Lecture 2

Question 1

what does the human karyotupe consist of?

define: heterogametic, homogametic

Answer 1

• 22 pairs of autosomes
• 1 pair of sex chromosomes
• heterogametic: XY
• homogametic: XX
• arrangment of biggest to smallest

Question 2

define

metacentric, arocentric, telocentric, submetacentric

Answer 2

metacentric: at the middle of the chromosome ex. chr1
acrocentric: asymmetrically placed ex. chr13
telocentric: right at the end
submetacentric: just off the middle ex. chr 2

Question 3

how do we karyotype?

Answer 3

1. get sample
2. straining: Giesmsa stain (stains DNA blue at A-T rich regions)
3. visualize: G-bonding

light bands from at GC rich areas: euchromatic DNA - more active DNA
dark bands form at AT rich areas: heterochromatic - gene poor

Question 4

define

p and q arm

and how to count how much bands

Answer 4

• p: petite arm, shorter length
• q: long arm
• count from the centromere

Question 5

nomenclature

how do we name karyotypes

Answer 5

autsomes(A):sex