BIOL239 Study Guide - Spring 2018, Comprehensive Midterm Notes - Protein, Gene, Chromosome
11 Oct 2018
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Department
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BIOL239
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Introduction
-Artificial selection: purposeful mating
- eg domestication (genetic process)
- as opposed to taming (merely behavioural; nature vs nurture)
- dogs and their breeds - same genes (same species) b/w dogs and wolves, just
different variations
- genetically close enough that their offsprings would be fertile; wouldn’t
naturally breed together
- human civilization is based on the genetics of our food supply
Set 1: Mendelian Genetics
Pages 16-31, 40-41 (2.1-2.2)
●Advantages to Mendel’s use of garden peas:
oEasy to cross-fertilize
oLarge numbers of offspring (numbers game)
oShort growing season
oClear-cut alternative forms of particular traits – alternative phenotypes
(observable and measurable)
▪ purple vs white flowers, yellow vs green peas; round vs wrinkled peas
oEstablishment of pure-breeding (true-breeding) lines
▪offspring carry parental traits that remain constant (always express the
same phenotype) from generation to generation
oCarefully controlled breeding – use of reciprocal crosses and self-fertilization
oSelf- vs Cross-fertilization (cross pollination)
▪ self: can be self reproduced, has ovules and anthers in one
▪ cross: anthers removed to prevent self-fert; another male pollen (ex
purple) added to female stigma (ex white) → when you examine the seeds
that form, you can see how each male and female dominates and later on
the germination (outcome)
find more resources at oneclass.com
find more resources at oneclass.com
●each seed is genetically different (~ fraternal twins; diff colour
corn)
●see dominance and recessiveness
o⇒ observed consistent pattern of inheritance…
●Phenotype = observable characteristic (largely determined by genotype)
o commonly referred to as a trait
o can be influenced by environment
●Genotype = genetic makeup; underlying description of the genetic information carried by
an individual
●Theories prior to Mendel:
oOne parent contributes most to an offspring’s inherited features – disproved
through reciprocal crosses (esp male, bc they are bigger and stronger)
oParental traits become mixed and forever changed in the offspring (disproved
through reappearance of recessive traits) → cannot be reversed
●Monohybrid crosses (differ in only one trait)
oP → F1 → F2 (refers only to inbreeding, no outcrosses)
o y x g ⇒ all yellow in first filial → (self-fert) lost green reappeared in 2nd filial
(always 3:1 ratio)
▪ why? bc the F1 has both traits from P (even though they only express the
dominant trait), so they would express either of the traits in the 3:1
dominant/recessive ratio when self fertilization
●Alleles: discrete units of inheritance; alternative forms of a gene – different DNA
sequences
o Hypothetical example… although irl it is more complicated
▪ Gene for trait = eye pigment, skin pigment, height, hair texture
▪ Allele = brown or blue, albino or pigmented, tall or short
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Each seed is genetically different (~ fraternal twins; diff colour corn) See dominance and recessiveness: observed consistent pattern of inheritance . Phenotype = observable characteristic (largely determined by genotype) o o commonly referred to as a trait can be influenced by environment. Genotype = genetic makeup; underlying description of the genetic information carried by an individual. Polymorphic gene may have several alleles that normally occur in a population not one as dominant, can easily find variations (eg. gene for blood type) o. Monomorphic gene has only one allele that is normally present in a population (other alleles are very rare) Gamete = reproductive cells o pollen/ovules = sperm/eggs. Mendel"s law of segregation : the two alleles for each trait separate (segregate) during gamete formation, then unite at random, one from each parent, at fertilization: describes how alleles of one gene behave, punnett square - shows possibilities. 3:1 phenotypic ratio simple dominant and recessive traits; cross between monohybrids: predictive.
