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126 Cards in this Set

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  • Back
what are 3 things holland says genetics is about?
1. nuclear DNA
2. mitochondrial DNA
3. epigenetics
what is epigenetics?
gives example in notes of mule vs. hinnie and how their development depends on whether mom was horse or donkey
what's the short arm of chromosomes called?
p = petite
what's long arm of chromosome called?
q because q follows p in alphabet
what nucleotides are most common in centromeres of all organisms?
AT
what are one of the functions of centromeres?
is site for kinetochore attachment
helps with chromosome separation in mitosis, meiosis
would i be able to tell the difference between centromeres on different chromosomes?
yes; they are chromosome-specific
how much of our DNA is in our centromeres?
10% of human DNA heavily concentrated in centromeres
in what direction is nucleic acid replicated?
5' to 3'
what is telomerase?
is reverse transcriptase
uses RNA template to make DNA

also is ribozyme - has RNA and protein components
what does telomerase do?
replicates end of chromosomes
do all cells have telomerase?
no; only those that are dividing frequently
what kinds of cells have telomerase?
bone marrow cells, RBCs, WBCs, gonadogensis cells
i thought rbcs did not divide once they were made? he must be thinking of their precursors
what kinds of abnormalities can be picked up by a karyotype?
large problem
big deletions, insertions, inversions, translocations, extra chromes
in karyotyping, what do the dark and lighter bands in the chromosomes represent?
dark = inactive DNA
light = active DNA
what is one thing from the cytosol that sperm can contribute to the zygote?
centrosols - organizing centers
what makes the outer part of the egg hard so that other sperm can't get into it once one has?
autoantibodies are produced that react with something in the egg and you have agglutination
how many diseases are known to be caused by single gene variations?
4000
what's the most time-consuming part of trying to diagnose someone's genetic disease?
getting the DNA from all extended family members
what's the incidence, or percentage of kids in the population born with a genetic disease?
3%
what portion of pediatric hospital admissions are from children with one gene-caused genetic diseases?
1/3 to 1/2
what's the percentage of adult hospital admissions from one gene-caused genetic diseases?
10%
what's most common genetic disease?
down syndrome
what's the percentage of spontaneous abortions that are due to lethal chromosome alterations?
50%
what are the major groups of common genetic disorders?
1. down syndrome - chromosomal aberration
2. one-gene caused mutations
3. compound disorders
4. germ-line mutations
5. mitochondria disorders
what are compound genetic disorders?
are complex diseases with interaction of 2 or more genes
mutation in one will not cause disease, mutation in 2nd will not cause disease, need mutation in both
can we use classic models of modes of inheritance to characterize compound genetic diseases?
no
what's an example of a disease caused by mutations in the germ line?
cancer
what types of tissues are most affected by mitochondrial disorders?
those that use a lot of ATP
muscle, neural cells
how many recombination events typically occur in human meiosis?
3500
does recombination always occur?
no - can have gametes that are exactly like parents, some that look like parents some that don't, and situation where all sperm or egg from one precursor have recombined = non-parental ditype
what does non-parental ditype mean?
is when gamete precursor cell produced gametes that all recombined so that none of them look exactly like the parental chromosomes
what does locus mean?
is just position on chromosome
what does "wild-type" mean?
is referring to normal allele
what's a compound heterozygote?
means that person has two mutant alleles, but they're different kinds of mutants
what does the term heterozygous technically mean?
means that person has one normal or wild-type allele and one mutant
what's the definition of genotype?
is DNA of an individual or structure of person's genome
what's a phenotype?
is behavior or how genotype presents, how genes are expressed against environmental background
what's definition of dominant allele?
allele that is expressed in phenotype in heterozygote
how does one test whether alleles are dominant or recessive?
look at heterozygote
are terms dominant and recessive referring to genotype or phenotype?
phenotype
is sickle cell anemia dominant or recessive?
recessive
what does the term trait in genetics refer to?
phenotype true ONLY FOR HETEROZYGOTES
example of sickle cell anemia where have very different phenotype for carriers or heterozygotes than have for either those with disease and totally healthy people
what usually causes recessive phenotype in terms of protein interference?
is loss of function
carrier usually will have 50% of active gene - usually enough to have normal phenotype
what is mode of transmission of hypercholesterolemia?
autosomal dominant
what does allelic heterogeneity mean?
just means there are many alleles for the mutant phenotype
compound heterozygotes
what does locus heterogeneity mean?
means there are mutations at 2 different genes causing same disease
what's an example of locus heterogeneity?
osteogenesis imperfecta
what causes osteogenesis imperfecta?
loss of function of alpha 1 or alpha 2 collagen
what's fine line between locus heterogeneity and defining two different diseases? like alpha or beta thalassemia?
is based on technology of geneticists
how easy for them is it to distinguish between different causes of phenotype
in case of osteogenesis imperfecta, they can't distinguish between mutation in one spot vs. mutation in another
in hemophilia, they can, so those mutations are considered different diseases
what's penetrance?
person has genotype for disease, but may not have phenotype
100% penetrant = everyone with genotype will have phenotype
phenotype does not have degrees - you either have disease, or you don't
what does variable expressivity mean?
is degree of severity of phenotype
environment affects both variable expressivity and penetrance, but in different ways
here, can use diet and drugs to lessen severity of disease
what is anticipation?
genetic diseases where disease isn't present in family history, then pops up suddenly and gets progressively worse in progressive generations
what is a feature common to anticipation?
triplet expansion
can you have a case where the mutant allele gets an uppercase designation?
yes, when it is dominant
what kind of inheritance does autosomal dominant mode of inheritance reflect? horizontal or vertical?
vertical
disease will run in the family
affects boys and girls equally
what's an example of an autosomal dominant disease?
familial hypercholesterolemia
what's an example of an autosomal recessive disease?
cystic fibrosis
in autosomal dominant disease, which is usually worse, being homozygous or heterozygous with disease allele?
homozygous usually, although there are exceptions
in huntington's disease, homo or hetero is no difference
in familial hypercholesterolemia is big difference
what's the penetrance of cystic fibrosis usually?
100%
what's incidence for disease of CF when 1 in 20 people are carriers?
1 in 1600
because need 2 carriers to get together - that would be 1/20 x 1/20
then 1/4 of their children will be homozygous recessive, so multiply 1/400 by 1/4 = 1/1600
will autosomal recessive run in family from generation to generation?
no
what?
because carrier needs to marry another carrier
CF children will seem to pop out of nowhere
what's the inheritance pattern of autosomal recessive diseases? horizontal or vertical? why?
horizontal
because would need intermarriage tween close relatives to see disease continuously pop up in family

