Podcast
Questions and Answers
What is the main function of apoptosis in cellular biology?
What is the main function of apoptosis in cellular biology?
Which pathway of apoptosis is initiated by the activation of cell surface death receptors?
Which pathway of apoptosis is initiated by the activation of cell surface death receptors?
What role do initiator caspases play in the apoptosis process?
What role do initiator caspases play in the apoptosis process?
What critical proteins are released from mitochondria during the intrinsic pathway of apoptosis?
What critical proteins are released from mitochondria during the intrinsic pathway of apoptosis?
Signup and view all the answers
Which of the following statements about caspases is correct?
Which of the following statements about caspases is correct?
Signup and view all the answers
What is a consequence of inappropriate levels of apoptosis?
What is a consequence of inappropriate levels of apoptosis?
Signup and view all the answers
During DNA fragmentation in apoptosis, which enzyme is involved in cleaving the DNA?
During DNA fragmentation in apoptosis, which enzyme is involved in cleaving the DNA?
Signup and view all the answers
What is the effect of extracellular survival factors on apoptosis?
What is the effect of extracellular survival factors on apoptosis?
Signup and view all the answers
What role does positive feedback play in the activation of m-cdk?
What role does positive feedback play in the activation of m-cdk?
Signup and view all the answers
What is the key regulatory event in the late M phase?
What is the key regulatory event in the late M phase?
Signup and view all the answers
How does the Anaphase-promoting complex/cyclosome (Apc/c) function?
How does the Anaphase-promoting complex/cyclosome (Apc/c) function?
Signup and view all the answers
What happens to cdc25 and Wee1 when m-cdk is activated?
What happens to cdc25 and Wee1 when m-cdk is activated?
Signup and view all the answers
What triggers DNA replication in the cell cycle?
What triggers DNA replication in the cell cycle?
Signup and view all the answers
What effect does the stable G1 phase have on the cell?
What effect does the stable G1 phase have on the cell?
Signup and view all the answers
What triggers the separation of sister chromatids during mitosis?
What triggers the separation of sister chromatids during mitosis?
Signup and view all the answers
What is the role of the spindle assembly checkpoint in mitosis?
What is the role of the spindle assembly checkpoint in mitosis?
Signup and view all the answers
Which structure holds sister chromatids together during cell division?
Which structure holds sister chromatids together during cell division?
Signup and view all the answers
Which molecule is cleaved to allow sister chromatids to separate?
Which molecule is cleaved to allow sister chromatids to separate?
Signup and view all the answers
How is m-cdk inactivated as cells prepare to enter a new cell cycle?
How is m-cdk inactivated as cells prepare to enter a new cell cycle?
Signup and view all the answers
What component of the mitotic spindle helps determine the plane of cell division?
What component of the mitotic spindle helps determine the plane of cell division?
Signup and view all the answers
How does rhoA influence the process of cytokinesis?
How does rhoA influence the process of cytokinesis?
Signup and view all the answers
What happens immediately after the last sister chromatid pair becomes bi-oriented on the spindle?
What happens immediately after the last sister chromatid pair becomes bi-oriented on the spindle?
Signup and view all the answers
During which phase of mitosis do chromosomes segregate into daughter cells?
During which phase of mitosis do chromosomes segregate into daughter cells?
Signup and view all the answers
Which of the following statements about cytokinesis is true?
Which of the following statements about cytokinesis is true?
Signup and view all the answers
What event triggers the start of the cell cycle?
What event triggers the start of the cell cycle?
Signup and view all the answers
Which phase do cells have double the DNA content due to DNA replication?
Which phase do cells have double the DNA content due to DNA replication?
Signup and view all the answers
What occurs during the G2/M transition in the cell cycle?
What occurs during the G2/M transition in the cell cycle?
Signup and view all the answers
Which protein complex initiates the transition from metaphase to anaphase?
Which protein complex initiates the transition from metaphase to anaphase?
Signup and view all the answers
What function do cyclins serve in the cell cycle control system?
What function do cyclins serve in the cell cycle control system?
Signup and view all the answers
What is the role of the Cdk inhibitor protein (cki)?
What is the role of the Cdk inhibitor protein (cki)?
Signup and view all the answers
How is the cyclin-Cdk complex activated?
How is the cyclin-Cdk complex activated?
Signup and view all the answers
What happens to the Cdk proteins during the cell cycle?
What happens to the Cdk proteins during the cell cycle?
Signup and view all the answers
What triggers the conformational change in Apaf1 leading to apoptosome formation?
What triggers the conformational change in Apaf1 leading to apoptosome formation?
Signup and view all the answers
What is the role of Bak in the process of apoptosis?
What is the role of Bak in the process of apoptosis?
Signup and view all the answers
How do BH3-only proteins like Bad contribute to apoptosis?
How do BH3-only proteins like Bad contribute to apoptosis?
Signup and view all the answers
What is MOMP and its significance in apoptosis?
What is MOMP and its significance in apoptosis?
Signup and view all the answers
What role do anti-apoptotic Bcl2 family proteins play?
What role do anti-apoptotic Bcl2 family proteins play?
Signup and view all the answers
Which statement correctly describes IAP proteins?
Which statement correctly describes IAP proteins?
Signup and view all the answers
What is the primary function of cytochrome C in apoptosis?
What is the primary function of cytochrome C in apoptosis?
Signup and view all the answers
What is the expected outcome when pro-apoptotic factors are activated?
What is the expected outcome when pro-apoptotic factors are activated?
Signup and view all the answers
What role does the protein m o m p play in relation to apoptosis?
What role does the protein m o m p play in relation to apoptosis?
