Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MBG 2040 > Pre Midterm Notes > Flashcards

Pre Midterm Notes Flashcards

1
Q

what is it called when you cut just one strand of DNA?

A

a nick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how does DNA become super coiled

A

single strand nick
multiple 360 rotation
ligation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is it called when you seal the nick?

A

ligation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how much bigger is a eukaryote than a prokaryote?

A

10x

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is supercoiling?

A

a double helix (as of DNA) that has undergone additional twisting in the same direction as or in the opposite direction from the turns in the original heli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how large is the human nucleus?

A

5-10 micrometers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is a eukaryotic chromosome composed of?

A
  • one large linear molecule of DNA
  • 5 histones (positive charged)
  • divergent group of non-histone proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

DNA + histone + protein =

A

chromatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how many levels of DNA packaging are in chromatin

A

3:

  1. nucleosome
  2. 30 nm chromatin fiber
  3. inter-phase chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

level 1 : nucleosomes

A
  • 146 nucleotide pairs of DnA wrapped as 1 3/4 turns around an octamer histone
  • linker DNA carry in length from 8-114 nucleotide pair
  • width: 11 nm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Nucleosome core

A

-consist of 2 molecules of each of the 4 histones 2(H2a + H2b + H3 + H4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what does H1 do

A
  • comes in and seals the 1 3/4 turn
  • just one
  • becomes complete nucleosome once H1 is involved
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

level 2: 30 nm chromatin fibre

A
  • have chromatin DNA and protein
  • least elegant step
  • compact everything into a fibre that ends up being 30 nm wide
  • linear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

level 3: inter-phase chromosome

A
  • divergent non-histone proteins
  • fibre forms loops (less space)
  • 300 nm wide
  • tethered to scaffold
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is inter-phase chromosome?

A

how your DNA in your cells look when they’re not dividing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is simplest level of DNA?

A

double stranded helical structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does interphase chromosome wrap around to become metaphase chromosome?

A

chromosome scaffold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is another level of packaging that a chromosome undergoes during mitosis?

A

the metaphase chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what kind of DNA does each eukaryotic chromosome contain?

A

nucleosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is a nucleosome?

A

1 giant molecule of DNA packaged into 11 nm ellipsoidal beads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is a gene?

A

a genetic factor that helps determine a characteristic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is an allele?

A

One of two or more alternative forms of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how is genetic info carried?

A

DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

where are genes located?

A

chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the flow of genetic info transfer?

A

DNA to RNA to protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is a locus?

A

Specific place on a chromosome occupied by an allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is a genotype?

A

Set of alleles possessed by an individual organism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is a heterozygote?

A

An individual organism possessing two different alleles at a locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is a homozygote

A

An individual organism possessing two of the same alleles at a locus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is a phenotype?

A

The appearance or manifestation of a character

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what did Gregor Johann Mendel discover?

A

the basic principles of heredity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is the phenotypic ratio in the F2 generation of a monohybrid cross?

A

3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is the phenotypic ratio in the F2 generation of a dihybrid crop?

A

9:3:3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what do we assume if the trait is rare and autosomal recessive?

A

individuals who marry into the pedigree are not carriers: homozygous for the normal allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what are the 2 types of recessive mutations?

A

null/amorphic alleles

hylomorphic alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what is a Null/Amorphic allele?

A

a nonfunctional protein is produced
or
no protein is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what is a hylomorphic allele?

A

a poorly functioning protein is produced
or
reducing amounts of a normally function protein is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

when do you use the multiplication rule?

A

when the word AND is used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

when do you use the addition rule?

A

when the word OR is used

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what often involves a loss of gene function?

A

recessive mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

what are the 2 types of dominant mutations?

A

dominant hypermorphic alleles
or
neomorphic alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

what often involves gain/change of gene function?

A

dominant mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what is a dominant hypermorphic alleles?

A
  • Negative phenotypic consequences due to the over-production of a normal protein
    OR
  • Negative phenotypic consequences due to the production of a protein with increased activity levels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what is a neomorphic allele?

A
  • Negative phenotypic consequences due to the presence of an altered protein that has a new function
  • Negative phenotypic consequences when the altered protein interferes with the wildtype protein (Dominant-negative allele
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

why for traits that are rare and dominant, affected individuals are most likely to be heterozygous (Bb)?

A

If the trait is rare in the population, then matings between Bb individuals would be infrequet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

what is incomplete dominance?

A

Bb is intermediate between homozygous phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

what is codominance?

A

Bb exhibits phenotypes of both homozygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

true or false:

Multiple Alleles Often Exist for a Gene at a Particular Locus

A

true

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what does the IA allele in blood encode?

A

a transferase which adds acetylgalactosamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

what does the IB allele in blood encode?

