PSYC 2410 Study Guide - Midterm Guide: Ligand-Gated Ion Channel, Chromatin, Axon Hillock

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Published on 16 Apr 2013
University of Guelph
PSYC 2410
Neuroscience Midterm #2 Notes
- Dichotomous traits: phenotypes that are all-or-none (traits that are one way or another, not in between)
ex. brown and white
- True breeding lines: if you have brown and brown making babies, you’ll get brown. Two organisms with a
particular trait only produce offspring that have that trait as well.
- Gene: each inherited factor
- Alleles: two genes that are in one person for a single trait.
- Genotype: the actual genetic make-up
- Phenotype: the actual PHYSICAL and OBSERVABLE characteristics.
- Operator gene: controls one or more structural genes
o structural genes are genes that activate mRNA (the production of a protein/peptide)
o operator genes are also called enhancers or promoters
- Transcription: DNA to RNA. Translation: RNA to protein.
- Splicing: introns are removed because they have no significance to protein synthesis
- Alternative splicing: exons are re-arranged to make different mRNAs that can code for different proteins
- Epigenetics: a change in phenotype that is heritable but does not involve gene mutation
- Epigenetics in Parental Care:
o Good mom vs. bad mom (high licking vs. low licking)
o Turns out that it’s due to low levels of anxiety instead
o Even during cross-fostering (one mom has mice, the other nurses) they turn out to be good
moms (aka low anxiety) in BOTH situations (i.e. if bad mom had children + good mom nursed, or
if good mom had children + bad mom nursed)
o Sometimes, there can be spontaneously bad moms. Not all of this is heritable.
- DNA Methylation: addition of methyl to cytosine bases (high methylation = reduced transcription)
o De-methylation involved in the suppression of stress responses (better moms [aka lower anxiety]
resulted from de-methylation)
- Histones: group of proteins found in chromatin
- Histone modifications: they can be phosphorylated (addition of phosphate)
o Or they can be acetylated (addition of acetyl groups to histone tails)
o This opens chromatin! And activates transcription
o De-acetylation removes histones, therefore would stop transcription.
- Adaptive behaviour is maintained; maladaptive behaviour is not
- Behavioural phylogeny: species to which the organism belongs + how that has changed them
- Behavioural ontogeny: individuals lifespan, their experiences + the stimuli to which they’ve been exposed
throughout their lifespan
- Maze-bright rats vs. Maze-dull rats
o Bred maze-dull rats with other maze-dull rats
o Bred maze-bright rats with other maze-bright rats
o Kept breeding the dullest of the maze-dull rats and the brightest of the maze-bright rats until
they were completely separated
o Did cross-fostering: dull mice raised by bright parents, bright mice raised by dull parents & found
gene does have effects because the bright children were still bright and the dull rats were still
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o But this inbreeding didn’t affect just one trait (found out that the brighter ones were smarter
because they were less fearful. Therefore, more likely to travel around)
o BUT!!!! Learning also has an effect (experience). Those who had an enriched environment,
regardless of being bright or dull, performed similar and were smarter than those who had an
impoverished environment.
- P25 = associated with neurodegenerative disorders; significant difference in spatial memory in rats who
were given P25 in a malnourished environment vs. an enriched environment
o Even though neurodegeneration, environmental enrichment can still help
- Fear conditioning: prevents from doing something bad; rats usually “freeze” in response to something
- Siamese fighting fish: very aggressive NORMALLY. A fish that wins a couple fights gets an increase in
aggression. A fish that loses a couple fights decreases in aggression. Temperaments can change due to
- Bird songs: Behavioural development
o Male birds sing to attract females. They learn their songs via listening to other males sing. (this if
the first stage. Sensory phase). Then, they start to practice their own song and eventually perfect
it! (this is the second stage. The sensorimotor phase). They need to be raised around other males
or else their voice won’t be the same.
o Some birds are age-limited learners: songs stay the same throughout time
o Some birds are open-ended learners: their songs can adapt and change throughout time
- The Canary Song Circuit:
o Males have a bigger voicebox than females
o Anterior forebrain pathway is associated with song learning
o Descending motor pathway is associated with song production
o Seasonal plasticity: their brain part that is associated with the songs gets bigger in the spring
- Multiplier effect: when a specific gene encourages an individual to seek out certain environments
- Cell membrane has a semi-permeable barrier (hydrophilic heads and hydrophobic tails)
- Different proteins allow for the influx or efflux of ions. Transmembrane/integral proteins and Peripheral
membrane proteins.
o Transmembrane: goes from one side of the membrane to the other
Signal vs. Channel
Signal proteins: send msgs to the rest of the cell
Channel proteins: allow specific ions to go through
o Peripheral: on one side of the cell membrane (allow input only from one side)
Facilitate chemical reactions (usually enzymes)
- Active transport: from low to higher concentration with use of proteins or enzymes
- Facilitated diffusion: allows things to flow with help from proteins
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