cell division

Question 1

binary fission (what is it used for)

Answer 1

Type of asexual cell division that results in reproduction in prokaryotic cells (bacteria).

Question 2

binary fission (steps)

Answer 2

1. DNA replication
2. Condensation of DNA to form two identical circular chromosomes
3. Attachment of each chromosome to the inside of the cell membrane
4. The cell elongates (increases length wise) which separates the chromosomes.
5. The chromosomes move to opposite ends of the cell
6. A new cell wall and cell membrane form and the cell divides into two daughter cells each with one circular chromosome.

Question 3

mitosis prophase

Answer 3

• chromatin condenses into visible chromosomes
• nuclear envelope + nucleoli disintegrate
• centrioles + spindle fibres form
  PLANT CELLS DO NOT HAVE CENTRIOLES

Question 4

mitosis metaphase

Answer 4

• chromosomes line up at the metaphase plate along the equator and attach to spindle fibres (LINE UP IN A LINE)
• sister chromatids face opposite poles

Question 5

mitosis anaphase

Answer 5

• sister chromatids seperate and are pulled to opposite poles

Question 6

mitosis telophase

Answer 6

• new nuclear envelope form, nucleoli reappear
• chromosomes uncoil and revert back to chromatin

Question 7

cytoskinesis

Answer 7

• production of 2 daughter cells, cytoplasm fully divides

Question 8

asexual reproduction methods

Answer 8

• binary fission and mitosis both produce genetically idnetical daughter cells
• contains number + type of chromosomes as parent cells

Question 9

haploid cells

Answer 9

-contains only ONE set of chromosomes
- all gametes are haploid
- haploid cells are derived from haploid cells via meiosis

Question 10

diploid cells

Answer 10

• contains PAIRS of homologus chromosomes
• will possess two alleles for each gene
• homologus pair= one maternal + one paternal chromisimes
• NOT GENETICALLY IDENTICAL

Question 11

Homologus pairs

Answer 11

homologus pairs share
- the same structural features
- same size, banding patterns, centromere position
- same genes at the same loci positions
- genes are the same, alleles are different

Question 12

why does DNA replicate prior to cell division

Answer 12

• to ensure that each daughter cell recieves the exact same genetic information as the parent
• same number + type of chromosome

Question 13

type of haploid/diploid that each process undergoes

Answer 13

diploid –> haploid (meiosis)
haploid –> diploid (fertilisation)
diploid –> diploid (mitosis)

Question 14

Meiosis

Answer 14

• sexually reproduces of gametes
• created HIPLOID cells

Question 15

key points of meiosis

Answer 15

• meiosis I involves HOMOLOGUS chromosomes
• meoisis II involves SISTER chromatids of non-homologus chromosomes

Question 16

ANAPHASE I

Answer 16

whole chromosomes seperate

Question 17

METAPHASE I

Answer 17

homologus chromosomes, attach spindle fibres and line up along the equator in PAIRS
- independent assortment occurs

Question 18

PROPHASE I

Answer 18

crossing over occurs

Question 19

fertilisation

Answer 19

• fusion of ovum (egg) + sperm to create zygote
• restores diploid number

Question 20

crossing over

Answer 20

• occurs in prophase I
• involves non-sister chromatids of homologus chromosomes touch, break + rejoin at the chiasma to exchange genetic information
• creates new combinations of genes + alleles increasing genetic variation

Question 21

independent assortment

Answer 21

• occurs in metaphase I
• involves the paternal + maternal chromosomes randomly lining up + facing opposite poles
• creates new combination of genes to alleles increasing genetic variation