Meiosis

Question 1

Characteristics of homologous chromosomes

Answer 1

-same size
-same centromere position
-same sequence of genes at the same loci

Question 2

How do differences arise in homologous chromosomes?

Answer 2

Since the chromosomes are inherited from different parents, the alleles of the genes on each homologous chromosome may be different.

Question 3

What is meiosis?

Answer 3

The division of the nucleus that results in the formation of haploid gametes from a diploid gametocyte

Question 4

Meiosis 1

Answer 4

-interphase
-prophase
-crossing over
-metaphase 1
-independent assortment
-anaphase 1
-telophase 1

Question 5

Interphase

Answer 5

The chromosomes, which have replicated prior to meiosis 1, each consist of two genetically identical chromatids attached at the centromere.

Question 6

Prophase

Answer 6

The chromosomes condense and the homologous chromosomes pair up.

Question 7

Crossing over

Answer 7

Chiasma form at points of contact between non-sister chromatids of a homologous pair. The crossing over of DNA is random and produces genetically different recombinant chromosomes. Therefore it helps to increase variation. Sections of DNA are exchanged.

Question 8

Metaphase 1

Answer 8

Spindle fibres attach to the homologous pairs and line them up at the equator of the spindle.

Question 9

Independent assortment

Answer 9

The orientation of the pairs of homologous chromosomes at the equator is random - each pari of homologous chromosomes is positioned independently of the other pairs, irrespective of their maternal and paternal origin.

Question 10

Anaphase 1

Answer 10

The chromosomes of each homologous pair are separated and move towards opposite poles/

Question 11

Telophase 1

Answer 11

Cytokinesis occurs and two daughter cells form.

Question 12

Meiosis 2

Answer 12

-metaphase 2
-anaphase 2
-telophase 2

Question 13

Metaphase 2

Answer 13

Spindle fibres attach to the chromosomes and they once again line up at the equator of the spindle

Question 14

Anaphase 2

Answer 14

The sister chromatids of each chromosome are separated and move towards opposite poles

Question 15

Telophase 2

Answer 15

Cytokinesis occurs, producing 4 haploid cells that are capable of becoming gametes.

Question 16

Meiosis summary

Answer 16

1. The process by which 4 genetically different haploid cells are formed.
2. Requires two divisions
3. Ensures the chromosome compliment is maintained from one generation to the next
4. Increases variation via crossing over and independent assortment.