Lecture 2- Cell Division

Question 1

4 function fo cell dividion:

Answer 1

1.Growth
2.Development
3.Repair
4.Reproduction

Question 2

Cell cycle overview:

Answer 2

Nuclear genome duplicates, DNA strands separate creating two parent strands that are duplicated. Results new duplex contains one parent and one daughter strand. Then semiconservatice replication occurs.

Question 3

Phases of cell cycle:

Answer 3

-G0 (cell cycle arrest)
-G1 (cell growth and preparation)
-S (DNA replication)
-G2 (resting phase, where the cell checks for duplicated chromosomes and repairs errors)
-Mitosis (cell divides)

Question 4

Mitosis vs Meisois

Answer 4

-Mitosis occurs in somatic cells and produces diploid cells (2n)
-Meiosis generates gameres and produces haploid cells (n)

Question 5

Phases of Mitosis

Answer 5

-Interphase (G1, S and G2)
-Prophase
-Prometaphase
-Metaphase
-Anaphase
-Telophase (and cytokinesis)

Question 6

Interphase:

Answer 6

A nuclear envelope surrounds the nucleus, DNA is replicated in S, the sister chromatids join at the centromere.

Question 7

Prophase:

Answer 7

The chromatin fibres condense into chromosomes.
-The mitotic spindle begins to form
-Centrosomes begin to move to opposite ends of the cells and are propelled by the microtubules.

Question 8

Prometaphase:

Answer 8

-The nucelar envelope falls apart
-The microtubules bind to some of the chromosomes and kinetochores.
(Not all microtubules bind).

Question 9

Metaphase:

Answer 9

-The centrosomes migrate to opposite poles of the cell.
-The chromsomes line up at the metaphase plate in the middle of the cell.
-All chromosomes are attached to microtubles through their kinetochore.

Question 10

Anaphase:

Answer 10

-The sister chromatids break apart
-The chromosomes move to oppsoite ends of the cells. (so each end of the cell has equal no of chromosomes)

Question 11

Teleophase:

Answer 11

-2 daughter nuclei form and the nuclear enevlope forms again.
-DNA decondense and the spindle microtubules depolymerize.
Mitosis (division of nucleus) is now complete

Question 12

Cytokinesis

Answer 12

Is the division of the cytoplasm as a cleavage furrow forms and the cell divides into 2 separate cells.

Question 13

Mitotic spindle

Answer 13

Is constructed from microtubules and proteins in order to seperate sister chromatids.

Question 14

What is the mitotic spindle composed of:

Answer 14

-Aster
-Polar microtubule
-Kinetochore microtube
-Kinetochore
-Centriole pair
-Centrosome

Question 15

What is the centrosome?

Answer 15

Microtubule organizing centre

Question 16

What is the centromere:

Answer 16

Specific DNA sequence, essential for segregration during cell division.
-If the centromere doesn’t attach to the spindle it is not passed to daughter cells.

Question 17

Phases of Meiosis

Answer 17

meiosis I (prophase I, metaphase I, anaphase I, telophase I) and meiosis II (prophase II, metaphase II, anaphase II, telophase II)

Question 18

Why is there more stages in meiosis then mitosis

Answer 18

Because homologous chromosomes are separated during a first round of cell division, called meiosis I. Sister chromatids separate during a second round, called meiosis II.

Question 19

What is recombination?

Answer 19

It is the exchange between maternal and paternal chromosomes to create homologoue pairs.