Genetics Part II

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3 types of chromosomes based on centromere

metacentric, submetacentric, and acrocentric

long arms has what letter


short arm has what letter


metacentric has what structure

centromere at center, p=q

acrocentric has what structure

no P. Just satellite structures

satellite structres encode for what


submetacentric has what structure

p < q.

what is euploidy

polyploidy in multiples of 23

what is aneuploidy

+ or - not in multiples of 23

two forms of euploidy

triploidy and tetraploidy

what is triploidy

there are three copies of each chromosome. (69) Not compatible with life. NOT TRISOMY

what is tetrapoloidy

4 copies of each chromosome (92). Lethal.

what are the two forms of aneuploidy

monosomy and trisomy.

what is monosomy

loss of a chromosome. Not compatible with life unless its an X.

what is trisomy

have an extra chromosome (47). Not triploidy

what is the syndrome of monosomy at X

turners syndrome

trisomy at 21 is

downs syndrome

trisomy at 18 is

edward syndrome

trisomy at 13 is

patau syndrome

anueploidy monosomy of X is

turners syndrome

anueploidy trisomy at X (XXY) is

Klinefelter syndrome

downs, trisomy at 21, how does it arise

meiotic I nondisjunction in oogenesis

how to diagnose trisomy

interphase FISH

risk factor for downs

maternal age

how to get trisomy at 18 and 13, mechanism

also nondisjunction during oogenesis

edward syndrome symptoms

clenched fist, rock bottom feet, low ears and small jaw, congenital heart defects

patau syndrome feuttures

polydactaly, cleft lip and palate, microphthalmia, heart anaomolies

downs feutures

shrot, depressed nasal bridge, single palmer crease

tuners kids are males or females

alywas female

klinefelter kids are male or female

XXY, always male

turner kids feutures

short, webbed neck, streak ovaries (infetile) and amenorrhea (no mensturation).

turner people body/genetic composiiton

they are mosaics. some are 45 X, some ar 46XX and 47XXX.

turner and barr body's

none. 45X has no inactivated X chromosme

klinefelter feutures

testicular atrophy, female hair distribution, infertility, gynecomastia

klinefelters and barr bodies

oddly, see a barr body in males. kind of a defining feuture.

what cells can you check for the barr bodies

buccal mucosal cells

is turners always from nondisjunction of meiosis 1

nope. it can be from Meiosis I when homologous do not separate OR from meiosis II when sis chromatids do not separate

meiosis I nondisjunction produces the same or different copies of maternal chromosomes in a cell


meiosis II nondisjunction produces the same or different copies of maternal chromosomes in a cell


downs sydnrome is NDJ of meiosis I or II


meiosis I nondisjunction in the dad gives what disease


so what nondisjunctions cause klinefelters

NDJ in I or II of mom. OR NDJ I in dad

why not meiotic NDJ II in dad

that would give XYY

when do we see somatic mosalicism in terms of chromosome number

nondisjunction in the somatic cells during emvryonic development.

so downs syndrome from NDJ in male or female


types of translocations

reciprocal and robertsonian

explain a reciprocal translocation

two non-homologous chromomes swap a part. Cell still has same genetic material, just some genes have swapped places

effects of reciprocal translocation

SOMATIC CELL: can have no effect (silent), can cause cancer. GERM CELL: can cause abortion

give two cancers that occur this way

CML and burkitts lymphoma

CML what type of tranlocation

9 to 22 on philadelphia chromosome.

this translocation connects what

bcr and abl

what causes burkitts lymphoma

translocation 8 to 22

so a reciprocal translocation alternate segragation during meiosis produces what

normal gametes. Its balanced material just like parent. The fertilized zygote will just carry the translocation

so a reciprocal translocation adjacent segragation during meiosis produces what

results in unbalanced gametes, partial trisomy and partial monosomy gametes. upon fertilization get abortion.

3 outcomes from translocation carrier babies

normal, translocation carrier child, aborted child

which chromosomes can have a robertsonian translocation

13, 14, 15, 21, 22

what are these chromosomes considered

acrocentric chromsomes

what is lost at a robertsonian translocation

the satellite structure (rRNA)

what actually occurs in a robert transl

two long (q) arms fuse.

gametes (post meiosis) after a robertsonian translocation

of the four. 2 are ok. 1 is normal and one is a balanced translocation carrier (alternate segragation). 2 from the adjacent segragation will be bad. They will both have trisomy. one will be aborted one could cause DS

DS from rob trans karyotype looks like what

its trisomy, but technically 46 XX. the extra chromosome 21 is there but its the long arm attached to the long arm of 14

DS from robs trans is a result of adjacent or alt segragation


two microdeletion syndromes from large deletions

wolf-hirshchhorn and cri du chat

wolf hischorn is a deletion where


cri du chat is a deletion where


feutures of a cri du chat syndrome

cat like cry, speech problems, and microcephaly

how to test for cri du chat


other name for diGeorge syndrome

velocardiofacial syndrome

what causes velocardiofacial syndrome

microdeletion on chromosome 22q

digeorges feutures

heart defects, no thymus, cleft lip/palate, learning disability

deletions on chromosme 15 cause what

angelman & prader willi syndrome

deletion of maternal 15 gives


deletion of paternal 15 is

prader willi

wolf hirschhorn feutures

facial anomolies and widely spaced eyes. cardiac and metnal problems

ch 11 microdeletion causes

WAGR syndrome

WAGR syndrome has

wilms tumor, aniridia, genitourinary malformations, retardation

name the 2 types of inversions

pericentric and paracentric

which involves the centromere


problems that arise from inversions

usually ok, silent

how to check for inversions

karyotype. Look for banding.

