7B- meiosis

Question 1

meiosis

Answer 1

a specialised form of cell division used to produce gametes in sexually reproducing organisms

Question 2

gametes

Answer 2

reproductive cells that arise from germ line cells and contain half the genetic material (n) of a somatic cell. the gametes in animals are sperm and egg cells

Question 3

zygote

Answer 3

the diploid cell formed by the combination of two haploid gamete cells

Question 4

germ line cells

Answer 4

cells that are involved in the generation of gametes in eukaryotes

Question 5

gonads

Answer 5

the organs that produce gametes from germline cells. in humans these are the testes and the ovaries

Question 6

metaphase plate

Answer 6

the equator of a dividing cell where chromosomes will line up during metaphase

Question 7

microtubules

Answer 7

long tube-like fibre proteins that form part of the cytoskeleton of a eukaryotic cell and help give the cell its structure. Microtubules are used for a variety of cell movements, including transport of cell organelles and the movement of chromosomes during cell division

Question 8

cytokinesis

Answer 8

the division of the cytoplasm and formation of two daughter cells

Question 9

crossing over

Answer 9

the exchange of genetic material between non-sister chromatids during prophase I of meiosis, resulting in new combinations of alleles in daughter cells

Question 10

chiasma

Answer 10

the point/location of overlap between two non sister chromatids

Question 11

independent assortment

Answer 11

the random orientation of homologous chromosomes along the metaphase plate during metaphase I

Question 12

what is meiosis?

Answer 12

meiosis is a specific type of cell division where a single cell divides to produce 4 unique daughter cells/gametes each with half the number of chromosomes of the original.
it is a specialised form of cell division that produces gametes in sexually reproducing organisms

Question 13

what are the gametes in humans?

Answer 13

in humans, the gametes present are sperm and egg (ova) cells that contain one copy of each chromosome (n). they fuse together during fertilisation to create two copies of each chromosome (2n) inside a developing zygote

Question 14

what is the dividing cell in humans?

Answer 14

germ line cells. they are involved in the generation of gametes in eukaryotes

Question 15

where are germ line cells found?

Answer 15

gonads are the organs that produce gametes from germ line cells and are the testes and ovaries

Question 16

how many cellular divisions are there in meiosis?

Answer 16

2
meiosis I→ separates homologous chromosomes into 2 different cells meiosis II→ separates sister chromatids into 4 different cells

Question 17

before division

Answer 17

there are a homologous pair of chromosomes
2n,2s

Question 18

interphase

Answer 18

chromosomes replicate
homologous pair of replicated chromosomes
identical to that of mitosis, where the cell grows and duplicates all of its chromosomes to prepare for division
2n,4s

Question 19

meiosis I

Answer 19

first cell division
each homologous chromosome is separated into a different haploid cell
n,2s and n,2s

Question 20

meiosis II

Answer 20

second cell division
each sister chromatid is separated into one of four haploid cells
n,s x4- 4 HAPLOID DAUGHTER CELLS

Question 21

input of mitosis (start of G1)

Answer 21

1 somatic cell, 2n

Question 22

output of mitosis (end of cytokinesis)

Answer 22

2 identical somatic cells, 2n

Question 23

input of meiosis (start of G1)

Answer 23

1 germ line cell (2n)

Question 24

output of meiosis (end of cytokinesis(

Answer 24

4 genetically unique gamete cells (n)

Question 25

prophase I

Answer 25

nuclear membrane breaks down as chromosomes condense and line up in homologous pairs
important for crossing over of genetic material between the homologues

Question 26

crossing over

Answer 26

exchanging of genetic material from one homologue to the other during prophase I. homologous chromosomes cross over at the chiasma swapping part of their DNA with each other
this forms new recombinant chromatids each with its own unique combination of alleles, adding to the genetic diversity of the resulting haploid daughter cell. the sister chromatids that they inherit aren’t identical.

Question 27

metaphase I

Answer 27

homologous chromosomes randomly line up on opposite sides of the metaphase plate with one copy (paternal/maternal) on either side
each chromosome attaches to microtubules of whichever pole its closest too, preparing to be separated
2 lines

Question 28

independent assortment

Answer 28

random assortment of homologous chromosomes along the metaphase plate occur irrespective of the orientation of other pairs.
they line up on opposite sides of the plate, resulting in a combination of alleles in each daughter cell are randomised as what is inherited is dependent on which side of the plate each chromosome is positioned. around 8 million different combinations

Question 29

anaphase I

Answer 29

homologous chromosomes move apart towards opposite poles of the cell
sister chromatids remain attached to one another at the centromere. chromosomes are pulled apart

Question 30

telophase I

Answer 30

chromosomes arrive at opposite ends of the cell and the nuclear membrane cleaves
a cleavage furrow forms in preparation for cytokinesis

Question 31

aim of meiotic division

Answer 31

to produce gametes that are genetically distinct from each other and from the parent cell from which they originated. this occurs due to intricate processes that contribute to increased genetic diversity in the resulting daughter cells

Question 32

prophase II

Answer 32

two cells prepare- nuclear envelope breaks down causing chromosomes to condense. spindle fibres form in preparation to pull apart the sister chromatids

Question 33

metaphase II

Answer 33

chromosomes align along the metaphase plate of the cell and microtubules from opposite poles of the cell prepare to pull the chromosomes apart
1 line

Question 34

anaphase II

Answer 34

sister chromatids are separated and pulled towards opposite poles of the cell by microtubules that are attached at each centromere. chromatids are pulled apart

Question 35

telophase II

Answer 35

individual chromatids are at each pole of the cell and so separate nuclear membranes begin to form around each set as the chromosomes decondense and unravel

Question 36

cytokinesis

Answer 36

splits each of the chromosome sets at opposite ends of the cell into 4 new individual cells, resulting in haploid daughter cells.

Question 37

meiosis before interphase

Answer 37

46 chromosomes and 46 chromatids

Question 38

meiosis after interphase

Answer 38

46 chromosomes and 92 chromatids

Question 39

after meiosis I

Answer 39

23 chromosomes and 46 chromatids

Question 40

after meiosis II

Answer 40

23 chromosomes and 23 chromatids

Question 41

how many chromosomes in human body cells and gametes

Answer 41

46 chromosomes in human body cells and 23 chromosomes in gametes

Question 42

how to count chromosomes

Answer 42

the amount of centromeres present

Question 43

mitosis before interphase

Answer 43

46 chromosomes and 46 chromatids

Question 44

mitosis after interphase

Answer 44

46 chromosomes and 92 chromatids

Question 45

during mitosis

Answer 45

46 chromosomes and 92 chromatids

Question 46

after mitosis (per daughter cell)

Answer 46

46 chromosomes and 46 chromatids