The cell cycle is the series of events that cause a cell to duplicate its DNA and divide into two daughter cells. It consists of interphase, where the cell grows and duplicates its DNA, and the mitotic phase where the cell divides. Interphase includes G1, S, and G2 phases focused on growth, DNA replication, and preparation for division. The mitotic phase includes mitosis and cytokinesis to split the cell contents and form two new cells. Checkpoints ensure proper DNA replication and chromosome separation before progression.
A cell cycle is a series of events that takes place in a cell as it grows and divides. The process has to be correct and regulated. This slide illustrated Cell cycle and its regulation. Check the slides to know more.
This slideshow contains various stages of cell cycle regulation, cell cycle checkpoints and their proteins involved in regulation. Cell cycle checkpoints transition phases.
A cell cycle is a series of events that takes place in a cell as it grows and divides. The process has to be correct and regulated. This slide illustrated Cell cycle and its regulation. Check the slides to know more.
This slideshow contains various stages of cell cycle regulation, cell cycle checkpoints and their proteins involved in regulation. Cell cycle checkpoints transition phases.
Cell Communication, Cell Junction and Cell Signaling.pptxSheetal Patil
-Cellular Communication
-There are three stages of cell: communication
a.Reception
b.Transduction
c. Response
-Receptors And Ligands
There are two basic types of receptors:
a.Internal receptors
b.Cell surface receptors
-Internal receptors-often steroid hormones
-There are several different types of ligands
a.Hydrophobic ligands
b. Water soluble hydrophilic ligands
-Three stages of cell communication
-How insulin works
Cell Junction
-There are three types of cell junctions:
1.Adhesive (Anchoring) junctions
2.Tight Junctions
3.Gap Junactions
-The two main kinds of adhesive cell-cell junctions are:
a.Adherens junctions
b.Desmosomes
a. Adherens junctions:
Adherens junction is the cell to cell junction, which connects the actin filaments. In adherens junction, the membranes of the adjacent cells are held together by some transmembrane proteins called cadherins.
b. Desmosome
Desmosome is a cell to cell junction, where the intermediate filaments connect two adjacent cells. Desmosome is also called macula adherens. Desmosomes function like tight junctions. The trans-membrane proteins involved in desmosome are mainly cadherins.
2. Tight Junctions
The cell membranes are connected by strands of trans-membrane proteins such as claudins and occludins.
Tight junctions bind cells together, prevent molecules from passing in between the cells, and also help to maintain the polarity of cells.
-Functions of Tight Junctions:
Another function of tight junctions is simply to hold cells together.
3. Gap Junction
Gap junctions are a type of cell junction in which adjacent cells are connected through protein channels. Gap junctions are made up of connexin proteins. Groups of six connexins form a connexon, and two connexons are put together to form a channel that molecules can pass through. Other channels in gap junctions are made up of pannexin proteins.
-Functions of Gap Junction
The main function of gap junctions is to connect cells together so that molecules may pass from one cell to other.
This allows for cell-to-cell communication.
-Cell Signaling
Cell signaling is the process of cellular communication within the body. The binding of extracellular signaling molecules to their receptors
-Modes of cell-cell signaling
1.Direct cell-cell signaling
2. Signaling by secreted molecule
a.Endocrine signaling:
-E. g. hormones produced by endocrine glands including pituitary, pancreas, adrenal, parathyroid glands etc.
b.Paracrine signaling:
-E.g. action of neurotransmitters in carrying signals between nerve cells at a synapse.
c.Autocrine signaling:
-When interleukin-1 is produced in response to external stimuli, it can bind to cell-surface receptors on the same cell that produced it.
d.Synaptic signaling:
-Types of signaling molecules
a.Nitric oxide
b.Carbon monoxide
c.Neurotransmitter
d.Peptide hormone
-Intracellular signaling pathway activated by an extracellular signal molecule
This slide describes the various stages of the Eukaryotic cell cycle. The diagrams included here explains the various changes that take place during the mitotic division of a eukaryotic cell.
