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Genetics > Genome Structure > Flashcards

Genome Structure Flashcards

1
Q

describe eukaryotic nuclear genomes

A

typically large, linear, and made of many separate chromosomes; large intergenic spaces and introns (only 1.5% of human genome is protein coding)

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2
Q

describe prokaryotic genomes

A

typically small (100,000 - 5 million bp), circular, often just a single chromosome; very compact, most of the genome encodes proteins, few intergenic spaces and no introns

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3
Q

why are prokaryotic genomes so small compared to ours?

A

vast majority of size difference is due to non-protein coding sequences (basically just promoters and protein coding sequences - no exons in bacteria)

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4
Q

why is gene regulation simpler in single-celled organisms versus multicellular organisms?

A

because they don’t have to make different types of cells

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5
Q

main reason for bacteria to regulate genes

A

to respond to their environment

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6
Q

what did chloroplasts and mitochondria evolve from?

A

symbiotic prokaryotes (bacteria)

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7
Q

mitochondria have their own ___. it looks similar to a _______.

A

genome; bacterial genome

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8
Q

describe our mitochondrial genome

A

circular, very tiny and compact, most genome encodes protein, few introns and intergenic sequences

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9
Q

mitochondrial genome bp in humans vs yeast, why is there a big difference?

A

17,000 bp in humans; 78,000 bp in yeast
eukaryotic cells provide a lot for the mitochondria (give food, break things down) so the mitochondria don’t need as much of the genome

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10
Q

describe the chloroplast genome

A

circular, not as small as mitochondrial genome, compact, few introns and intergenic regions

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11
Q

how many bp in a chloroplast genome?

A

100,000-200,000 bp

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12
Q

how many chloroplasts in a leaf cell?

A

100-10,000 chloroplasts

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13
Q

how many mitochondria are in an animal cell?

A

1,000-5,000 mitochondria

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14
Q

does yeast have a linear or circular genome?

A

eukaryote so linear

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15
Q

size (in bp) of human nuclear genome

A

3.2 billion bp

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16
Q

how many chromosomes do we have (haploid)?

A

23

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17
Q

size (in bp) of each chromosome

A

57-250 million bp

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18
Q

size (in protein coding genes) of each chromosome

A

200-2000 protein coding genes

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19
Q

total protein-coding genes combined (on all chromosomes)

A

20,000 protein coding genes

20
Q

what percent of genome is translated?

A

1.5% translated (protein-coding)

21
Q

what percentage of the human genome consists of repetitive elements?

A

60%

22
Q

what do most of the repetitive sequences of DNA consist of?

A

transposable elements (transposons)

23
Q

what are transposons?

A

“jumping genes” that can cut, or copy, and then past themselves into new locations in the genome

24
Q

what kind of transposons encode proteins that allow them to jump?

A

autonomous transposons

25
Q

what do retrotransposons contain that allow them to be transcribed?

A

have a promoter and get transcribed

26
Q

autonomous retrotransposons are translated into?

A

2 proteins, one of which is a reverse transcriptase which creates a complementary DNA sequence that is then integrated into the genome

27
Q

what does it mean for most retrotransposons to be inactive?

A

they are mutated so that they can’t be transcribed and/or translated; they are molecular fossils

28
Q

what step allows one retrotransposon to become many?

A

the transcription step

29
Q

what % of the human genome is retrotransposons?

A

41%

30
Q

what percent of the human genome is DNA transposons?

A

3%

31
Q

are DNA transposons transcribed?

A

transcribed and translated, but there is no reverse transcriptase

32
Q

when can DNA transposons be duplicated?

A

if it “jumps” during DNA replication

33
Q

short DNA sequences over and over again in tandem

A

tandem repeat sequences

34
Q

what are tandem repeat sequences classified by?

A

size of repeated sequence

35
Q

percent of human genome that is tandem repeat sequences?

A

3%

36
Q

what are minisatellites?

A

group of tandem repeat sequences; 10-60 bp long repeated 5-50 times

37
Q

what are microsatellites?

A

group of tandem repeat sequences; 1-9 bp long and highly variable between individuals in a species

38
Q

what are microsatellites useful for?

A

DNA fingerprinting

39
Q

how might mini or micro satellites be extended or shortened?

A

by basal slippage of DNA polymerase during replication

40
Q

what kind of repetitive DNA sequences DO NOT need DNA polymerase to be duplicated?
a) DNA transposons
b) retrotransposons
c) microsatellites
d) minisatellites

A

b) retrotransposons

41
Q

define polyploidy

A

having multiple copies of the whole genome

42
Q

why do related plants and animals have very different genome sizes?

A

mostly due to polyploidy, also due to frequency of repetitive elements like retrotransposons

43
Q

genome size DOES NOT correlate to the ____ of an organism

A

complexity

44
Q

the cell doesn’t seem to care about the amount of DNA, rather _____

A

the number of genes

45
Q

most multicellular organism have _____ of protein-coding genes; which is around _____

A

the same; 20,000

46
Q

how many protein-coding genes do unicellular organisms have?

A

5000 protein-coding genes

Genetics (11 decks)

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