The Cell Cycle

Question 1

What are the three main phases of the cell cycle?

Answer 1

Interphase, Mitosis, Cytokinesis

Interphase is further divided into G1, S, and G2 phases.

Question 2

What happens during the G1 phase of interphase?

Answer 2

First phase of growth; increase in cytoplasm and organelles

G1 stands for Gap Phase 1.

Question 3

What occurs during the S phase of interphase?

Answer 3

Synthesis of DNA; semi-conservative replication and new histones synthesized

S stands for Synthesis.

Question 4

What is the role of G2 phase in the cell cycle?

Answer 4

Second phase of growth; replicated DNA is checked

G2 stands for Gap Phase 2.

Question 5

What is mitosis?

Answer 5

Nuclear division

Mitosis is part of the M phase of the cell cycle.

Question 6

What is cytokinesis?

Answer 6

Division of the cytoplasm

Cytokinesis usually follows mitosis.

Question 7

List the phases of mitosis.

Answer 7

• Prophase
• Metaphase
• Anaphase
• Telophase

These are the stages of nuclear division.

Question 8

What is the purpose of checkpoints in the cell cycle?

Answer 8

To ensure it is safe for the process to continue

Checkpoints occur at key points like G1, G2, and M phases.

Question 9

What is the mitotic index formula?

Answer 9

Mitotic Index = Number of cells undergoing cell division / Total number of cells in the field of view

This helps quantify the number of cells in mitosis.

Question 10

What type of cells undergo binary fission?

Answer 10

Prokaryotic cells

Eukaryotic cells undergo mitosis.

Question 11

What are stem cells?

Answer 11

Unspecialized (undifferentiated) cells with the ability to differentiate into any type of cell

Found in bone marrow, umbilical cord blood, and embryos.

Question 12

What are tumor suppressor genes (TSG)?

Answer 12

Genes that make proteins involved in slowing cell division or causing apoptosis

Mutations in TSG can lead to uncontrolled cell division.

Question 13

What are proto-oncogenes?

Answer 13

Genes that stimulate cell division by producing proteins

Mutated proto-oncogenes are called oncogenes.

Question 14

What is hypermethylation?

Answer 14

Addition of methyl groups that can silence gene expression

Abnormal methylation can contribute to cancer development.

Question 15

True or False: Mitosis is an uncontrolled process.

Answer 15

False

Mitosis is a controlled process regulated by genes.

Question 16

Fill in the blank: The cell cycle typically lasts _______ hours.

Answer 16

less than 24 hours

The length can vary based on temperature, nutrients, and oxygen.

Question 17

Where can mitosis be observed in plants?

Answer 17

In tissues called meristems, found at the growing tips of shoots and roots

Meristems consist of undifferentiated cells.

Question 18

What is the significance of the metaphase checkpoint?

Answer 18

Checks that chromosomes are attached to the spindle

This ensures proper chromosome alignment before separation.

Question 19

What happens to chromosomes during prophase?

Answer 19

Chromosomes condense and the nuclear envelope breaks down

Centrioles move to opposite poles of the cell.

Question 20

What is the primary cancer?

Answer 20

Where the cancer begins

Secondary cancer refers to where cancer spreads to other areas.