Cell Cycle and DNA Replication Quiz
29 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which phase of the cell cycle is characterized by DNA replication?

  • G2 phase
  • S phase (correct)
  • G1 phase
  • M phase

What is the primary role of the G1 phase in the cell cycle?

  • Preparation for mitosis
  • Cell division
  • Cellular component synthesis (correct)
  • DNA synthesis

How is the duration of the cell cycle primarily divided?

  • G1, G2, M phases only
  • G1, S, G2, M phases (correct)
  • G2, M, and Go phases only
  • G1, S, G2, interphase only

What occurs during the M phase of the cell cycle?

<p>Splitting into two daughter cells (D)</p> Signup and view all the answers

Which checkpoints are crucial for the regulation of the cell cycle?

<p>G1, G2, and M phases (D)</p> Signup and view all the answers

What happens to daughter cells immediately after the M phase?

<p>They enter Go phase or re-enter the cell cycle (A)</p> Signup and view all the answers

What is the approximate duration of the complete cell cycle?

<p>24 hours (A)</p> Signup and view all the answers

In which phase does a cell primarily exist when it is not actively dividing?

<p>Go phase (D)</p> Signup and view all the answers

During which phase of the cell cycle is maximum phosphorylation of p53 observed?

<p>Mitosis (D)</p> Signup and view all the answers

What type of CDK inhibitor is primarily active when a cell should not undergo the cell cycle?

<p>INK4 inhibitors (C)</p> Signup and view all the answers

What is the primary action of growth factors in cellular activity?

<p>To bind to growth factor receptors and stimulate gene transcription (C)</p> Signup and view all the answers

Which of the following drugs inhibits nucleotide synthesis by targeting dihydrofolate reductase?

<p>Methotrexate (B)</p> Signup and view all the answers

What is the role of topoisomerase inhibitors in cancer therapy?

<p>To allow the tangling of parental DNA strands and prevent replication (D)</p> Signup and view all the answers

Which checkpoint is responsible for preventing entry into the S phase until the G1 phase is completed?

<p>G1-S checkpoint (A)</p> Signup and view all the answers

What happens if DNA damage is detected at checkpoints during the cell cycle?

<p>The cell undergoes apoptosis if the damage cannot be repaired (A)</p> Signup and view all the answers

What role do cyclins play in the cell cycle?

<p>They help transition between different phases of the cell cycle (D)</p> Signup and view all the answers

Which of the following is NOT a type of cell cycle regulatory protein?

<p>Enzymes for DNA replication (B)</p> Signup and view all the answers

What is a potential consequence of checkpoint mutations?

<p>Uncontrolled cell growth leading to cancer (B)</p> Signup and view all the answers

Which of the following describes the role of cyclin-dependent kinases (CDKs)?

<p>They phosphorylate substrates essential for cell cycle transition (B)</p> Signup and view all the answers

Why might a checkpoint fail to arrest the cell cycle despite the presence of DNA damage?

<p>Cells may resume the cycle even with unresolved damage (D)</p> Signup and view all the answers

Which cyclin is primarily associated with the G2-M checkpoint?

<p>Cyclin B (C)</p> Signup and view all the answers

What is the primary role of cyclin-dependent kinases (CDKs) in the cell cycle?

<p>To regulate cell cycle checkpoints (A)</p> Signup and view all the answers

Which of the following statements about Rb protein is correct?

<p>Rb protein is inactive when phosphorylated (B)</p> Signup and view all the answers

How does P53 protein function in the cell cycle?

<p>It inhibits CDKs to prevent cell cycle progression (D)</p> Signup and view all the answers

What happens to P53 after a cell passes the restriction point in the G1 phase?

<p>It is phosphorylated and inactivated (D)</p> Signup and view all the answers

What triggers the release of transcription factors like E2-F from inhibition by Rb protein?

<p>Phosphorylation of Rb protein (C)</p> Signup and view all the answers

Which cyclin-dependent kinases are activated during the G1-S checkpoint?

<p>CDK 4 and CDK 6 (A)</p> Signup and view all the answers

Which statement best describes the role of tumor suppressor genes?

<p>They protect against cancer by regulating cell cycle progression (C)</p> Signup and view all the answers

What is one consequence of the inactivation of Rb protein?

<p>Uncontrolled transcription of cell division proteins (D)</p> Signup and view all the answers

Flashcards

G1 Phase

The cell synthesizes components needed before DNA replication.

Cell Cycle

The series of events that occur in a cell's lifetime leading up to the next division.

S Phase

The phase where DNA replication takes place.

G2 Phase

Cell synthesizes proteins for two new cells.

