Chapter 18 -> The Cell Division Cycle

Question 1

All living organisms are products of repeated rounds of cell ______ and _______

Answer 1

Growth, Division

Question 2

What is the Cell Cycle?

Answer 2

Cycle of duplication and division

Question 3

Universal truths of the cell cycle

• Cells must copy and pass on their _________ to the next generation of cells
• DNA in chromosomes must be ________
• Replicated chromosomes must be ________ into the two daughter cells

Answer 3

Genes
Duplicated
Seperated

Question 4

What are the three overview steps of the cell cycle?

Answer 4

1) Cell Growth and Duplication
2) Chromosomes Segregation
3) Cell Division

Question 5

Why is a fly’s cell cycle faster than a bacterial cell cycle?

Answer 5

The number of Origins of Replications is greater in the fly than the bacteria

Question 6

The eukaryotic Cell Cycle is divided into what 4 phases?

Answer 6

M Phase
G1 Phase
S Phase
G2 Phase

Question 7

What occurs during the M Phase of the cell cycle?

Answer 7

Nucleus divides, Cytoplasm divides, and Cell Splits into 2 (cytokinesis)

Question 8

Interphase constitutes what phases of the cell?
What occurs during Interphase?

Answer 8

G1, G2, and S Phases
Cell increases in size

Question 9

What occurs during the S phase of Interphase?

Answer 9

DNA is replicated
S phase is in between the G1 and G2 resting phases

Question 10

What occurs during G1 Phase of Interphase?

Answer 10

Completion of M phase to beginning of S phase
Sort of a gap/growth period in the cell cycle

Question 11

What occurs during G1 Phase of Interphase?

Answer 11

Completion of M phase to beginning of S phase
Sort of a gap/growth period in the cell cycle

Question 12

What is the main purpose of G1 and G2 phases of the cell cycle?

Answer 12

Allows for time for cell to grow and duplicate organelles

Question 13

A central control system triggers the major processes of the cell cycle
When this mechanism breaks, what occurs?

Answer 13

Cancer

Question 14

The central control system in the cell cycle is regulated at certain points by _________ from the processes

Answer 14

Feedback

Question 15

Two important checkpoints in G1 and G2

G1 checkpoint allows cell to confirm that…
G2 checkpoint ensures that cells don’t enter mitosis until damaged ______ is repaired and DNA replication is complete

Answer 15

environment is favorable for proliferation and DNA is intact before going to S Phase

DNA

Question 16

What are the two types of machinery that are involved in cell division?

How does the cell cycle control system control all of this?

Answer 16

Manufacturing new components of growing cell
Hauling components into correct places

Switches the machinery on and off at correct times throughout cycle

Question 17

The cell cycle control system depends on ___________

The system can cyclically activate then deactivate key proteins that initiate or regulate __________ (3 things)

Answer 17

Cyclically activated protein kinases

DNA replication, Mitosis, Cytokinesis

Question 18

____________ and ____________ are common ways for cells to switch the activity of proteins on or off

Answer 18

Phosphorylation, Dephosphorylation

Question 19

What do protein kinases do?

Answer 19

Transfer P group from ATP to a protein changing the conformation of the protein

Question 20

What do protein phospatases do?

Answer 20

Remove P group

Question 21

Cyclin-dependent kinases rely on a set of proteins called _________ to switch them on and off at the appropriate time

Cyclins have to bind to the cell cycle kinases before the kinases can become ________

Answer 21

Cyclins

Activated

Question 22

Cyclin dependent protein kinases are regulated by the accumulation and destruction of ________

Answer 22

Cyclins

Question 23

Cyclin Example: M-cyclin (M-CDK Complex)

synthesis of M-cyclin starts after cell division, continues through interphase and continues to rise in concentration
This times the onset of ________, cells entering M-phase
After, M-cyclin is rapidly eliminated and cells then exits the _ phase

Answer 23

Mitosis
M

Question 24

M-CDK Complex Summary

Flooding of M-cyclin causes _________ to becomes active and ready to phosphorylate key proteins that push the cell into M-phase

For M-CDK to be active and at its max, it has to be ___________ at certain sites and _____________ at other sites