Signup and view all the answers
Which protein is responsible for phosphorylating and inactivating bad in the apoptotic pathway?
Which protein is responsible for phosphorylating and inactivating bad in the apoptotic pathway?
Signup and view all the answers
Why do some nerve cells undergo apoptosis during development?
Why do some nerve cells undergo apoptosis during development?
Signup and view all the answers
What is the significance of phosphatidylserine in the context of apoptosis?
What is the significance of phosphatidylserine in the context of apoptosis?
Signup and view all the answers
How do extracellular survival factors generally inhibit apoptosis?
How do extracellular survival factors generally inhibit apoptosis?
Signup and view all the answers
What happens to flippase during the apoptotic process?
What happens to flippase during the apoptotic process?
Signup and view all the answers
What can happen if apoptosis is either excessive or insufficient?
What can happen if apoptosis is either excessive or insufficient?
Signup and view all the answers
What is the function of scramblase in the apoptosis process?
What is the function of scramblase in the apoptosis process?
Signup and view all the answers
Study Notes
Cell Cycle
- Eukaryotic cells divide to produce genetically identical daughter cells
- Cell cycle has several phases involved in chromosomal duplication and segregation
- Major chromosomal events of the cell cycle occur in S phase (duplication) and M phase (segregation).
- Interphase includes G1, S, and G2 phases
- G1 phase: cell growth and normal metabolic roles
- S phase: replication of DNA
- G2 phase: cell growth and preparation for mitosis
Eukaryotic Cell Division
- M phase typically occupies a small fraction of the cell cycle
- Interphase includes S phase and gap phases
- Stages of mitosis:
- Prophase: chromosomes condense
- Prometaphase: spindle microtubules attach to chromosomes
- Metaphase: chromosomes align at cell equator
- Anaphase: sister chromatids separate
- Telophase: chromosomes arrive at opposite ends
Cytokinesis
- Division of the cytoplasm, forming 2 cells
- Two major regulatory steps in mitosis involve:
- M-cdk and other protein kinase drive entry into mitosis
- Apc/c triggers the destruction of securin, initiating sister chromatid separation
Cell Cycle Control
- Cell cycle control at three major regulatory transitions:
- Start, when the cell commits to cell cycle entry and DNA replication
- G2/M transition, when the cell triggers mitosis
- Metaphase to anaphase transition, which triggers sister chromatid separation
- Hundreds of cdk substrates are phosphorylated in a defined order
- Not well understood how the correct order of phosphorylation is achieved
- Positive feedback generates the switch-like behavior of cell-cycle transitions
Cell Cycle Control System
- Depends on cyclically activated cyclin-dependent protein kinases (cdks)
- Cyclins undergo a cycle of synthesis and degradation in each cell cycle
- Cyclical changes in cyclin protein levels result in cyclic assembly and activation of cyclin–cdk complexes
- Concentrations of three major cyclin types oscillate during the cell cycle
- A separate regulatory protein complex, the APC/C, initiates the metaphase to anaphase transition
- Phosphorylation of Cdk2 (by CAK) activates the enzyme
- Cdk activity is regulated by inhibitory phosphorylation (Wee1) and activation (Cdc25 phosphatase)
Regulation of Cdk Activity
- The active cyclin-cdks are off when kinase Wee1 phosphorylates two sites above the active site.
- Removal of these phosphates by phosphatase Cdc25 activates the complex
- CAK adds the activating phosphate
- cdk inhibitors (CKIs) can inhibit Cdk activity
- Protein phosphatases reverse the effects of cdks
Mitosis
- Major steps summarized:
- Prophase: chromosomes condense
- Prometaphase: spindle microtubules attach to chromosomes
- Metaphase: chromosomes align at cell equator
- Anaphase: sister chromatids separate
- Telophase: chromosomes arrive at opposite ends
- Cytokinesis: division of the cytoplasm
Cell Cycle and DNA Replication
- S phase: DNA replication occurs only once per cell cycle
- Chromosome duplication requires duplication of chromatin structure
- Cohesins hold sister chromatids together.
Meiosis
- Special type of nuclear division that differs from mitosis
- In animals, meiosis occurs in the gonads
- Results in four genetically unique daughter cells (gametes) each with just one set of chromosomes
- Duplicated homologs pair during meiotic prophase
- Crossing over holds bivalents together, and contributes to genetic variation
Mitosis-Telophase
- Chromosomes are packaged in daughter nuclei
- Actin and myosin II in the contractile ring guide the process of cytokinesis
Cytokinesis
- Microtubules of the mitotic spindle determine the plane of animal cell division
- This ensures that the cleavage plane is between the two daughter nuclei
Control of Cell Division and Growth
- Mitogens stimulate cell division, primarily by triggering a wave of G1/S-cdk activity
- Growth factors stimulate cell growth by promoting protein synthesis
- Survival factors promote cell survival by suppressing apoptosis
- Many human cells have a limitations on the number of times they can divide
DNA Damage
- DNA damage leads to accumulation of active p53 protein, arresting the cell in G1 until DNA repair is required
Apoptosis
- Apoptosis eliminates unwanted cells
- Depends on an intracellular proteolytic cascade mediated by caspases
- Extrinsic pathway: activation of cell surface death receptors
- Intrinsic pathway: depends on proteins released from mitochondria
- Inhibitors of apoptosis (IAPs) help control caspase activation
- Caspases are proteases that cleave targets after aspartate residue.
- Initiator caspases activate execution caspases which lead to controlled apoptotic death.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the mechanisms of apoptosis and the cell cycle. This quiz covers key processes like initiator caspases, mitochondrial proteins, and the regulation of cell division. Perfect for students studying cellular biology at an advanced level.