Stages of The Cell cycle #
Interphase #
G1-phase (Gap 1 phase)
- metabolic changes prepare the cellfor all division
- intensive cellular synthesis eg new organelles
- cell growth occurs
- substance produces to inhibit or stimulate onset of next phase
S-phase (Synthesis phase)
- DNA replication occurs
- proteins molecules called histones are synthesised and cover each DNA strand
- each chromosome become chromatid joined together at the centromere
- the cell becomes 4n
G2-phase (Gap 2 phase)
- intensive cellular synthesis
- mitochondia and chloroplast replicates
- energy store inceases
- mitotic spindle begins to form
Miotic phase (M-phase)
- The mother cell divides into 2 genetically identical daughter cells
- cytokenesis (cleavage of cytoplasm)
Mitosis in Pig Kidney Epithelial Cells
Cc: www.microscopyu.com
Multiple choice questions #
Which cyclin-CDK (cyclin-dependent kinase) complex is primarily responsible for driving the cell from G1 phase into the S phase of the cell cycle?
A) Cyclin A-CDK1
B) Cyclin B-CDK1
C) Cyclin D-CDK4/6
D) Cyclin E-CDK2
2: During which phase of the cell cycle does DNA replication occur?
A) G1 phase
B) G2 phase
C) S phase
D) M phase
3: The G2 checkpoint ensures that the cell:
A) Has enough energy to complete mitosis.
B) Has replicated its DNA without errors.
C) Has properly aligned chromosomes on the metaphase plate.
D) Is of sufficient size to enter the next cell cycle phase.
4: In which phase of the cell cycle are the sister chromatids separated and pulled to opposite poles of the cell?
A) Anaphase
B) Telophase
C) Metaphase
D) Prophase
5: Which of the following is a tumor suppressor protein that plays a crucial role in preventing the cell cycle from progressing when DNA is damaged?
A) Cyclin A
B) Cyclin B
C) p53
D) CDK4
6: The protein complex known as the anaphase-promoting complex (APC/C) is responsible for:
A) Initiating DNA replication.
B) Promoting the transition from G1 to S phase.
C) Regulating the progression from metaphase to anaphase.
D) Controlling cytokinesis during telophase.
7: Which of the following statements accurately describes the role of centrosomes in the cell cycle?
A) Centrosomes replicate during S phase and migrate to opposite poles during anaphase.
B) Centrosomes ensure proper DNA replication during G2 phase.
C) Centrosomes are responsible for monitoring the cell’s size during G1 phase.
D) Centrosomes organize the microtubule spindle fibers during cell division.
8: The phenomenon of “mitotic catastrophe” refers to:
A) A cell successfully completing mitosis without errors.
B) A cell undergoing apoptosis during G1 phase.
C) A cell entering a state of prolonged arrest during G2 phase.
D) A cell attempting mitosis with severely damaged or misaligned chromosomes.
9: Which of the following is a key characteristic of meiosis that distinguishes it from mitosis?
A) Two rounds of chromosome replication
B) Formation of a cleavage furrow during cytokinesis
C) Production of genetically identical daughter cells
D) Exchange of genetic material between homologous chromosomes
10: The process of “senescence” in cells is associated with:
A) Rapid cell division during the G1 phase.
B) The inability of cells to enter the G2 phase.
C) Permanent cell cycle arrest due to factors like DNA damage or telomere shortening.
D) A cell’s inability to undergo apoptosis during the M phase.
Solutions
- D) Cyclin E-CDK2
- C) S phase
- B) Has replicated its DNA without errors.
- A) Anaphase
- C) p53
- C) Regulating the progression from metaphase to anaphase.
- D) Centrosomes organize the microtubule spindle fibers during cell division.
- D) A cell attempting mitosis with severely damaged or misaligned chromosomes.
- D) Exchange of genetic material between homologous chromosomes
- C) Permanent cell cycle arrest due to factors like DNA damage or telomere shortening.
