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Genetics > Lecture--Chapter 12 > Flashcards

Lecture--Chapter 12 Flashcards

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Biology 101 flashcards
1
Q

Chromosomes have a DNA helix of 2 strands, which are complexed with _____.

A

proteins

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2
Q

The relaxed DNA molecule of a single chromosome is longer than the ________ of the cell.

A

greatest dimension

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3
Q

Human genome (23 chromosomes) is about _____ long.

A

1 meter

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4
Q

To fit into cells, DNA must be ____.

A

compacted

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5
Q

generally a single circular DNA helix

A

bacterial chromosome

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6
Q

main chromosome + any plasmids:

A

genome

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7
Q

Multiple copies of genome may be present during times of _____.

A

fast growth

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8
Q

Genome is located as a _____, not in a nucleus.

A

nucleoid

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9
Q

bacterial “chromosome” (lacks chromatin)

A

genophore

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10
Q

Bacterial chromosome is a few million ____ in length.

A

nucleotides

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11
Q

E. coli has ~______ base pairs.

A

4.6 million

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12
Q

Haemophilus influenzae has ~_____ base pairs.

A

1.8 million

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13
Q

structural genes (encoding proteins)

A

transcribed gene sequences

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14
Q

intergenic regulatory regions

A

nontranscribed DNA segments

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15
Q

start site for DNA replication

A

origin of replication

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16
Q

Bacterial DNA must be packed about ______ smaller than its relaxed length.

A

1000-fold

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17
Q

Intergenic and repetitive sequences include regions with roles in ______.

A

chromosome packing

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18
Q

With bacterial DNA. compaction is largely accomplished by ____ and ____.

A

looping; supercoiling

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19
Q

additional coils due to twisting forces

A

supercoil

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20
Q

different structural conformations of a molecule

A

topoisomer

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21
Q

Coiled coils form loops in response to _____.

A

twisting forces

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22
Q

_____ supercoiling is the ______ state.

A

negative; normal

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23
Q

Negative supercoiling creates tension which promotes _____.

A

strand separation

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24
Q

Negative supercoiling: DNA replication in _____.

A

cell division

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25
Q

Negative supercoiling: DNA transcription for ______.

A

gene expression

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26
Q

Supercoiling is _____.

A

regulated

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27
Q

enzymes that either create or reduce supercoiling

A

topoisomerases

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28
Q

reduce (“relax”) negative supercoiling

A

type I topoisomerases

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29
Q

break a single strand, allow rotation around the unbroken strand, and re-form phosphodiester backbone

A

type I topoisomerases

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30
Q

creates negative supercoiling

A

DNA gyrase

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31
Q

DNA gyrase plays a part in ____.

A

type II topoisomerases

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32
Q

makes a double strand break, redirects the broken strand, then re-seals

A

type II topoisomerases

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33
Q

essential for bacteria to survive

A

DNA gyrase

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34
Q

_______ is one way to cure some bacterial diseases.

A

inhibiting DNA gyrase

35
Q

broad-spectrum antibiotics for UTIs, hospital-acquired pneumonia

A

quinolones

36
Q

drug-resistance, side effects issues

A

quinolones

37
Q

A eukaryotic genome is the complete set of _____ chromosomes.

A

nuclear

38
Q

Long ____ DNA molecules complexed with proteins.

A

linear

39
Q

Nearly all eukaryotic genomes have ______ of DNA.

A

multiple pieces

40
Q

human genome:

A

3.1 billion nucleotides, 22,000 genes

41
Q

human genome: initial draft completed in ____, final draft in ____.

A

2003; 2006

42
Q

human genome: useful for ____ research, _____, _____ studies.

A

biomedical; forensics; evolution

43
Q

Large variation in genome size among _____.

A

species

44
Q

many per chromosome, about every 100,000 base pairs

A

origins of replication

45
Q

one per chromosome

A

centromere

46
Q

defined DNA sequence of ~125 base pairs, yeast

A

point centromere

47
Q

long repetitive DNA sequences, most common

A

regional centromere

48
Q

both ends, specialised repeated sequences

A

telomeres

49
Q

stabilise and protect the ends of the chromosomes

A

telomeres

50
Q

the number of times a particular motif appears throughout a genome

A

DNA sequence complexity

51
Q

usually occur only once or a few times

A

unique sequences

52
Q

encode proteins (gene exons)

A

structural genes

53
Q

control expression

A

regulatory regions

54
Q

100s to 1000s of copies

A

moderately repetitive sequences

55
Q

Moderately repetitive sequences: _____ and ____ protein genes.

A

ribosomal RNA; histone

56
Q

Moderately repetitive sequences: remnants of _____.

A

transposable elements

57
Q

10s of thousands to millions of copies

A

highly repetitive sequences

58
Q

Highly repetitive sequences: Alu and LINE ______.

A

transposable elements

59
Q

clusters of highly repetitive sequences (satellites)

A

tandem arrays

60
Q

Tandem arrays: polymerase errors in ____.

A

replication

61
Q

Tandem arrays: _____ (chromosome pairing) and ____.

A

centromeres; telomeres

62
Q

Eukaryotic DNA must be _____ packed to fit.

A

tightly

63
Q

Eukaryotic DNA increased ___ and ____ makes compaction difficult.

A

size; complex structure

64
Q

a double-stranded segment of DNA wrapped around an octamer of histone proteins

A

nucleosomes

65
Q

basic proteins that bind to negatively charged phosphates in the minor groove of the DNA backbone

A

histones

66
Q

Eukaryotic Chromosome Compaction: DNA is wrapped around the nucleosome (_____).

A

beads on a string

67
Q

Eukaryotic chromosome compaction: nucleosomes coil to form ______.

A

30 nm fiber

68
Q

Eukaryotic Chromosome Compaction: 30 nm fiber organised into ______.

A

radial loop domains

69
Q

Eukaryotic Chromosome Compaction: MARs are:

A

matrix attachment regions

70
Q

Eukaryotic Chromosome Compaction: Additional packing of radial loops and further packing is seen in ____ chromosomes.

A

metaphase

71
Q

discrete nuclear locations of each chromosome

A

chromosome territories

72
Q

Compaction state of ____ chromosomes is variable.

A

interphase

73
Q

tightly compacted regions, generally not transcribed

A

heterochromatin

74
Q

always heterochromatic and inactive

A

constitutive heterochromatin

75
Q

chromatin that can interconvert between heterochromatin and euchromatin

A

facultative heterochromatin

76
Q

less condensed regions capable of gene transcription

A

euchromatin

77
Q

the entire chromosome is packed into heterochromatin

A

mitotic chromatin

78
Q

compacted radial loops remain anchored to a _____.

A

protein scaffold

79
Q

protein that coats individual chromosomes at the beginning of mitosis, then folds the strands.

A

condensin

80
Q

loops on matrix fiber

A

euchromatin

81
Q

matrix fiber folded

A

heterochromatin

82
Q

chromatin attached to scaffold proteins

A

condensin

83
Q

family of ATPases that catalyse changes in chromosome structure (condensins and cohesins)

A

structural maintenance of chromosomes (SMC) proteins

84
Q

proteins that promote binding between sister chromatids and regulate their separation during nuclear division

A

cohesin

Genetics (18 decks)

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