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2014 Genetics Topic 1:CM > L3 > Flashcards

L3 Flashcards

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1
Q

what is spacer DNA

A

unique non coding DNA

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2
Q

what are non coding functional sequences

A

do not produce proteins but still important

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3
Q

what are human globin genes for

A

codes for oxygen carrying molecule in humans

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4
Q

what is a heme

A

iron carrying molecule

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5
Q

true or false, eukaryotic genomes tend to be larger than prokaryotes

A

true

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6
Q

true or false, there is no relationship between genome size and phenotypic complexity

A

true

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7
Q

true or false, the number of genes in a species is often lower than expected when compared to the size of its genome

A

true

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8
Q

true or false, there is no strong relationship between genome size and number of genes

A

true

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9
Q

which has fewer genes but a larger genome in a given number of base pairs, eukaryote or prokaryote

A

eukaryote

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10
Q

true or false, of the genomes sequenced so far, humans and other mammals have the lowest gene density

A

true

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11
Q

what do the genes of most bacteria consist of

A

genes for proteins tRNA or rRNA with the remaining consisting of non transcribed regulatory regions

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12
Q

true or false, in eukaryotes the vast majority of DNA neither encodes protein nor is transcribed into RNA of known function

A

true

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13
Q

true or false, humans have 10 000 times as much non coding DNA as bacteria

A

true

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14
Q

what are unique sequence DNA

A

aka spacer DNA
mainly consist of genes which in addition to coding regions contain intervening sequences that are not translated ( has exons and introns).

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15
Q

true or false, gene related regulatory sequences and introns account for 20% and 5% of the human genome respectively, the remainder is 15% unique non coding DNA

A

true

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16
Q

what are pseudogenes

A

non functional gene within a family of genes

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17
Q

why have some genes evolved into tandem arrays

A

this is because cells need a large amount of products of those genes

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18
Q

what is the purpose of telomeres

A

it acts as a cap stabilizing the end of the chromosome and stops it from being degraded; the G rich strand often protrudes beyond the complementary C-rich strand at the end of the chromosome

19
Q

true or false, special proteins bind to the single-strand sequence protecting the telomere from degredation

A

true

20
Q

what does the telomeric sequence solve

A

solves the problem of replicating the ends of a linear DNA molecule

21
Q

what enzyme can extend the G-overhang

A

telomerase (reverse transcriptase)

22
Q

where is telomerase present

A

in single-celled organisms, germ cells, early in embryonic cells and certain somatic cells

23
Q

true or false, most somatic cells have little or no telomeras activity

A

true

24
Q

true or false, once the telomeres have shortened beyond a critical point the chromosome becomes unstable

A

true

25
Q

what are centromeric repeats

A

highly repeat sequences with no known function

26
Q

what are centromeric repeats also known as and what type of chromatin are they usually

A

aka satellite DNA, usually heterochromatic, short A-T rich tandem repeats flanking the centromeres

27
Q

what are variable number of tandem repeats (VNTRs)

A

A DNA sequence consistent of variable number of tandem repeat units

28
Q

what are the two principal families of VNTRs

A

microsatellites and minisatellites

29
Q

what is a microsatellite

A

The repeat unit in microsatellite is 2-6 bp long

most common is repeat CA complement GT

30
Q

what is a minisatellite

A

between 15-100 bp long

31
Q

what uses do mini and micro satellites have

A

can be used in DNA fingerprinting and paternity tests

32
Q

What are transposable elements

A

are mobile DNA sequences found in the genome of all organisms; they make up 45% of the human DNA; able to insert into many different locations in the genome

33
Q

how do transposable elements cause mutation

A

often cause mutation either by direct insertion into gene or by promoting DNA rearrangement such as chromosome deletions, duplication, inversions

34
Q

what are the classes of transposable elements in eukaryotes

A

retrotransposons and DNA transposons

35
Q

What are retrotransposons

A

make RNA copies of themselves which are then reverse transcribed into DNA and inserted into chromosome;
the RNA is copied into DNA by enzyme reverse transcriptase

36
Q

what do you call the mechanism which retrotransposons transpose

A

copy and paste, because they leave a copy behind

37
Q

what is the enzyme which is encoded by transposon

A

transposase

38
Q

what are two types of retrotransposons

A

LINE and SINE

39
Q

what is LINE

A

long interspersed elements; have an element which encodes reverse transcriptase but lack LTRs

40
Q

what is SINE

A

short interspersed elements; are non autonamous LINEs

41
Q

what do you call the most abundant SINE in humans

A

Alu

42
Q

How do we survive with so much mobile DNA in our genome?

A
  • most transposable elements are found in the introns and therefore are removed during RNA splicing
  • the vast majority of mobile elements are currently inactive and cannot move or increase in copy number
  • most are relics and have been inactivated by mutations
  • some are rendered inactive by host regulatory mechanisms
43
Q

what is the overall frequency of mutation due to class 2 elements in humans

A

low, 0.2% of all mutations

2014 Genetics Topic 1:CM (11 decks)

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