mitosis/meiosis

Question 1

what happens in interphase- mitosis

Answer 1

G1-protein synthesis
S-DNA replication
G2-organelle divides

-proteins are made
-DNA copied
-cell organelles divide
-ATP produced
-cell gets bigger.

Question 2

what does chromatin do to genetic material

Answer 2

chromatin stains genetic material.

Question 3

what happens in mitosis prophase

Answer 3

chromatin condenses t form chromasomes.
-nucleolus disappears.
-nuclear membrane breaks down.
-centrioles move to poles.

Question 4

what happens in mitosis metaphase

Answer 4

chromosomes line up on equator and become attached to spindle fibres by centromere.

Question 5

what happens in mitosis anaphase

Answer 5

chromatids move to poles caused by shortening of spindle fibres.

Question 6

what happens in mitosis telophase-

Answer 6

chromatids reach the poles.
-nucleus and nuclear membrane reforms
-chromosomes unwind.

Question 7

is mitosis new cell diploid or haploid

Answer 7

diploid-same no of chromosomes as original.

Question 8

name 3 differences between mitosis and meiosis

Answer 8

mitosis occurs in all organs meiosis occurs in gonads only.
-mitosis produces diploid cells, meiosis creates haploid cells.
-mitosis produces genetically identical daughter cells, meiosis creates 4 genetically non-identical daughter cells.in meiosis there is 2 divisions of chromosomes.

Question 9

in meiosis chromasomes occurs in pairs what is this called

Answer 9

homologous -one chromasomes from maternal and one from paternal.

Question 10

what is fertilisation

Answer 10

fusion-re-establishes the diploid no and produces a cell that has homologous pairs of chromosomes.

Question 11

where does mitosis occur

Answer 11

all organs for gowth and aesexual reproduction

Question 12

what happens during cytokenesis mitosis

Answer 12

Cytokinesis – during cytokinesis the parent and replicated organelles move to
opposite sides of the cell and the cytoplasm divides thus producing two daughter cells.

Question 13

what happens during mitosis interphase

Answer 13

Interphase – during this stage the cell grows and then prepares to divide –
chromosomes and some organelles are replicated, chromosomes also begin to condense.

Question 14

describe what changes occur during both divisions in meiosis

Answer 14

division 1-homologous chromosomes seperate forming two cells each with 1 chromosome from each homologous pair. Each chromosome is still 2 chromatids.
division 2-
chromatids seperate forming 4 cells each with example of each chromosome.

Question 15

when are chromosomes visable

Answer 15

prophase

Question 16

what happens in meiosis interphase

Answer 16

DNA content doubles in replication and organelles replicated.

Question 17

what is independant assortment

Answer 17

only 1 chromosome from each pair ends up in each gamete. The way the chromosomes line up on the equator is random creatong a series of different allele combinations.

Question 18

what is crossing over

Answer 18

homologous pairs of chromosomes are in close contact in prophase 1. At contact points chromatids can break and rejoin exchanging DNA sections. The point at which they break is called chiasma, resulting in a new combination of alleles.

Question 19

what is chiasma

Answer 19

the point t which chromatids join and break in crossing over.

Question 20

what happens in prophase 1-meiosis

Answer 20

chromosomes become shorted and thicker.
-each chromosome is visable with two chromatids.
-homologous chromosomes associate forming a bivalent.
-crossing over can occur.
-centriole move to poles and spindle forms.
-nuclear membrane disappears.

Question 21

what happens in metaphase 1-meiosis

Answer 21

homologous pairs line up on equator of spindle and attach to same spindle fibre by centrioles.
-independent assortment can occur

Question 22

what happens in anaphase 1-meisosis

Answer 22

chromosomes of each bivalent seperate and pulled to opposite poles. chromosomes are still double structures.

Question 23

what happens in telophase 1-meiosis

Answer 23

-nuclear envelope forms around each group of chromosomes. Thw two nuclei are haploid. The cytoplasm divides and 2 cell form.
-Each chromosome is still double stranded.

Question 24

what happens in cytokenesis 1

Answer 24

in animals cytoplasm divides and two haploid cells are formed. In plant cells meisosis 11 occurs before any cyoplasmic division due to long time to produce cell wall.

Question 25

what happens in prophase 2-meiosis

Answer 25

-new spindle forms at right angles to original.

Question 26

what happens in metaphase 2-meiosis

Answer 26

-chromosomes line up on equator of spindle and attach by centromere.
-each chromosomes attaches to separate spindle fibre.

Question 27

what happens in anaphase 2-

Answer 27

centomere divides -chromatids seperate and pulled to opposite poles.

Question 28

what happens in telophase 2-meiosis

Answer 28

chromsomes lengthe.
-spindle disappears and nuclear envelope forms around each group of chromosomes.

Question 29

what happens in cytokenesis 2-meosis

Answer 29

cytoplasm divides reulting in 4 haploid cells. each daughter cell is genetically non-identical.

Question 30

what are the ways to achieve genetic variation

Answer 30

-crossing over
-independent assortment
-random fertilization-fusion of gametes is random.
-genotype mixed.

Question 31

describe how to stain chromasomes for mitosis

Answer 31

acetic orcein stain

Question 32

what is the mitotic index

Answer 32

number of cells visable chromasomes
divided by total no. of cells