INTRO TO BASIC GENETICS
Genetics:
fraction of bio that studies hereditary
gene activity underlies all biological processes
fraction of bio that studies hereditary
gene activity underlies all biological processes
study of genetics involves understanding of biological properties transmitted from parents to offspring
study genes, molecular nature of these genes, how genes transmitted
study how these genes are expressed, how genes' activity is regulated
how these genes control all biological processes
Genotype: inside gene
Phenotype: physical appearance
Classic genetics:
from Mendel to Central Dogma of genetics 1866-1941
experiments in plant hybridization 1865
Mendel's Garden Pea Pisum sativum
Modern genetics:
from Central Dogma of genetics 1941
George Beadle & Edward Tartum: one gene, one enzyme/one gene-one peptide from mutant strains of common bread mold neurospora grown in baths of chemical nutrients
Watson & Crick: DNA structure
Paul Berg: genetic engineering
Subdisciplines:
1. Transmission genetics: deals with how genes/traits transmitted from generation to generation/parents to offspring, how they recombine
Mendel's peas
2. Molecular: molecular structure and fx of genes
Modern genetics
3. Quantitative: hereditary of a trait in a population
discontinuous distribution of shell color (a polygenic trait) in snail Cepaea nemoralus from a population in England
4. Population: hereditary of one or few genes in a population
distribution & inheritance of lactose intolerance in different ethnic American
Basic research: to gain understanding of fundamental phenomena
Applied research: solve specific problem experiment
Tools in genetic research:
classic tech of breeding: crosses, backcrosses, testcrossing
microscopic: SEM, TEM
molecular: DNA sequencing, PCR, cloning
construction of genetic maps
genetic databases
nucleotide 6 billion pair diploid
3 billion parental + 3 billion marental
23 + 23 chromosomes
Basic concepts
1. DNA: genetic material in all prokaryotes, eukaryotes, some viruses
nucleotide = phosphate PO4-3, pentose 5C sugar, nitrogen base
genes/factors: specific sequences of nucleotides
genome: full sequence of DNA/all genes
(molecular subdiscipline)
2. Chromosomes
many prokaryotes have a single circular chromosome made of DNA only
eukaryotes, DNA located in nucleus forming linear chromosomes, each chromosome consists a single DNA molecule + histone proteins
(molecular)
3. Alleles
homozygous: a pair of identical alleles
heterozygous: a pair of different alleles
genotype: complete genetic makeup of an organism
phenotype: physical expression of genotype/observable properties of an individual
(transmission, molecular)
4. Mendel 1st & 2nd law
Principle of segregation: alleles Aa segregate independently into gametes during meiosis produce A and a
Principle of independent assortment: 2 alleles Aa controlling one trait segregate independently from 2 alleles controlling another trait Bb
(transmission)
5. Environmental factor
(transmission, molecular, population, quantitative)
被太阳晒的还是本来皮肤就黑？
6. Gene expression: process of a gene produces its product
one gene one peptide
each gene expressed as a protein
protein can be the final product (e.g. hair protein) or an enzyme that catalyzes formation of final product
transcription: DNA to mRNA
translation: mRNA to protein
Central Dogma of Genetics
7. Evolutionary process
mutations: change in genetic material
recombination: exchange of genetic material btwn chromosomes
selection: particularly favorable gene combinations in a given environment
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