Test 2 Flashcards
(173 cards)
1
Q
Linked genes
A
genes located on the same chromosome
2
Q
What stage during crossing over occur?
A
prophase I
3
Q
Complete linkage
A
there is no CROSSING OVER, only 2 gamete types are made
4
Q
Coupling vs. Repulsion
A
coupling phase=cis
- parental types Ab and ab (AB/ab)
- recombinant types: Ab and aB
Repulsion phase=trans
- parent types Ab and aB
- Recombinant types AB and ab
5
Q
Map distance
A
is numerically equal to the percentage of recombination(crossing over) between the loci
ex: 1% recombination= 1 Centimorgan
6
Q
NCO and DCO
A
NCO= biggest number DCO= smallest number
7
Q
Coefficient of Coincidence formula
A
(Observed DCO)/(expected # DCO)
8
Q
Crossover for R1 (just that, nothing happens in R2)
A
(.5)(R1)
9
Q
Crossover for R2 (just that, nothing happens in R1)
A
(.5)(R2)
10
Q
No cross in R2 (nothing happens in R1)
A
(.5)(1-R2)
11
Q
DCO
A
(.5)(R1)(R2)(C)
12
Q
NCO
A
(.5)(1-R1-R2+DCO)
13
Q
Crossover in R1
A
(.5)(R1-DCO)
14
Q
Crossover in R2
A
(.5)(R2-DCO)
15
Q
Neurospora
A
?
16
Q
Mapping distance between the gene and centromere of a Neurospora
A
(.5)(#second division asci/total)(100)
17
Q
1st and 2nd division segregation patter of neurospora
A
1st division: AAAAaaaa
-no cross over between gene and centromere
2nd Division: AAaaAAaa, aaAAaaAA, aaAAAAaa, AAaaaaAA
-crossover between genes and centromere
18
Q
Lod Scores
A
(logarithm of odds)
- scores are used to determine whether or not two genes are linked based on pedigrees
- Lod score is the logarithm of the ratio of the probability of observing the progeny if the genes are linked to the probability the progeny if the genes are not linked.
- If lod score is greater than or equal to 3, the genes are linked/
- less than the they assort indepedantly
19
Q
Genome Wide Association studies (GWAS)
A
form of mapping
- looks for associations between a trait and various markers scattered across the genome
- studies populations of individuals not pedigrees of a particular family
- indentify haplotypes that are associated with a particular trait
- many of these markers are molecular markers called SNPs( Single nucleotide polymorphism)
20
Q
What are the molecular molecules called in GWAS
A
SNPs- single nucleotide Polymorphisms
21
Q
Somatic Cell hybridization: Synteny Testing
A
Use SENDAI VIRUS to fuse mouse and human cells. After several mitotic divisions, human chromosomes are randomly lost producing several synkaryon lines
22
Q
Heterokaryon
A
cell has two nuclei (one from each source)
23
Q
What are the advantages of using bacteria and viruses for genetic studies?
A
- reproduction is rapid
- many progeny are produced
- haploid genome allows all mutations to be expressed directly
- asexual reproduction simplifies the isolation of genetically pure strains
- Growth in the laboratory is easy and requires little space.