Answer 24

Kinases

Phosphorylated, Dephosphorylated

Question 25

At the end of M-phase, a fall in ____-______ concentration occurs, causing _________ to tag protein then demolish it to control tagging of m-cyclin, a protein complex called the ______ ________ _______ adds Ubiquitin tags to the cyclin *This complex is only switched on late in M-phase*

Answer 25

m-cyclin, Ubiquitins Anaphase Promoting Complex

Question 26

Universal cyclin property the concentration of each type of cyclin rises ________ then falls ________ as a result of Ubi degradation

Answer 26

slowly, rapidly

Question 27

Summary of M-Cyclin Control Mechanism 1) M-cyclin concentration _______ throughout interphase interacting with kinases, forming ____-______ complexes, but they are not yet active 2) When appropriate concentration is reached, ______________ step activates CDK-Cyclin complex and pushed cell into mitosis 3) Late in the M-phase, _________ causes M-cycliin to be tagged for degradation by ________ 4) M-cyclin degraded complex is now inactive and cell can move on from mitosis

Answer 27

1) Increases, CDK-Cyclin 2) dephosphorylation 3) APC, Ubiquitin Tags

Question 28

DNA damage causes an increase in concentration and activity of _______ P53 then activates the production of ________ P21 binds to G1/S-CDK and S-CDK preventing cell from going into ____ phase

Answer 28

P53 P21 S

Question 29

What happens if p53 is missing or defective

Answer 29

Replication of damaged DNA occurs, leading to production of cancerous cells

Question 30

Mutations in p53 gene are found in about ______ of all human cancers

Answer 30

Half

Question 31

Apoptosis The number of cells in an organism are controlled by rates of cell division and rates of cell death

Question 32

Steps of Apoptosis 1) The cells shrinks and condenses 2) ________ collapses 3) Nuclear envelope dissasmebles 4) Nuclear DNA breaks into _________ 5) Cell surface is altered -> attracts ________ cells 6) Cell engulfs and splits contents

Answer 32

Cytoskeleton, Phagocytic

Question 33

What is cell necrosis?

Answer 33

The spilling of cell contents onto neighboring cells

Question 34

What proteases enzyme carries out apoptosis by cutting up other proteins? Activated caspases cleave and activate other members of the family resulting in a cascade Once a cell reaches a critical point along the path to destruction it cannot turn back

Answer 34

Caspases

Question 35

Apoptosis Summary 1) occurs in developing or adult ________ where cells receive a signal to die 2) Process is controlled by the enzyme ______ 3) Procaspases (the inactive form of a caspase) are activated by cleavage leading to the formation of ____________ 4) This causes a caspase _________ cascade 5) Results in cytoskeleton, nuclear membrane, and DNA damage followed by _______

Answer 35

1) tissues 2) caspase 3) apoptosome 4) protein 5) phagocytosis

Question 36

What does the myostatin gene do?

Answer 36

Causes everything to look buff as hell

Question 37

Cyclin dependent protein kinases are regulated by the accumulation and destruction of ________ The cyclin that helps drive cells into m phase is called _______ The active complex that it forms with its CDK is called ______

Answer 37

Cyclins M-Cyclin M-CDK

Question 38

M-CDK Complex Summary Synthesis of M-cyclin starts after _______ and continues throughout interphase M-cyclin accumulate, causing the onset of _______ It is then rapidly eliminated and cell exits M-Phase

Answer 38

Cell Division Mitosis

Question 39

The activity of CDKs is regulated by ___________ and ___________ Example: for M-CDK to be maximally active, it has to be phosphorylated at certain sites and dephosphorylated at other sites *The removal of ____ group by a phosphatase is the final step that activates MCDK at the end of interphase

Answer 39

Phosphorylation and Dephosphorylation P

Question 40

Summary of M-Cyclin Control Mechanism 1) M-cyclin concentration increases throughout _______ all the time complexing with kinase to form _______________ complex, but is not active 2) When the appropriate concentration is reached, dephosphorylation by ______ activates CDK-Cyclin complex, pushing cell into mitosis 3) Late in M-Phase, _____ causes M-Cyclin to be tagged for degradation by ______ 4) At end of mitosis, M-cyclin degraded CDK-Cyclin complex is therefore ________ 5) Cell pushed from mitosis and the process begins again

Answer 40

1) Interphase, CDK-Cyclin 2) Wee1 3) APC, UBI 4) Inactive