Chromosomes, Cell Division, Meiosis and Chromosome Abnormalities

Question 1

Outline the structure of a eukaryotic chromosome structure

Answer 1

• Linear
• Telomere
• Centromere
• Heterochromatin
• Euchromatin

Question 2

Telomeres have hundreds of copies of what sequence of bases at their ends?

Answer 2

5’-TTAGGG-3’

Question 3

During the cell cycle and division what do the letters G1, S, G2, M mean and how long do they approx. take?

Answer 3

G1 - 10-12hrs - Growth
S - 6-8hrs -DNA replication
G2 - 2-4hrs - Growth
M - 1-2hrs - Mitotic

Question 4

The centromeres are the site of what?

Answer 4

Kinetochore

Question 5

DNA packaged with histone proteins into packages called what?

Answer 5

Nucleosomes

Question 6

Further wrapping of nucleosomes forms into 40nm sizes packages is referred to as what kind of structure?

Answer 6

Solenoid

Question 7

What is the purpose of packaging DNA?

Answer 7

• Negatively charged DNA is neutralised by positive histone proteins
• Takes up less space
• Inactive heterochromatin can be folded into inaccessible locations until required

Question 8

What is karyotype?

Answer 8

A test to determine shape and size of chromosomes

Question 9

What is a metacentric karyotype chromosome?

Answer 9

Where the centromere is near the middle of the full length of the chromosome

Question 10

What is a sub-metacentric karyotype chromosome?

Answer 10

Where the centromere is away from the middle of the chromosome

Question 11

What is acrocentric karyotype chromosome?

Answer 11

Where the centromere is near the end of the length of a chromosome

Question 12

What is FISH?

Answer 12

Fluorescent in situ hybridisation

Question 13

What is FISH used for?

Answer 13

Identifying the locus of a gene

Question 14

Name the four kinds of FISH probes

Answer 14

• Unique sequence
• Centromeric probes
• Telemetric probes
• Whole chromosome probes