A

a transferase which adds galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

what does the i allele in blood encode?

A

a non-functional transferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

what does the IAIB blood type encode?

A

acetylgalactosamine and galactose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

what is a wild type allele?

A

a functional enzyme or other protein is produced (most common found in a natural population)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

what is a loss of function allele?

A

an enzyme or other protein is no longer being produced, is produced at lower levels, or is nonfunctional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

what is haplosufficiency?

A

Half as much protein is synthesized yet this is often sufficient to achieve the wildtype phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

what’s an example of a gain of function dominant allele?

A

Huntington’s disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

what is haploinsufficent?

A

in the heterozygote, half as much protein is synthesized and this is not sufficient for a normal phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

when do you get a severe mutant phenotype?

A

recessive amorphic loss-of-function allele does not produce a functional polypeptide
OR
dominant-negative allele produces a polypeptide that interferes with the wild-type polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

when do you get a mild mutant phenotype?

A

recessive hylomorphic loss-of-function allele produces a partially functional polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

what is penetrance?

A

The proportion of individual organisms having a particular genotype that express the expected phenotype
-variation in the population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

what is expressivity?

A

The degree to which a phenotype is expressed (mild to severe);
variation in the individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

what is polydactyly an example of?

A

incomplete penetrance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

what are some examples of variable expressivity?

A

split hand-foot syndrome
piebaldism
Huntington’s disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

what causes incomplete penetrance and expressivity?

A

due to the effects of other genes and to environmental factors that can alter or completely suppress the effect of a particular gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

what are the 4 environmental factors that can affect phenotypic expression?

A
  1. age
  2. sex
  3. temperature
  4. chemicals
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

what is the norm of reaction?

A

The range of phenotypes expressed by a single genotype under different environmental conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

what is a phenocopy?

A

change in phenotype arising from environmental factors that mimic the effects of a mutation in a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

what is Mendel’s law of independent assortment?

A

The inheritance pattern of one trait will not affect the inheritance pattern of another trait

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

when will complementation occur?

A

when two strains of an organism with different homozygous recessive mutations that produce the same phenotype, produce offspring of the wild-type phenotype when mated or crossed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

true or false:

complementation can occur if the mutations are in the same gene

A

false:

only if they’re in different genes

71
Q

what is a heterogeneous trait?

A

a mutation in any one of a number of genes can give rise to the same phenotype

72
Q

what is epistasis?

A

The masking of the expression of one gene by another.

No new phenotypes are produced

73
Q

what is the F2 phenotypic ratio of the recessive epistasis?

A

9:3:4

74
Q

what is the F2 phenotypic ratio of the dominant epistasis?

A

12:3:1

75
Q

what is the F2 phenotypic ratio of the recessive lethal allele?

A

2:1

76
Q

what is the F2 phenotypic ratio of the incomplete dominance or codominance?

A

1:2:1

77
Q

what is the F2 phenotypic ratio of complementation?

A

9:7

78
Q

what is pleiotropy?

A

when A single gene can be responsible for a number of distinct and seemingly unrelated phenotypic effects

79
Q

what is heterosis?

A

when 2 different inbred lines are crossed

80
Q

what does inbreeding do?

A

increases the frequency of homozygotes and decreases the frequency of heterozygotes

81
Q

what is the Hardy Weinberg principle?

A

predicting genotypes through allele frequencies in a population

82
Q

what is the Hardy Weinberg equation?

A

p^2 + 2pq + q^2

83
Q

what needs to be absent for the Hardy Weinberg Principle t be correct?

A

evolutionary influences:

  1. Nonrandom mating
  2. Unequal survival
  3. Population subdivision
  4. Migration
84
Q

what is the expected frequency of heterozygotes in a population with allelic frequency x and y that is in Hardy–Weinberg equilibrium?

a. x+ y
b. xy
c. 2xy
d. (x-y)2

A

c. 2xy

85
Q

what is dosage compensation?

A

a way of equalizing gene expression in the face of different gene dosa

86
Q

what are the only 2 chromosomes that pair even though they’re not homologous?

A

the X and Y

87
Q

where are X and Y chromosomes homologous?

A

only at pseudoautosomal regions

88
Q

what is a Barr body?

A

inactive X chromosome

89
Q

how many active X chromosomes can a person have?

A

1

90
Q

what are genetic mosaics?

A

females that are heterozygous for X-linked traits

91
Q

what is polyploid?

A

more than 2 sets of chromosomes

92
Q

how much of the plant kingdom is polyploidy?

A

30-35% of flowering plants

93
Q

true or false:

polyploidy is rare in the animal kingdom

A

true

94
Q

describe autopolyploids

A
  • the chromosome sets are all identical

- All chromosomes are derived from the same species

95
Q

what d autopolyploid plants usually have?

