BGM1004/L08 Eukaryotic Genes

Question 1

Give 4 characteristics than genomic DNA controls.

Answer 1

Development
Form and function
Behaviour
Interaction with environment

Question 2

What is the relationship between complexity and gene number?

Answer 2

As complexity increases, gene number increases (not linearly)

Question 3

What is the relationship between complexity and gene number called?

Answer 3

The C-value paradox

Question 4

Approximately what percentage of the human genome does protein-coding make up?

Answer 4

2%

Question 5

How many chromosomes do all eukaryotes have?

Answer 5

At least 2

Question 6

What is mild proteolysis?

Answer 6

Breakdown of proteins

Question 7

What is the process and banding pattern in G-banding ?

Answer 7

Mild proteolysis followed by GIEMSA
Dark bands are AT rich

Question 8

What is the process and banding pattern in R-banding?

Answer 8

Heat denaturation followed by GIEMSA
Dark bands are GC-rich

Question 9

What is the process and banding pattern in Q-banding?

Answer 9

Stain with quinacrine
Dark bands are AT-rich

Question 10

What is the process and banding pattern in C-banding?

Answer 10

Barium hydroxide followed by GIEMSA
Dark bands are constitutive heterochromatin

Question 11

When are chromosomes highly condensed and therefore visible?

Answer 11

During nuclear division in mitosis

Question 12

What are mitotic chromosomes known as during mitosis?

Answer 12

Chromatids

Question 13

When are chromosomes decondensed?

Answer 13

During interphase

Question 14

How are chromosomes visualised via ‘painting’?

Answer 14

DNA sequences specific to one chromosome are fluorescently labelled and hybridised

Question 15

What is the region in which decondensed chromosomes occupy?

Answer 15

Territories

Question 16

What is a centromere?

Answer 16

A region where sister chromatids are held together

Question 17

Where is the assembly site for the kinetochore?

Answer 17

Centromere

Question 18

Describe the base sequence in the centromere.

Answer 18

Large arrays of repeated sequences

Question 19

What is a metacentric chromosome?

Answer 19

A chromosome where p arm length = q arm length

Question 20

What is a submetacentric chromosome?

Answer 20

A chromosome where p arms are slightly shorter than q arms

Question 21

What is an arcocentric chromosome?

Answer 21

A chromosome where p arms are much shorter than q arms

Question 22

What is a telocentric chromosome?

Answer 22

A chromosome where there are no p arms

Question 23

What is a telomere?

Answer 23

A specialised region at the end of chromosomes with the repeating motif (5’-TTAGGG-3’)

Question 24

Give the 2 major functions of the telomere.

Answer 24

Allow cell to distinguish real chromosome from unnatural end caused by DNA break
Solve problem that cells have replicating ends of a linear chromosome

Question 25

Describe the End Replication Problem.

Answer 25

During DNA replication, the 3' terminal portion of chromosome can't be copied so ssDNA overhang is degraded

Question 26

How does telomerase prevent chromosome shortening?

Answer 26

Uncopied region recognised by telomerase Telomerase adds multiple copies of 'TTAGGG' repeat Replication machinery synthesises other strand

Question 27

Why do most cells turn off telomerase?

Answer 27

To reach 'replicative cell senescence'

Question 28

What is DNA wrapped around?

Answer 28

An octane of histones

Question 29

What is the structure formed by DNA wrapped around histones called?

Answer 29

Nucleosomes

Question 30

What is chromatin?

Answer 30

Protein complex of DNA wrapped around histones

Question 31

What is euchromatin?

Answer 31

'True chromatin' Relatively uncondensed, associated with active genes

Question 32

What is heterochromatin?

Answer 32

Condensed, repressive, inactive, repetitive gene poor regions

Question 33

What are minichromosomes?

Answer 33

Chromosomes relatively short but rich in genes

Question 34

What are B chromosomes?

Answer 34

Additional chromosomes possessed by some but not all individuals in a population

Question 35

What are holocentric chromosomes?

Answer 35

Chromosomes without a single centromere but with multiple kinetochores throughout their length

Question 36

What are polytene chromosomes?

Answer 36

Giant chromosomes made by larval cells of certain insects