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Genes and Proteins. Lecture 2 PSY391S John Yeomans. Why Use Genes?. Behavior = Genes <=> Environment Psychologists have studied environmental effects on behavior best for a century. Human genome project now gives us all the genes. What an opportunity!

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genes and proteins
Genes and Proteins

Lecture 2

PSY391S

John Yeomans

why use genes
Why Use Genes?
  • Behavior = Genes <=> Environment
  • Psychologists have studied environmental effects on behavior best for a century.
  • Human genome project now gives us all the genes. What an opportunity!
  • Most of these genes are found in lower animals such as mice.
  • Behavioral effects of single genes can be studied in mice and humans.
slide3
DNA
  • 4 Bases: Cytosine and guanine, adenine and thymine.
  • Deoxyribose backbones hold 2 complementary chains each with full information.
  • Can separate and then self-replicate.
  • Hold all genetic information in higher animals.
  • Human genome 3.1 billion bases (2000).
messenger rna
Messenger RNA
  • Single chain with 4 bases, C, G, A and uracil instead of T.
  • Ribose backbone.
  • Transcribed from DNA in nucleus, then spliced (“edited”), then translated into proteins by ribosomes in cytoplasm.
proteins
Proteins
  • Single chain of 20 amino acids.
  • 1 Codon: 3 bases1 amino acid.
  • Start (AUG) and stop codons.
  • Genes (about 25,000) and pseudogenes.
  • Folding of proteins into complex 3D structurescomplex functions.
  • Trafficking of proteins into many different cell sites.
what is a gene
What is a Gene?
  • A DNA sequence that codes for 1 protein.
  • Hard to count genes. First, find start and stop codons.
  • Exons and introns--Junk DNA?
  • But some fragments don’t work as proteins--Pseudogenes.
  • No agreement on exact number.
gene technology
Gene Technology
  • Cutting DNA with restriction enzymes.
  • Measuring lengths with gel electrophoresis.
  • Copying DNA by cloning or PCR.
  • Automated sequencing by computer (Mbases per day)
  • Complete genomes of hundreds of species.
functional studies
Functional Studies
  • Hybridization of DNA and RNA.
  • Blotting to find specific chains: Southern-DNA, Northern-RNA, Western-proteins.
  • In situ hybridization: Find RNA in brain.
  • Immunocytochemistry: Find proteins in brain.
chromosomes

Chromosomes

Lecture 3

PSY391S

John Yeomans

mutations chromosomes and genetic diseases lecture 3 psy391s
Mutations, Chromosomes and Genetic DiseasesLecture 3 PSY391S
  • Mutants
  • Chromosomes
  • Chromosome Disorders
  • Gene Disorders
  • Linkage of Genes to Diseases
  • Gene Therapy and Ethics
mutants
Mutants
  • Random mutations: spontaneous, or induced by chemicals (ENU) or radiation.
  • Targetted mutations of single genes: transgenic--added copies; knockouts--deleted copies.
  • Flies and mice used commonly.
  • About 1/3 of behavioral neuroscience now studies of mutants, especially mice.
knockout mice
Knockout Mice

Sedivy & Joyner,

1992

chromosome maps
Chromosome Maps
  • Breaks and Crossovers: Genes are linked on each chromosome by distance.
  • Morgan: Use linkage to map gene distances on each chromosome--cM.
  • Genome Projects: Each Ch mapped in megabases (Mb).
  • Genetic diseases can be mapped by distance from markers!
chromosome disorders
Chromosome Disorders
  • Extra Chromosome: trisomy 21 (Down’s syndrome), trisomy 18.
  • Deletions: 5p- (Cri du chat), 7q- (Williams’)
  • Breaks: Fragile X
  • Most large chromosome additions and deletions are lethal and lead to spontaneous abortions.
neurogenetic disorders
Neurogenetic Disorders
  • Huntington’s: extra CAG repeats on 4p.
  • Fragile X: extra CGG on X.
  • Alzheimer’s: point mutations on Ch1, 21 etc.
  • Recessive and Dominant
  • Disease Gene Searches: Chromosome link, to gene link, to base change links.
  • Animal Models of Disease.
gene therapy and ethics
Gene Therapy and Ethics
  • Spontaneous Abortions
  • Amniocentesis and Counselling
  • Life Planning
  • Adult Gene Therapy?
  • Future of Species?