BIO1130 - Microbiology

BIO1130 - Microbiology - Microbiology What is...

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Microbiology What is Microevolution: - Allele frequencies (traits) – where variation is occurring - Evolutionary changes that result from changes in allele frequencies in a population, or in chromosome structure or numbers due to mutation and recombination - Looking at actual source of variation and change within a population of a single species Population: - Includes all the individuals of a single species that live together in the same place and time Gene Pool: - The sum of all alleles at all gene loci in all individuals is called the populations gene pool - Genotype frequencies: o Percentage of individuals possessing each genotype o Each diploid organism has 2 alleles at each gene locus - Allele frequencies: o Relative abundance of different alleles in a population (has to follow HW principles if want to calculate it) Null hypothesis: - The Hardy – Weinberg principle is a null model because it predicts what they would see if a particular factor had NO effect - Genetic Equilibrium: o Neither allele frequency or genotype frequency change in successive generations Allele frequencies and Evolution ( Hardy – Weinberg Principle): (Null Hypothesis – Measure of something not happening) - Rule: p 2 + 2pq + q 2 = 1 Assumptions: - No Natural Selection : o Selection changes allelic frequencies if one of the alleles is not fit to survive and reproduce gametes-allele disappears, therefore cause microevolution o Effect of Selection: Darwin said Change is GRADUAL what is the mechanism? Hardy-Weinberg’s rule (probability theory) o For Heterozygotes: (favoured) If heterozygotes favoured the allele frequencies for heterozygotes will prevail in a population Sickle Cell Anemia: (Model for heterozygote selection) Single Codon error in haemoglobin causes RBC to take a sickled shape Not in healthy donut shape do not absorb enough oxygen (respiratory stress) o Homozygous for Sickle Cell: Real bad – all RBC are sickled o Heterozygous for Sickle Cell: Still not healthy – partially sickled However will survive malaria disease Immune system picks up that the RBC’s are damaged and it destroys those sickled RBC’s Since immune system can do this people who get infected with malaria, the plasmodium virus invades the sickle cell as well, which is ultimately DESTROYED! (Cure for malaria, maybe?) Against Recessive: (Heterozygotes will prevail) When we select against the recessive, it will disappear and the frequency of the dominant allele will increase(heterozygotes)
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Microbiology Directional Selection: When individuals near one end of the phenotypic spectrum have the highest relative fitness Directional selection shifts trait towards that extreme Example: birds with longer tails have higher fitness (sexy times) than birds with shorter tails, therefore population tends to shift towards favoured trait Stabilizing Selection: decreasing the amount of variability that is in the population by taking out the two
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This note was uploaded on 01/17/2010 for the course BIO BIO1130 taught by Professor Houseman during the Fall '09 term at University of Novi Sad.

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BIO1130 - Microbiology - Microbiology What is...

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