since 1/4 of children between two carriers will be affected and most people have an average of 2 kids, won't see many recessives
how are x-linked diseases typically passed on?
from father to daughters

sons of affected man can't get disease because they could only get y from dad

father to son transmission NEVER happens
men with x-linked disease have to get the disease from which parent?
their moms
what's an example of an x-linked disease?
fragile x
can we predict with certainty how the phenotype of someone is going to be?
no
have environmental influences...
if see a disease mostly in first cousin marriages, what mode of inheritance should i predict?
autosomal recessive
what's significance of men garav and basin outlined in 2nd lecture?
they first discovered genetic diseases in late 1800s about same time as mendel, although garav was clueless regarding mendel's work
other men in 40s and 50s tried to take credit for discussion of genetic disease - beetle and tatum
garav discovered that inborn errors in metabolism don't usually show up until what point in a person's life?
until they're older
what does glucose 6 phosphate dehydrogenase refer to?
example of african american men in korean war who were given anti-malarial drug who had hemolytic problems because their bodies were already immune to malaria
what's mechanism of glucose 6 phosphate abnormality?
deficiency in making normal amount of NADPH
have oxidative stress
half-life of enzyme in RBC shorter than normal, leads to lower NADPH levels
what was an experiment that tested the environmental influence over genetic disease?
swedish study
smoking vs. non-smoking in serpin alpha 1 antitrypsin activity - protein accumulates
same genotype, 1 environmental factor difference
what's mode of inheritance for alpha antitrypsin?
autosomal dominant
what does problem with alpha antitrypsin cause ultimately?
problem in cells uptaking cholesterol
results in familial hypercholesterolemia
what are 2 features of the familial hypercholesterolemia study that i should know?
1. enzyme called HNGCo-a-reductase activity goes up when cholesterol amount in blood increases because it can't get into the cell
is body's response to need for cholesterol - this is like hypothyroid condition
2. LDL receptor
creation of LDL receptors increases also because cell isn't getting enough cholesterol
what does HNG Co-a-reductase do?
is enzyme in process of cholesterol creation
what was a secondary discovery of researchers who were studying familial hypercholesterolemia?
receptor-mediated encocytosis
why are statins so effective at treating high cholesterol?
they not only
1. reduce blood cholesterol levels,
2. they reduce production of enzyme to make cholesterol, and also
3. reduce rate of production of LDL receptors
who were guys who did major study on familial hypercholesterolemia?
brown and goldstein
what mutations cause familial hypercholesterolemia?
mutations in every step of process
blocking secretion [of what?]
problems of something getting to surface
problems with something binding to ligand
problem with receptor getting to surface
problem with receptor locating to clathrin coated pits
problem with receptor that won't release LDL into cytoplasm
what's difference between heterozygote and homozygote for familial hypercholesterolemia?
heterozygote has 1 type of functioning LDL receptor
what's mechanism of statin?
inhibits HMG co-a reductase
still get increase in LDL receptor action
how much of cholesterol can be managed by diet?
10-15%
how much of cholesterol level can be reduced by statin?
25%
would a statin be enough to treat a person with famlial hypercholesterolemia?
no
heterozygote has 300-600 mg/dl cholesterol levels before statin
after statin, could still have over 300 and that's bad
why is liver affected by anion exchangers to treat hypercholesterolemia?
liver tries to reabsorb cholesterol thinking body needs it

