Chromosomes, Cell Division, Meiosis and Chromosome Abnormalities

Question 1

What are the 3 features of chromosome structure?

Answer 1

Telomere
Centromere
Heterochromatin/Euchromatin

Question 2

DNA replication is symmetric/asymmetric?

Answer 2

Asymmetric.

Question 3

What happens when DNA polymerase binds to the next Okazaki fragment on the lagging strand?

Answer 3

Bind fragments together with DNA ligase.

Question 4

What is needed to start every replication including individual fragments?

Answer 4

RNA primer sequence.

Question 5

What problem does RNA primer sequence have for the last part of DNA to be replicated?

Answer 5

End-replication problem. Can start to decay.

Question 6

What can bind to the end of DNA to stop it’s problem?

Answer 6

Telomerase enzyme which adds DNA using an RNA template.

Question 7

What are the 4 stages of cell cycle and division?

Answer 7

G1
S
G2
M

Question 8

What happens during prophase?

Answer 8

Chromosomes condense
Nuclear membrane disappears
Spindle fibres form from centriole

Question 9

What happens during metaphase?

Answer 9

Chromosomes align at equator
Attach by fibre to centriole
Max condensation of chromosome

Question 10

What happens during anaphase?

Answer 10

Sister chromatids separate longitudinally

Move to opposite ends of cell

Question 11

What happens during telophase?

Answer 11

New nuclear membrane forms

Each cells contains 46 chromosomes

Question 12

What happens during cytokinesis?

Answer 12

Cytoplasm separates

Two new daughter cells.

Question 13

What are centromeres the site of?

Answer 13

Kinetochore

Question 14

What is a kinetochore?

Answer 14

Protein complex that binds to microtubules.

Question 15

Heterochromatin are ______ genes and euchromatin are ______ genes.

Answer 15

Silenced

Active

Question 16

What are the two types of tandemly repeated DNA sequences?

Answer 16

Satellite

Microsatellite

Question 17

What are the 2 types of highly repeated interspersed DNA sequences?

Answer 17

SINE

LINE

Question 18

DNA is packaged with histone proteins to form what?

Answer 18

Chromatin

Question 19

What charge do DNA and histone proteins have?

Answer 19

DNA is negative and histone proteins are positive.

Question 20

What is a nucleosome?

Answer 20

DNA wrapped 2 around core of 8 histone proteins.

Question 21

How many nucleosomes are in each turn?

Answer 21

6

Question 22

What is the process of condensing chromatin?

Answer 22

Nucleosome
Chromatin fibre
Fibre-scaffold complex
Chromosome

Question 23

What are the 3 reasons for packaging DNA?

Answer 23

Uses less space
Neutralised DNA
Inactive DNA folded until required.

Question 24

What is the process of chromosome analysis?

Answer 24

Blood 
Separate red cells
Incubate white cells
Add colchicine 
Separate white cells
Add hypotonic saline
Fix cells to spread
Stain
Photograph
Karyotype

Question 25

What is colchicine?

Answer 25

Microtubule inhibitor

Question 26

What are metacentric karyotypes?

Answer 26

Centromere very central

Question 27

What are submetacentric karyotypes?

Answer 27

Centromere less central

Question 28

What are acrocentric karyotypes?

Answer 28

Centromere no where near central.

Question 29

What does FISH stand for?

Answer 29

Fluorescent in situ hybridisation

Question 30

What are the 4 types of FISH probes?

Answer 30

Unique Centromeric Telomeric Whole chromosome

Question 31

What does meiosis do to diploid cells?

Answer 31

Half them to haploid.

Question 32

What happens to chromosomes in meiosis?

Answer 32

Passed on as recombined copies creating genetic variation.

Question 33

How many cycles occur in one meiosis?

Answer 33

2

Question 34

What are the 4 steps of meiosis?

Answer 34

Prophase Metaphase Anaphase Telophase

Question 35

What is oogenesis?

Answer 35

Process of egg formation

Question 36

What is spermatogenesis?

Answer 36

Process of sperm formation.

Question 37

When do sperm go through their 2nd meiosis cycle?

Answer 37

Puberty

Question 38

When do ovules go through their 2nd meiosis cycle?

Answer 38

Ovulation

Question 39

Where do mitochondria only come from?

Answer 39

Mother via egg.

Question 40

What is x-inactivation?

Answer 40

Random inactivation of one X chromosome in females.