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MBG 2040 > Midterm > Flashcards

Midterm Flashcards

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1
Q

Null/ amorphic alleles

A

nonfunctional or no protein is produced

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2
Q

hypomorphic alleles

A

poorly functioning protein or reduced amount of a normal functioning protein are produced

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3
Q

dominant hypermorphic alleles

A

negative phenotypic consequences due to: - over production of a normal protein - production of a protein with increased activity levels

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4
Q

neomorphic alleles

A

negative phenotypic consequences due to: - presence of an altered protein that has new function - when altered protein interferes with the wild type protein (dominant- negative allele)

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5
Q

incomplete dominance

A

Bb is intermediate between homozygous phenotypes (red, white, pink)

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6
Q

codominance

A

Bb exhibits phenotypes of both homozygotes (blood type)

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7
Q

an allelic series

A

describes dominance hierarchy of multiple alleles

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8
Q

null allele vs hypomorphic

A

null is nonfunctional and hypomorphic has partial function

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9
Q

wildtype allele

A

a functional enzyme or other protein is produced (often dominant over loss of function)

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10
Q

loss of function allele

A

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

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11
Q

Haplosufficiency

A

half as much protein is synthesized yet is often sufficient to achieve the wild type phenotype

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12
Q

example of dominant allele that can gain function mutations

A

huntingtons disease (where mutant allele produces a protein that is increased detrimental function)

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13
Q

example of dominant allele that can be loss of function alleles

A

tailless cats (manx) where the heterozygote has half as much protein synthesized and is not sufficient for normal phenotype (haploinsufficient)

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14
Q

recessive lethal allele

A

only expressed in the homozygote

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15
Q

dominant lethal allele

A

can be expressed in both heterozygote and homozygote

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16
Q

penetrance

A

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

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17
Q

expressivity

A

degree to which a phenotype is expressed (mild to severe) - variation in individuals

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18
Q

complete penetrance

A

identical known genotypes yield 100% expected phenotype

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19
Q

incomplete penetrance

A

identical known genotype yield less than 100% expected phenotype

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20
Q

constant expressivity

A

identical known genotypes with no expressivity effect yield 100% expected phenotype

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21
Q

variable expressivity

A

identical known genotypes with an expressivity effect yield a range of phenotypes

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22
Q

incomplete penetrance with variable expressivity

A

identical known genotypes produce a broad range of phenotypes due to a varying degree of gene activation and expression

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23
Q

main difference btw penetrance and expressivity

A

expressivity described individual variability and penetrance is statistical variability amount a population or genotypes