- Genomes are small
- Techniques are available for isolating and manipulating their genes
- They have medical importance
- They can be genetically engineered to produce substance of commercial valu
24
Q
What are the advantages of E. Coli as a model organism
A
- small size
- rapid reproduction, dividing every 20 ins under optimal conditions
- easy to culture in liquid medium or on petri plates
- small genome
- many mutants available
- numerous methods availabe for genetic engineering
25
Taxonomy of E. Coli
Eubacteria
26
Size of E. Coli
1-2um in length
27
Anatomy of E. Coli
Single cell surrounded by cell wall with nucleoid region
28
habitat of e. Coli
intestinal tract of warm-blooded animals
29
What are the contributions to genetics from E. Coli
- gene regulation
- molecular biology and biochemistry of genetic processes, such as replication. transcription, translation, recombination
- gene structure and organization in bacteria
- workhorse of recombinant DNA
- Gene mutations
30
Prototroph
mutant bacteriacan grow on minimal media
31
Auxotroph
mutant bacteria Require additional nutrients
32
Mal
maltose
33
lac
lactose
34
gal
galactose
35
xyl
xylose
36
ara
arabinose
37
what are "ose" words
carbon source
38
Antibiotic resistance:
| str, amp, tet
streptomycin
ampicillin
tetracycline
39
Phage resistance: S, R, Ton
S=sensitive so won't live if agent present
R=resistant so will live in presence of agent
Ton=T1 bacteriaphage
40
Nutrients: +,-, Pro, met, thi, bio
+ =strain can make its own
- = strain cannot synthesize this, so it will not grow unless this is added to the media
pro-proline
met-methionin
thi-thiamin
bio-biotin
41
Conjugation
temporary fusion of 2 single-cell organisms for the sexual exchange of genetic material
42
Mechanism for Conjugation
2 cell types: F+ and F-
F+ contain an episome called the F factor and is the donor cell
F- is the recipient cell
F+ has extensions called pili that contact F-
A conjugation tube is formed to connect the cells
The F factor is nicked and begins to transfer 1 strand to the F- cell
DNA replication occurs so that both cells end up with a double stranded F factor
The cells break apart
Exconjugants are both F+
43
Hfr
High frequency Recombination
-these cells transfer genes from bacterial chromosomes at high frequency due to an integrated F Factor. Crossing over between the F factor and the bacterial chromosome in an F+ cell results in an Hfr cell.
44
Mechanism of interrupted mating
HfrxF-
- Part of the f factor leads the way into the F- cell (5' end leading)
- The transferred strand is replicated
- Cell separate prior to transfer of entire bacterial chromosome
- Recombination occurs between newly transferred DNA and original bacterial chromosome in the recipient cell
- This can lead to a genetic change in the recipient cell, but the recipient cell will not be an F+ or an Hfr strain
45
When the F factor can "pop out" of the bacterial chromosome what does it produce?
F' cell
46
what is the the product of the F' cell and F- cell called?
F' merozygote
| -partial diploid
47
what does Hfr x F- result in
one Hfr cell and one cell that MAY HAVE ALTERED BACTERIAL CHROMOSOME GENES, but will almost never become an F+
48
what does F' x F result in
in one F' cell and one F' merozygote, which is diploid for the transferred bacterial chromosome genes
49
Transformation
Exogenous DNA transfers genes to competent bacterial cell and brings about heritable change in the cell
50
Competent Cell
cell is in proper state to take in DNA
51
Heteroduplex DNA
different alleles on the 2 strands
52
GENES THAT ARE CLOSE TOGETHER WILL BE CONTRANSFORMED MORE frequently than genes that are far apart
...
53
Lytic cycle
phage infects, takes over, replicates, and lyses cell
54
Plaques
seen on lawn of bacteria when lysis occurs
55
Life cycle of a Temperate Phage
-a temperate phage can be either lytic or lysogenic
56
Prophage
when the phage is integrated into the bacterial chromosomes
57
Lysogenic
bacteria containing a prophage
58
Where do phages produce plaques on the bacterial lawn?
where cells are lysed
59
Transduction
viral mediated gene transfer
60
Generalized Transduction
- During phage replication, the host DNA is degraded into pieces
- The transducer genres can incorporate into the new host cell through recombination similar to the transformation mechanism
- This results in RANDOM gene transfer
-USEFUL IN MAPPING SINCE 2 Genes co-transduce, they are probably close together on the bacterial chromsoms
61
Specialized transduction
- Prophage posts out of bacterial chromosome and take one or a few genes with it. The progeny virus particles transfer these genes when they infect other cells
- NOT useful in mapping the bacterial chromosomes since only genes near the site of integration are transduced
62
Is cell contact required in Transformation?
NO
63
is cell contact required in Conjugation?
YES
64
is cell contact required in Transduction?
NO
65
Is transformation sensitive to DNase?
yes
66
is conjugation sensitive to DNase
NO
67
is transduction sensitive to DNase
NO
68
What is it called when two mutations are on the same chromosome of a heterozygous individual?
CIS
69
What is it called when two mutations are on two different chromosomes of a heterozygous individual?
