Mitosis & Meiosis

Question 1

What is the structure of DNA?

Answer 1

Double helix
Complimentary base pairs
Coils around nucleosomes
Coils again into supercoils and again into chromosomes

Question 2

How many chromosomes in the human genome?

Answer 2

46 chromosomes (22 pairs + sex chromosomes xy)

Question 3

Each human chromosomes contains a complex DNA duplex of …

Answer 3

10^7 bp and contain several hundred genes

Question 4

Which is the long arm in a chromosome?

Answer 4

Q

Question 5

Which is the short arm in a chromosome?

Answer 5

P

Question 6

How are the long and short arm separated?

Answer 6

By the centromere

Question 7

What dye is used to identify and analyse the G banding?

Answer 7

Giemsa

Question 8

What dye is used to identify and analyse the Q banding?

Answer 8

Quinacrine

Question 9

How many bands does G banding give?

Answer 9

400-500 bands / haploid human chromosome set

Question 10

How long is each band in G-banding?

Answer 10

6-8 Mbp

Question 11

What is mitosis for?

Answer 11

Producing two daughter cells
Genetically identical to parent cells
Growth
Replace dead cells

Question 12

What happens in the S-phase?

Answer 12

DNA replication
Centrosome replication

Question 13

What happens in prophase?

Answer 13

Chromatin condenses into chromosomes
Centrosomes nucleate microtubules and move to opposite poles of nucleus leaving a web of cytoskeleton filaments between them

Question 14

What happens in prometaphase?

Answer 14

Nuclear membrane breaks done
Microtubules invade nuclear shape
Chromatids attach to microtubules

Question 15

What happens in metaphase?

Answer 15

Chromosomes line up along equatorial plane (metaphase plate)

Question 16

What happens in anaphase?

Answer 16

Sister chromatids separate and are pushed to opposite poles of the cell

Question 17

What happens in telophase?

Answer 17

Nuclear membranes reform
Chromosomes unfold into chromatin
Cytokinesis begins

Question 18

What drug is a inhibitor of kinesin spindle protein?

Answer 18

Ispinesib

Question 19

What drugs inhibit the mitotic spindle?

Answer 19

Taxol
Vinca alkaloids ( vinblastine, vincristine )

Question 20

What drug inhibits mitosis in the anaphase stage?

Answer 20

Colchicine

Question 21

What happens in meiosis?

Answer 21

Only in gametes
Recombination of genetic material which generates diversity
Two cell divisions
4 haploid daughter cells

Question 22

What is spermatogonia?

Answer 22

The process by which haploid spermatozoa develop from primordial germ cells by mitosis in the seminiferous tubules of the testis

Question 23

When do meiotic divisions of sperm commence?

Answer 23

Puberty

Question 24

What is oogonia?

Answer 24

A cell produced at an early stage in the formation of an ovum developed from primordial germ cells

Question 25

How many mitoses to form a oogonia?

Answer 25

30

Question 26

When do oogonia enter prophase of meiosis 1?

Answer 26

8th mouth of intrauterine life

Question 27

When is meiosis 1 in egg cells completed?

Answer 27

Ovulation

Question 28

When is meiosis 2 in egg cells completed?

Answer 28

When fertilisation occurs

Question 29

What is non-disjunction?

Answer 29

Failure of chomosone pairs to separate in meiosis 1 or sister chromatids to separate properly in meiosis 2

Question 30

What do most cases of down syndrome result from?

Answer 30

Regular trisomy 21

Question 31

What is regular trisomy 21?

Answer 31

Most common chromosomal anomaly in humans, genetic condition caused by an extra chomosone

Question 32

What is gonadal mosaicism?

Answer 32

A condition in which a post fertilisation mutation is confined to the gamete precursors and is not detected in somatic tissues

Question 33

When does gonadal mosaicism occur?

Answer 33

When precursor germline cells to ova or spermatozoa are a mixture of two or more genetically different cell lines One cell line is normal, the other mutated

Question 34

What increases the chance of gonadal mosaicism?

Answer 34

Advancing paternal age

Question 35

What is the most common inheritance patten for gonadal mosaicism?

Answer 35

Autosomal dominant and x-linked

Question 36

Name conditions in which gonadal mosaicism is observed

Answer 36

Osteogenesis imperfecta Duchenne muscular dystrophy

Question 37

What is the purpose of the telomere?

Answer 37

Stops the chromosomes from unravelling

Question 38

What happens to the telomere after each division?

Answer 38

They get shorter

Question 39

What happens to cells that are mitotically inactive?

Answer 39

They done enter the all cycle, they enter G0

Question 40

Is cytokinesis a phase in mitosis?

Answer 40

No

Question 41

What is a characteristic of aggressive tumours?

Answer 41

Tumours with high mitotic figures

Question 42

What happens in prophase in males?

Answer 42

Cytoplasm divides evenly

Question 43

What happens to the cytoplasm during mitosis in females?

Answer 43

Cytoplasm divides unequally

Question 44

What are microtubules made of?

Answer 44

Tubulin