Genetics Flashcards Preview

Biology > Genetics > Flashcards

Flashcards in Genetics Deck (134)
1

Nucleotide: monomer

A sugar (deoxyribose) with a phosphate group attached to it and a base

2

Deoxyribose bases

Adenine (A), Guanine (G), Cytosine (C), or Thymine (T)

3

Protein: polypeptide

Long chain of 20 types of amino acids, each linked by a covalent peptide bond

4

Protein: pH 7

Both the amino and carboxyl groups are ionized

5

optical isomers

Proteins consist of exclusively L amino acids

6

Lysine side chain

Basic NH3+ amide group

7

Arginine side chain

Basic NH2+ resonance

8

Histidine side chain

Basic NH+ weak pentagon

9

Deoxyribose sugar

H at the 2' carbon position

10

Ribose sugar

OH at the 2' carbon position

11

Purine bases

Adenine and Guanine with double rings

12

Pyrimidine bases

Thymine, Cytosine and Uracil with single rings

13

Nucleoside

A base attached to only a sugar: adenine+ribose-->adenosine

14

Adenosine triphosphate

ATP nucleotide containing adenine, ribose, and three phosphate groups

15

Guanosine triphosphate

GTP nucleotide containing guanine, ribose, and three phosphate groups

16

deoxyadenosine triphosphate

dATP nucelotide containing adenine, deoxyribose, and three phosphate groups

17

phosphodiester bond

two covalent phosphoester bonds with phosphate attached to 5' carbon of one sugar and 3'carbon of another sugar

18

Chargaff's rule

Equal amounts of A&T, G&C. A+G=T+C

19

DNA directionality

Phosphate group adds on to 3' hydroxyl end

20

Complete helix turn

One helix turn is 3.4 nm and contains 10 nucleotides

21

Bases: hydrogen bonds

G and C -> 3 bonds. A and T -> 2 bonds

22

A DNA

Right handed helix and tilted on axis

23

B DNA

Predominant DNA in living cells, right handed helix

24

Z DNA

Left handed helix, may affect transcription and level of chromosome compaction

25

RNA helix

RNA can be single stranded or be double stranded at some points

26

Structural gene

Nucleotide sequences that encode proteins

27

Intergenic regions

nontranscribed regions of DNA located between adjacent genes

28

Bacteria chromosome

Mos bacteria contain circular chromosomal DNA and one chromosome with few million bp

29

Bacteria genes and origin

several thousand different genes and one origin of replication

30

Bacteria DNA compaction

DNA must be compacted about 1,000 fold

31

DNA gyrase

In bacteria travels in front of DNA helicase and relaxes positive supercoils

32

Topoisomerase I

In bacteria relaxes negative supercoils

33

Quinoline + coumarin

Drugs that inhibit gyrase and bacterial topoisomerases but not eukaryotic topoisomerase

34

Chromatin

DNA-protein complex found within eukaryotic chromosomes

35

Centromere

Recognition site for kinetochore proteins during mitosis and meiosis

36

Eukaryotic origin of replication

each chromosome contains OR every 100,00 bp

37

Eukaryotic Chromosome bp

Tens of millions to hundreds of millions bp

38

Telomeres

inhibit chromosomal rearrangements such as translocations

39

Nucleosome

double stranded segment of DNA wrapped around octamer of histone proteins

40

DNA:nucleosome

150 bp around histones + 20-100 bp linker region

41

Interphase compaction

Nucleosomes+zigzag 30 nm fiber+radial loops

42

Radial loops

Chromosome sequences matrix attachment regions attaching to nuclear matrix

43

Euchromatin

capable of gene transcription and forms radial loop domains during interphase

44

heterochromatin

compacted regions at centromere and telomere

45

Facultative heterochromatin

chromatin that can occasionally interconvert between heterochromatin and euchromatin

46

histone code hypothesis

Patterns involving phosphorylation of serine at first position in H2A and acetylation of 5th and 8th lysine in H4 may attract chromatin loosening proteins

47

Condensin

Enters nucleus at M phase and converts euchromatin in chromatids to heterochromatin

48

cohesin

promotes binding between sister chromatids after s phase through prophase along entire length

49

Separase

cohesins at centromere remain attached until anaphase

50

Semiconservative model

14N and 15N radioiosyptes showed DNA replication

51

bacteria ori

DnaA binds to ori and recriuts DNA helicase

52

DNA helicase

when this enzyme encounters double stranded regions it breaks the hydrogen bonds between the strands to generate single strands

53

Single strand binding proteins

binds to single DNA strands and prevents double helix

54

DNA primase

synthesizes short strands of RNA called RNA primers

55

DNA polymerase III

synthesizes DNA in leading and lagging strand

56

DNA polymerase I

removes RNA primers and fills in with DNA

57

okazaki fragment

1,000-2,000 fragments in length

58

bacterial primosome

DNA helicase+primase

59

bacterial replisome

2 DNA polymerase holoenzymes+primosome

60

DNA polymerase III fidelity

1 mistake in 100 million nucleotides

61

oriC regulation

DnaA protein amount and GATC methylation sites in oirigin

62

Eukaryotic origins

replication proceeds bidirectionally from many origins during S phase

63

ARS elements

50 bp and necessary to initiate chromosome replication

64

DNA polymerase y(gamma)

replication of mitochondria DNA

65

DNA polymerase a(alpha)

associates with primase to synthesize RNA primers followed by 20 DNA bp

66

DNA polymerase delta

possible greater role in lagging strand synthesis

67

DNA polymerase e(epsilon)

possible greater role in leading strand synthesis

68

telomerase

synthesizes additional repeats of telomeric sequences

69

homologous chromosomes

homologs - the maternal and paternal chromosomes of a pair

70

human karyotype

cytogeneticists use the 46 human chromosomes displayed at mitosis to view abnormalities

