Genetic code: Mitosis and Meiosis

Question 1

Karotype

Answer 1

no. and appearance of chromosomes in a cell

Question 2

Mitosis

Answer 2

1 parent cell produces two genetically identical daughter cells

Question 3

Purpose of mitosis

Answer 3

growth and replace dead cells

Question 4

Chromatin

Answer 4

when cell not in replication

Question 5

Chromosomes

Answer 5

during replication

Question 6

Chromatids

Answer 6

after replication

Question 7

Steps of Mitosis

Answer 7

Interphase 
Prophase
Metaphase
Anaphase
Telophase

Question 8

Interphase

Answer 8

cell cycle - for mitosis to occur it must be in cell cycle

Question 9

G1

Answer 9

no visible activity BUT
new organelles produced
protein synthesis of those involved in spindle formation

Question 10

S (synthesis)

Answer 10

DNA replication (it doubles)
centrosome replication

Question 11

G2

Answer 11

chromosomes condense

mitochondria and centrioles double

Question 12

Centrioles

Answer 12

minute cylindrical organelles near the nucleus,involved in the development of spindle fibres in cell division ??

Question 13

Prophase

Answer 13

chromatin condenses into chromosomes

centrosomes move to opposite poles of nucleus by microtubules

Question 14

Prometaphase

Answer 14

nuclear membrane breaks down
chromatids bind to microtubules
cell no longer has nucleus

Question 15

Metaphase

Answer 15

chromosome line up along equatorial plane

Question 16

Anaphase

Answer 16

sister chromatids separate and are pushed to opposite sides of the poles

Question 17

Telophase

Answer 17

nuclear membrane reforms
chromosomes unfold into chromatin
cytokinesis begins
(have cell w/ 2 nuclei)

Question 18

Meiosis

Answer 18

only in gametes
recomb. of genetic material = genetic diversity
2 cell divisions
4 haploid daughter cells (half no. chromosomes)–> genetically distinct from each other and parent cell
NOT A CYCLE

Question 19

Meiosis 1

Answer 19

no. chromosomes is halved

Question 20

Prophase 1

Answer 20

crossing over betw. non-sister chromtids (occurs independently) = genetic diversity

Question 21

Metaphase 1

Answer 21

random assortment on metaphase plate = genetic diversity

Question 22

Meiosis 2

Answer 22

sister chromatids separate

haploid cells produced

Question 23

Gametogenesis

Answer 23

1st stage is the proliferation of primordial germ cells by mitosis
timing of this differs greatly in males and females

Question 24

Primordial

Answer 24

undifferentiated

Question 25

Germ cells

Answer 25

developing gametes

Question 26

Gametogenesis (males)

Answer 26

primordial germ cells>lots of mitoses>spermatogonia
some mitosis at embryonic stages to produce primary spermatocytes
mitosis rlly begins at puberty and then continues
cytoplasm divides evenly
after meiosis 2: 4 equal size gametes

Question 27

Spermatogonia

Answer 27

mature sperm

Question 28

Gametogenesis (females)

Answer 28

primordial germ cell>30 mitoses>oogonia(cells that undergo meiosis)
cytoplasm divides unequally- 1 eggs and 3 polar bodies
meiosis 1 completed at ovulation - 1 big cell, 1 small cell w/ diploid DNA
after fertilisation- divide again to from egg and 3 polar bodies
meiosis 2 only completed if fertilisation occurs

Question 29

Problems with meiosis

Answer 29

non-disjunction

gonodal mosaicism

Question 30

Non-disjunction

Answer 30

failure of chromosome pairs to separate in meiosis 1
or
failure of sister chromatids separating properly in meiosis 2

Question 31

Gonadal mosaicism

Answer 31

precursor germline cells to ova or spermatozoa are a mixture of genetically different cell lines
one cell line is normal, other is mutated
parent healthy but foetus may have genetic diseases
more common in males
can be observed in any inheritance pattern - most common = autosomal dominant and x-linked