A detailed description of molecular level of cell cycle. Its regulation by different checkpoints. The Structure and Function of MPF. Description of MPF discovery.
Cytoskeleton - microtubules ,microfilaments and intermediate filamentsBIOTECH SIMPLIFIED
The cytoskeleton is a structure that helps cells maintain their shape and internal organization, and it also provides mechanical support that enables cells to carry out essential functions like division and movement. There is no single cytoskeletal component. Rather, several different components work together to form the cytoskeleton.
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.
Cell Communication, Cell Junction and Cell Signaling.pptxSheetal Patil
-Cellular Communication
-There are three stages of cell: communication
a.Reception
b.Transduction
c. Response
-Receptors And Ligands
There are two basic types of receptors:
a.Internal receptors
b.Cell surface receptors
-Internal receptors-often steroid hormones
-There are several different types of ligands
a.Hydrophobic ligands
b. Water soluble hydrophilic ligands
-Three stages of cell communication
-How insulin works
Cell Junction
-There are three types of cell junctions:
1.Adhesive (Anchoring) junctions
2.Tight Junctions
3.Gap Junactions
-The two main kinds of adhesive cell-cell junctions are:
a.Adherens junctions
b.Desmosomes
a. Adherens junctions:
Adherens junction is the cell to cell junction, which connects the actin filaments. In adherens junction, the membranes of the adjacent cells are held together by some transmembrane proteins called cadherins.
b. Desmosome
Desmosome is a cell to cell junction, where the intermediate filaments connect two adjacent cells. Desmosome is also called macula adherens. Desmosomes function like tight junctions. The trans-membrane proteins involved in desmosome are mainly cadherins.
2. Tight Junctions
The cell membranes are connected by strands of trans-membrane proteins such as claudins and occludins.
Tight junctions bind cells together, prevent molecules from passing in between the cells, and also help to maintain the polarity of cells.
-Functions of Tight Junctions:
Another function of tight junctions is simply to hold cells together.
3. Gap Junction
Gap junctions are a type of cell junction in which adjacent cells are connected through protein channels. Gap junctions are made up of connexin proteins. Groups of six connexins form a connexon, and two connexons are put together to form a channel that molecules can pass through. Other channels in gap junctions are made up of pannexin proteins.
-Functions of Gap Junction
The main function of gap junctions is to connect cells together so that molecules may pass from one cell to other.
This allows for cell-to-cell communication.
-Cell Signaling
Cell signaling is the process of cellular communication within the body. The binding of extracellular signaling molecules to their receptors
-Modes of cell-cell signaling
1.Direct cell-cell signaling
2. Signaling by secreted molecule
a.Endocrine signaling:
-E. g. hormones produced by endocrine glands including pituitary, pancreas, adrenal, parathyroid glands etc.
b.Paracrine signaling:
-E.g. action of neurotransmitters in carrying signals between nerve cells at a synapse.
c.Autocrine signaling:
-When interleukin-1 is produced in response to external stimuli, it can bind to cell-surface receptors on the same cell that produced it.
d.Synaptic signaling:
-Types of signaling molecules
a.Nitric oxide
b.Carbon monoxide
c.Neurotransmitter
d.Peptide hormone
-Intracellular signaling pathway activated by an extracellular signal molecule
This slide describes the various stages of the Eukaryotic cell cycle. The diagrams included here explains the various changes that take place during the mitotic division of a eukaryotic cell.
A detailed description of molecular level of cell cycle. Its regulation by different checkpoints. The Structure and Function of MPF. Description of MPF discovery.
Cytoskeleton - microtubules ,microfilaments and intermediate filamentsBIOTECH SIMPLIFIED
The cytoskeleton is a structure that helps cells maintain their shape and internal organization, and it also provides mechanical support that enables cells to carry out essential functions like division and movement. There is no single cytoskeletal component. Rather, several different components work together to form the cytoskeleton.
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.