A

–More vegetative growth (larger cells, thicker leaves, bigger flowers, larger plants, bigger fruits)
–Less seed production

96
Q

why are many polyploids sterile?

A

due to problems with pairing and separation of homologous chromosomes in meiosis

97
Q

what are allopolyploids?

A

polyploids that are the result of the crosses between 2 or more species

98
Q

describe polyploidy in animals

A
  • interspecies crosses can result in a sterile animal

- Chromosome doubling which potentially could restore fertility is not well tolerated

99
Q

what is aneuploidy?

A

Diploid genome which lacks a chromosome or has an extra chromosome

100
Q

what can cause aneuploidy?

A

Meiotic nondisjunction

101
Q

what are the only 3 autosomal trisomies seen as live births in humans?

A
  • trisomy 21 (Down syndrome)
  • trisomy 13 (Patau syndrome)
  • trisomy 18 (Edwards syndrome)
102
Q

what are the aneuploid conditions involving sex chromosomes?

A
  • X0 Turner Syndrome
  • XXY Klinefelter Syndrome
  • XXX Triple X Syndrome
  • XYY Double Y male
103
Q

what is another word for bivalent?

A

homologous pair

104
Q

a diploid organism has 2n = 36 chromosomes. How many chromosomes will be found in a trisomic member of this species?

A

2n + 1 = 36 + 1 = 37

105
Q

what is the cause of Down’s syndrome?

A

96% meiotic non-disjunction

4% Robertsonian translocation of the chromosome 21 long arm onto the long arm of chromosome 14

106
Q

Why Is There A Correlation Between The Incidence Of Trisomies And Maternal Age?

A

Bivalents with crossovers near the ends of the chromosomes are fragile and are increasingly unstable over time

107
Q

in humans, where do germ cells remain until ovulation?

A

arrested prophase 1

108
Q

what sorts of chemicals can cause nondisjunction?

A 
colchicine
Bisphenol A (BPA)
109
Q

what is deletion?

A

a missing chromosome segment

110
Q

what is duplication?

A

an extra chromosome segment

111
Q

what is paracentric inversion?

A

not including the centromere in the inversion

112
Q

what is pericentric inversion?

A

including the centromere in the inversion

113
Q

when does translocation occur?

A

when a segment from one chromosome is detached and reattached to a different (nonhomologous) chromosome

114
Q

what is reciprocal translocations?

A

pieces of two nonhomologous chromosomes are exchanged without any net loss of genetic material

115
Q

how are compound chromosomes formed?

A

by the fusion of homologous chromosomes, sister chromatids, or homologous chromosome segments

116
Q

how are Robertsonian translocations formed?

A

by the fusion of two nonhomologous chromosomes at their centromeres

117
Q

true or false:

genes that are of the same chromosome travel through meiosis together

A

true

118
Q

what did TH Morgan discover?

A
  • Genes are “linked” if present on the same chromosome

- The divergence from linkage is called recombination

119
Q

what did AH Sturtevant discover?

A

The frequency of recombination reflects distance between genes

120
Q

map units =

A

recombinants / total x 100

121
Q

if genes are linked, what do you see in F1?

A

two major classes of offspring with equal frequencies with two minor classes of offspring that are the result of recombinant gametes in the dihybrid parent

122
Q

when does homologous recombination occur?

A

prophase 1 of meiosis

123
Q

what is a chiasma?

A
  • the physical junction between the homologous chromatid

- site where recombination occur

124
Q

true or false:

multiple crossovers can be simultaneously taking place over the same tetrad

A

true

125
Q

when does crossing over occur?

A

prophase of meiosis 1

126
Q

true or false:
the closer genes are to each other on the chromosome, the likelier they are to crossover together, decreasing the likelihood of a recombinant gamete

A

true

127
Q

what are the 3 possible scenarios for dihybrid cross AaBb X AaBb

A
  1. Genes A and B are independently assorting (4 classes of offspring with a 9:3:3:1 ratio)
  2. Genes A and B are tightly linked so that crossing over does not happen (2 classes of offspring with a 3:1 ratio)
  3. Genes A and B are linked and crossing-over occurs (variations in the 3:1 ratio)
128
Q

what is recombination caused by?

A

by a physical exchange between paired homologous chromosomes early in prophase of the first meiotic division after chromosomes have duplicated

129
Q

true or false:
At any one point along a chromosome, the process of exchange (crossing over) involves only two of the four chromatids in a meiotic tetrad

A

true

130
Q

when do crossovers become visible as chiasmata?

A

late in prophase 1

131
Q

how can linkage between human genes be detected?

