BIO 325 Topic 16 Human Genome

What is Polymorphism?

Places in the genome where DIFF people have DIFF base-pair sequences

• SNP- Single nucleotide polymorphism

• SSR- Simple sequence repeat

SNP

Simple Nucleotide Polymorphism

SNPS are most disease alleles

1 bp, present ever 10bp

300 million SNP loci in a human genome

SSR

Simple Sequence Repeat

SSRs are used to solve crimes in DNA profiles

1-10 bp repeat unit

longer repeats caused by slipped misprint in DNA

Common variants that don’t affect gene function

SNP: Introns, synonymous codons

SSR: outside genes

Rare variants that affect gene function 

SNP: promotoer/splice junctions, codons

SSR: in trinucleotide repeat genes

What is PCR and what does it do? 

Polymerase chain reaction, repeats cycles of DNA synthesis of a target region exponentially

PCR Components:

1. Dna Sample

2. Primers

3. Nucleotide bases

4. Mix buffer

5. Per tube

6. Taq polymerase

• 7. Thermal cycler

PCR steps:

1. Denaturing DNA

2. Primers hybridize

• 3. Extension (synthesize new strand)

PCR rules:

20 nt base sequences at each end to performance PCR

Primers can be ~1000 bp apart

INSTAPOLL:
If a double-stranded DNA molecule is amplified by PCR, how many double-stranded DNA molecules will exist after FOUR cycles?

16

Stallion 2