Molecular event during Cell cycle By KK Sahu SirKAUSHAL SAHU
WHAT IS CELL?
WHAT IS CELL DIVISION OR CELL CYCLE?
WHY DO CELL DIVIDE?
HISTORY
CELL CYCLE
INTERPHASE
M-PHASE
MOLECULAR EVENT DURING CELL CYCLE AND CELL REGULATION
TYPES OF CELL DIVISION
IMPORTANCE OF CELL DIVISION
ABNORMALTIES OF CELL CYCLE
REFRENCES
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm and other components into two daughter cells in a process called cell division.
here u will find every detail of cell cycle.
for more details ,visit @biOlOgy BINGE-insight learning
WHAT IS CELL?
WHAT IS CELL DIVISION OR CELL CYCLE?
WHY DO CELL DIVIDE?
HISTORY
CELL CYCLE
INTERPHASE
M-PHASE
MOLECULAR EVENT DURING CELL CYCLE AND CELL REGULATION
TYPES OF CELL DIVISION
IMPORTANCE OF CELL DIVISION
ABNORMALTIES OF CELL CYCLE
REFRENCES
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
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 .
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
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.
5. What is Cell
Cycle?
The cell cycle, or cell-
division cycle, is the series
of events that take place in
a cell leading to its division
and duplication of its DNA
(DNA replication) to
produce two
daughter cells. ... To ensure
the proper division of
the cell, there are control
mechanisms known as cell
cycle checkpoints
6. PHASES OF CELL
CYCLE
In eukaryotes, the cell
cycle consists of a long
preparatory period,
called interphase.
. Interphase is divided into
G1, S, and G2 phases.
The mitotic phasebegins
with karyokinesis (mitosis),
which consists of 4 stages:
prophase, metaphase,
anaphase, and telophase.
7. G-1 Phase
• In G-1 phase the cell
increase in size due to
rapid growth
• Cells also synthesize new
protiens and organells.
• Approximately continue
for 11 hours
8. S-Phase
• S phase (synthesis phase) is
the part of the cell cycle in
which DNA is replicated,
occurring between
G1 phase and G2 phase.
• When replication done
properly then it pass to the
G-2 phase
• S phase will continue for 8
hours
G-2 Phase
• In G2 phase they prepare
some more protien which help
to guide the cell to the next
stage of the cell cycle
• Also make some RNA which
are important to make
protiens
• G2 phase for nearly 4 hours
• These are the 3 stages for
synthesis of DNA,RNA and
protien known as interphase
9. M phase
• During the mitotic (M) phase, the celldivides
its copied DNA and cytoplasm to make two
new cells. M phase involves two
distinct division-related processes: mitosis
and cytokinesis.
10.
11. Go Phase
• The
G0 phase, G zero phase, or
'resting phase' is a period in
the cell cycle in
which cells exist in a
quiescent state.
• G0 phase is viewed as
either an extended
G1phase, where the cell is
neither dividing nor
preparing to divide, or a
distinct quiescent stage that
occurs outside of the cell
cycle.
12. CELL CYCLE CHECKPOINTS
• 3 major checkpoints
• G1/S
• They check cytoplasm to nucleus
ratio
• G2/M
• Replication occur properly or not
• Spindle checkpoint
• Proper allingment of chromosome
and microtubule assembely
13. Cell cycle Signals
Cell cycle controls
> Cyclins
regulatory protien
> Cdk’s
phosphorylated cellular protiens
activates or inactivates protien
> Cdk-cyclin complex
trigger passage through different
stage of cell cycle
14. QUALITY CONTROL
• Systems for interupting the cell cycle if
something goes wrong
• 1.DNA damage chechpoints
1.Happens at G1 checkpoints+S phase+M
phase.
2.p53 gene- tumor suppressor
15. • The p53 protein senses DNA damage and can
halt progression of the cell cycle in G1 (by
blocking the activity of Cdk2)
• The p53 protein is also a key player
in apoptosis, forcing "bad" cells to commit
suicide
