This set of Cytogenetics Multiple Choice Questions & Answers (MCQs) focuses on “Mitosis Stages Overview”.
1. Mitosis occurs in _________
a) Nephron
b) Hair follicles
c) Neurons
d) Ovary
View Answer
Explanation: Mitosis occurs in proliferative somatic cells. This doesn’t occur in ovary where oogenesis is via meiosis, and nephron and neurons don’t proliferate. Mitosis occurs in a hair follicle.
2. Anaphase is brought about by the change in which cytoskeletal element?
a) Tubulin
b) Actin
c) Myosin
d) Dyanin
View Answer
Explanation: Tubulin is the subunit of the microtubules that form the spindle fibres that help separate the chromatids.
3. Which of the following doesn’t take place in prophase if mitotic cell?
a) Chromosome starts to contract
b) The nuclear membrane breaks down
c) The nucleolus disappears
d) The chromosomes pair up with their homologue
View Answer
Explanation: Chromosomal pairing is a characteristic of meiotic cell not mitotic cell. Most of the steps in prophase of meiosis and mitosis being the same we observe the rest of the steps in mitotic prophase.
4. If you use colchicines, which of the cell division phases is prevented?
a) DNA replication
b) Prophase
c) Anaphase
d) Telophase
View Answer
Explanation: Colchicine disrupts the microtubule structure which leads to the absence of anaphase. While DNA replication is not prevented, so colchicines can effectively lead to chromosomal doubling.
5. If your chromosome is submetacentric, what will be the anaphase shape while separation?
a) I
b) J
c) L
d) V
View Answer
Explanation: During anaphase separation the chromatins are under a force, they tend to form L shaped structure if they are metacentraic. I, J and V structures are formed by telocentric, acrocentric and metacentric chromosomes respectively.
6. Cdc20___________________ anaphase.
a) Promotes
b) Prevents
c) Slows
d) Unrelated to
View Answer
Explanation: Cdc20 is a cell cycle component that promotes anaphase by decreasing the M-Cdk level and also leading to breakdown to cohesion.
7. Which one of the following doesn’t help in degrading cohesion?
a) Cdc20
b) M-Cdk
c) Securin
d) Separase
View Answer
Explanation: Securin binds to separase unless it’s broken down by Cdc20. This separase breaks down cohesion. The degradation of cohesion is also assisted by M-Cdk as it activates Cdc20. So, among these only securing prevents Cohesin degradation.
8. If a permanent cell re enters cell cycle it is ______________
a) Differenciation
b) Redifferenciation
c) Dedifferenciation
d) Apoptosis
View Answer
Explanation: While differenciation is the process by which a mitotic cell becomes permanent, dedifferenciation is the reverse. On the other hand re-differenciation is the differenciation of the de-diffenenciated cell.
9. _________________ follows __________________
a) Karyokinesis, mitosis
b) Cytokinesis, Karyokinesis
c) Mitosis, Karyokinesis
d) Karyokinesis, Cytokinesis
View Answer
Explanation: Karyokinesis is the diffusion of the nuclear materials which takes place before the cytoplasmic separation. Thus, cytokinesis follows karyokinesis.
10. Is it true that a cell can keep on replicating forever?
a) True
b) False
View Answer
Explanation: A replicating cell, especially a somatic cell, has a limit called Hayflick’s limit. This is due to the shortening of the telomere with every cycle of replication that ultimately results in stopping of the replication when telomere is too short.
11. Chromosomal compaction is brought about by ________
a) Cohesin
b) Thrombin
c) Condensin
d) Sequrin
View Answer
Explanation: The condensing molecule has two parts where each bind to two coils of a chromosome and bring them close. This results in chromosome compaction. Cohesin brings two chromosomes together during synapsis.
Sanfoundry Global Education & Learning Series – Cytogenetics.
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