130 likes | 283 Views
Test Cross for dihybrids. These work the same as monohybrid crosses To determine if an individual is homozygous or heterozygous for a trait we cross with a homozygous recessive individual!!!. MUTATIONS. MAH - YEAR 12 BIOLOGY. DO NOW. How does genetic variation arise? 9:3:3:1 means what?
E N D
Test Cross for dihybrids • These work the same as monohybrid crosses • To determine if an individual is homozygous or heterozygous for a trait we cross with a homozygous recessive individual!!!
MUTATIONS MAH - YEAR 12 BIOLOGY
DO NOW • How does genetic variation arise? • 9:3:3:1 means what? • What does crossing over mean? • Write four ‘facts’ regarding meiosis? • Carry on with genetics handout I gave you the other day
MIND MAP • Two parts: • Genetics: Genes, alleles, chromosomes, dominance, recessive, genetic variation, meiosis, recombination, independent assortment, fertilisation, mutations, gene mutations, chromosome mutations, dihybrid crosses, F1, F2 • Evolution: variation, gene pool, evolution, natural selection ( 3 types), mate selection, genetic drift, founder effect, bottleneck, gene migration (gene flow)
What is a Mutation? .....A change in a DNA base sequence that can not be easily repaired Varying effects based on type of mutation Normal spontaneous mutation rate is about 106 to 108 replications
What causes Mutations? • MUTAGENS: are agents that causes genes to mutate • THEY INCLUDE: • High energy radiation – cosmic rays, x-rays, ultraviolet radiation, radioactive decay • Chemicals – nitrogen mustards, epoxides, nitrous acid, formaldehyde, acridine dyes and alkylating agents, Pg. 169 Bayley – summarise how radiation and chemicals effect DNA Pg 81/82 Biozone
Thesunwashotbuttheoldmandidnotgethishat The sun was hot but the old man did not get his hat. The sun was hot but thy old man did not get his hat Thsunw ash otbuttheoldm and idnotg eth ish at.
Effects of Mutations • Proteins • Changing biochemical pathways • Changes to chromosomes (repeats: fragile X) • Changes in cell division processes • Mutations lead to evolution, because the protein formed from a mutation may be useful producing an organism more suited to its environment
Mutations • If a mutation occurs in a somatic cell it only affects that organisms and cannot be passed on. • If the mutation occurs in a gametic cell it may be passed on to the offpspring