Module 5 Cell Cycle and Cell Division: 3/29

Question 1

Necrosis

Answer 1

Natural Cell death due to catastrophic loss of homeostasis
* Due to external factors like: toxins, lack of nutrients, lack of oxygen, pathological reasons, organelle damage

Question 2

Apoptosis

Answer 2

Programmed cell death
* Required as a part of maintaining the correct number of healthy cells in the body
* Triggered if DNA damage too severe to correct

Question 3

p53 Tumor Suppresor, a checkpoint protein

Answer 3

• When cellular damage occurs, P53 arrests cell cycle until damage is repaired.
• DNA Damage -> P53 -> Cell cycle arrest -> DNA repair -> Cell cycle restart

Question 4

Cancerous Cells

Answer 4

Cells that divide uncontrollably

Question 5

Apoptosis Process

Answer 5

1. Change in refractive index
2. Cell shrinkage; Chromatin condensation; Junctions are severed
3. Membrane blebbing; Nuclear fragmentation
4. Apoptotic body formation; Phagocytosis / Absorption by surrounding cells

Question 6

Caspases, a proteolytic digestive enzyme

Answer 6

Mediates apoptosis
* Called procaspases when inactivated
* Activated by other caspases: termed proteolytic caspase cascade

Question 7

Activation of intitial procaspases:

Answer 7

by extracellular or intracellular death signals

Question 8

Extracellular signals

Answer 8

Provided by interactions with immune system cells

Question 9

Intracellular signals

Answer 9

Involve organelle damage, including leakage of enzymes from mitochondria into cytoplasm

Question 10

Why do cells need to self-destruct?

Answer 10

1. Cells become damaged, injured, or infected by pathogens
2. Cells might be killed to play a non-living structural role (keratinized cells in skin)
3. In plants, infected cells “sell themselves off” from the rest of the plant
4. A cell may no longer be needed (webbing in between fingers of developing human embryo)

Question 11

Cell death in skin cells

Answer 11

The most basal (inner) layer of cells are constantly being replenished. Outer layers self-destruct and shed off throughout the day.

Question 12

DNA Replication

Answer 12

During the S phase, the cell with devote much of its energy to replicating its entire genome

Question 13

Sister Chromatid

Answer 13

replicated DNA held together by a centromere

Question 14

Process of DNA replication requires:

Answer 14

1. Parental DNA molecule: Template to copy
2. Enzymes: To perform the copying
3. Nucleotide Triphosphates: Building blocks to make the new copy

Question 15

*Important: Recognize Nucleotide Triphosphate build

Nucleotide Triphosphate structure

Answer 15

1. Precursor dNTP
2. 5’ phosphate end
3. 3’ OH end

Question 16

Phosphodiester Bond Formation

Answer 16

5’ phosphate end attaches to 3’ OH end