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Cell Bio > Chapter 5 > Flashcards

Chapter 5 Flashcards

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Biology 101 flashcards
1
Q

Linear sequence of nucleotides

A

ATGC

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2
Q

Structure of DNA

A

double helix composed of antiparallel DNA strands held by hydrogen bonds between G-C and A-T base pairs

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3
Q

G is paired with

A

C

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4
Q

A is paired with

A

T

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5
Q

Genetic material of a eukaryotic cell is contained in a

A

set of chromosomes

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6
Q

When a gene is expressed, part of its nucleotide sequence is

A

transcribed into RNA, which are translated to make proteins

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7
Q

In eukaryotic chromosomes, the DNA is

A

tightly folded

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8
Q

What makes eukaryotic DNA tightly folded

A

Set of histone proteins and nonhistone chromosomal proteins

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9
Q

pack the DNA into a repeating array of DNA–protein par-ticles called nucleosomes

A

Histones

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10
Q

The loosening of chromatin to a more decondensed state allows

A

proteins in gene expression, DNA replication, and DNA repair to gain access to necessary DNA sequences

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11
Q

a high degree of condensation occurs on all chromosomes during

A

Mitosis and in the heterochromatin of interphase chromosomes

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12
Q

Building block of DNA is

A

phosphate + sugar (deoxyribose) +base

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13
Q

Four different kinds of bases

A

Purines: A and G
Pyrimidines: T and C

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14
Q

Bases in DNA are linked together in one strand by

A

covalent bonds between the 3’-hydroxyl (-OH) group of
one sugar and the 5’-phosphate of another

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15
Q

G-C base pairs use how many hydrogen bonds

A

3

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16
Q

A-T base pairs use how many hydrogen bonds

A

2

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17
Q

Which base pairs are more stable

A

G-C because they require higher temps to melt

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18
Q

The base pairs are located __ the double helix and the phosphate groups on the sugar phosphate backbone are __ charged on the __

A

inside, negatively, outside

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19
Q

Each strand of the double helix contains a sequence that is

A

exactly complementary to its partner strand

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20
Q

DNA encodes information in the order or sequence of its nucleotides

A

A T C G

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21
Q

How do four nucleotides specify the sequence of twenty different amino acids

A

A two base pair code could only specify 16 (4 x 4) amino acids, A three base pair code could specify 64 (4 x 4 x 4) amino acids

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22
Q

process by which the DNA nucleotide sequence of a gene is transcribed into an RNA nucleotide sequence and then translated into the amino acid sequence of a protein.

A

Gene expression

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23
Q

The complete set of information in an organism’s DNA is called its

A

genome

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24
Q

The complex of DNA and protein

A

chromatin

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25
Q

In interphase chromatin, the DNA is compacted

A

~500-fold

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26
Q

In humans, __nucleotide base pairs are distributed into _ chromosomes

A

3.2 x 10^9
24

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27
Q

Homologous chromosomes known as

A

autosomes

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28
Q

There are how many homologous chromosomes

A

2 sets of 22

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29
Q

How many sex chromosomes

A

2, XX or XY

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30
Q

Each human chromosome can be identified using

A

chromsome painting

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31
Q
  • A display of the full set of 46 chromosomes
A

karyotype

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32
Q

Cytogeneticists use __ to identify chromosomal abnormalities due to chromosome loss or
rearrangements

A

karyotypes

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33
Q

Approximately how many genes in humans

A

25,000

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34
Q

Cell replication occurs in

A

interphase

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35
Q

Chromosome duplication requires __ origins of replication per chromosome

A

multiple

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36
Q

Proper duplication of the two ends of the chromosome requires

A

two telomeres

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37
Q

The duplicated chromosomes (chromatids) are held together by their

A

centromeres

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38
Q

What happens in the M phase or mitosis

A

the chromosomes become even more compacted to form mitotic chromsomes

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39
Q

The nuclear envelope breaks down and the chromosomes attach to…

A

the microtubules of the miotic spindle by their kinetochores

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40
Q

centromeric DNA plus specialized centromere binding proteins

A

kinetochores

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41
Q

What type of DNA occupies discrete territories in the nucleus

A

Interphase

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42
Q

The genes encoding __ are located on different chromosomes
but these regions cluster together in the __

A

ribosomal RNAs (rRNAs), nucleolus

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43
Q

site of rRNA synthesis and packaging with ribosomal proteins

A

Nucleolus

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44
Q

Proteins have two classes in chromosome packing

A

Histones and non-histone chromosomal proteins

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45
Q

What protein is very abundant and highly basic

A

Histones (Lysines and arginines)

46
Q

1st level of chromosome packing is done by the

A

nucleosome

47
Q

Nucleosomes are composed of a

A

Histone octamer

48
Q

Histone octamer contain

A

two copies of H2A, H2B, H3, and H4

49
Q

There are how many turns of DNA/nucleosome in chromosome packing

A

1.7

50
Q

Mild treatments that partially unfold DNA reveal

A

“beads on a string”

