Lecture 15 Notes
ProfessorJean Jiang Nash
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BIO120 Lecture 15 Nov 10 2010
Variation- variation among individuals in a population
Heredity- progeny resemble their parents more than unrelated individuals
Selection- some forms better at surviving and breeding in a given environment
Genotype- genetic constitution of an organism. Aa Bb
Phenotype- the organism as observed. Used when discussing a train. Product of
interaction between genes and environment.
Genome- the entire organisms DNA including both genes and non-coding
What is a gene:
Functional unit of inheritance
Contains info located on chromosomes consisting of DNA
Dna sequence composed of codons.
Where does genetic variation come from?:
1. mutation- ultimate source of genetic variation
3. gene flow
Through independent assortment at meiosis we get enormous genetic diversity.
This diversity if manifest when individuals mate and produce offspring.
It is the most important source of variability as we more from one generation to
Amount of variation you get from independent assortment is enormous relative to
A stable change in DNA sequence resulting in a change of genotype
Occurs at very low but variable rate in all organisms
Effects: neutral, deleterious, lethal, beneficial, in manu cases their fitness effects
depend on environment
Ultimate source of variation.
All diversity on earth is connected through mutation over long periods.
Characteristics of Mutation:
Mutation rates can vary
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