71

human genes

approximately 25,000

72

Avg gene size

27,000 nucleotide pairs or 9,000 amino acids

73

Avg # exons/gene

10

74

nuclease

breaks down DNA by cutting between the nucleosomes

75

histone octamer

two molecules each of H2A, H2B, H3, and H4

76

Histone

high salt dissociates the ionic (salt) linkages between DNA and histones

77

histone deacetylase complex

HDAC-removes acetyl groups (COCH3) from lysine and removing gene expression proteins

78

histone acetyl transferase

HAT-commonly adds acetyl group to lysine on histones and recruits proteins that turn on gene expression. Also adds acetyl to transcription factors

79

histone methyl transferase

adds methyl groups

80

acetylation vs methylation

A methylated lysine cannot be acetylated and vice versa

81

histone covalent modifications

acetylation+methylation of lysines, phosphorylation of serine+threonine, methylation of arginine, ubiquityl+sumoyl+biotin of lysine

82

Histone synthesis

synthesized during S phase

83

histone variants

synthesized during interphase binding to specific chromatin sites

84

histone code potential

signals that stretch of chromatin is newly replicated, chromatin damaged or needs repair

85

reader-writer complex

A gene regulatory protein will recruit a histone modifying enzyme, which attracts a code reader protein causing a repetitive effect

86

barrier sequence

cluster of proteins such as histone acetylase enzymes blocks chromatin condensing

87

lampbrush chromosomes

extended meiotically paired chromosomes in amphibian oocytes allows viewing of interphase chromosomes

88

polytene chromosome

all homologous chromosomes are side by side and allow viewing of dark heterochromatin DNA bands; first seen drosophila

89

Chromosome puff

duirng transcription, the DNA puffs out on a polytene chromosome

90

Heterochromatin types

different types of heterochromatin allow different levels of compaction

91

nucleus subcompartments

cajal bodies, nucleolus, and repair factories create specialized environments in nucleus

92

homologous gene

genes similar in nucleotide sequence and function because of common ancestry

93

pseudogene

one copy of a duplicated gene can be seen to have become irreversibly inactivated by multiple mutations

94

Globin gene duplications

The globin gene family has duplicated and diverged over eveolution from a single globin to variety of globins during development

95

point mutation

change in a single base pair within the DNA

96

base substitution

one base is substituted for another base

97

transition mutation

base substitution where a pyrimidine is substituted for a pyrimidine or purine for a purine

98

transversion mutation

base substitution where a pyrimidine is substituted for a purine

99

silent mutation

base mutation that does not alter the amino acid sequence even though the nucleotide has changed

100

missense mutation

base substitution where amino acid sequence changes from one amino acid to another with one nucleotide change

101

nonsense mutation

change from a normal codon to a stop codon

102

operon polarity

nonsense mutation occurs in a bacterial operon it might inhibit downstream gene expression

103

frameshift mutation

addition or deletion of a number of nucleotides not divisible by 3

104

neutral mutation

silent mutation and when a missense mutation has not detectable effect on protein

105

wild type genotype

relatively prevalent genotype and if multiple alleles could have mutliple wild type alleles

106

mutant allele

a rare mutation that changes the wild type genotype by altering DNA gene sequence

107

conditional mutants

affect the phenotype under a defined set of conditions such as temperature sensitivity

108

suppressor mutations

a second mutation that affect the phenotype expression of the first mutation by affecting protein

109

intragenic suppressor

when the second mutation is within the same gene (such as LacY) as the first mutation

110

intergenic suppressor

suppressor mutation the is in a different gene from first mutation

111

promoter mutations

up promoter or down promoter mutations affect transcription

112

splice mutation

mutations in eukaryotic genes can alter splice junctions and affect the order and/or number of exons that are contained within mRNA

113

trinucleotide repeat expansion

repeated sequence of 3 nucleotides can readily increase in number from one generation to the next

114

position effect mutation

Genes may be moved next to regulatory sequences such as promoters or heterochromatin regions

115

genetic mosaic mutation

somatic regions that are genotypically different from each other

116

spontaneous mutation

changes in DNA structure that result from abnormalities in biological processes

117

induced mutation

abnormalities caused by environmental agents

118

spontaneous mutation cause

molecular change in DNA caused by depurination, deamination, tautomeric shift

119

depurination

removal of a purine (adenine, guanine) from DNA which breaks covalent bond between deoxyribose and purine causing apurinic site

120

deamination

removal of an amino group from cytosine which produces uracil or changes 5-methylcytosine to thymine

121

T+G tautomers

common form is keto form and rare is enol form

122

A+C tautomers

common form is amino form and rare is imino form

123

tautomeric shift

if the base tautomers shift right before DNA replication a mutation can occur

124

deamination mutagen

nitrous acid replaces amino groups with keto groups in bases

125

hypoxanthine

deamination of adenine. hypoxanthine pairs with cytosine

126

5-bromouracil

base analogue that has tautomeric shifts commonly

127

UV mutagen

thymine dimers between bases in DNA

128

photolyase

in plants and yeast thymine dimers are split

129

alkyltransferase

protein removes methyl or ethyl groups from guanine bases mutated by alkylating agents

130

base excision repair

enzyme DNA glycosylase that recognizes abnormal bases and cleaves the bond to sugar

131

nucleotide excision repair

direct repair of nucleotides

132

homologous recombination repair

repairs double stranded breaks by exchanging DNA between broken and unbroken sister chromatids during S and G2 phase

133

nonhomologous end joining

repairs double stranded breaks by filling DNA gaps and ligates them together

134

bacteria origin of replication

bacterial chromosomes have a single origin of replication and proceeds bidirectionally