Signup and view all the flashcards

M Phase

Cell division (mitosis) occurs during this phase.

Signup and view all the flashcards

Go Phase

A non-dividing or dormant phase of the cell.

Signup and view all the flashcards

Cell Cycle Regulation

Controlling when a cell grows and divides.

Signup and view all the flashcards

Interphase

The period between cell divisions (M phase) including G1, S, and G2 phases.

Signup and view all the flashcards

Cell Cycle Checkpoints

Control points in the cell cycle that ensure proper progression by monitoring DNA replication, chromosome segregation, and integrity.

Signup and view all the flashcards

G1-S Checkpoint

A critical point in the cell cycle where the cell checks for DNA integrity before entering the S phase (DNA replication).

Signup and view all the flashcards

S phase Checkpoint

A point in the cell cycle that monitors DNA replication to ensure proper duplication before proceeding to the next phase.

Signup and view all the flashcards

G2-M Checkpoint

The final checkpoint in the cell cycle, ensuring DNA replication is completed and chromosomes are correctly assembled before mitosis begins.

Signup and view all the flashcards

Cyclins

Proteins that regulate transitions between cell cycle phases by activating cyclin-dependent kinases (CDKs).

Signup and view all the flashcards

Cyclin-Dependent Kinases (CDKs)

Enzymes that are activated by cyclins and phosphorylate target proteins to initiate various cell cycle events.

Signup and view all the flashcards

Cell Cycle Arrest

A temporary halt in the cell cycle when DNA damage is detected to allow time for repair.

Signup and view all the flashcards

Apoptosis

Programmed cell death to eliminate cells with unrepairable DNA damage, preventing the spread of damaged genetic material.

Signup and view all the flashcards

CDK Inhibitors

Proteins that regulate cell cycle progression by inhibiting cyclin-dependent kinases (CDKs), enzymes that control cell cycle transitions.

Signup and view all the flashcards

INK4 Family

A family of CDK inhibitors that primarily bind to CDK4 and CDK6, preventing the formation of complexes that promote cell cycle entry.

Signup and view all the flashcards

WAF/KIP Family

A family of CDK inhibitors that bind to a wider range of CDKs (e.g., CDK1, 2, 4, and 6), including those involved in later phases of the cell cycle.

Signup and view all the flashcards

p21/WAF1

A member of the WAF/KIP family that inhibits CDKs and is involved in various cellular functions, including cell cycle arrest, DNA repair, senescence, and apoptosis.

Signup and view all the flashcards

Growth Factors & Cell Cycle

Growth factors stimulate cell proliferation by activating signaling pathways leading to transcription of genes essential for cell cycle progression, such as cyclin D.

Signup and view all the flashcards

What are CDKs?

Cyclin-dependent kinases (CDKs) are a group of enzymes that control the progression of the cell cycle by activating or inhibiting the phosphorylation of other proteins. They are inactive on their own, and require binding to cyclin proteins for activation.

Signup and view all the flashcards

How do CDKs work?

When a specific cyclin binds to its corresponding CDK, the complex becomes active. This activated complex then phosphorylates other proteins involved in the cell cycle, triggering the next phase.

Signup and view all the flashcards

What is the role of Rb protein in the cell cycle?

Rb protein acts as a tumor suppressor by binding to and inhibiting a family of transcription factors (e.g. E2-F), which are responsible for activating genes necessary for cell division.

Signup and view all the flashcards

How does phosphorylation affect Rb activity?

When CDKs phosphorylate Rb, Rb becomes inactive and releases the transcription factors, allowing cell division to proceed. This inactivation of Rb is a key event in the cell cycle.

Signup and view all the flashcards

What is the function of P53?

P53 is a tumor suppressor gene that acts as a guardian of the genome by preventing cells with damaged DNA from dividing, thus reducing the risk of cancer.

Signup and view all the flashcards

How does P53 stop the cell cycle?

P53 binds to DNA and activates the production of the protein p21, which in turn inhibits CDKs and prevents them from inactivating Rb. This keeps the cell cycle in check.

Signup and view all the flashcards

What happens to P53 after the restriction point?

After the restriction point, CDK2 is activated and phosphorylates P53, making it inactive and displacing it from the nucleus. This allows the cell to continue through the cell cycle even with damaged DNA.

Signup and view all the flashcards

What are tumor suppressor genes?

Tumor suppressor genes code for proteins that help regulate the cell cycle, preventing uncontrolled cell growth and the development of cancer. Mutations in these genes can lead to cancer.