anion exchanger interferes with absorption of cholesterol being secreted by body with bile salts
how can heterozygous individuals for familial hypercholesterolemia be treated?
1. statin to reduce de novo production of cholesterol
2. anion exchanger reduces cholesterol uptake
2. something stimulates LDL receptor
is there any treatment for homozygous individuals with familial hypercholesterolemia?
can partially help them but would still worry about peripheral tissue - why?
what's usual test for CF?
DNA
what's test for CF?
DNA
use PCR to amplify upstream and downstream of place where known mutation is
hybridize with labeled probe that tells you if have three bases or not
how does linkage analysis work?
1. need permission and existence of disease in family
2. need affected close relative to affected person you're studying
3. still need unaffected person
4. use polymorphic markers near disease gene
what diseases should be tested using linkage analysis?
those with multiple genes
familial hypercholesterolemia
what's needed to diagnose someone with familial hypercholesterolemia?
high cholesterol levels
linkage analysis
what does FISH stand for and what does it do?
Fluorescence in situ hybridization
is microscopic visualization of specific chromosomes
abnormalities in what part of the chromosome can lead to aneuploidy?
centromere
what nucleic acid is most common in telomeric DNA?
guanine
what are the repeats most common in telomeric DNA?
TTAGGG
how long are telomeres usually?
12 kb
how many base pairs can be lost in telomeres per mitotic cycle?
50-200
at what point in a woman's life is telomerase low or non-existent?
low = early proliferative phase in menstrual cycle
non-existent = pregnant, postmenopausal (not having a period)
low or non-existent when lining doesn't need to build
is activation of telomerase activity good or bad?
can be bad - it occurs in more than 90% of human malignancies
what is satellite DNA usually used for?
is particular to individuals and used for pedigree determinations

variants also provide measures of global genomic mutation
how much of the human NUCLEAR genome is satellite DNA?
10%
where is satellite DNA found in human chromosome?
all three chromosome regions - arms, telomeres, centromere
how did satellite DNA get its name?
when centrifuged, it bands separately from rest of DNA
what areas of chromosome are satellite DNA repeats generally found?
centromeric, telomeric
what are the different classes of satellite DNA?
are 3
1. alpha satellite DNA
2. minisatellite DNA
3. microsatellite DNA
what is alpha satellite DNA?
is made up of tandem repeats of 171 bp that can extend several MILLION bp or more
what is minisatellite DNA?
are tandem repeats of 20-70 bp that can extend for a few thousand bp as whole
what is microsatellite DNA?
is tandem repeats of 2-4 bp that can extend for a few hundred bp
what's difference tween alpha, minisatellite and microsatellite DNA?
ALPHA - biggest - 171 bp repeats for millions of bps
MINISATELLITE - intermediate size - 20-70 bp repeats for few thousand bps
MICROSATELLITES - 2-4 bp repeats for few hundred bps
how much of human nuclear genome is satellite DNA?
10%
how much of human nuclear genome is dispersed repetitive DNA?
15%
what are the different types of dispersed repetitive DNA?
are 2 types
1. SINEs = short interspersed elements
2. LINEs = Long interspersed elements
how long are SINEs and what are they?
they are Short Interspersed Elements that are 90-500 bp long
how long are LINEs and what are they?
they are Long Interspersed Nuclear Elements and they are up to 7,000 bps long!
what's an example of a SINE?
Alu family
what is the Alu family, what does it mean and where are they?
what are they - interspersed repeats that have recognition site for restriction enzyme Alu 1

what they do -
1. make copies of themselves which insert into other DNA sites, including coding regions
2. cause unequal crossing over during homologous recombination - this happens in LDL receptor gene in familial hypercholesterolemia

where they are
usually in introns and intergenic DNA
how much of nuclear DNA is dispersed repetitive DNA?
2-3%
how long are dispersed repetitive DNA segments and how many of them are there?
are 300 bps long and there are about 500,000 throughout nuclear human genome
what makes up the heritable genome?
2 parts
1. nuclear genome
2. mitochondrial genome
what's the definition of gene?
is basic unit of heredity
includes upstream regulatory elements, coding regions and introns
what cellular structures are inherited from the father/sperm to the embryo?
1. centrioles
2. nuclear DNA
3. plasma membrane
what cellular/DNA structures are inherited from mom/egg by embryo?
1. mRNA
2. nuclear DNA
3. mitochondria
4. plasma membrane
how could something inherited by the father result in preimplantation loss?
embryo inherits part of plasma membrane from sperm
as result, could be target of anti-sperm-antibody-completment-mediated cell lysis that usually works to clear other sperm from mother's body