Lecture 48

Question 1

What is an inversion found in 1-3% of the world’s population?

Answer 1

inv(9)

Question 2

Why is Cri-du-chat harmful?

Answer 2

not enough CTNND2 genes harms neurons in brain

Question 3

Some balanced rearrangements are harmful. Examples?

Answer 3

rearrangements have breakpoints

some breakpoints eliminate genes, some make harmful genes

EXAMPLE (gene deletion)
horse inversion (3), breakpoint disrupt pigmentation gene - white patches

EXAMPLE (new harmful gene)
t(9;22)(q34;q11)
this is the Philadelphia chromosome, creates BCR-ABL fusion gene, causes chronic myelogenous leukemia (CML)

Question 4

Balanced chromosome rearrangements are common in evolution. Chromosomes changed repeatedly during ape evolution.

What happened in human lineage for chromosome 2?

Answer 4

resulted from a Robertsonian translocation of 2 ancestral ape chromosomes

Question 5

Why might duplications be important for evolution?

Answer 5

most mutations are harmful

solution: duplication creates extra copies - one maintains function while other evolves new functions