EX1 Q1

Question 1

What are the 3 parts of interphase?

Answer 1

G1,S,G2

Question 2

What happens in G1 phase?

Answer 2

Cell growth

Question 3

What happens in S phase?

Answer 3

DNA replication

Question 4

What happens in G2 phase?

Answer 4

the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis.

Question 5

What happens in preprophase?

Answer 5

determination of the future plane of division by the prophase band

Question 6

What happens in prophase?

Answer 6

-Disappearance of the preprophase band
-Spindle fibers appear
-Nuclear membrane disappears
-Chromosomes condense

Question 7

What happens in metaphase?

Answer 7

-Alignment of chromosomes at the metaphase plate
-Nuclear envelope reabsorbed into a polar ER network

Question 8

What happens in anaphase?

Answer 8

-Kinetochore spindle microtubules shorten to separate sister chromatids and pull them towards the poles of the cell

Question 9

What happens in telophase?

Answer 9

-Chromosomes start decondensing
-Nuclear envelope reforms
-Phragmoplast starts to form

Question 10

What happens in cytokinesis?

Answer 10

-Cell plate formation
-Chromosomes completely decondensed
-Two cells formed
-Sections of the ER cross the cell plate and form the basis of the plasmodesmata

Question 11

What is MPF (mitosis promoting factor)? Where is it located?

Answer 11

-induces mitosis in eukaryotes
-located in the cytoplasm of M-phase cells

Question 12

What are the requirements to pass the G1 checkpoint?

Answer 12

-adequate cell size
-sufficient nutrients
-social signals present
-undamaged DNA

Question 13

What are the requirements to pass the G2 checkpoint?

Answer 13

-successful chromosome replication
-undamaged DNA
-activated MPF is present

Question 14

What are the requirements to pass the metaphase checkpoint?

Answer 14

-all chromosomes are attached to the spindle apparatus

Question 15

What is the composition of MPF? What do the two subunits do?

Answer 15

-made of two subunits: a protein kinase and a cyclin
-An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein.
-the cyclin acts as a regulatory protein

Question 16

When is the highest concentration of cyclin recorded?

Answer 16

the start of M phase

Question 17

What happens when a protein is tagged with Q?

Answer 17

it will be destroyed by a proteasome

Question 18

Why do the cyclin levels decrease during M phase?

Answer 18

enzymes that were synthesized during anaphase attach Q to the cyclin subunits

Question 19

What are cyclin-dependent kinases?

Answer 19

-They are enzymes involved in M phase that phosphorylate a wide array of proteins.
-Each phosphorylation event occurs at an appropriate point during the cell cycle, thereby stimulating or inhibiting a particular cellular process involved in cell division.

Question 20

mitotic cyclins

Answer 20

Activates cdc2 (cyclin), which allows the passage from G2 to mitosis

Question 21

What are the three steps of S phase?

Answer 21

initiation, elongation, termination

Question 22

What are cyclins?

Answer 22

Cyclins are cell cycle regulatory proteins that “switches” kinases on and off

Question 23

What are Cyclin-dependent kinases (Cdk)?

Answer 23

Cyclin-dependent kinases (Cdk) are cell cycle control enzyme kinases that are regulated by cyclins.

Question 24

Cyclin-dependent kinases (Cdk) regulate the events happening in the cell cycle by ____ and ____ target proteins as a way of activating/deactivating them. However, a Cdk can only be activated if a ____ binds to it.

Answer 24

-phosphorylating
-de-phosphorylating
-cyclin

Question 25

Drives the G1 - S transition

Answer 25

Cyclin D & Cdk 4,6

Question 26

Regulation of G1 - S transition

Answer 26

Cyclin E &Cdk 2

Question 27

Initiation of DNA replication in S phase

Answer 27

Cyclin A & Cdk 2

Question 28

Transition from G2 to M phase

Answer 28

Cyclin B & Cdk 1