Biology 1a Lecture 25

Overview

Today is a 51 minute lecture on human genetics.  This is an alright talk.  Things can get deeper naturally.

Details

MicroRNAs or miRNAs bind to the 3′ UTR region.  The miRNA binds to a complementary sequence.

The exome is all the exome or protein coding regions of the genome.  It’s about 1-2% of the total genome.  The exome costs $2300 to sequence.  The goal is to make full genome sequencing under a thousand dollars.

The human genome is 3.2 billion nucleotide bases with 25,000 genes.  Sequencing costs are going down dramatically.  It is probable that your own genome will be sequenced in the next ten years.  About 503 miRNA encoding genes.  Half the proteins made are enzymes, half are structural proteins.

There are about 3 million SNPs or 1% of the genome.  15K in protein coding regions.  20% of SNPs are unique or private.

Synonymous mutations do not change the amino acid.  Non-synonymous mutations do change the amino acid sequence.  Non-sense mutations create a premature stop codon.  On average, the mutation rate is 10^-8 base pairs/generation

Hardy Weinburg Equalibrium: Allele frequencies achieve equilibrium as long as mating is random.  This is a simplification, but it’s his plantation.  Recall that an allele is just a different form of a gene.  I’m not going to go into the math if he’s just blasting through it.

Epigenetic changes are also heritable.  They are also changes to the structure of DNA but not the sequence.  DNA methylation in man uses two classes of DNA methylase.  De nove methylase can establish new patterns on an unmethylated subtrates.  Maintenence methylases only methlate DNA that has been methlyated before.  Recognizes homomethlyating substrates.

X chromosome dosage compensation: women get two X’s.  Men get XY.  At the 1000 cell stage, the blastula stage, one of the X chromosomes is inactivated.  It exists as a Barr body at the edge of the nuclei.  XIST is a huge miRNA that coats the X chromosome.

Review

Cochlea: scala vmt vestibuli, media, tymponi

Extraoccular Innervation: 3,4,6

Tissues: connective, muscular, nervous, epithelial

Rods for dark, cones for light

Fovea contains 35K cones

Taste: sour, salty, sweet, bitter

G = H -TS

PV = nRT

K = products/reactants

Brain: diencephalon, cerebrum, cerebellum, brainstem

Brainstem: midbrain, pons, medulla oblongata

SNS = fight or flight PNS = rest of digest-