51
Q

To isolare histone octamers…

A

treat core particles with high salt

52
Q

What histone tail extends from the core particle

A

N-terminal

53
Q

2nd level of chromosome packing is done by

A

Histone H1

54
Q

Chromatin are packed

A

nucleosome

55
Q

8 protein histone molecules attach to DNA, forming a compact tight loop

A

Nucleosome

56
Q

Chromatin remodeling involves what two strategies

A

ATP-dependent chromatin remodeling complexes and histone modifying enzymes

57
Q

What chromatin remodeling process repositions the DNA around the nucleosome

A

ATP-dependent chromatin remodeling complexes

58
Q

Histone modifying enzymes remodel chromatin by

A

covalently modify amino acids on the histone tails

59
Q

Covalent modifications of histones include

A

addition and/or removal of acetyl, methyl, or
phosphate groups to specific amino acids

60
Q

Regions of chromosomes that contain active genes are

A

more extended and seen as euchromatin

61
Q

Regions of chromosomes with inactive or silent genes are

A

more compacted and seen as heterochromatin

62
Q

Example of epigenetic inheritance

A

one X chromosome is
randomly inactivated by heterochromatin formation in each cell; pattern of X-chromosome inactivation is inherited by daughter cells. Tissues in adult female end up as mosaics

63
Q

Epigenetic changes allow long lived cells to..

A

alter their patterns of gene expression from environmental changes.

64
Q

The pattern of modification of histone tails can determine…

A

how a stretch of chromatin is handled by the cell

65
Q

Structure of DNA

A

Nucleotides, phosphodiester bonds, base pairing

66
Q

A nucleotide consists of a

A

Nitrogen base, 5C sugar, and phosphate Groups

67
Q

The subunits of nucleic acids

A

Nucleotides

68
Q

Deoxyribose lacks the __

A

2’ OH group

69
Q

From 5’ to 3’: order of nucleotides

A

GCAT

70
Q

The helix is __ handed

A

Right

71
Q

The negatively charged phosphate groups are

A

Outside the helix

72
Q

Bases pair form

A

Hydrogen bonds inside

73
Q

Each chromosome has

A

1 double stranded DNA molecules

74
Q

Identify individual chromosomes using

A

DNA hybridization

75
Q

Chromosome painting enables

A

Detection of some chromosomal abnormalities

76
Q

In cancer cells, segments
of chromosomes are

A

Frequently swapped

77
Q

Chromosomes are packaged & organized in discrete territories inside the

A

Nucleus

78
Q

__ DNA sequence elements are required for chromosome duplication and segregation

A

3

79
Q

Each chromosome has what elements

A

1 centromere
2 telomeres
Multiple origins of replications

80
Q

the __ attaches the chromosome to the mitosis spindle

A

Centromere

81
Q

Chromosome packaging occurs at multiple levels: first three levels

A
  1. DNA wraps around nucleosome
  2. H1 histone packages nucleosomes into fiber
  3. Non histone chromatin proteins fold the fiber into loops
82
Q

basic units of chromosome structure

A

Nucleosokes

83
Q

__ are conserved, basic (positively charged) proteins

A

Histones

84
Q

Binding is a DNA sequence specific: T or F

A

False

85
Q

N-terminal tails of the histones in the octamer…

A

Extend outward

86
Q

Histones are what charges

A

Positive

87
Q

binds linker DNA to change its path as it
exits the nucleosome core particle

A

H1 histone

88
Q

What proteins fold the chromatin into a series of loops

A

Specialized non histone chromosomal proteins

89
Q

The chromatin loops are further condensed to produce

A

Interphase chromosome

90
Q

Changes in chromatin structure allow access to DNA: what two processes

A

• Chromatin Remodeling Complexes
• Histone Modification

91
Q

Changes in chromatin structure alter

A

Gene expression

92
Q

Changes in chromatin structure can be

A

Inherited by daughter cells

93
Q

Interphase chromosomes contain

A

Euchromatin and Heterochromatin

94
Q

Compact chromosomes, transcription is inactive in

A

Heterochromatin

95
Q

Less compact chromatins, transcription is active in….

A

Euchromatin

96
Q

Chromatin remodeling complexes use

A

ATP

97
Q

Regulate condensation of
chromatin by locally

A

Altering the arrangement of nucleosomes on the DNA

98
Q

Regulating condensation of chromatin makes the DNA either

A

More or less accessible to dna binding proteins

99
Q

Modification of amino acids in histone tails create a

A

Histone code

100
Q

Modifications often serve as

A

Protein binding site

101
Q

highly condensed form of chromatin that is
concentrated at telomeres and centromeres

A

Heterochromatin

102
Q

Genes located in regions of heterochromatin are

A

Inactive or silenced

103
Q

Euchromatin is associated with

A

Active genes

104
Q

Chromatin structure changes with

A

Differentiation and cell type

105
Q

Condensed chromatin (heterochromatin) is __ darkly stained than
less condensed chromatin (euchromatin).

A

More

106
Q

Changed s in chromatin structure can be

A

Inherited

107
Q

Example of change in chromatin structure

A

X chromosome inactivation in females

108
Q

As DNA is replicated, Histones…

A

Form new nucleosomes

109
Q

Modified histones recruit __ to modify new nucleosomes

A

enzymes

110
Q

How can chromatin structure be inherited?

A
  1. Parental nucleosomes with modified Histones
  2. 1/2 of the daughter nucleosomes have modified Histones.
  3. Parental pattern of histone modification re-established by proteins that recognize the same modifications they catalyze
111
Q

Nucleotides are joined together by

A

Phosphodiester bonds

Cell Bio (15 decks)

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