18

Question 1

What is the purpose of the Cell Cycle?

Answer 1

Ensures cell duplicate all contents and split properly, and genetic info transfer

Question 2

What are the phases of the Cell Cycle?

Answer 2

M Phase & Interphase

Question 3

What occurs in M phase?

Answer 3

Nuclear and Cytoplasmic Division (mitosis & cytokinesis)

Question 4

What occurs in Interphase?

Answer 4

Cell Growth;
G1; growth
S ; DNA synthesis
G2 ; preparation for mitosis

Question 5

Cdks do what?

Answer 5

regulate the cycle; by phosphorylating target proteins

Question 6

Ckds require what to be active?

Answer 6

Cyclin; triggers various cycle phases

Question 7

What is the mechanism of Cdks?

Answer 7

activation via phosphorylation / de-phosphorylation

Question 8

What are the purpose of the Checkpoints of the cycle?

Answer 8

They ensure proper conditions and DNA integrity before progression

• they stop the cycle under unfavourable conditions or DNA damage

Question 9

What is cell cycle arrest?

Answer 9

cells may enter a non-dividing state (G0) if conditions are not met

Question 10

What 3 main conditions are checked for at checkpoints?

Answer 10

1. Sufficient nutrients in environment
2. Chromosomes have been accurately replicated
3. Chromosomes are aligned to separate properly

Question 11

What is Cyclin?

Answer 11

a Regulatory Subunit

Question 12

True or False: Cyclin concentrations stay consistent throughout cell cycle.

Answer 12

False: Cycling concentrations fluctuate during cell cycle

Question 13

During the cycle, when are Cyclin levels low, and when do they rise?

Answer 13

Low after Mitosis
Rise during interphase

Question 14

High M-Cyclin concentrations lead to what?

Answer 14

leads to active M-Cdk complex, and then to entry into mitosis

Question 15

True or False: Different cyclin-Cdk complexes trigger various cell cycle stages.

Answer 15

True

Question 16

Why mismatch between cyclin levels and M-Cdk?

Question 17

What turns off M-Cdk activity?

Answer 17

When

Question 18

How are Cdks activated?

Answer 18

phosphorylation by kinases and
dephosphoryaltion by phosphatases

Question 19

Describe the destruction process of Cdks.

Answer 19

M-cyclin is tagged with ubiquitin and directed to the proteasome for degradation, leading to M-Cdk inactivation and progression to the next cell cycle stage.

Question 20

If issues are detected, what occurs? (Cdk activity)

Answer 20

cells can halt progression or enter G0, a non-dividing state

Question 21

Cdk inhibitor proteins can prevent the formation of what?

Answer 21

Active cyclin-Cdk complexes

Question 22

What is M Phase?

Answer 22

The phase of the cell cycle where mitosis (nuclear division) and cytokinesis (cytoplasmic division) occur

Question 23

What is Interphase?

Answer 23

The phase of the cell cycle between cell divisions, consisting of G1, S, and G2 phases, where the cell grows and prepares for mitosis

Question 24

What is G1 Phase?

Answer 24

The first gap phase of interphase; the cell grows and prepares for DNA synthesis

Question 25

What is S Phase?

Answer 25

The phase of interphase where DNA replication occurs, doubling the genetic material

Question 26

What is G2 Phase?

Answer 26

The second gap phase of interphase; the cell prepares for mitosis by producing necessary proteins and organelles

Question 27

What is G0 Phase?

Answer 27

A resting state where the cell exits the cycle and stops dividing, often seen in fully differentiated or non-dividing cells like neurons

Question 28

What are Cyclins?

Answer 28

Regulatory proteins whose concentrations fluctuate during the cell cycle, activating cyclin-dependent kinases (Cdks)

Question 29

What are Cdks?

Answer 29

Enzymes that drive the cell cycle forward by phosphorylating target proteins when activated by cyclins

Question 30

What are the checkpoints?

Answer 30

A control mechanism ensuring that conditions are favorable for progression through the cell cycle, such as proper DNA replication and alignment of chromosomes

Question 31

What are Cdk Inhibitors?

Answer 31

Proteins that block the assembly or activation of cyclin-Cdk complexes, halting the cell cycle when issues are detected

Question 32

What is the Positive Feedback Loop?

Answer 32

A mechanism where an activated Cdk complex promotes further activation of upstream regulators, amplifying the signal

Question 33

What is Ubiquitin?

Answer 33

A small protein that tags cyclins for destruction, leading to the inactivation of Cdks and progression to the next cell cycle phase

Question 34

What is a Proteasome?

Answer 34

A protein complex that degrades ubiquitin-tagged proteins, such as cyclins

Question 35

What is the DNA Damage Checkpoint?

Answer 35

A specific control point where the cell detects and repairs DNA damage before proceeding through the cycle

Question 36

What is the Spindle Assembly Checkpoint?

Answer 36

Ensures chromosomes are properly attached to the mitotic spindle before separation during mitosis

Question 37

What is the Mitotic Cdk (M-Cdk)?

Answer 37

A cyclin-Cdk complex that triggers entry into mitosis by phosphorylating key proteins for chromosome condensation and spindle formation

Question 38

What is Cyclin Destruction?

Answer 38

The targeted degradation of cyclins (e.g., M-cyclin) by ubiquitin-proteasome pathways to reset the cell cycle machinery

Question 39

What is Phosphorylation / Dephosphorylation?

Answer 39

The addition or removal of phosphate groups on proteins, regulating their activity and enabling cell cycle progression

Question 40

What is Chromosome Alignment?

Answer 40

The organization of replicated chromosomes along the metaphase plate during mitosis to ensure proper separation