Lecture--Chapter 12 Flashcards Preview

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Flashcards in Lecture--Chapter 12 Deck (84):
1

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

proteins

2

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

greatest dimension

3

Human genome (23 chromosomes) is about _____ long.

1 meter

4

To fit into cells, DNA must be ____.

compacted

5

generally a single circular DNA helix

bacterial chromosome

6

main chromosome + any plasmids:

genome

7

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

fast growth

8

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

nucleoid

9

bacterial "chromosome" (lacks chromatin)

genophore

10

Bacterial chromosome is a few million ____ in length.

nucleotides

11

E. coli has ~______ base pairs.

4.6 million

12

Haemophilus influenzae has ~_____ base pairs.

1.8 million

13

structural genes (encoding proteins)

transcribed gene sequences

14

intergenic regulatory regions

nontranscribed DNA segments

15

start site for DNA replication

origin of replication

16

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

1000-fold

17

Intergenic and repetitive sequences include regions with roles in ______.

chromosome packing

18

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

looping; supercoiling

19

additional coils due to twisting forces

supercoil

20

different structural conformations of a molecule

topoisomer

21

Coiled coils form loops in response to _____.

twisting forces

22

_____ supercoiling is the ______ state.

negative; normal

23

Negative supercoiling creates tension which promotes _____.

strand separation

24

Negative supercoiling: DNA replication in _____.

cell division

25

Negative supercoiling: DNA transcription for ______.

gene expression

26

Supercoiling is _____.

regulated

27

enzymes that either create or reduce supercoiling

topoisomerases

28

reduce ("relax") negative supercoiling

type I topoisomerases

29

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

type I topoisomerases

30

creates negative supercoiling

DNA gyrase

31

DNA gyrase plays a part in ____.

type II topoisomerases

32

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

type II topoisomerases

33

essential for bacteria to survive

DNA gyrase

34

_______ is one way to cure some bacterial diseases.

inhibiting DNA gyrase

35

broad-spectrum antibiotics for UTIs, hospital-acquired pneumonia

quinolones

36

drug-resistance, side effects issues

quinolones

37

A eukaryotic genome is the complete set of _____ chromosomes.

nuclear

38

Long ____ DNA molecules complexed with proteins.

linear

39

Nearly all eukaryotic genomes have ______ of DNA.

multiple pieces

40

human genome:

3.1 billion nucleotides, 22,000 genes

41

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

2003; 2006

42

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

biomedical; forensics; evolution

43

Large variation in genome size among _____.

species

44

many per chromosome, about every 100,000 base pairs

origins of replication

45

one per chromosome

centromere

46

defined DNA sequence of ~125 base pairs, yeast

point centromere

47

long repetitive DNA sequences, most common

regional centromere

48

both ends, specialised repeated sequences

telomeres

49

stabilise and protect the ends of the chromosomes

telomeres

50

the number of times a particular motif appears throughout a genome

DNA sequence complexity

51

usually occur only once or a few times

unique sequences

52

encode proteins (gene exons)

structural genes

53

control expression

regulatory regions

54

100s to 1000s of copies

moderately repetitive sequences

55

Moderately repetitive sequences: _____ and ____ protein genes.

ribosomal RNA; histone

56

Moderately repetitive sequences: remnants of _____.

transposable elements

57

10s of thousands to millions of copies

highly repetitive sequences

58

Highly repetitive sequences: Alu and LINE ______.

transposable elements

59

clusters of highly repetitive sequences (satellites)

tandem arrays

60

Tandem arrays: polymerase errors in ____.

replication

61

Tandem arrays: _____ (chromosome pairing) and ____.

centromeres; telomeres

62

Eukaryotic DNA must be _____ packed to fit.

tightly

63

Eukaryotic DNA increased ___ and ____ makes compaction difficult.

size; complex structure

64

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

nucleosomes

65

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

histones

66

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

beads on a string

67

Eukaryotic chromosome compaction: nucleosomes coil to form ______.

30 nm fiber

68

Eukaryotic Chromosome Compaction: 30 nm fiber organised into ______.

radial loop domains

69

Eukaryotic Chromosome Compaction: MARs are:

matrix attachment regions

70

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

metaphase

71

discrete nuclear locations of each chromosome

chromosome territories

72

Compaction state of ____ chromosomes is variable.

interphase

73

tightly compacted regions, generally not transcribed

heterochromatin

74

always heterochromatic and inactive

constitutive heterochromatin

75

chromatin that can interconvert between heterochromatin and euchromatin

facultative heterochromatin

76

less condensed regions capable of gene transcription

euchromatin

77

the entire chromosome is packed into heterochromatin

mitotic chromatin

78

compacted radial loops remain anchored to a _____.

protein scaffold

79

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

condensin

80

loops on matrix fiber

euchromatin

81

matrix fiber folded

heterochromatin

82

chromatin attached to scaffold proteins

condensin

83

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

structural maintenance of chromosomes (SMC) proteins

84

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

cohesin