Cell Cycle and Apoptosis

Question 1

Main Jobs of the Cell Cycle (2)

Answer 1

To accurately transmit the genetic information

To maintain normal ploidy (i.e. diploidy)

Question 2

Define: Euploidy

Answer 2

Addition of whole chromosome sets (e.g. n, 2n, 3n, 4n = haploid, diploid, triploid, tetraploid)

Question 3

Define: Aneuploidy

Answer 3

Addition or subtraction of one or more single chromosomes (e.g. 2n+1, 2n-1, 2n+2, etc)

Question 4

Interphase consists what % of the cell cycle?

Answer 4

90-95%

Question 5

What occurs during Interphase (3)

Answer 5

Organelle Duplication
DNA Replication
Growth

Question 6

What are the 3 phases of Interphase?

Answer 6

G1
S
G2

Question 7

Define: G0

Answer 7

Long term transient state depending on microenvironemnt and if there are ideal conditions

Question 8

What occurs during M Phase?

Answer 8

Mitotic Phase + Cytokinesis

Question 9

[G1 Phase]

With _________ duplication, but no _______ replication

Answer 9

Organelle Duplication

DNA Replication

Question 10

[S Phase]

What happens when this starts?
What happens to chromosomes?

Answer 10

Committed to Cell Division
DNA Replication

Chromosomes -> Chromatids

Question 11

[S Phase]

Sister Chromatids are tethered together by?

Answer 11

Cohesin

Question 12

[S Phase]

What happens to DNA number?
What happens to the ploidy number?

Answer 12

DNA number doubled

Ploidy of the cells remains the same

Question 13

[G2 Phase]

What forms here?
What happens to cellular content?
How many chromatids present?
How many chromosomes present?
What is the ploidy at this level?

Answer 13

Mitotic Spindle
Increases
92 Chromatids
46 Chromosomes
4N

Question 14

Division of the cellular nucleus is called?

Answer 14

Karyokinesis

Question 15

Stages of Mitosis (5)

Answer 15

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

Question 16

[What Happens]

Prophase

Answer 16

Chromatin condenses into chromosome structures and chromatin becomes visible under microscope

Question 17

[What Happens]

Prometaphase
What forms during this stage? Function?

Answer 17

Nuclear membrane disintegrates and breaks into membrane vesicles

Kinetochores form during this stage, they become attached to the microtubules that radiate from the centrosome at the spindle poles

Question 18

[What Happens]

Metaphase
What drives this occurrence?

Answer 18

Condensed chromosomes line up in the middle

Driven by motor proteins, kinesin and dynein, associated with microtubules

Question 19

[What Happens]

Anaphase

Answer 19

Chromosomes break up and sister chromatids are pulled to the opposite poles of the cell

Question 20

[What Happens]

Telophase

Answer 20

Daughter nuclei are formed and chromosomes unravel back into original expanded chromatin formation

Question 21

4 Requirements for Transmission of Chromosomes

Answer 21

1. Only one centromere
2. Functional telomere at both ends
3. Chromosomes must be fully replicated
4. Chromosomes cannot be too large or too small

Question 22

[Cytokinesis]

Is it a phase of mitosis?
When does it begin?

Answer 22

No

Early anaphase

Question 23

[G1 Checkpoint]

What is is it dependent on?

Answer 23

Nutrient availability and cell size (No division if its too small)

Question 24

[G2 Checkpoint]

Between what?
When is it stopped?

Answer 24

Between G2 and M Phase

No M phase if DNA replication is not completed

Question 25

[Spindle Assembly Checkpoint] Between what? What must happen?

Answer 25

Metaphase and Anaphase | Chromosomes must be properly attached to the spindle via TF4/Kinetochore

Question 26

What are spindle fibers made of?

Answer 26

Alternating alpha and beta tubulins, heterodimers

Question 27

Progression of the Eukaryotic cell cycle is driven by?

Answer 27

Cyclin-Dependent Kinases

Question 28

What residues are phosphorylated by Cdk?

Answer 28

Serine and/or Threonine

Question 29

How many Cdk targets in humans? | How many in Xenopus?

Answer 29

292 | 77

Question 30

4 Main Cyclins in Vertebrates

Answer 30

``` Cyclin: A B E D ```

Question 31

Function: Cyclin D

Answer 31

Binds CDKs early to mid G1, and together with Cyclin E/CDK2 inactivates pRB (cell cycle inhibitor)

Question 32

Function: Cyclin E

Answer 32

Binds to CDK2; Cycline E/CDK2 phosphorylates p27 (Cyclin D inhibitor) which tags it for degradation Functions G1 to S transition, promotes expression of Cyclin A

Question 33

Function: Cyclin A

Answer 33

S-Phase Cyclin, binds CDK2 Functions for G1 to S transition

Question 34

Function: Cyclin B

Answer 34

Functions in entry to M Phase Mitotic cyclin, binds CDK! to make MPF (Maturation Promoting Factor)

Question 35

Function: Mitogens

Answer 35

Allow cell to enter cell cycle

Question 36

What makes a cell undergo apoptosis? (2)

Answer 36

1. Withdrawal of Positive Signals | 2. Receipt of Negative Signals

Question 37

[Cell Positive Signals] (2)

Answer 37

Growth Factors | IL-2

Question 38

[Cell Negative Signals] (3)

Answer 38

``` Increased level of oxidants Damage to DNA by oxidants Death activators: TNF-a Lymphotoxin (TNF-b) Fas ligland (FasL) ```

Question 39

[Features of Apoptosis]

Answer 39

1. A number of activities take place  Occupation of death receptors  Dimerization of Bcl-2 family members Release of cytochrome c  Activation of caspases  Activation of DNase 2. Translocation of phosphatidylserine to OM 3. ATP dependency 4. Internucleosomal DNA fragmentation *Ladder pattern – in the gel, sign of a cell dying 5. No apoptosis at +4C 6. No inflammation

Question 40

[Apoptotic Cells in Culture] Pathway

Answer 40

Normal -> Blebs -> Spikes -> Blisters

Question 41

Define: Karyolysis

Answer 41

Nuclear Fading: Chromatin dissolution due to DNAses and RNAses

Question 42

Define: Pyknosis

Answer 42

Nuclear Shrinkage: DNA condenses into shrunken basophilic mass

Question 43

Define: Karyorrhexis

Answer 43

Nuclear Fragmentation: Pyknotic nuclei membrane ruptures and undergoes fragmentation