A

by analyzing pedigrees

132
Q

true or false:

pedigree analyses can have a limited success in complex genetic traits

A

true

133
Q

what are the mechanisms of genetic exchange in bacteria?

A

conjugation
transformation
transduction

134
Q

what makes bacteria a valuable research object?

A
  • Small size
  • Rapid reproduction
  • Selective media (e.g., antibiotics) that can easily identify the presence of an active allele
  • Simple structures and physiology
  • Genetic variability
135
Q

how do bacteriophages reproduce?

A

by infecting bacterial cells

136
Q

what do bacteriophages produce on plates with dense bacterial cultures?

A

plaques

137
Q

describe bacteriophage T4

A
  • Protein head
  • Genome contains 168,800 base pairs and 150 characterized genes
  • This is a fairly large and complex genome
  • The phage goes through a lytic phase
138
Q

describe bacteriophage lambda

A
  • Genome contains, 48,502 base pairs and about 50 genes

- May be lytic or lysogenic

139
Q

Conjugation between an F+ and F− cell usually results in which of the following?

a. Two F+ cells
b. Two F− cells
c. An F+ and an F− cell
d. An Hfr and an F+ cel

A

a. Two F+ cells

140
Q

what is the bacterial genome?

A

circular molecules of several million base pairs, called bacterial chromosome

141
Q

where does additional genetic material reside?

A

in plasmids (small circular DNA) that can replicate independently of the bacterial chromosome

142
Q

what is an episome?

A

large circular DNA that can integrate into the bacterial chromosome for replication or remain separate

143
Q

true or false:

bacteria have meiosis

A

false

144
Q

true or false:

gene transfer in bacteria is unidirectional

A

true:

from donor cell to recipient cell

145
Q

how can gene mutations in bacteria be observed?

A
  • Colony colour and morphology
  • Nutritional mutants (can not metabolise certain sugars, like lactose or galactose)
  • Prototrophs and auxotrophs (can not make certain amino acids, these need to be added to the growth medium)
  • Antibiotic resistance
146
Q

define transformation

A

transfer of a free (out of the cell) piece of DNA from one bacterium into another

147
Q

define conjugation

A

direct transfer of DNA from one cell to another via the establishment of a cytoplasmic bridge

148
Q

define transduction

A

transfer of genes from one cell to another via bacteriophage (vector)

149
Q

which parasexual process in bacteria requires cell contact?

A

conjugation

150
Q

which parasexual process in bacteria is sensitive to DNase?

A

transformation

151
Q

true or false:

Transformation can be used to determine the distance between bacterial gene

A

true

152
Q

what is transformation measured as?

A

a change in phenotype that occurs with a certain frequency

153
Q

what is the sexual reproduction in conjugation mediated by?

A

the Fertility or F factor

154
Q

how does an F-factor exist?

A

as an extra-chromosomal DNA
OR
it can insert into the bacterial chromosome and replicate as part of it

155
Q

true or false:

in general plasmids are not required for the survival of the host cell

A

true:

they serve as auxiliary genetic elements

156
Q

what are the functions of the genetic material?

A

must replicate, control the growth and development of the organism, and allow the organism to adapt to changes in the environment

157
Q

where is genetic info of most living things stored?

A

in DNA

158
Q

where is genetic info present in some viruses?

A

RNA

159
Q

how are nucleotides joined?

A

phosphodiester bonds

160
Q

true or false:

%A=%C

A

false:
%A=%T
%C=%G

161
Q

true or false:

A+G=T+C

A

true

162
Q

which are the 2 purines?

A

A and G

163
Q

which are the 2 pyrimidines

A

T and C

164
Q

what did Erwin Chargaff determine?

A

the precise base composition of different types of DNA

165
Q

what did William Astbury discover?

A

X-ray diffraction Analysis showed that DNA is a polymer of stacked bases

166
Q

what did Rosalind Franklin & Maurice Wilkins discover?

A

DNA is a helix

167
Q

what are the assumptions of the Watson and Crick model?

A
  • DNA is a double helix
  • The two strands were anti-parallel
  • The sugars form a phosphate backbone
  • The bases are held together by H bonds
168
Q

true or false:

DNA has antiparallel strands

A

true

169
Q

true or false:

The two strands of the helix have opposite chemical polarity (5’ and 3’ ends)

A

true

170
Q

true or false:

the U-tube experiment concluded that genetic exchange requires direct contact between bacterial cells

A

true

171
Q

true or false:

the rate of cotransformation is proportional to the distance between genes

A

false:

inversely proportional

172
Q

what is the transforming substance in the Avery–MacLeod–McCartyexperiment?

A

DNA

173
Q

what is the genetic material of TMV?

A

RNA

MBG 2040 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions