Meiosis 2.1.6 (f,g)

Question 1

what is a diploid cell?

Answer 1

a cell with the normal number of chromosomes

Question 2

what is a haploid cell?

Answer 2

a cell with half the number of chromosomes

Question 3

what does mitosis result in?

Answer 3

two genetically identical daughter diploid cells

Question 4

what is a gamete?

Answer 4

a sex cell
are haploid cells

Question 5

what is a zygote?

Answer 5

the fertilised egg
are diploid cells

Question 6

why is meiosis reduction division?

Answer 6

each gamete produced by meiosis are haploid cells
- have half the number of chromosomes than parents

Question 7

what are homologous pairs of chromosomes?

Answer 7

a pair of chromosomes which are the same size and have the same gene

Question 8

where do homologous pairs of chromosomes come from?

Answer 8

after fertilisation, one chromosome comes from the dad and one chromosome comes from the mum

Question 9

what are the products of meiosis?

Answer 9

4 haploid daughter cells which are all genetically unique to each other with a different combination of chromosomes

Question 10

what is an allele?

Answer 10

different versions of the same gene

they have the same gene loci

Question 11

what is the gene locus?

Answer 11

the position of an allele on a chromosome

Question 12

what are the two stages of meiosis?

Answer 12

meiosis I
meiosis II

Question 13

what happens in meiosis I?

Answer 13

the reduction division:
the pairs of homologous chromosomes are separated into two new cells

Question 14

product of meiosis I?

Answer 14

two genetically unique haploid cells

Question 15

what happens in meiosis II?

Answer 15

similar to mitosis:
the individual chromosomes are separated in both of the newly produced cells

Question 16

product of meiosis II?

Answer 16

four genetically unique haploid cells

Question 17

prophase I

Answer 17

the chromosomes coil and condense

the homologous chromosomes pair up with each other

centrioles move to opposite poles

nuclear membrane breaks down

crossing over occurs

Question 18

metaphase I

Answer 18

the homologous chromosomes attach to spindle fibres at their centromeres which lines them up on the metaphase plate

independent assortment occurs

Question 19

anaphase I

Answer 19

the pair of homologous chromosomes are pulled apart when the spindle fibres contract

Question 20

telophase I

Answer 20

the nuclear membrane reforms

chromosomes uncoil

cytokinesis occurs to produce two haploid daughter cells

Question 21

prophase II

Answer 21

the chromosomes coil and condense into sister chromatids bound together by the centromere

the nuclear membrane breaks down

centrioles move to opposite poles of cell

Question 22

metaphase II

Answer 22

the sister chromatids attach to the spindle fibres and are moved to the metaphase plate

independent assortment happens again

Question 23

anaphase II

Answer 23

the individual chromatids are pulled apart by the contraction of the spindle fibres to opposite poles

Question 24

telophase II

Answer 24

the separated chromatids uncoil and the nuclear membrane reforms

cytokinesis occurs to produce four haploid daughter cells

Question 25

in what ways is genetic variation produced during meiosis?

Answer 25

crossing over
independent assortment of chromosomes

Question 26

at what stages does crossing over occur?

Answer 26

prophase I

Question 27

at what stages does the independent assortment of chromosomes occur?

Answer 27

metaphase I
metaphase II

Question 28

what is crossing over?

Answer 28

when homologous chromosomes pair up in prophase I, their chromatids twist around each other and exchange alleles

this leads to a different combination of alleles

means that the four haploid cells produced at the end will have different allele combinations to their parents

Question 29

what is independent assortment?

Answer 29

chromosomes line up completely independent of each other both in metaphase I and II

therefore the four haploid cells produced will have a completely random combination of maternal and paternal chromosomes

Question 30

independent assortment in meiosis I

Answer 30

independent assortment of homologous chromosomes

the paternal and maternal chromosomes pair up randomly

Question 31

independent assortment in meiosis II

Answer 31

independent assortment of sister chromatids

they can end up in either of the daughter cells so is random