LS1_lecture_4

LS1_lecture_4 - Dr. Allison Alvarado, mariposa@ucla.edu...

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Dr. Allison Alvarado, mariposa@ucla.edu Office hours: Fridays 9:30-11:30 am SH 2847
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± CCLE: Demo Quizzes ± Due at 8 AM Tues ± Mastering Biology: ± Reading Quizzes ± Due at 8 PM Sun ± Mastering Biology: ± Post-Lecture HW ± Due following day at 8 PM ± Textbook
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Natural Selection ± Increase in traits that enhance reproduction from one generation to the next ± If a phenotype is successful, all alleles in the individual will be selected ± Differential reproduction of different genotypes in a population ± Natural selection does not deal principally with survival, but rather with reproduction
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Genetic Definitions ± Gene – a section of DNA that encodes information for a protein ± Locus – the physical placement of that gene on a chromosome ± Allele – One of the forms of that gene ± Dominant allele: determines phenotype of heterozygote ± Recessive allele: phenotypic effect only seen in homozygote ± Co-dominant: heterozygotes exhibit both traits seen in either homozygote (e.g. blood type AB) ± Heterozygote – having two different alleles of a certain gene ± Homozygote – having two identical alleles of a certain gene
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Genotype vs. Phenotype Phenotype: Physical and physiological traits of an individual, determined by its genetic makeup Genotype: All of the alleles of every gene in an individual Genes regulate many biological processes: ± Biochemical processes ± Growth and development patterns ± Morphological traits (limb length, eye color) No variation in genes No variation in these processes, patterns, & traits
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± Variation in genetic marker(s) between individuals and populations ± This is where it all starts, the stuff of evolution -- the amount of evolutionary potential lies in the amount of genetic diversity present (i.e. genetic variation is the material for future adaptation) ± Genetic variation is essential for the ability to respond to environmental change Genetic Diversity
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Forms of Evolution ± Microevolution is evolution on a small scale — within a single population. That means narrowing our focus to one branch of the tree of life. ± Macroevolutio n refers to evolution of groups larger than an individual species.
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Genetic diversity can be thought of at three levels: Varia%on within individuals: e.g. heterozygosity Intra-popula%on varia%on: Gene%c diference among individuals within a popula%on Inter-popula%on varia%on: Gene%c diference among popula%ons
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Why is genetic variation within individuals important? ± Without heritable genetic variation……no natural selection ± Natural selection acts at the level of the individual ± Neutral genetic variation ± Majority of genetic material is non-coding ± Non-coding DNA is heritable ± Natural selection does not act on non-coding DNA ± Adaptive genetic variation ± Genetic material that does code for something, & has a function
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LS1_lecture_4 - Dr. Allison Alvarado, mariposa@ucla.edu...

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