Genetics Chapter 10

DNA polymorphisms

sequence differences between genomes

500

how many different polymorphisms are present in just three people? 

2%

codons make up less than what percentage of the genome?

taken out my natural selection

what usually happens to deleterious mutations in the genome?

1. single nucleotide polymorphism

2. deletion inserted polymorphism

3. simple sequence repeats 

4. copy number variants 

what are the four types of genetic variations? 

single nucleotide polymorphism 

• type of genetic variation

• one nucleotide change 

• most common polymorphism

• 1 bp size

• 1 kb frequency

deletion inserted polymorphism

• type of genetic variation

• short inserts/deletes of one to a few base pairs 

• 1-100 bp size

• 10 kb bp frequency 

simple sequence repeats

• type of genetic variation

• 1-10 base sequences repeated 15-100 times in tandem 

• 1-10 bp repeat size

• 30 kb frequency 

copy number variants

• type of genetic variation

• large blocks of duplication/deletion

• super rare! (less than 1% of the population)

• 10bp-1Mb size

• 3Mb frequency 

unequal crossing over of chromosomes, misalignment during meiosis 

what causes the production of copy number variants (the big duplications/deletion sequences)

inherited

are CNVs usually inherited, or naturally occuring? 

polymerase chain reaction

• method of making many copies of a target region of DNA

• developed in 1985 by kary mullins 

• faster, less money, more flexible 

• efficient! 

1. denature strands 

2. base pairing of primers 

3. polymerization from primers along templates 

three steps of PCR 

gel electrophoresis

what can you use to determine the size of DNA target regions

looking at fetal cells during pregnancy and before implantation

what additional uses is PCR being used for?

huntington’s disease

autosomal dominant condition

34

42

what is the normal CAG allele repeat?

what is the CAG repeat amount for someone with huntington’s disease?

short tandem repeat

highly polymorphic repeat sequence

getting a PCR of this gives you the genotype 

manny alleles, 2 at a given locus

20 pairs of PCR primers labeled with dye

probability of having the same alleles is SUPER low

CODIS database

FBI database that holds genetic information

hybrid will not be stable of at high temperatures

what is known about the hybrid if there is a mismatch between the probe and target when hybridizing oligonucleotides 

hybrid will be stable at high temperatures 

what is known about the hybrid if there is a match between the probe and target when hybridizing oligonucleotides 

four million

up to how many loci can be genotyped with oligonucleotide hybridization?

• fragmented 

• adapter attached

• amplified by PCR and denatured to be single stranded

• dye attached 

what are the steps to prepare DNA for hybridization? 

positional cloning

identify disease genes by causing linkage to polymorphic loci

analyzing two point crosses 

find candidate genes by using DNA markers, evaluate expression 

one gene tracked with genotype, one with phenotype

what is the difference between positional cloning and everything else? 

compound heterozygote

different mutant alleles of the same gene 

locus heterogenicity

caused by mutation in one of two or more different genes

allelic heterogenicity

same gene, different mutation

responding to medications can be different

$500

how much does it cost to have an entire genome sequenced?

high throughput sequencing

• DNA molecules anchored

• base identified one by one

• increased sensitivity

3 million 

each individual differs genetically in how many locations? 

1. transmission pattern 

2. predicted effect of protein function

3. clues from other genome sequences

what three things can you use to tell which polymorphism causes disease?