Eukaryotic Cells

Question 1

Describe the structure of a chromosome

Answer 1

• 2 chromatids attached centrally at the centromere

Question 2

When is the structure of a chromosome visible in the cell cycle?

Answer 2

• During metaphase

Question 3

Describe the structure of a chromatin

Answer 3

• has a beads on a string structure whereby the beads are Histone proteins and the string is DNA

Question 4

Describe the properties of Histone Proteins.

Answer 4

• An octamer (8 units)
• Rich in Lysine and Arginine
• They are positively charged

Question 5

In gene expression what is a Spliceosome?

Answer 5

• A multi-subunit complex that completes splicing

Question 6

What is meant by protein diversity?

Answer 6

That several forms of a protein can be derived from the same gene due to splicing.

Question 7

What is an intron?

Answer 7

• a non-coding portion of a gene

Question 8

• What is transcription?

Answer 8

When RNA is written from DNA

Question 9

What is the TATA box?

Answer 9

A section of bases that promotes transcription

- this occurs approximately 25 bases before the start of transcription

Question 10

What is translation?

Answer 10

The writing of polypeptide chains from RNA

Question 11

What is an Exon?

Answer 11

a Coding sequence in a gene

Question 12

When does splicing occur?

Answer 12

• between Transcription and translation

Question 13

What happens if splicing defects occur?

Answer 13

• disease occurs due to the mutations in the genes

Question 14

In replication how may replication forks are there?

Answer 14

there a 2 replication forks working in both directions

Question 15

What does telomerase do?

Answer 15

Extends the 3’ end under certain circumstances

Question 16

When does telomerases function occur?

Answer 16

• in foetal development

- in cancer cells

Question 17

Why does the lagging strand get shorter at each replication?

Answer 17

• in normal cells telomerase cannot extend the 3’ end meaning it will be shorter by approximately 50 bases at each replication
• This limits the cells life

Question 18

What are the stages of the cell cycle?

Answer 18

• S (Synthesis)
• G2 (Gap 2)
• M (Mitosis)
• G1 (Gap 1)

Question 19

What occurs during the S stage of the cell cycle?

Answer 19

The DNA is replicated and the Chromosome is duplicated

Question 20

What occurs during the G2 stage of the cell cycle?

Answer 20

This is a period of cell growth as the cell prepares for mitosis

Question 21

What occurs during the M stage of the cell cycle?

Answer 21

• Prophase - condensation of chromatin and the disappearance of the nucleus
• Metaphase - Chromosomes align in the centre of the cell
• Anaphase - The chromosomes split
• Telophase - Chromosomes move to the poles and the cell splits

Question 22

What occurs during the G1 stage of the cell cycle?

Answer 22

This is a period of cell growth

- the organelles duplicate in preparation for synthesis