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Flashcards in Cell Cycle Deck (33):
1

Describe the purpose of the cell cycle control system

It is used to control the sequence and timing of the different parts of the cell cycle

2

Identify where in the cell cycle the three main transition points are

G1 to S phase

G2 to M phase

Metaphase to anaphase

3

G1 to S phase transition period

Confirms environment is favorable for proliferation (replication etc) (if unfavorable cell will delay replication and enter rest G0 stage by the signals from other cells blocking cell proliferation)

4

G2 to M phase transition period

Confirms DNA is undamaged and intact after replication

5

Metaphase to anaphase phase transition period

Ensures spindle fibers are attached to chromosomes before pulling apart

6

List the two compounds animal cells need to transition from G1-S

Animals need sufficient nutrients and specific signal molecules in extra cellular fluid.

7

Define extracellular fluid

The fluid located outside of the cell, composed of plasma, interstitial fluid, etc

8

Explain what G0 entails

This is the stage cells enter when it's found that the environment in unfavorable for proliferation in the G1-S phase transition point. It is a rest stage where the cell is not dividing or preparing to divide, it's just sort of waiting for the signal that the environment is favorable

9

List the two ways other cells can influence cell proliferation

Other cells can send signals to either stimulate or block cell proliferation

10

State another name for spindle fibers

Mitotic spindles

11

Differentiate between the two types of machinery in the cell cycle

One manufactures new components of the growing cell

The other moves components to correct locations and isolates them during division

12

What's the connection between the cell cycle control system and this machinery

The cell cycle control system switches this machinery on and off at appropriate times.

13

Identify the chemistry and activating or deactivating a protein or protein complex

Activating and deactivating proteins and protein complexes happens through phosphorylation and dephosphorylation

14

Define phosphorylation

Adding a phosphate to a compound

15

Define protein kinase

Controls phosphorylation. It's an enzyme that catalyzes the transfers of PO4 to a different compound (substrate)

16

Define substrate

Regulates the activation of protein kinases. They are proteins that bind kinases to activate them

17

Identify the protein used to regulate protein kinases

Cyclin

18

When are protein kinases activated?

At specific times in the cell cycle

19

State and identify the name of the new complex formed

Cyclin-dependent protein kinases (cdks)

20

List the 4 types of cdks

M-cdk
S-cdk, G1
S-cdk
G1-cdk

21

Function of M-cdk

Triggers entry into M phase (mitosis)

22

Function of S-cdk, G1

Starts the S phase (replication)

23

Function of S-cdk

Starts the S phase (replication)

24

Function of G1-cdk

Moves the cell through G1 (growth)

25

Two ways that the concentration of cyclin is controlled

By transcription and proteolysis

Gradual increase in concentration of cyclin is due to increased transcription of cyclin gene

Abrupt decrease is due to concentrated destruction of protein

26

Cyclin a turn on ___________ even though their concentration levels increase slowly

Abruptly

27

Identify the three places where the cell cycle control system can pause the cell cycle

G1 to S transition

G2 to M transition

End of mitosis

28

G1 to S pause explain

Cdk inhibitors are used to keep cell out of S phase and DNA replication

29

G2 to M pause explain

An inhibitory kinase is used to inactivate the complex

30

End of mitosis pause explain

Inhibits APC (anaphase promoting complex) which tags the complex for destruction (if complex isn't destroyed, cell doesn't enter anaphase)

31

What would happen if cyclin cdk complexes aren't stopped at the end of M phase

The cell goes right back into mitosis with no growth

32

3 systems used to neutralize or block cyclin cdk complexes

Eliminating all existing cyclins

Blocking the formation of new cyclins

Deploying cdk inhibitor proteins

33

Explain process of eliminating all existing cyclins

A ubiquitin chain is added to the cyclin, ubiquitin is recognized by a complex called a proteasome, proteasomes have many proteases in them which chop up the protein that was tagged