Cell Cycle

Question 1

Cell Cycle

Answer 1

process by which cells replicate their chromosomes and separate them into two new cells
- Resulting cells contain the same genetic material as the original

Question 2

Prokaryotic

Answer 2

• Lack a true nucleus or sub cellular organelles
• Bacteria and archaea

Question 3

Eukaryotic

Answer 3

• have a true nucleus and sub cellular organelles
• all other organisms on this planet (fungi, plants, and humans)

Question 4

Prokaryotic cell cycle

Answer 4

Reproduce asexually
1.) Bacterial chromosome is replicated (copied)
2.) Two copies are anchored on opposite sides of the cell
3.) Binary fission

Question 5

Binary fission

Answer 5

cell divides in half
- Each resulting cell has an identical copy of the bacterial chromosome = genetically identical

Question 6

Who coined the term mitosis?

Answer 6

Walther Flemming observed cell division and coined term mitosis

Question 7

Mitos

Answer 7

“warped thread”

Question 8

• osis

Answer 8

process

Question 8

Interphase

Answer 8

all other cells that are between mitosis

Question 9

G1 of interphase

Answer 9

Gap (Growth) phase
- normal cellular function/preparation for S

Question 9

G0 of interphase

Answer 9

cell cycle exit (arrest)
- normal cellular function WITHOUT dividing

Question 9

S phase of interphase

Answer 9

Synthesis phase
- DNA replication

Question 9

G2 phase of interphase

Answer 9

Gap (growth) phase
- preparation for mitosis

Question 9

Mitosis

Answer 9

division of the nucleus
cytokinesis: division of the cytoplasm

Question 9

Cell cycle control

Answer 9

controlled through reversible phosphorylation and dephosphorylation

Question 10

Molecular switches

Answer 10

Addition of phosphate group turns activity of proteins on and/or off

Question 11

Kinase

Answer 11

enzyme that adds phosphate groups

Question 12

Phosphatase

Answer 12

enzyme that removes phosphate groups
- depends on protein (and/or the phosphorylation site), can either activate or repress a protein’s function

Question 13

Cyclin Dependent Kinases (Cdks)

Answer 13

Add phosphates to other proteins
- drive transitions between phases of the cell cycle

Question 14

Are Cdks always present in the cell?

Answer 14

Yes, but can be inactive

Question 15

Activation of Cdks

Answer 15

1.) Bound to cyclin (cyclin levels fluctuate with the cell cycle; Cdk is only turned on when the cell wants to progress through the cell cycle)
2.) Addition of an activating phosphorylation (Cyclin-Cdks can auto phosphorylate themselves)
3.) Removal of inhibitory phosphates is done by phosphatase

Question 16

Different cyclin-cdk complexes regulate different phases of the cell cycle

Answer 16

G1-Cdk
S-Cdk
M-Cdk
Activation of the next cyclin-Cdk complex induces inactivation of the previous phase cyclin-Cdk

Question 17

Ex. what causes the destruction of S phase cyclin?

Answer 17

M-Cdk; turns off the S-Cdk during mitosis

Question 18

How is Cyclin degradation done?

Answer 18

Via ubiquitin-mediated proteolysis

Question 19

76 aa protein

Answer 19

Ubiquitin (Ub)

Question 20

Phosphorylation of the cyclin is the signal for ubiquitylation

Answer 20

- Poly-Ub signal for protein to be degraded ~ Directs protein to proteasome - Ubiquitylated proteins (cyclin) degraded in proteasome

Question 21

Two types of cell death

Answer 21

1.) Necrosis 2.) Apoptosis

Question 22

Necrosis

Answer 22

Usually resulting from injury or disease

Question 23

Characteristics of Necrosis

Answer 23

- Affects groups of neighboring cells - Chromatin clumping/random DNA fragmentation - Swollen cell/organelles - Burst mitochondria - Cellular lysing and release of intracellular components - Inflammation of neighboring tissues

Question 24

Apoptosis

Answer 24

Programmed cell death

Question 25

Characteristics of Apoptosis

Answer 25

- Affects single cell - Ordered (non-random) DNA fragmentation - Nuclear compaction and fragmentation - Mitochondria remain intact - Cell membrane blebbing - Phagocytosis by neighboring cells = no inflammation response

Question 26

Which cell death shows distinctive blebbing from the cell surface?

Answer 26

Apoptosis

Question 27

Critical part of many developmental processes

Answer 27

Apoptosis (ex. frog losing its tadpole tail) (ex. humans get rid of the webbing between fingers)

Question 28

G0 Phase

Answer 28

Animal cells can exit the cell cycle and remain quiescent

Question 29

G1 Phase

Answer 29

cell grows in size - cell doubles organelles - LONGEST phase

Question 30

S Phase

Answer 30

DNA replication

Question 31

G2 Phase

Answer 31

Proteins needed for division are synthesized