Mod. 2 Cell division (meiosis)

Question 1

diploid

Answer 1

two chromosomes of each type in the nucleus. most cells

Question 2

haploid

Answer 2

one chromosome of each type in the nucleus. gamete cells. made by reduction division.

Question 3

homologous chromosomes

Answer 3

each chromosome in the pair has the same gene in the same loci.

Question 4

alleles

Answer 4

Different types of the same gene. The alleles code for differences in a gene in the same locus.

Question 5

What are the two parts of meiosis?

Answer 5

meiosis 1 - reduction division causes the daughter cells to be haploid.
meiosis 2 - similar to mitosis, homologous chromosomes are split into separate daughter cells.

Question 6

What happens in meiosis prophase 1?

Answer 6

Chromosomes condense, the nuclear envelope disintegrates, spindle formation begins. Homologous pairs of chromosomes pair up and form bivalents. The chromatids tangle and cross over.

Question 7

What happens in meiosis metaphase 1?

Answer 7

Homologous pairs of chromosomes line up along metaphase plate. There is no organisation, it is independent assortment, so paternal and maternal genetic information is mixed up. Provides genetic variation.

Question 8

What happens in meiosis anaphase 1?

Answer 8

Homologous chromosomes pulled to opposite ends of cell, chromatids remain joined together. Some sections of the chromatids that entangle during crossing over break off and rejoin, at points called chiasmata. This will result in more genetic variation because the alleles in the chromatid pairs will different, resulting in more genetic variation.

Question 9

What happens in meiosis telophase 1?

Answer 9

Chromosomes assemble at each pole, the nuclear membrane reforms and the chromosomes uncoil. Cell undergoes cytokinesis and divides cell down the metaphase plate.

Question 10

What happens in meiosis prophase 2?

Answer 10

Chromosomes condense, nuclear envelope breaks down, spindle fibres form.

Question 11

What happens in meiosis metaphase 2?

Answer 11

Individual chromosomes gather on metaphase plate. There is further independent assortment, more genetic variation.

Question 12

What happens in meiosis anaphase 2?

Answer 12

Chromatids of individual chromosomes are pulled apart after division of centromeres.

Question 13

What happens in meiosis telophase 2?

Answer 13

chromatids assemble at the poles, chromosomes uncoil and form chromatin again. Nuclear envelope reforms. Cytokinesis results in the two daughter cells of meiosis 1 being divided into two futher daughter cells each, so 4 total daughter cells.