T5 module 1: genetic variation

Question 1

define DNA polymorphism

Answer 1

the * spice * of genetic diversity

one of 2+ alternative forms (alleles) at a chromosomal region (or locus) that differs in either…

• a single nucleotide base
• or variable numbers of tandem nucleotide repeats

in a given population of individuals.

Question 2

define SNPs

Answer 2

single nucleotide polymorphism
- common type of genetic variation
- single nucleotide base change that occurs in a significant portion of population
- in coding and non-coding regions
- heritable
- can be used as markers in coding genes if close enough

Question 3

how are SNPs analyzed?

Answer 3

micro array analysis

1) oligonucleotides (known sequence with desired SNP) attached to chip
2) fluorescent subject DNA added
- see where DNA lines up with SNPs to detect which one the individual has
- fluorescence shows where individuals are hetero/homogenous for tested alleles

Question 4

define variable number of tandem repeats (VNTRs)

Answer 4

• patterns of 1+ repeated nucleotides
• adjacent to each others
• identified using PRC and gel
• used for DNA “fingerprinting” because non related individuals have different VNTR profiles

Question 5

variation and disease example: sickle cell anemia

Answer 5

• variation in coding region = change in phenotype = less O2 uptake, blood vessel blockages

homozygous (healthy)
genotype: HbA/HbA
phenotype: no sickle cell

homozygous (disease)
genotype:HbS/HbS
phenotype:no functional beta-globin pr-

heterozygous (healthy)
genotype: Hba/HbS
phenotype:no symptoms

VARIATION IN POPULATIONS
- sickle cell anemia may be advantageous in some areas with malaria outbreaks