Cell Cycle and Mitosis

Question 1

Define Interphase

Answer 1

Cell growth stage where cells increase in size and duplicate DNA in preparation for replication

Question 2

What are the two parts of the replication stage?

Answer 2

Mitosis and Cytokinesis (meiosis)

Question 3

What are the 4 phases cell cycle? Which phases are part of interphase?

Answer 3

• G1 Phase
• S phase
• G2 Phase
• Mitosis and Cytokinesis

Question 4

What happens in the G1 phase? Conditions required to move to next stage? State of DNA

Answer 4

• Growth
• Big cell size, undamaged DNA, favorable environment
• relaxed chromatin (1)

Question 5

What does the term homologous mean?

Answer 5

Same genes in the same order but the DNA sequence is not identical

Question 6

What happens in the S phase? Conditions required to move to next stage? State of DNA

Answer 6

• DNA synthesis/replication
• 2 copies of DNA from replication
• relaxed chromatin (1–>2)

Question 7

What happens in the G2 phase? Conditions required to move to next stage? State of DNA

Answer 7

• More growth, preparation for cell division
• No DNA damage, if environment is still favorable
• relaxed (2)

Question 8

What is the use of cell cycle checkpoints?

Answer 8

Ensure that cells only move to next phase if everything ready

Question 9

What happens at the G1/S Checkpoint?

Answer 9

• Is the environment favourable?
• Check for undamaged DNA, is the cell big enough?
  if yes move to S phase

Question 10

G2/M Checkpoint?

Answer 10

• are chromosomes replicated?
  -DNA undamaged?
  if yes start mitosis

Question 11

M-Phase Checkpoints

Answer 11

-Are chromosomes attached to spindle apparatus?
-If yes are chromosomes properly segregated?
If yes finish mitosis

Question 12

What is the G0 Phase?

Answer 12

Mature cells and cells that can’t divide again leave the cell cycle and enter G0 phase

Question 13

Is chromosome number duplicated in S phase? If not what is?

Answer 13

No, DNA is replicated but chromosome number stays the same.

Question 14

A cell can be experimentally made top move through the cell cycle more quickly but if it hasn’t passed through the _ phase, then it has no hope for survival?

Answer 14

s-phase because if you have not replicated your DNA then mitosis cannot be an option.

Question 15

What do we call the protein structure that helps join the mitotic spindle to the chromosome?

Answer 15

kinetochore

Question 16

What is the difference between mitosis and cytokinesis?

Answer 16

Mitosis is the separation of the DNA and cytokinesis is the division of the rest of the cytoplasm

Question 17

Mitosis

What is separated in mitosis?

Answer 17

Sister chromatids

Question 18

First Phase of Mitosis

Prophase

Answer 18

• chromosomes condense and become visible
• nucleolous dissapears
• centrosomes move to opposite sides of the cell
• spindle fibres emerge from centrosmes
• nuclear envelope breaks down
• the sister chromatids coil more tighlty with the help of condesin protein

Question 19

Second Phase of Mitosis

Prometaphase

Answer 19

• mitotic spindle continues to develop as the microtubules enlarge
• chromosomes become more condensed
• kinetochores appear at the centromeres
• mitotic spindle microtubules attach to kinetochore

Question 20

Metaphase

Answer 20

• Mitotic Spindle is Fully Developed
• chromosomes are lined up at the metaphase plate
• each sister chromatid is attached to a spindle fiber originating from opposite poles

Question 21

Mitosis

Anaphase

Answer 21

• condesin protein binding sister chromatid breaks down
  -sister chromatids separate at the centromere
• sister chromatids (now chromosomes) are pulled to opposite poles
  non-kinetochore spindle fibres lengthen, elongating the cell

Question 22

Mitosis

Telophase

Answer 22

• Chromosomes arrive at opposite poles and begin to decompose (relaxing back int chromatin
• nuclear envelope material surrounds each set of chromosomes
• The mitotic spindle breaks down

Question 23

Cytokinesis

Answer 23

Animal Cells: a cleavage furrow separates the daughter cells

Plant Cells: a cell plate separates the daughter cells

Question 24

Mitosis

What is Non-disjunction?

Answer 24

Imporoper separation of chromosomes, usually fatal to both cells but minimal impact to organism.

Question 25

Haploid Versus Diploid

Answer 25

Haploid: one complete chromosome set / one copy of each chromosome (none homologous chromosomes)

Diploid: Two copies of each chromosome (pairs of homologous chromosomes)