TRANS
70
What is it called when the two mutation can be in the same gene?
alleles
71
What is it called when the two mutations are in different genes
nonalleles
72
Complementation
production of a wild-type (normal) phenotype when two mutant types are combined in the trans configuration
73
Ciastron
region of dNA in which two mutations cannot complement each other in TRANS configuration
74
Population Genetics
Study of inherited variation within and between populations over time and space
75
Gene frequency
allele frequency
76
Population
local group of a species among which mating can occur
77
Hardy-Weinberg Law
Allele and genotypic frequencies will arrive at and remain at equilibrium frequencies after one generation of random mating if all assumptions below are met.
p^2AA + 2pq+ q^2aa
p and q are the frequencies of the allele
78
Degrees of freedom
number of genotypes - # of alleles
79
Genetic conclusion
?
80
Mutation
an important source of variability
| -origin of new alleles
81
Mutation Formula
?
82
Gene frequency changes from mutation are____.
small
83
Migration
change in gene frequency depend on migration rate and on the frequency of the immigrants
84
formula for migration
p'=(1-m)p + mP
p'=Frequency of A allele after migration
p=frequency of A allele on island initially
m=proportion of migrants after immigration occurred probability that a parent will come from the mainland
P=average allele frequency of the donor popoulation
85
Directional selection
- favors one extreme or the other
| - population mean increases or decreases depending on which extreme is favored
86
Stabilizing Selection
- heterozygote is favored
- decreases variance
- leads to polymorphisms (both alleles remain in population)
87
Disruptive selection
- advantage for both extremes
| - leads toward bimodal population
88
Viability selection
some individuals are more likely to survive to reproduction than others
89
Assortive mating
mate based on phenotype
90
Two different types of assortative mating
positive- mating like individuals together, results in similar situations as inbreeding, BUT ONLY FOR LOCI UNDER SELECTION
negative- opposites attract would keep diversity in the population and tends to increase the frequency of heterozygous individuals FOR THE LOCI UNDER SELECTION
91
inbreeding
mating of related individuals changes frequency of genotypes, but not allele frequency leads to more homozygous individuals in population over time. AFFECTS ALL LOCI IN THE ORGANISM
92
Non-random matting changes frequency of _____ but not _____ frequency.
genotye, allele
- increases frequencies of both homozygous genotypes
- decreases frequency of heterozygote
- Eventually everyone in the population will be homozygous and the genotypic array will be pAA + qaa
93
Inbreeding formula
(p^2 + Fpq)AA + 2(1-F)pq Aa + (q^2 + Fpq)aa
94
What are the effects of small population size
Random Drift/Genetic Drift- random loss and fixation of alleles
Inbreeding: mating between relatives (consanguinity) is more likely in a small population resulting in inbreeding
95
Genetic drift
random variation in gene frequency form generation to generation due to small population size and sampling error
-leads to random fixation or loss of alleles over time
96
Founder Population
small population that colonies a new area
-have small size and likely to undergo genetic drift
-allele frequencies in the founder population may differ from those in the original population
-selection pressures on found population will probably be different from those on original population since they are in a different environment.
(often this is a harsher environment causing more selection pressure and a more rapid change due to selection)
97
What increases genetic variation within populations?
mutation
migration
some types of natural selection
98
What decreases variation within population?
Genetic drift
| Some types of natural selection
99
What increases genetic variation between populations?
mutation
genetic drift
Some types of natural selection
100
What decreases genetic variation between populations?
