BGM1004/L08 Eukaryotic Genes Flashcards

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1
Q

Give 4 characteristics than genomic DNA controls.

A

Development
Form and function
Behaviour
Interaction with environment

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2
Q

What is the relationship between complexity and gene number?

A

As complexity increases, gene number increases (not linearly)

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3
Q

What is the relationship between complexity and gene number called?

A

The C-value paradox

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4
Q

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

A

2%

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5
Q

How many chromosomes do all eukaryotes have?

A

At least 2

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6
Q

What is mild proteolysis?

A

Breakdown of proteins

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7
Q

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

A

Mild proteolysis followed by GIEMSA
Dark bands are AT rich

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8
Q

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

A

Heat denaturation followed by GIEMSA
Dark bands are GC-rich

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9
Q

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

A

Stain with quinacrine
Dark bands are AT-rich

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10
Q

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

A

Barium hydroxide followed by GIEMSA
Dark bands are constitutive heterochromatin

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11
Q

When are chromosomes highly condensed and therefore visible?

A

During nuclear division in mitosis

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12
Q

What are mitotic chromosomes known as during mitosis?

A

Chromatids

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13
Q

When are chromosomes decondensed?

A

During interphase

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14
Q

How are chromosomes visualised via ‘painting’?

A

DNA sequences specific to one chromosome are fluorescently labelled and hybridised

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15
Q

What is the region in which decondensed chromosomes occupy?

A

Territories

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16
Q

What is a centromere?

A

A region where sister chromatids are held together

17
Q

Where is the assembly site for the kinetochore?

A

Centromere

18
Q

Describe the base sequence in the centromere.

A

Large arrays of repeated sequences

19
Q

What is a metacentric chromosome?

A

A chromosome where p arm length = q arm length

20
Q

What is a submetacentric chromosome?

A

A chromosome where p arms are slightly shorter than q arms

21
Q

What is an arcocentric chromosome?

A

A chromosome where p arms are much shorter than q arms

22
Q

What is a telocentric chromosome?

A

A chromosome where there are no p arms

23
Q

What is a telomere?

A

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

24
Q

Give the 2 major functions of the telomere.

A

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

25
Q

Describe the End Replication Problem.

A

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

26
Q

How does telomerase prevent chromosome shortening?

A

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

27
Q

Why do most cells turn off telomerase?

A

To reach ‘replicative cell senescence’

28
Q

What is DNA wrapped around?

A

An octane of histones

29
Q

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

A

Nucleosomes

30
Q

What is chromatin?

A

Protein complex of DNA wrapped around histones

31
Q

What is euchromatin?

A

‘True chromatin’
Relatively uncondensed, associated with active genes

32
Q

What is heterochromatin?

A

Condensed, repressive, inactive, repetitive gene poor regions

33
Q

What are minichromosomes?

A

Chromosomes relatively short but rich in genes

34
Q

What are B chromosomes?

A

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

35
Q

What are holocentric chromosomes?

A

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

36
Q

What are polytene chromosomes?

A

Giant chromosomes made by larval cells of certain insects