populate our brain and transmit signals up and down our spinal cord.

very complex, huge numbers of connections at one end with sensory and/or other interneurons, and at the other end with other interneurons and/or motorneurons

rhodopsin: general light sensitive receptor, a single photon of light can activate, which detects light by an adjunct biochemical [in rods]

retinal (vit A): seven-transmembrane protein that sends a second messenger inside the rod cells to open ion channels and cause a depolarization that leads to action potentials, in the dark it is in cis conformation, when a photon is absorbed by it, it converts to trans configuration. This causes an action potential

1. sensory neurons (bipolar, pick up the signal from the environment and sends it to interneurons)
2. sensory receptors (branched endings of sensory neurons detect specific stimuli)
3. nerve pathways (lead to the brain)
4. specific brain regions (process input)
5. the brain (identifies sensation)

light receptor of retinal-120 million

blue-green light

may be activated by a single photon

responds to most wavelenghts of light

receptor protein: rhodopsin

light receptor of retina-7 million

red, green or blue

contain 3 color opsins

Protein: color opsins, are wavelength specific

(only one to detect color)

dense array of cones

sharpens vision

contains few or no rods

no blood vessels

density of cones decreases outward

rods are more common in perihery

neither rods nor cones where it leaves the retina

blind spot 10 degrees off center

collect signal from many receptor cells

brain registers which ganglion cell sends signal

1 million collect signals from 127 million rods/cones

between optic nerve and amacrine cell

proteins of pigment that is in the rods and cones

7-transmembrane domain protein

about 350 amino acids long

special in primates not other mammals

requires 3 additional special opsins expressed in particular cone cells, they respond to different wavelengths of light because of thier specific amino acids (red, green and blue)

red and green on X chromosome so men can be red/green color blind

red-responds to wavelength 700nm

green-responds to wavelegth 500nm

blue-responds to wavelength 400 nm

there is only one kind or receptor protein

respond to several stimuli

each receptor encoded by a different gene 1000

5% of genome encodes for these receptors

60% of our receptors are no longer functional

1. salt
2. sour
3. bitter
4. sweet
5. umami (aged cheese, triggered by glutamates)

each sweet or bitter cell expresses multiple receptors so we can only tell sweetness or bitterness

1800 different chemoreceptors genes/proteins

expressed like this in neurons that either signal attraction or repulsion

like us

60 odorant receptors

60 taste receptors

occurs in bilaterally symmetrical animal

brain

medulla oblongata

cerebellum

pons

cerebrum/grey matter

most elaborate

divided into coloration, hemispheres, lobes

corpus callosum (connection between hemispheres)

left hemisphere is analythical

right is creative/artisitc

lobes, frontal, occipital, temporal, parietal

prefrontal cortex

memory, planning, inhibition of unsuitable behaviors

primary somatosensory cortex

input form skin/joints

perception of taste

integrates viseral input/sensory input form skin

integrtes vision

optic chiasmal are internal to frontal lobe

auditory impulses

advanced visula processing

controls emotions and has a role in memory

(damage to substantia nigra of hippocampus leads to Parkinson's disease)

long term requires protein synthesis

consists of multiple components constructed around a distributed network of neurons

inducible, encoding the protein needed to metabolize various substrates

in the absense of lactose the lac repressor binds to the operator region that overlap the promoter of the Lac operon, preventing transcription

lac repressor alway available but in small amounts

negative feedback regulation

repressible operon

the presensce of the final product activates the appropriate repressor thus preventing transcription

genes encode proteins involve synthetic pathways (amino acid synthesis)

his operon has 11 genes encoding all the enzymes needed to make the amino acid histidine from scratch and is transcribed when there is no available histidine in the cell environment

1. transcriptional (most important to class, promoters and interactions at DNA level)
2. transcript processing (splicing or other modification of pre-mRNAs)
3. translational (behavior of ribosomes on the transcript and the rapid degradation of transcript)
4. Post-translational (modification of proteins, cutting or phosphorylation or adding sugars, or complexing with other proteinsand rate of degredation of protein)

controls of gene expression

bind upsteam of the promoters and control the binding of RNA polymerase and transcription

determines when and in which cell each gene is transcribed

type of regulation of gene expression

happens in calico cat (one X controls expression of black fur the other expresses orange fur)

female mammals have two X chromosomes and one is inactivated as a Barr body in every cell

cells contain normal copies of oncogenes

these genes that normally promote cell division so when over expressed by an infecting virus, can convert cells to cancerous fates

skin cancer

dangerous metastasis occures quickly

works similar to DNA polymerase

single protein at core of enzyme, the whole thing is a huge complex of 15-30 proteins

processing of mRNA before it moves to th e cytoplasm as mature mRNA

G-Cap=added to 5 prime end

poly-A tail=added to the 3 prime end

inrons spliced out

HIV (single cell) 10 genes, 10000base pairs

E.Coli (single cell) 4600 genes, 4500000base pairs

Yeast (single cell) 6000 genes, 12000000base pairs

nematode(mult cell) 20000genes, 100000000base pairs

drosphila(mult cell) 15,000 genes 150000000base pairs

human(mult cell) 20000 genes, 3000000000base pairs

lungfish, salamanders, crickets(mult cell), 20000 genes, 100000000000base pairs

triplet code

64 codons only 61 for amino acids

3 stop codons

1 start codon

often redundant, multiple codons code for same amino acid

essentially universal (except mitocondria/UGA not stop but tryptophan)

short, fold into 3D

anticodon triplet of 3 bases on one end and an amino acid acceptor site on the other

DNA-RNA-Protein

transcription (DNA-RNA) is a two way path but translation (RNA-protein) is not

DNA and RNA may replicate but not proteins

proteins affecting other proteins

Scrapie=in sheep

Bovine spongiform encephalopathy

kuru=humans eating brains in New Guinea

Creutzfeld-jacob disease (CJD)=humans, spontaneous/transplant

Variant CJD-humans eating BSE cow

Wasting disease=unguulates like elk and deer

single amino acid change in hemoglobin

amino acid substitution or changes in the first or second codon positon leads to this

single amino acid deletiion from the CFTR protein

deletion of multiple of 3 base pairs

3 billion base pairs

23 chromosomes

length of DNA inone sperm cell is 1m long

1% of our genome encodes for amino acids in proteins

5% of our genome is conserved in sequence over the last 100Myr

50% of our genome is dead retroviruses, decayed copies of genes, and "junk"

the smalles genome of all vertebrates

3X10^8 bp  or 1/10 of a humane genome

Cloning method

human genomic DNA and Plasmid DNA cut by restriction enzymes and when the human DNA pieces attach themselves in-between the open "sticky" ends of plasmids a DNA ligase is used to seal these joints

the mixture is then transformed back to E coli bacteria, only a few bacteria will get a single recombinant plasmid/human DNA molecule

amplification of particular stretches of DNA using polymerase chain reaction or PCR

amplifying short tandern repeats that commonly differ in length and so are DNA fingerprints (paternity test and forensic)