migration
| some types of natural selection
101
Deletion
missing part of a chromosome
102
What disease is an example of a deletion
Cri Du Chat-missing part of short arm of chromosome number 5
103
Terminal deletion
produces acentric fragment is lost during cell division
104
Interstitial Deletion
Requires two breaks
105
Effects of Deletion
segments that do not contain a centromere are lost (acentric fragments are lost)
- deletions may cause an imbalance in the amount of gene products produced (Haploinsufficiency)
- deletion of normal allele on one chromosome may allow the recessive allele on the homolog too be visible causing mutant phenotype (pseudo dominance)
106
Haploinsufficiency
single copy of gene is not enough to allow the wild-type phenotype to occur
107
Pseudodominance
expression of normally recessive phenotype because there is no homologous allele due to a deletion (loss of big A allele in heterozygote)
108
Duplication
extra copy of part of the chromosome
109
Tandem dupliction
the duplicated sequence is back-to-back to normal duplicated part
ABCDEFDEFG
110
Reverse Tandem
the duplicated sequence is the reverse order back-to-back of the normal duplicated part
ABCDEFFEDG
111
Displaced duplication (homobrachial)
also called homobrachial
-duplicated section is located at the end of sequence
AB.CDEFGDEF
112
Displaced Duplication (heterobrachial)
duplicated seeunce is located at the beginning
| DEFABCDEFG
113
Unbalanced Gene Dosage
Bar eye in Drosophila Melanogaster
-importance is the position effects on phenotype of the BAR
LOOK IN NOTES
114
SUSUMU OHNO (theory, ex)
-duplication is essential to origin of new genes in a species
THEORY:
- unique genes are essential to survival and therefore cannot accumulate mutations
- Duplicated copy is "extra" and can accumulate mutations and may even develop a different function over time
- EX:similarites in sequence but not function
- myoglobin and hemoglobin
- hemoglobin and parts of immunoglobin
- trypsin and chymotrypson
115
Inversion
segment of chromosome is removed, turned 180 degrees and reinserted into chromosome
116
Paracentric Inversion
- Inverted area does not include centromere
- does not change arm ratio of chromosome
AbcdE.FGH
AdcbE.FGH
117
Pericentric inversion
- inverted are does include centromere
- can alter arm ratio
ABCde.fGH
ABCf.edGH
118
Dicentric bridges
are common in anaphase I when a crossover in a PARACENTRIC inversion loop
119
Inversion characteristics
suppress crossing over
- actually, crossing over occurs within inversion loop, but recombinant products are often inviable
- duplications and deletions result when crossing over occurs in inversion loops
120
Two-stranded Double Crossover
-no dicentric bridges, but gametes have duplications and deletions that can result in reduced viability
121
What is the EVOLUTIONARY significance of INVERSIONS
- often see related species with differences between their chromosomes that appear to be due to inversion
- the fact that crossover types are often inviable may lead to divergence between individuals of different inverted sequence
- presence of inversions tends to preserve a gene sequence along length of chromosomes that is more favorable
- Different inverted forms may be favored in different enviroments
122
Reciprocal Translocations
two non homologous chromosomes exchange arms (or parts of arms) (NO GAIN OR LOSS OF DNA)
123
NON-reciprocal translocations
a segment from one chromosome is moved to a nonhomologus chromosome (no overall gain or loss of DNA)
-part of one chromosome is moved to a non-homologous chromosome
AB.CDEFG AB.CFG
JK.LM JK.LDEM
124
Robertsonian Translocations
- two telocentric/nearly telocentric chromosomes combine to make one larger, more metacentric chromosome (lose a bit of DNA, usually not noticeable)
- isochromosomes- two chromosomes joined are homologs
-LARGER PIECES FUSE TOGETHER
125
Isochromosomes
- compound chromosomes
- two homologous chromosomes join to form 1 chromosome. The two tend to stay together if there is only one centromere so twice as much of that chromosomes genetic information is transmitted to a gamete
126
Familial Down syndrome
can be due to either robertsonian translocation or isochromosomes
- robert-joining between chromosomes 14 and 21
- isos- if two chromosome 21 join together
- the individual has 46 chromosomes, but still has 3 copies of the information from chromosome 21
- the parent with the robertsonian translocstion has only 45 chromosomes and is normally phenotypically (NO DOWN SYNDROM) and has 2 copies of chromosome 21 info
127
Burkitt's Lymphoma
abnormal function of B cells (normally B cells secrete antibodies)
- reciprical translocation between chromosomes 8 and 14 places c-myc (oncogene) next to enhancer which normally stimulates production of immunoglobulin
- position effect- same genes are present, but chromosomal location alters the phenotype
128
assumptions for Hardy-weinburg law
```
Infinitely large population
random mating (panmictic)
no selection
no migraton
no mutation
```
129
Aneuploidy
number of chromosome in an interphase somatic cell is not exact multiple of the haploid number
EX; humans are 2n=46 so haploid number is 23
130
Monosomic
XX22334
| on less of a chromosome
131
Nullisomic
XX2233 no copies of one number
| D
132
Double Monosomic
XX2234 missing one copy of two numbers
133
Trisomic
XX2233444 three copies of one number
134
tetrasomic
XX22334444 four copies of one number
135
Double Trisomic
XX22333444 three copies of two numbers
136
Down syndrome
Trisomy 21
137
Nondisjuction
can result in aneuploid progeny
| -happens in anaphase I and II
138
What are some human Aneuploid conditions
Klinefelter syndrome (47,XXY)-male
Down Syndrome (47, 21+)
Turner syndrom (45,XO) mixing sex chromosome
Edward syndrom (47,18+)
Human Female (47,XXX)
Patau Syndrom (47, 13+)
139
Uniparental Disomy
a pair of chromosomes comes from the same parent
140
What is the effects of uniparental disomy
could get 2 copies of a recessive allele from 1 parent and nothing from the other so child shows recessive trait even when 1 parent is not carrier
141
What is the suspected origin of uniparental disomy
thought hat probably arise through a trisomic condition where one of the try is lost early in development thereby resulting in a child with normal 46 chromosomes.
