Cell division

Question 1

What are histones?

Answer 1

Proteins that encircle DNA to make it more compact (forming nucleosomes) so that it can be packaged into chromosomes

Question 2

What is mitosis?

Answer 2

Mitosis is a type of cell division that results in the exact copying of cells - one parent cell dividing to form 2 identical daughter cells

Question 3

How many chromosomes are there in a diploid cell i.e. a fertilised egg?

Answer 3

22 pairs of homologous autosomal pairs and 1 pair of sex chromosomes (46 chromosomes)

Question 4

What is interphase?

Answer 4

Interphase is the phase before division, in mitosis, it consists of G1 (when the cell grows), Synthesis (when the cell replicates it’s DNA) and G2 (when the cell continues to grow). Most cells live the majority of their cell cycle in this phase before division

Question 5

What is a chromatid?

Answer 5

One copy of DNA. Two identical sister chromatids form a chromosome

Question 6

What are the phases of mitosis?

Answer 6

Interphase, prophase, metaphase, anaphase, telophase IPMAT

Question 7

What happens in prophase?

Answer 7

Chromatin condenses into chromosomes

Question 8

What happens in metaphase?

Answer 8

Chromosomes line up in the centre of the cell, nuclei disappear, mitotic spindles form and the chromosomes attach to the spindles (forming kinetochore microtubles) (MEET)

Question 9

What happens in anaphase?

Answer 9

The kinetochore microtubules shorten, separating the chromatid pairs and the spindles start to pull the sister chromatids to the poles of the cell (APART)

Question 10

What happens in telophase?

Answer 10

(The end). The chromatids reach the poles of the cells. The spindles disappear. Two new nuclei form and the chromosomes decondense.

Question 11

What is cytokinesis?

Answer 11

Cytokenesis occurs after telophase, the cell splits in half (the cytoplasm divides) to form two cells.

Question 12

What is meiosis?

Answer 12

Cell division that results in 4 haploid daughter cells (i.e. the formation of gametes)

Question 13

How do mitosis and meisois differ?

Answer 13

Mitosis results in 2 identical diploid daughter cells, meiosis results in 4 haploid daughter cells. Mitosis undergoes IPMAT once, Meiosis undergoes IPMAT twice. In meiosis there is the possibility for variation so new combination of genes can be inherited (mendelian inheritance occurs in prophase 1)

Question 14

What does Northern blotting show?

Answer 14

RNA

Question 15

What does Southern blotting show?

Answer 15

DNA

Question 16

What does Western blotting show?

Answer 16

Proteins (this process requires protein antibodies)

Question 17

What is aneuploidy?

Answer 17

Presence of an abnormal number of chromosomes i.e. down’s syndrome and turner’s syndrome

Question 18

What are the short and long arms of chromosomes called?

Answer 18

short arm = p for petite

Long arm = q for QOLLOSAL