Chromosomes and cell division.

Question 1

What is the end of the chromatids called?

Answer 1

The telomere.

Question 2

What is telomerase and why is it required?

Answer 2

Telomerase in an enzyme that repairs telomeres. They require to be repaired as the ends of chromosomes cannot replicate properly, so shorten.

Question 3

Which part of the chromosome connects the two sister chromatids.

Answer 3

Centromere

Question 4

Which part of the chromosome does the spindle fibre attach too?

Answer 4

the centromere.

Question 5

Does the euchromatin have densely packed DNA, or lightly packed DNA? How does this affect the activity of the DNA .

Answer 5

Lightly packed DNA, lots of activity.

Question 6

Describe the DNA in heterochromatin.

Answer 6

Densely packed, not much activity.

Question 7

Put these steps of the cell cycle in order.

G2, M, S, G1.

Answer 7

G1 -> S -> G2 -> M

Question 8

What protein does DNA wrap itself around to become more tightly packed.

Answer 8

Histone.

Question 9

What does DNA and histone form?

Answer 9

Chromatins -> Nucleosomes -> Chromosomes.

Question 10

What can you see from a karyotype?

Answer 10

A chromosomes shape, size, the number of them.

Question 11

What can you check by FISH (fluorescent in situ hybridisation)?

Answer 11

Chromosome number, translocation and chromosomal abnormalities.

Question 12

What happens during the metaphase part of mitosis.

Answer 12

The chromosomes line up at the equator, spindle fibres attach to them.

Question 13

what does the kinetochore protein do?

Answer 13

Forms on the centermere to bind to the spindle fibres.

Question 14

Does meiosis form diploid cells or haploid cells?

Answer 14

Haploid.

Question 15

Where does meiosis occur?

Answer 15

Ovaries and testes.

Question 16

Where does cross over/recombination take place in meiosis.

Answer 16

Prophase 1

Question 17

Where does independent assortment take place in meiosis?

Answer 17

Metaphase 1

Question 18

What is the process of egg formation called?

Answer 18

Oogenesis.

Question 19

what is the process of sperm formation called?

Answer 19

Spermatogenesis.

Question 20

Does sperm formation or egg formation have more chance of mutation?

Answer 20

Sperm formation - it goes through many more cell divisions.

Question 21

When does oogenesis occur?

Answer 21

early embryonic life.

Question 22

When does spermatogenesis occur?

Answer 22

puberty .

Question 23

When sperm and egg join, they form a diploid cell. What is this called?

Answer 23

A zygote.

Question 24

Where does mitochondria and mitochondrial DNA come from?

Answer 24

Maternal Inheritance.

Question 25

When a zygote is formed, both X chromosomes are active. However, in early embryonic development, something happens. What happens and why?

Answer 25

Random X inactivation. Only happens in females as males only have one X chromosome anyway. This prevents a ‘double dose’ of genes.

Question 26

What is fluorescent in situ hybridisation?

Answer 26

fluorescent probes that only bind to specific parts of the DNA

Question 27

What is centromeric prob can find?

Answer 27

chromosome number

Question 28

telomeric probe can find?

Answer 28

rearrangements - can find the source of unexplained mental retardation

Question 29

whole chromosome propes?

Answer 29

translocation and rearrangement