Cell Cycle

Question 1

What is cell division?

Answer 1

New cells are formed by splitting of pre-existing cells

Question 2

What is the significance of observing newly developing organisms (embryos)?

Answer 2

Confirms that plants and animals start life as single-celled embryos and grow through a series of cell divisions

Question 3

What are the two main processes involved in cell division?

Answer 3

• Mitosis
• Cytokinesis

Question 4

What is a chromosome?

Answer 4

A single long piece of DNA with associated proteins

Question 5

What happens to chromosomes before mitosis?

Answer 5

Chromosomes are replicated and condense into compact structures

Question 6

What is a chromatid?

Answer 6

Each copy of a replicated chromosome

Question 7

What binds sister chromatids together?

Answer 7

Cohesins

Question 8

What are the two phases of the cell cycle?

Answer 8

• M phase
• Interphase

Question 9

What occurs during interphase?

Answer 9

Chromosomes are uncoiled, cells are growing and preparing to divide or fulfilling specialized functions

Question 10

What are the phases of interphase?

Answer 10

• G1 phase
• S phase
• G2 phase

Question 11

What is the function of the G1 phase?

Answer 11

Decides to begin replication and transition to S phase

Question 12

What is the purpose of the G2 phase?

Answer 12

To prepare for M phase before mitosis

Question 13

What begins the process of mitosis?

Answer 13

Chromatin condenses

Question 14

What happens to sister chromatids during mitosis?

Answer 14

They separate to form independent daughter chromosomes

Question 15

How many subphases does mitosis have?

Answer 15

Five

Question 16

List the subphases of mitosis.

Answer 16

• Prophase
• Prometaphase
• Metaphase
• Anaphase
• Telophase

Question 17

What forms during prophase?

Answer 17

Spindle apparatus

Question 18

What is the role of the spindle apparatus?

Answer 18

Moves replicated chromosomes during early mitosis and pulls chromatids apart in late mitosis

Question 19

What happens during prometaphase?

Answer 19

Nuclear envelope breaks down and microtubules attach to chromosomes at kinetochores

Question 20

What occurs during metaphase?

Answer 20

Chromosomes are lined up on the metaphase plate

Question 21

What is the function of kinetochore microtubules?

Answer 21

Attach to chromosomes and help in their movement

Question 22

What happens during anaphase?

Answer 22

Cohesins split, sister chromatids are pulled toward opposite poles

Question 23

What occurs during telophase?

Answer 23

New nuclear envelope forms around each set of chromosomes and they begin to decondense

Question 24

What is cytokinesis?

Answer 24

Cytoplasm divides to form two daughter cells

Question 25

How does cytokinesis differ in plants and animals?

Answer 25

* Plants: Vesicles form cell plate * Animals: Actin and myosin filaments form cleavage furrow

Question 26

What is binary fission?

Answer 26

Process by which bacteria divide

Question 27

What is M phase-promoting factor (MPF)?

Answer 27

A protein complex that triggers progression of the cell cycle

Question 28

What are the components of MPF?

Answer 28

* Protein kinase * Cyclin

Question 29

How is MPF activated?

Answer 29

Cdk is phosphorylated and one phosphate group is removed late in G2 phase

Question 30

How is MPF turned off?

Answer 30

Cyclin is degraded by the ubiquitin-proteasome system

Question 31

What are cell-cycle checkpoints?

Answer 31

Critical points in the cell cycle that regulate whether the cell proceeds with division

Question 32

What is the G1 checkpoint responsible for?

Answer 32

Deciding if the cell will continue through the cycle or enter G0

Question 33

What factors affect passage through the G1 checkpoint?

Answer 33

* Size * Availability of nutrients * Social signals * DNA damage

Question 34

What role does the p53 protein play in the G1 checkpoint?

Answer 34

Activates repair proteins or initiates apoptosis if DNA is damaged

Question 35

What occurs at the G2 checkpoint?

Answer 35

Checks if chromosome replication has proceeded properly and if DNA is damaged

Question 36

What does the M-phase checkpoint ensure?

Answer 36

That sister chromatids do not split until all kinetochores are attached