2.3 b) Meiosis

Question 1

What is meiosis?

Answer 1

the division of the nucleus which creates four gametes from a gametocyte

Question 2

Meiosis is the ___ of the ___ which results in the production of ___ gametes from a ___ ___.

Answer 2

division, nucleus, haploid, diploid gametocyte

Question 3

A gametocyte is a cell which ___ (by meiosis) to form ___.

Answer 3

divides, gametes

Question 4

In diploid cells, chromosomes typically appear as ___ ___.

Answer 4

homologous pairs.

Question 5

What are homologous chromosomes?

Answer 5

chromosomes of the same size, centromere position and sequence of genes at the same loci
(loci = specific point on chromosome)

Question 6

Homologous chromosomes are chromosomes of the same ___, ___ ___, and sequence of ___ at the same loci.

Answer 6

size, centromere position, genes

Question 7

Meiosis is split into which stages?

Answer 7

Meiosis I and Meiosis II

Question 8

The chromosomes (which replicated ___ meiosis I) each consist of two genetically ___ chromatids, attached at the ___.

Answer 8

before, identical, centromere

Question 9

During meiosis I the chromosomes ___ and the ___ chromosomes line up along…

Answer 9

condense, homologous, the equator of the spindle. (They line up perpendicular to the equator)

Question 10

___ form at the points of contact between the non-___ chromatids of a ___ pair, and sections of ___ are ___.

Answer 10

Chiasmata, sister, homologous, DNA, exchanged

Question 11

What is a chiasmata?

Answer 11

the point at which non-sister chromatids of a homologous pair touch/cross over, before sections of DNA are exchanged

Question 12

The crossing over of ___-___ chromatids occurs at a chiasmata, resulting in new ____ of ___ in the affected ____.

Answer 12

non-sister,
combinations, alleles, genes

Question 13

Linked genes are those in the ___ ___.

Answer 13

same chromosome (they are close together)

Question 14

The exchange of DNA sequences at a chiasmata leads to the ___ of ___ of linked genes.

Answer 14

recombination, alleles. (Linked genes are more likely to stay together when sections of DNA are exchanged at the chiasmata -as they are close together)

Question 15

The transfer of DNA at a chiasmata is ___, and produces genetically ___ recombinant ___.

Answer 15

random, different, chromosomes

Question 16

Recombination is responsible for the production of genetically different ___.

Answer 16

gametes

Question 17

Spindle fibres attach to the ___ ___ and line them up parallel to the…

Answer 17

homologous pairs, equator of the spindle

Question 18

The ___ of the pairs of ___ ___ at the equator is ___.

Answer 18

orientation, homologous chromosomes, random

Question 19

Each pair of ___ ___ is positioned ___ compared to the other pairs at the equator of the spindle.
They are arranged irrespective of their ___ or ___ origin.
This is known as ___ ___.

Answer 19

homologous chromosomes, independently, maternal, paternal.

independent assortment

Question 20

What is independent assortment?

Answer 20

the fact that homologous chromosomes are positioned independent of the other pairs, regardless of its maternal or paternal origin.

Question 21

Chromosomes of each ___ pair are separated, and move towards ___ ___ of the cell.
Then ___ occurs, creating two ___ ___.

Answer 21

homologous, opposite poles.
cytokinesis, daughter cells

Question 22

In meiosis II, each of the two cells produced in ___ _, undergoes a further ___ in which the ___ ___ of each ___ are separated.

Answer 22

meiosis I, division, sister chromatids, chromosome.

Question 23

At the end of meiosis II, a total of _, ___ cells are formed.

Answer 23

4, haploid (tho the cells produced in meiosis 1 were also haploid, just with two chromatids per chromosome)

Question 24

What happens in meiosis I?

Answer 24

1. the (homologous) chromosomes condense and line up along the equator.
2. sections of DNA are exchanged between non-sister chromatids at the chiasmata.
3. Spindle fibres attach to the homologous pairs and line them up along the equator of the spindle. (independent assortment happens)
4. The chromosomes are pulled to opposite poles of the cell.
5. cytokinesis happens, producing 2 haploid cells

Question 25

What happens in meiosis II?

Answer 25

the 2 haploid cells produced in meiosis I divide into 4 haploid gametes

Question 26

During the Prophase of Mitosis, the chromosomes (condense/decondense), and they (condense/decondense) during the Telophase.
At the start of Meiosis I, the chromosomes (condense/decondense).

Answer 26

Prophase: condense
Telophase: decondense
meiosis I: condense