
gradients are eliminated
• Molecular Size
– Ions and small molecules diffuse more rapidly
• Temperature -
– temp., motion of particles
• Steepness of concentrated gradient -
– The larger the concentration gradient, the faster diffusion
proceeds
• Membrane surface area -
– The larger the area, the faster diffusion proceed
16. Permeable membrane: Membrane, which allows passage
of both solute and solvent molecules indiscriminately.
Semipermeable membrane: allows passage of solvent
molecules but not solute molecules.
Differentially permeable membrane: Allows passage of
some solute molecules along with solvent molecules.
Osmotic pressure (OP):is a pressure equivalent to
prevent the passage of solvent (like water) molecule
from a low concentration to high concentration zone
through SPM, thereby preventing increase in the volume
of that solution.
17.
18. OSMOSIS
Osmosis is the process of moving water across a
semi permeable membrane towards ion or solute
rich region in a solution
19. • Tonicity - ability of a solution to affect fluid volume and
pressure within a cell
– depends on concentration and permeability of solute
• Isotonic solution
– solution with the same solute concentration as that of the cytosol;
normal saline
• Hypotonic solution
– lower concentration of nonpermeating solutes than that of the cytosol
(high water concentration)
– cells absorb water, swell and may burst (lyse)
• Hypertonic solution
– has higher concentration of nonpermeating solutes than that of the
cytosol (low water concentration)
– cells lose water + shrivel (crenate)
20. • Important because large volume changes caused by
water movement disrupt normal cell function
• Cell shrinkage or swelling
– Isotonic: cell neither shrinks nor swells
– Hypertonic: cell shrinks
– Hypotonic: cell swells
22. Cell does use energy :-
Protein Pumps
Endocytosis
Exocytosis
high
low
This is gonna
be hard
work!!
23. What is active transport?
Active transport is the
transport of substances
from a region of lower
concentration to higher
concentration using energy,
usually in the form of ATP.
Examples: Na, K and Ca
active transport.
24. Active Transport
needed for,
1. Maintaining the
Chemical and
Electrical Charge at
rest.
2. Intake of Substances
through gated
Channels.
3. Collecting of ions with
more concentration.
25. ACTIVE TRANSPORT - WHY ?
Cells cannot rely solely on
passive movement of
substances across their
membranes.
In many instances, it is
necessary to move
substances against their
electrical or chemical
gradient to maintain the
appropriate
concentrations inside of
the cell or organelle.
26. VESICULAR TRANSPORT
It is the transport of membrane bounded
substances moving across plasma membrane
It is classified into:
1. Endocytosis 2. Exocytosis.
27. It is a process by which the large number
of particles are taken with forming the
vesicle into the cell.
The cell membrane invaginates the
material from ECF.
It is pinched off from the membrane and
takes the material into ICF
28. Exocytosis
Exocytosis is a process in which an intracellular
vesicle (membrane bounded sphere) moves to
the plasma membrane and fused the substance
into the Extra cellular fluids
For example a few of the processes that use Exocytosis are:
1. Secretion of proteins like enzymes
and antibodies from cells.
2. Release of neurotransmitter from
presynaptic neurons
3. Acrosome reaction during fertilization
29. 29
Facilitated Diffusion
Permeases may be passive (facilitated diffusion) or an active
transport one
Along concentration gradient.
When the permeases operate against gradient called active
transport
copyright cmassengale
30. 30
Facilitated Diffusion Mechanism
1.Some Carrier
proteins do not
extend through the
membrane.
• They bond and
drag molecules
through the lipid
bilayer and
release them on
the opposite side.
2 hypothesis: 1. Carrier mechanism and 2. Fixed pore mechanism
31. 2. Fixed pore mechanism:
In this mechanism the carrier is represented by integral proteins that
transverse the membrane and which, once bound to the molecule to be
transported, undergo conformational changes. Example is penetration of
anions into RBC.
• Other carrier
proteins
change shape
to move
materials
across the cell
membrane
32. 32
• Fixed pore mechanism seems more
acceptable because it requires less
energy.
• Conformational change in fixed pore
mechanism is thermodynamically
feasible.
• Carrier mechanism is less acceptable
because:
• It requires more energy.
• Rotation is thermodynamically difficult.
33. Primary active transport
Primary active transport is
the transport of sustances
uphill using energy (ATP
hydrolysis)
It cause a conformational
change that results in the
transport of the molecule
through the protein.
Eg. Na+-K+ pump.
34. 1. It is responsible
for maintaining the
high K+ and low
Na+ concentration
inside the cell.
2. It maintains
intracellular
negativity.
35. It moves multiple molecules across the
membrane, powering the uphill
movement of one of molecules with
downhill movement of other molecules.
THE TRANSPORT MAY BE
In the same direction (SYMPORT)
Ex. SGLT2 glucose transporter.
In the opposite direction (ANTIPORT)
Ex. Na+/Ca2+ in cardiomyocyte. (heart
cell)
36.
37. • Cell biology- Karp, sixth edition
• Life sciences- Pathfinder
• ^Campbell, Neil A.: Brad Williamson; Robin J.
Heyden (2006). Biology exploring life.ps:
• https://www.khanacademy.org