142
Mosaicism
- different cells within the same person have different numbers of chromosomes
- Could be due to nondisjuction in mitosis of somatic cell with subsequent mitotic divisions of abnormal cells also resulting in cells with abnormal number
143
Polyploidy
more than 2 copies of haploid genome
144
Autopolyploidy
extra sets of chromosomes are identical to normal chromosome set (ALL SETS ARE FROM THE SAME SPECIES)
- tend to be sterile
145
Allopolyploidy
combination of sets of chromosomes from 2 species
-fertile as long as even number
146
Nondisjunction in anaphase of mitosis can result in?
doubling of chromosome number
147
Nondisjunction or all chromosomes in meiosis can result in?
gametes with extra sets of chromosomes
148
monoploids
- synthetic haploids
- produced through another culture to result in monoploid plant
- used to see genotype (no hidden recessives)
- can assay for a desirable trait
149
Colchicine
- used to double the chromosome number to obtain diploid plant that is homozygous for desired trait. can be used in breeding program
- is a spindle fiber poison. Treatment with colchicine prevents spindles from pulling chromatids to opposite poles in anaphase
150
Bivalent
2 chromosomes synapse together
151
Triploids
sterility problems due to irregular pairing/synapsis of meiosis.
-seedless fruits such as some bananas, winesap apples, european pears, seedless watermelons
AAA or AAB
152
amphidiploid
polyploid that behaves like a diploid in meiosis (2 different species are combined)
-most common form of polyploidy in plants
153
Potato
Autopolyploid
| 4n=48
154
banana
autopolyploid
| 3n=33
155
Peanut
allopolyploid
| 4n=40
156
Sweet Potato
autopolyploid
| -6n=90
157
Tobacco
Allopolyploid
| 4n=48
158
Cotton
Allopolyploid
| 4n=52
159
Wheat
allopolyploid
| 6n=42
160
Oats
allopolyploid
| 6n=42
161
Sugar cane
allopolyploid
| 8n=80
162
Strawberry
allopolyploid
| 8n=56
163
hypothesis for chi square
The population of____ has Hardy-weinburg proportions for the ____locus
164
Compensation loops
are seem at synapses in individuals heterozygotes for interstitial deletions and for individuals who are heterozygous for tandem and reverse tandem deletions
165
Fertilization of a gamete with abnormal chromosome number due to nondisjunction results in?
aneuploidy individuals
166
Plasmids
small circular DNA molecules that are found in bacteria and can replicate independently of the bacterial chromosome
167
Episomes
are a type of plasmid that can integrate into the bacterial chromosome
168
F factor
confers the ability to conjugate and has genes that allow formation of pili, which establish contact between cells
169
Do F+ and F' have the F factor? and in what FOrm? and who do they donate to?
yes, circularized form
| F-
170
Hfr
have the F factor incorporated into the bacterial chromosome. conjugation between these cells and F- cells often results in transfer of bacterial chromosome genes to the recipient cell
171
Virulent bacteriophages
cause lysis of a bacterial cell but cannot integrate into the bacterial chromosome
172
Temperate
bacteriophages may lysogenize a cell by incorporating their DNA into bacterial chromosomes
173
Prophage
the integrated DNA