Signup and view all the flashcards

Study Notes

Cell Cycle and DNA Replication

  • Cell cycle refers to events occurring during a cell's lifetime, specifically the period between two mitotic divisions.
  • Eukaryotic cells cycle through four major phases: G1, S, G2, and M.
  • G1 (Gap 1) phase is the longest phase, where cells synthesize components for replication.
  • S (synthesis) phase is where DNA replication occurs.
  • G2 (Gap 2) phase involves synthesizing proteins for cytoplasmic division.
  • M (mitotic) phase is where the cell divides into two daughter cells.
  • Some cells enter a non-dividing phase, G0.
  • The entire cell cycle typically lasts about 24 hours, though M phase is only 1-2 hours.
  • In normal cells, most are in G0 phase.
  • Interphase is the time between the end of M phase and the start of the next mitosis (G1, S, and G2 phases).

Regulation of Cell Cycle

  • Cell cycle regulation ensures proper growth and prevents division when conditions aren't right.
  • This regulation is achieved through proteins acting at checkpoints.
  • Checkpoints include G1-S, S, and G2-M.
  • DNA damage or flawed spindle formation can halt the cycle.
  • If repair is impossible, apoptosis (programmed cell death) occurs.
  • Checkpoints may fail due to intrinsic errors, enabling unrepaired damage which can lead to secondary lesions or mutations, potentially causing cancer.

Cell Cycle Regulatory Proteins

  • Cyclins: Proteins closely linked to cell cycle transitions. Key cyclins include A, B, D, and E.
  • Cyclical increases and decreases in cyclin concentration regulate the cell cycle.
  • Cyclin-dependent kinases (CDKs): When activated (by binding to cyclins), they initiate a cascade of phosphorylation reactions.
  • Different CDKs (such as CDK 1, 2, 4, 5, and 6) act at different checkpoints in the cell cycle.

Tumor Suppressor Genes

  • Rb (retinoblastoma) gene: Encodes Rb protein, an oncosuppressor protein. It was first found in retinoblastoma cancer cases.
  • Rb protein mechanism: Binds and inhibits transcription factors (such as E2-F), preventing the production of proteins crucial for cell division.
  • Virus-related tumor antigens: Viruses like SV40, HSV, and HPV may disrupt Rb protein function, leading to uncontrolled cell division and cancer.
  • P53 gene: Encodes P53 protein, a pivotal regulator of cell cycle progression and DNA repair processes. Its function includes monitoring cell cycle progression, and inducing apoptosis if DNA damage is irreparable.
  • P53 inactivation: In damaged cells, CDK2 activity increases after G1 phase, phosphorylating and inactivating P53.
  • P53 plays a crucial role in regulating cellular growth and potentially inducing cell death if necessary.

Cyclin-Dependent Kinase Inhibitors (CDKs Inhibitors)

  • INK4 family: A group of proteins crucial to cell cycle arrest. These proteins work when a cell is stressed or should not proceed to further division.
  • WAF/KIP family: proteins associated with wild-type P53 which contain p21/WAF1, previously discussed in detail.

Growth Factors

  • Growth factors bind to receptors, initiating signaling pathways.
  • This induces phosphorylation and the activation of specific transcription factors.
  • These factors then bind to DNA and stimulate the transcription of genes vital for cell cycle progression, like cyclin D gene.

Cancer and Cell Cycle

  • Cancer involves uncontrolled cell division.
  • In cancerous cells, a significant proportion are in mitosis and the S phase.
  • Many cancer therapies target DNA replication or the enzymes involved in it to block replication.
  • Specific examples of such drugs include methotrexate and 5-fluorouracil, which block nucleotide synthesis, and the topoisomerase inhibitors that prevent replication by causing DNA tangling, thus stopping its replication.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Cell Cycle & DNA Replication Lecture 5 PDF

Description

Test your knowledge on the cell cycle and DNA replication with this quiz. Explore the phases of the cell cycle, including G1, S, G2, and M, and understand the regulation mechanisms in eukaryotic cells. Perfect for students studying cell biology and genetics.

More Like This

Cell Cycle Regulation Quiz
6 questions

Regulation of Cell Cycle Quiz: Test Your Knowledge

EnrapturedBixbite avatar
EnrapturedBixbite
The Cell Cycle Quiz
5 questions

The Cell Cycle Quiz

FastGrowingDesert avatar
FastGrowingDesert
The Cell Cycle: Basics Quiz
15 questions

The Cell Cycle: Basics Quiz

WonderfulChaos avatar
WonderfulChaos
Cell Cycle Overview
5 questions

Cell Cycle Overview

ExceptionalSerpentine2596 avatar
ExceptionalSerpentine2596
Use Quizgecko on...
Browser
Open
Browser
Browser