genetics lab final better

PCR definition

Polymerase Chain Reaction; a technique used to amplify a specific DNA sequence

PCR purpose

To produce millions to billions of copies of a specific DNA sequence

PCR step 1

Denaturation; heating DNA to ~95°C to separate strands

PCR step 2

Annealing; cooling to ~42-62°C so primers bind to DNA

PCR step 3

Extension; Taq polymerase synthesizes new DNA at ~72°C

Taq polymerase

A heat-stable DNA polymerase used in PCR

PCR required components

Template DNA; primers; Taq polymerase; dNTPs; Mg2+; buffer

PCR amplification formula

Number of DNA copies = 2^n

Alu element

A short (~300 bp) repetitive DNA sequence in the human genome

PV92 no Alu insert genotype (-/-)

Produces a 641 bp band

PV92 Alu insert genotype (+/+)

Produces a 941 bp band

PV92 heterozygous (+/-)

Produces both 641 bp and 941 bp bands

Gel electrophoresis purpose

Separates DNA fragments based on size

Homozygous gel result

One band (either 641 bp or 941 bp)

Heterozygous gel result

Two bands (641 bp and 941 bp)

Drosophila why used

Short life cycle; many offspring; easy to study; clear traits; well-known genetics

Drosophila life cycle stages

Egg; larva; pupa; adult

Drosophila life cycle length

About 10 days

Wildtype allele (Drosophila)

w+; produces red eyes

Mutant allele (Drosophila)

w; produces white eyes

White gene location

X chromosome

X-linked inheritance

Males have one X chromosome; females have two

Cross A parents

Female (w+ w+) x Male (w)

Cross A F1 females

All red (w+ w)

Cross A F1 males

All red (w+)

Cross A F2 males

½ red and ½ white

Cross A F2 females

All red

Cross B parents

Female (ww) x Male (w+)

Cross B F1 females

All red (w+ w)

Cross B F1 males

All white (w)

Cross B F2 males

½ red and ½ white

Cross B F2 females

½ red and ½ white

Why use virgin female flies

They can store sperm from previous matings which can affect results

Male flies virgin requirement

Less critical but often assumed virgin

Punnett square

A diagram used to predict offspring genotypes

Chi-square test purpose

Compare observed vs expected ratios

Chi-square interpretation p > 0.05

Fail to reject (accept) null hypothesis

Chi-square interpretation p < 0.05

Reject null hypothesis

Hardy-Weinberg equation 1

p + q = 1

Hardy-Weinberg equation 2

p^2 + 2pq + q^2 = 1

p in Hardy-Weinberg

Frequency of dominant allele

q in Hardy-Weinberg

Frequency of recessive allele

p^2

Frequency of homozygous dominant genotype

2pq

Frequency of heterozygous genotype

q^2

Frequency of homozygous recessive genotype

Human karyotype normal

46 chromosomes total

Female karyotype

46 XX

Male karyotype

46 XY

Autosomes

Chromosomes 1-22

Sex chromosomes

X and Y chromosomes

Centromere

Region where chromatids are attached

Chromosome p arm

Short arm

Chromosome q arm

Long arm

Metacentric chromosome

Centromere in middle; equal arms

Submetacentric chromosome

Centromere slightly off center; unequal arms

Acrocentric chromosome

Centromere near one end

Euploidy

Normal number of chromosome sets

Aneuploidy

Abnormal number of chromosomes

Trisomy

One extra chromosome (3 copies)

Monosomy

Missing one chromosome

Down syndrome

Trisomy 21 (47, +21)

Patau syndrome

Trisomy 13

Edwards syndrome

Trisomy 18

Turner syndrome

45 X (monosomy X)

Klinefelter syndrome

47 XXY

Triple X syndrome

47 XXX

Balanced chromosomal rearrangement

No net gain or loss of genetic material

Unbalanced chromosomal rearrangement

Gain or loss of genetic material

Inversion

A chromosome segment is reversed

Translocation

Segments exchanged between chromosomes

Deletion

Loss of a chromosome segment

Yeast ADE2 mutation

Produces red colonies due to adenine pathway defect

Plasmid with ADE2 gene

Restores function and produces white colonies

Genetic complementation

One gene restores function of another mutation

Transposable elements

DNA sequences that can move within the genome

UV DNA damage

Forms thymine dimers that distort DNA

DNA repair after UV

Nucleotide excision repair removes and replaces damaged DNA