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24
Q

what causes incomplete penetrance and variable expressivity

A

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

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25
norm of reaction
range of phenotypes expressed by a single genotype under different environmental conditions
26
environmental factors that can affect phenotypic expression
age, sex, temperature, chemicals
27
phenocopy
a change in phenotype arising from environmental factors that mimic the effect of a mutation in a gene
28
Mendel's law of independent assortment
the inheritance pattern of one trait will not affect the inheritance pattern of another trait
29
genetic interaction
different combinations of alleles from 2 or more genes can result in different phenotypes because of interactions between their products at the cellular or biochemical level
30
heterogeneous trait
a mutation in any one of a number of genes can give rise to the same phenotype
31
epistasis
masking of the expression of one gene by another (no new phenotypes are produced)
32
recessive epistasis
homozygous recessive at one gene pair mask expression from the other
33
dominant epistasis
one dominant allele at one gene masks expression from the other gene
34
pleiotropy
a single gene can be responsible for a number of distinct and seemingly unrelated phenotypic effects (sickle cell disease- single mutation has several different effects)
35
inbreeding depression
inbred lines often less vigorous than hybrid lines
36
heterosis
when 2 different inbred lines are crossed, the hybrids are heterozygotes for many genes (these heterozygotes display heterosis, or hybrid vigor)
37
Hardy Weinberg principle
predicting genotypes through allele frequencies in a population (p2+ 2pq +q2)
38
Hardy Weinberg principle is only correct in absence of evolutionary influences including...
-nonrandom mating -unequal survival - population subdivision - migration
39
ploidy
number of complete chromosomes sets
40
homologous chromosomes
pair of matching chromosomes; one from each parent
41
eukaryotes
diploid adults, haploid gametes
42
function of meiosis
germ line cells produce haploid gametes
43
Mendel's first law
principle of equal segregation
44
Mendel's second law
principle of independent assortment
45
what is a karyotype
an image of a complete set of chromosomes
46
chromosomes can be autosomes or sex chromosomes..
autosomes: present in the same copy # in both males and females; number and morphology of autosomes in species specific sex chromosomes: present in different copies in males vs females
47
dosage compensation
way of equalizing gene expression in the face of different gene dosage
48
dosage compensation can occur in different ways:
-increasing expression from X chromosomes -decreasing expression from the 2 chromosomes -turning off expression from one X chromosome
49
X-inactivation
one X chromosome is inactivated in each cell- process is random, it is equally likely that the maternal or paternal X chromosome will be inactivated -process is random -equally likely that the maternal or paternal X chromosome will be inactivated
50
genetic mosaics
females that are heterozygous for X-linked traits are genetic mosaics
51
XO turner syndrome
females are sterile (ovaries fail to develop)
52
cytological techniques
geneticists use stains to identify specific chromosomes and to analyze their structures
53
polyploidy
more than 2 sets of chromosomes
54
autopolyploids
chromosome sets are all identical -all chromosomes are derived from the same species
55
autopolyploids usually have:
more vegetative growth (larger cells, thicker leaves, bigger flowers..) and less seed production
56
problems with polyploidy
many polyploids are sterile due to problems with pairing and separation of homologous chromosomes in meiosis -commercial bananas do not produce seeds (3N=33)
57
allopolyploids
some polyploids are the result of crosses btw 2 or more species (usually related species)
58
polyploidy in animals
interstices crosses can cause sterile animals (MULES)
59
endomitosis
involves chromosome replication without cell division (produces polyploid tissues)
60
polytene
are the resulting chromosomes if sister chromosomes don't separate
61
aneuploidy
diploid genome which lacks a chromosome or has an extra chromosome (meiotic nondisjunction can cause aneuploidy)
62
non disjunction is meiosis I
63
nondisjunction in meiosis II
64
reason for corelation btw incidence of trisomies and maternal age
theory: bivalents with crossover near ends of chromosomes are fragile and increasingly unstable over time... if bivalent chromosomes dissciate, nondisjunction of homologous - as you age come in contact with more chemicals and pollution can cause nondisjunction - chemicals: BPA and colchicine
65
deletion or duplication of chomosome segments
can occur random during meiosis - deletion or deficiency is missing chromosome segment - duplication is extra chromosome segment
66
Pericentric vs paracentric inversions
pericentric inversion includes centromere paracentric inversion excludes centromeres
67
translocations
occur when segment from one chromosome is detached and reattached to a different chromosome that is non homologous
68
reciprocal translocation
peices of 2 non homologous chromosomes are exchanged without any net loss of genetic material
69
compound chromosomes
formed by fusion of homologous chromosomes, sister chromatids or homologous chromosome segments
70
robertsonian translocation
formed by fusion of 2 non homologous chromosomes at there centromeres
71
life cycle of T4
1. T4 attavhes to an ecoli cell and injects its dna 2. synthesis of phage specific mRNAs begins 3. replication of phage dna begins; host dna has been degraded by phage encoded nucleases 4. dna filled heads, tails lacking tail fibers, and assemblied tail fibers first appear 5. the fist intact phage particles are assembled 6. host bacterium is lysed releasing about 300 progeny phage
72
bacteriophage T4
phage goes through lytic phase provides for quick and simple genetic experiment
73
bacteriophage Y
may be lytic (like T4) or lysogenic (inserts dna in host cell genome and goes into latency)
74
Transformation
transfer of free (out of cell) peice of DNA from one bacterium into another (no cell to cell contact)
75
conjugation
direct transfer of DNA from one cell to another via the establishment of a cytoplasmic bridge (conjugation channel) -sexual reproduction, mediated by fertility of F factor
76
Transduction
transfer of gene from one cell to another via bacteriophage (vecotr)- no cell to cell contact 2 types of transduction: 1. generalized transduction- random fragment of bacterial dna is packaged in the phage head in place of the phage dna 2. specialized transduction- recombination btw the phage chromosome and the host chromosome produces a phage chromosome containing a peice of bacterial dna
77
functions of genetic material
- must replicate - control the growth and development of the organisms - allow the organism to adopt to changes in the enviroment
78
chromatin includes
dna + histones + protein
79
episome
large circular dna that can integrate into the bacterial chromosome for replication or remain separate
80
what is a plasmid
an extra-chromosomal circular piece of DNA that can replicate independently of the chromosome
81
in bacteria, are plasmids required for survival of the host cell?
no. they serve as supplimentary/additional genetic elements
82
DNA vs RNA
DNA- deoxy ribose sugar, 1 less oxygen, double stranded, AT CG RNA- ribose sugar, single stranded AU CG
83
What are the 3 main steps of DNA synthesis?
1. chain initiation 2. chain elongation/extension 3. chain termination
84
semi conservative replication
* parental molecule is half conserved * sequence of bases in each parental strand is used as template

MBG 2040 (1 decks)

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