5.meiosis

Question 1

Autosomes

Answer 1

Autosomes are any chromosomes in humans that is not a sex chromosome

Question 2

Sex chromosomes

Answer 2

sex chromosomes are a chromosome responsible for determining the biological sex of an organism. In humans, sex chromosomes can be either an X or Y chromosome.

Question 3

What is meiosis

Answer 3

Process by which a germline cells gives rise to four genetically different cells. Each daughter cell inherits half of the set of DNA from the parent cell.

Question 4

Germline cells

Answer 4

• the precursors for gametes
• diploid
• 2n=46

Question 5

diploid

Answer 5

The number of chromosomes found as homologous pairs in a cell

Question 6

haploid

Answer 6

one of each pair of homologous chromosomes

Question 7

features of homologous chromosomes

Answer 7

• same size
• same length
• same centromere position
• share the same genes at a specific gene loci

Question 8

where does meiosis occur

Answer 8

Meiosis only takes place in the germline cells in the sex organs eg testes and ovaries
GONADS

Question 9

purpose of meiosis

Answer 9

• produce 4 haploid gametes

- haploid gametes fuse in fertilisation to create a diploid zygote

Question 10

how many rounds of DNA replication in meiosis

Answer 10

one round

Question 11

List the stages of meiosis

Answer 11

Interphase
-G1,S,G2

PMAT 1

Cytokinesis

PMAT 2

Final cytokinesis

Question 12

Prophase 1

Answer 12

• Chromosomes are visible and condensed

- Crossing over between homologous pairs occur

Question 13

Define Crossing over

Answer 13

Crossing over between homologues pairs of chromosomes is where alleles are exchanged. This creates new allele combinations on sister chromatids (they are no longer genetically identical) which leads to the genetic variation.

Question 14

Metaphase 1

Answer 14

• Homologous chromosomes align at the equator of the cell

- Independent assortment of chromosomes occurs

Question 15

Define Independent assortment

Answer 15

Independent assortment of chromosomes is where the chromosomes randomly align on the equator of the cell in their homologous pairs. This creates new chromosomal combinations

Question 16

Anaphase 1

Answer 16

• Homologous pairs seperate

- Centromere doesn’t divide

Question 17

Telophase 1

Answer 17

-two nuclei formed, each containing one of the homologous pairs

Question 18

Prophase 2

Answer 18

• DNA doesn’t replicate
• NO crossing over
• Chromosomes become visible

Question 19

Metaphase 2

Answer 19

-Chromosomes line up at the equator of the cell (not in pairs)

Question 20

Anaphase 2

Answer 20

-Centromeres disjoin and sister chromosomes (now called single chromosomes) move to opposite pole of the cell

Question 21

Telophase 2

Answer 21

-two nuclei form

Question 22

what are recombinant chromatids

Answer 22

Chromatids that have swapped DNA

Question 23

importance of fertilisation

Answer 23

In sexual reproduction, following meiosis, the final genetic variation comes from the random fertilisation of gametes.

Question 24

why is genetic variation important

Answer 24

populations are able to better adjust to changes in the environment eg natural disasters ,food shortages etc