Theme 4- Module 1 (Mitosis)

Question 1

Why is cell division also considered reproduction in prokaryotic cells?

Answer 1

Bc the division of one prokaryotic cell will give rise to a new organism

Question 2

What is binary fission?

Answer 2

The process of cell division (asexual reproduction) in prokaryotes

Question 3

What is the first step of binary fission?

Answer 3

DNA of the bacterial chromosome is attached by proteins to the inside of the plasma membrane

Question 4

True or false: in binary fission, newly synthesized DNA is also anchored to the plasma membrane

Answer 4

True

Question 5

What’s the difference between stem cells in the adult body and stem cells in embryos?

Answer 5

Adult stem cells cannot give rise to all cell types in the organism

Only able to replace non-reproducing specialized cells (ie. mammalian adult skeletal muscle)

Question 6

In what situation would stem cells replace mammalian adult skeletal muscle?

Answer 6

When the muscle is damaged

Question 7

What are the stages in interphase (in order)?

Answer 7

G1 phase (growth)

S phase (synthesis)

G2 phase (growth)

Question 8

What happens during the G1 phase?

Answer 8

Cell gets ready for synthesis

Question 9

What happens during the S phase?

Answer 9

Replication of DNA

Question 10

What happens during the G2 phase?

Answer 10

Cell gets ready for mitosis

Question 11

Give examples of cells that req freq turnover

Answer 11

Epithelial cells of the intestine or the skin

Question 12

Cells that make up the lenses of our eyes, nerve cells and even mature muscle cells enter into a permanent ____ phase

Answer 12

G0

Question 13

When does the G0 phase occur?

Answer 13

Somewhere between the M and S phase

Question 14

In what phase are the quiescent satellite stem cells in?

Answer 14

The G0 phase

Question 15

What are the five distinct stages of mitosis based/characterized on?

Answer 15

Morphometrically characterized based on the distinctive changes that occur to the chromosomes (position and features)

Question 16

Who discovered that distinct stages of mitosis could be staged based on chromosomal position and features?

Answer 16

Walther Flemming

Question 17

Describe Walther Flemming’s work

Answer 17

Analyzed developing salamander embryos that he had stained to be able to visualize the chromosomes

Question 18

What are the five phases of mitosis?

Answer 18

Prophase 
Prometaphase
Metaphase
Anaphase 
Telophase

Question 19

What are the main goals of interphase?

Answer 19

To duplicate and condense the chromosomes of cells

(to allow for the daughter cells to acquire the the same amount of genetic information as the parent cell in a relatively short period of time)

Question 20

What allows for tight compaction of the chromosomes?

Answer 20

Association with histones and other proteins

Question 21

True or false: the centromeres of the chromosomes do not get replicated

Answer 21

False

The centromere is fully replicated, it is simply so highly compacted that the paired centromeres appear fused together

Question 22

How many chromosome pairs do we have?

Answer 22

23

Question 23

How many homologous pairs of chromosomes do we have?

Answer 23

22

Question 24

How many sex chromosomes do we have?

Answer 24

1 pair (two in total)

Question 25

True or false: cytokinesis is the same in both plants and animals

Answer 25

False Plants have a cell wall, so they need to account for that. They lay down a newly developed cell wall along a cell plate region in the middle of the dividing cell. Once the forming cell wall fuses with the original cell wall, cytokinesis is then complete.

Question 26

Describe Tim Hunt's experiment and results

Answer 26

He decided to measure the protein level changes of dividing sea urchin embryos Procedure: Hunt added radioactively labelled methionine to the sea urchin eggs. He took samples of the rapidly dividing embryos every 10 minutes and visualized any changes in protein levels using gel electrophoresis. Results: - most protein bands on the gel became darker as cell division and embryonic development progressed - one protein oscillated; increased then decreased with each subsequent cell division. Called this protein cyclin

Question 27

What is gel electrophoresis?

Answer 27

A procedure that allows for distinct separation of different protein types

Question 28

What does the mitosis promoting factor do?

Answer 28

Allows for the transition from the G2 to M phase of the cell cycle; plays a regulatory role on cell cycle progression

Question 29

What does the mitosis promoting factor consist of?

Answer 29

A cyclin protein + a cyclin- dependent kinase (or CDK) protein

Question 30

What are kinases and what do they do?

Answer 30

They are enzymes that activate or inactivate other proteins by phosphorylating key amino acids on the target proteins

Question 31

Why have the kinases that regulate the cell cycle acquired the name "cyclin-dependent kinases"?

Answer 31

Bc for much of the time they are in an inactive form until they are activated by binding to cyclin proteins

Question 32

What does the activity of cyclin-dependent kinases depend on?

Answer 32

The changes in the concentration of its activating cyclin protein

Question 33

True or false: the conc of cyclin does not change

Answer 33

False It can change

Question 34

True or false: the conc of cyclin-dependent kinases does not change

Answer 34

True The conc doesn't change; just the number of them that are active

Question 35

True or false: the conc of cyclin DECREASES as the embryo divides by mitosis

Answer 35

True

Question 36

What are the different types of cyclin-CDK complexes that are involved in the regulation of each stage of the cell cycle?

Answer 36

G1/S cyclin-CDK complex S-cyclin-CDK complex M cyclin- CDK complex

Question 37

What does the G1/S cyclin-CDK complex do?

Answer 37

Helps to prepare the cell for DNA replication (such as increasing the expression of histone proteins) Needed for the transition from the G1 to S phase

Question 38

What does the S-cyclin-CDK complex do?

Answer 38

Helps to initiate DNA synthesis

Question 39

What does the M cyclin- CDK complex do?

Answer 39

Initiates the process of mitosis

Question 40

How do CDK complexes help initiate mitosis?

Answer 40

Phosphorylate structural proteins that are needed for: - nuclear membrane breakdown - regulation of the assembly of microtubules in the mitotic spindles

Question 41

What is the purpose of cell cycle checkpoints?

Answer 41

Able to block cyclin-CDK activity should something go wrong during the progression of the cell cycle - can pause cell division until the preparation for the next stage of the cell cycle is complete - an opportunity for damage to be repaired

Question 42

What are the three major checkpoints of the cell cycle and when do they occur?

Answer 42

DNA damage checkpoint at the end of G1 phase DNA replication checkpoint at the end of the G2 phase Spindle assembly checkpoint before anaphase during mitosis

Question 43

What is required in order for each cell to pass the G1 checkpoint (and enter S phase for replication)?

Answer 43

Undamaged DNA

Question 44

What is required in order for each cell to pass the G2 checkpoint (and enter mitosis phase)?

Answer 44

All DNA has to be replicated

Question 45

What is required in order for each cell to pass the M checkpoint (and complete mitosis)?

Answer 45

All chromosomes have to be attached to a microtubule from the mitotic spindle