Genetics SSN 2 Flashcards by X x

oocytes formed as

fetus

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female meiotic prophase at

14 weeks gestation

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first meiotic division stops at ____, resumes/completes at ovulatoin

diplotene (when homologs repel)

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meiosis II happens after

fertilization

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Chromosomes 13, 14, 15, 21, 22

acrocentric (look one-armed)

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Chromosomes 1,9,16, Y

heterochromatic region (tightly coiled, polymorphic)

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repeats of ribosomal genes, polymorphic, acrocentric

satellite region

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repeated info in the centromere

alpha satelite

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repeated info just next to centromere

classical satellite

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first unique sequence just next to telomere

telomeric sequences

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large region colored (unique gene sequences)

repeated region

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visually compares sample DNA to control DNA

CGH: comparative genomic hybridization

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noninvasive prenatal testing

sample fetal DNA in maternal blood

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copy DNA using normal and dideoxynucleotides, ddn are marker and tell you last nucleotide in sequence

sanger sequencing

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characterized by expansion of a CGG triplet repeat in the first exon of the FMR-1 gene on the long arm of the X chromosome

fragile X syndrome

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usually involve acrocentric chromosomes, which cluster together during meiosis.

robertsonian translocations

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effects number of copies of all chromosomes

-ploidy

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effects number of copies of individual chromosomes

-somy

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most common genetic anomaly in still-births, 10% one year survival

Trisomy 18

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brushfield spots, GI obstruction, Alzheimer’s

additional complications of Down syndrom

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only mild sterility, learning disabilities with speech

triple X

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tall, thin, slight IQ reduction, low testosterone, sterile, breast growth

Klinefelter XXY

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tall, acne, mild IQ reduction, no aggression increase

Klinefelter XYY

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Greek warrior helmet

4p deletion Wolf Hirschhorn

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Wolf Hirschorn and Cri du Chat are

partial deletions

Prader-Willi, Angelman, Williams, DiGeorge are

microdeletions (<1Mbp)

Paternal copy of 15q11.2 deleted

Prader-Willi

Maternal copy of 15q11.2 deleted

Angelman

Chromosome 7 microdeletion

Williams

Chromosome 22 microdeletion

DiGeorge

translocation where an acrosome is lost

robertsonian

When the information in region 15q11-q13 is derived only from a mother (either via uniparental disomy (both chromosomes from a single parent) or deletion on the paternal chromosome

Prader-Willi syndrome (the maternally imprinted chromosome is unable to express its genetic information )

consists mainly of a satellite and a thin stalk, containing multiple copies of genes encoding ribosomal RNAs

short arm of an acrocentric chromosome

therapies that increase fetal hemoglobin may help these patients

Sickle-cell

both forms of hemophilia B are

promoter mutations

triplet that increases in earlier onset Huntingtons

CAG

genetic variations present at a particular locus

allele

deletions of alpha chain hemoglobin, 2 genes per chromosome, more deletions, more severe phenotype

alpha thalessemia

large population, random mating, no selection, mutation rate is constant, no im/emigration

Hardy-Weinberg assumptions

Heterozygote advantage of the AS genotype manifests as

better resistance to malaria

one locus, multiple normal alleles

polymorphism

when calculating odds of AR transmission, don't forget

times one-half per parent (odds they will pass it)

different mutations in the SAME GENE cause similar phenotypes

allelic heterogeneity

different mutations in the SAME GENE cause different phenotypes

phenotypic heterogeneity

different mutations in DIFFERENT GENES cause same phenotype

locus heterogeneity

incomplete penetrance, variable expressivity, de novo mutation, germline mosaicism

AD pedigree problems

Known, micro: polymorphisms, insertions, deletions, NO heterozygotes

PCR

known, micro: deletions in heterozygotes

MLPA

known, macro: large scale deletions (>100bp)

Southern Blot

unknown, micro: determines sequence, NO short tandem repeats or copy-number variation

genome sequencing

unknown, micro: finds disease-causing genes, but stats may not be clinically useful (may identify marker, not gene of cause)

GWAS (Manhattan plots)

unknown, macro: detects chromosome-level changes such as copy number variation, NO <1 Mb

CGH (comparing sick and health genomes)

mRNA expressiong heatmapping, gene expression profile (cancer), BUT destroys architecture, can't distinguish if expression is tumor cell or other cell

microarray

stains mRNA in tissue, can see gene expression in intact cells, but only a few at a time

RNA in situ hybridization

use antibody probe to determine if protein is being expressed, is right size, but destroys architecture

western blot

stain for protein with architecture intact, but can't detect protein size

immunocytochemistry

sequence of 1-6 bps repeated many times

short tandem repeat (microsatellite)

sequence of 10-100bps repeated many times

variable tandem repeat (minisatellite)

good for CNVs but not microsatellites

array CGH. Use PCR and Sanger sequencing instead

detected with Guthrie assay (extra Phe on sample leads to bacterial growth)

PKU

detected with tandem mass spectrometry, avoid fasting!

MCADD

helps you rule out a disease

sensitivity (SNOUT)

helps you rule in a disease

specificity (SPIN)

methylation in a promoter region causes

DNA silencing

acetylation in a promoter region causes

increased DNA expression

still expressed on inactive X, helps to shut the X down

Xist

Mom wants it off, dad wants it on

Gene IGF2 (chromosome 11)

Mom wants it on, dad wants it off

Gene H19 (chromosome 11)

Oops, Mom turned IGF2 on (H19 normal)

Beckwith-Wiedemann: big baby

Oops, Dad turned on H19 (IGF2 normal)

Russell-Silver: small baby

imprinting diseases with epimutations

Russel-Silver, Beckwith-Weidman

imprinting diseases with real mutations

Prader-Willi, Angelman

mother's allele is normally off (chromosome 15)

Prader-willi (need to get from dad)

father's allele is normally off (chromosome 15)

Angelman (need to get from mom)

will have more methylation (which inactivates gene expression) and less acetylation (which activates gene expression)

inactive X chromosome

growth restricted genes are imprinted by

dad (to imprint=to turn OFF)

if monozygotic twins share a trait more often than dizigotic twins, that trait is

heritable

two genes segregate together due to proximity; one SNP is used to score a refion

linkage disequilibrium

under certain enviromental conditions, one genotype's phenotype resembles another

phenocopy

different genes causing same phenotype (early and late onset Alzheimer's, 18 genes responsible for cilia defects in Bardet-Beidl phenotype)

Genetic heterogeneity

smoking worsens prognosis in

alpha1 anti-trypsin disorder

In OI, missense mutation in α1 can lead to qualitative abnormalities in

¾ of type 1 collagen strands. Because of there are 2 α1 strands and 1 α2 strand in each collagen fibril, a mutation in α1 will cause defects in ¾ of the fibrils

The treatment for this condition is prenatal administration of cortisol, which prevents excess androgen production

congential adrenal hyperplasia

correct gene defects by gene addition, contain RNA

lentivirus vectors

Genetics SSN 2 Flashcards

(84 cards)