when can inversions be dangerous

if during meiosis. It can lead to a deletion of repetition of DNA segments.

what does this lead to

phenotypically nothing, but can cause abortion

what are isochromosmes

deletion of one arm of a chromosome and duplication of the other arm to replace it

what disease could be from an X isochromosome

turner syndrome.

what is a rind chromosome

when a chromosome loses genetic material at the terminal portions and the ends fuse to make a ring

what is the calculation for allele frequency

P + Q = 1

what is the calculation for genotype frequency

P2 + 2pq + q2 =1

p =1 with what sort of disease

autosomal recessive. they are so rare

if given incidence, how can we get q for an autosomal recessive

q = (srt) (I)

CF incidence is 1/2500. Find affected homozygots and hetero carriers

homo zygotes is sqrt of 1/2500. = 1/50.

hetero carriers are 2pq. p=1. so 2q. = 1/25

for auto recessive q=

sqrt of I

for X recessive, q =


auto dominant Incidence = (in words)

heterozygotes + homozygotes

in equaition form

I = 2q or q =.5I

4 assumptions of hardy weinberg equillibrium

1) population is large 2) Random mating 3) no new mutation 4) no migration

4 things that cause genetic variation in populations

1) New mutation 2) Natural selection 3) Genetic Drift 4) Consanguinity

heterozygote advantage is auto dominant or recessive

auto rec

what diseases are protective against malaria

SCA and B-thalasemia

what is reproductive fitness

ability to get to age and reproduce.

a disease were repro fit is, and why

Tay Sachs, do not get to age of repro

what is genetic drift and what is it about

not migration. its allele drift. In a large population, an allele freq should be pretty stready. In a small one its all over the place

describe the founder effect

in a community thats small, a new person comes in with a new allele. Its gonna increase in freq

describe consanguity

relatives mate. higher incidence of disease

what spec does consanguinity increase the chance of


do multifactorial inheritance diseases follow mendelian patterns


distribution of trats when something is polygenic

normal bel shaped curve.

but are diseases of multifactors bell shaped?

nope. either you have it or not.

eqn for disease susceptibility with genes and environment


what is liability

all the factors that contribute to the disease

what is threshhold

the limit to which we are affected

is this threhold the same for everybody?

nope, our genes and environemnt move it

what is familial relative risk

the closer the relative with the diease, more likely we will get disease

relative risk ratio (lambda r) means what

the familial aggregation of a disease (relative to population)

how to get it

prevelance of disease in relatives / prevelance in total populaton

what does a high lambda r mean

greater familial aggregation

what does lambda r = 1 mean

same ilkelyhood of getting it as population

if more than one close relative is affected, does our chance increase


can the threshold on the curve be diff for the same disease between men and women

yep. so women are less likely for a disease, their threshold is further to the right. need more bad genes/symptoms to get it

cancer is a genetic disease T/F

True. but more are caused by environment

Eqn for heritibility

Heritibility = genetic variance/total variance

monozygotic twins are (ovum)

from one ovum

how similar are they


dizygotic twons are (ovum)

from two ovum. 2 sperm, 2 eggs

how similar are they

like normal siblings (50%)

what does concordance mean with twins

both twins have the same disease

twins and discordance mens

one has it, not the other

which has more of an environmental input, concordance or disconrdace


using twins to get heritibility, whats the eqn

H^2 = (variance in DZ-variance in MZ)/(varianve in DZ)

what does the odds ratio tell you

risk of getting disease when you have a marker that has an assoc with the disease

eqn for odds ration

patient has alleles 1-A and 2-B. Controls have 1-C and 2-D. AD/BC=Odds ratio

which diabetes has a strong genetic componant

type I

familial alzheiumers chromosomes

1, 14, 21

gene on chromeomes 1, 14, and 21

1: presenilin-2 14: presenilin-1 21: amyloid precursor gene

sporadic for of AD on what chromosome


gene on 19


yellow agouti mice have a problem with

a-MSH binding to meanocortin 4 receptor

leptin protein def absent in

obese people

leptin protein receptor absent in


leptin comes from where

released from fat tissue

wheren is the leptin receptor

on the arcuate nucleus

arcute nucleus releases


MSH binds to

the hypothalmus

hypothalmus does what

stops want for food

mutations are a big problem when they happen at what point

during the S phase

explain why we might get an error through tautomerism

Thymine has a rare enol form. This enol for binds with a G

DNA pol corrects itself how

3' to 5' exonuclease activity

two types of frameshift mutations

insertions and deletions

frameshift mutations test to occur where

areas where there are base repeats

why at these spots

there could be a slipping of the DNA polymerase or a loop/kink can form

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