BIOL 112 lec 11

histone

proteins in nuclei that DNA coil around to form nucleosomes, organize chromatin and play role in gene expression

right number of X chromosomes

you can never have too many of ts

Barr body

inactivated X chromosome

why we have so many X chromosomes

all but 1 X chromosome inactivated by condensing it into Barr body, prevents transcription

lyonization

random inactivation of one X chromosome in each cell

calico cat fur

fur colour genes are on X chromosome, lyonization results in random deactivation of orange and black fur genes

euchromatin

lightly stained, less condense, transcriptionally active

heterochromatin

tightly wound, stained darkly, not transcribed

gene amplification

create multiple copies of same gene to pump out more

alternative splicing

post-transcriptional, sometimes when splicing intron out of RNA, exon gets spliced as well, protein misses chunk, affects how it functions

post-transcriptional control

regulation of gene expression after transcription, modifying mRNA before it becomes mature to change protein synthesis

exon order rule

must splice exons in order than they come, can’t jump back and forth

RNA stability

cell processing mRNA regulates its stability, RNA must be unstable or else there is no need to regulate transcription

Untranslated region function

5’ and 3’ regions of ts determines stability of RNA

translational control

affects ability of mRNA to be translated by ribosome

RNA interference

gene A makes tiny RNA that interferes by complementing mRNA of gene, can regulate mRNA from gene B (review this im confused)

post-translational controls

changing proteins after they’ve been synthesized

kinase control

Cyclin D and cdk4 form complex that phosphorylate proteins important for transition to S-phase

selective protein degradation

proteins tagged for destruction by ubiquitin, Cyclin D destroyed after G1 to tell cell to move to S phase

why different regulatory mechanisms

regulation transcription makes slow changes in expression but is more efficient because RNA/protein are not made when needed, regulating at level of protein is fast but inefficient because proteins wait around to be activated (make ts more concise)

bioengineered crops

corn, rice, canola, cotton

genetic engineering

changing phenotype by changing genotype

selective breeding

domesticating animals/plants + and breeding ones with traits we want, have to wait until we get mutation we want

gene cloning

move single gene from one organism with phenotype we want, move to another organism

why clone genes

to make organism have phenotype we want, to understand phenotype

liver function

stores glucose in form of glycogen so we have right amount of glucose in body

insulin function

signals to liver when to store glucose

beta islet cells

in pancreas, secretes insulin

alpha islet cell

sends out glucagon to tell liver to release glucose into bloodstream

problem with diabetes

beta islet cells stop functioning, too much glucose

insulin discovery

insulin discovered in animals, can substitute human insulin, but hard to purify

pig insulin

identical to human insulin except for single amino acid difference, human immune system doesn’t like

solution to insulin problem

make easily growable cells, bacteria, yeast, cultured mammalian cells make human insulin cheaply

obstacles of insulin engineering

where to get human gene, how to put it into another organism, how to get host to recognize + express gene

bacteria insulin production

solution to obstacles, make gene, put it in plasmid, transform it into a bacteria

restriction endonucleases

enzymes that cut up phage dna at specific 6 base-pair sequences, defend against phage infection

sticky ends

restriction nucleases create staggered cuts, results in stretches of single-stranded complementary where base-pair + hydrogen bonds occur (wtf?? review ts)