Lecture 18 notes Cell Biol C8 p.375-395 Nuclear Genome

Thalassemia Syndromes: Malaria = major selective pressure on human genome

Alternative splicing of globin RNA = "cryptic" sites used in mutants.

Raw material for natural selection

Splicing details = too complex (Rube Goldberg remnant of catalytic RNA World)

Unspliced hnRNA = stays in nucleus

rRNA = final product; no amplification of output like mRNA product (multiple copies of rRNA genes + "Christmas tree" of polytranscription sites by Pol I)

Ribosome assembly in nucleolus. 3H U used in "pulse-chase" to elucidate details

Nucleoli on tips of 5 chromosomes, absent in condensed chromosomes

Rable orientation: Centromere and telomeres toward opposite poles.

Centromeres "pulled to each spindle pole"? Eat their way along microtubules

In situ hybridization reveals order in nucleus.

PolII makes hnRNA, mRNA; PolII and III make structural RNAs

Evolution of nuclear genome: 1/1000 randomly changed every 200,000 years, so,

10,000 individuals, every substitution tried 50 times in a million years

"...advantageous ...rapidly propagated... most genes optimized" Not really...

Gene duplication, recombination, transposition = larger changes Stephen J. Gould

Genes close together stay the same. Translocation protects from this (globin genes)

Antibody structure

Triose phosphate isomerase in "all cells".

CoT curves = estimate # of copies of DNA based on rates of reannealing

Transposons affect evolution (transpositional bursts)

Parasitic, junk, selfish DNA