Exam 2 studyguide
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This 4 page Study Guide was uploaded by Tiffany Thomas on Monday January 18, 2016. The Study Guide belongs to 01202 at Rowan University taught by Dr. Grove in Fall 2015. Since its upload, it has received 156 views.
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Date Created: 01/18/16
First, dinosaurs are short, trees are short, trees are then tall, short dinosaur gene doesn’t get passed on because he can’t reach the trees so they don’t survive. The tall dinosaur gene is then more frequent because they have more food so they’re genes are passed on. Dino/tree examples 1. Evolution of both species 2. Role of variability 3. Role of heritability 4. Advantage/disadvantage of each trait 5. Change in average height overtime 6. Avoid “need”, “want”,” in order too”, “so that”, etc. Modes of selection worksheet Patterns o 1 extreme is good, 1 extreme is bad directional o Middle is good, extremes are bad stabilizing o Extremes are good, middle is bad disruptive o Examples: sheep smaller horns/weight=not hunted as often, salmon – reproduce earlier/later= not fished during optimal season, birth weight in humans – within a range Directional selection is the kind most people probably think of when they’re talking about evolution. This is when one particular value for a trait is more successful than others, so over time the average for the entire population shifts in that direction. For example, it might be that in a particular population faster individuals are more successful than slower ones (because they are better able to outrun predators or catch prey); over the course of generations, the average speed of the population would increase, since the faster individuals would have more offspring than their slower counterparts. Stabilizing selection is selection which maintains the status quo because individuals with extreme values (high or low) for a trait do less well. (Example: things are pushed to the middle/the middle ones are successful. Being medium will make you more successful than being small or large(BIRTHWEIGHT small and big babies don’t do well, but medium size ones do)) Disruptive selection is the opposite of stabilizing selection. Instead of the individuals with the current average value for a trait doing better, individuals with extreme values do better which results in selection away from the status quo. The most famous example is probably Darwin’s finches, which have evolved different sizes and shapes of beaks adapted to different kinds of food; for example, birds with big or small beaks can eat big or small seeds, respectively, but intermediate sized beaks would be too big from small seeds and too weak for big seeds (example: fish small. medium and large how an they achieve success at fertilizing eggs. 1) large one, bullies other fish to fertilize and defent territory 2) small one, sneaky hang around, zips in and zips in w/o being noticed. 3. Medium one, get pushed around and can’t be sneaky because its too big to not be noticed. (successful ones: small and large one/two extremes are successful) How does mean and variability change? (BAR CHART) Disruptive: Before selection (average size male) pushed to the extreme = numbers will be higher or lower, average may not change but the variability will be increased (higher error bar after). Stabilizing: things pushed to the middle; before evolution, the means may not change but the variability before will have a higher variability (more error bars before) Directional: Either lower or higher will be more successful (one extreme is good, one extreme is bad) the evolution mean before will be higher than after. (higher bar length before) Why do you sometimes look like other species? Where you live determines it (lizards who live on twigs have short legs/lizards that live in bushes have longer legs) o two lizards that live on twigs of different species relatively look alive because its good for them to have short legs (SIMILAR ENVIROMEMENT DUE TO SILIMAR ENVIROMENTS/SELECTION PROCESS) o examples: sticklebacks each individual lake they each came from the ocean, but you see that marine population have more plates and the freshwater fish have less plate numbers. (they all look the same) o Lake w/ predators higher pelvic score: lake w/o predatoryhow it’s a disadvantage? Using more energy/nutrients with it even though they don’t need it so they lose it overtime(conversion evolution) o 5 freshwater lakes: slightly different. Loberg is more different and higher error bar (more variability, not all have small number of plates) Calculating allele, genotype and phenotype frequencies Frequency of 0.50, if population doesn’t evolve, the allele frequencies will be the same. Is this population still evolving? Plate number controlled by a single gene:2 alleles: C(complete) and L(low) Genotype: CC,CL,LL Phenotype:20+ plates, 920 plates, 08 plates Genotype phenotype (OBSERVED) CC 0 CL 19 LL 147 Total 166 IS THE POPULATION EVOLVING??? 1. Allele frequency? (divide by sample size x 2) C(2x147)+19)/332= 0.06 L(2X19)+19)/332 = 0.94 IS IT IN EQUILIBRIUM? 2. Genotype frequency? (p for CC) P=0.06 Q=0.94 P^2= (0.06)^2=0.0036 2pq=0.1128 Q^2(0.94)^2=0.8836 3. Find expected # of each genotype? (MULTIPLE EACH BY SAMPLE SIZE) LL – 0.8836X166 147.5 CL – 0.1128X166 17.89 CC – 0.0036X166 0.54 4. Chi square test? [(expected observed)^2]/expected LL: (147.5147)^2/147.50.0017 CC: (0.540)^2/0.540.54 CL: (17.8919)^2/17.890.069 X^2 EQUALS approx 0.6 Less than 3.48, then you fail to reject nullMore than 3.48, reject null YOU FAIL TO REJECT NULL HYPTHESIS/ SO IT’S NOT EVOLVING!! Population genetics: DNA strands are transcribed in the 3’ to 5’ direction RNA strands are translated in the 5’ to 3’ direction RNA codon table is read in the 5’ to 3’ direction In DNA, the base adenine (A) is paired with the base thymine (T) In RNA, the base adenine (A) is paired with the base uracil (U) In both DNA and RNA, the bases guanine (G) and cytosine (C) are paired Part of a DNA strand to be translated has the following sequence: 3’ TAT CGC AAA GGC TCA 5’ a What is the sequence of RNA transcribed from this part of the strand? 5’ AUA GCG UUU CCG AGU 3’ b What sequence of amino acids does the RNA produce? Ile Ala – Phe – Pro Ser A codon is a 3base mRNA sequence that codes for a single amino acid or termination of the peptide sequence. The anticodon is the 3base tRNA sequence that compliments the codon on the mRNA. Each tRNA delivers a specific amino acid to the ribosome. point mutation is when a single base is substituted (change one base pair on DNA strand, then fix to compliment RNA then it changes the amino acid from the codon chart) deletion mutation is when bases are dropped addition mutation is when bases are added silent mutation is when a point mutation is made but doesn’t change the amino acid missense mutation is when a point mutation changes the amino acid encoded by that codon nonsense mutation is when a point mutation causes the codon to become a stop codon. This halts protein synthesis too early, and usually results in a nonfunctional or abnormal protein Alleles: variant forms of a gene, or variant nucleotide sequences at a particular locus Dominance: a condition in which one member of an allele pair is manifested to the exclusion of the other Evolution: changes in allele frequencies over time Gene flow: the spread of genes from one breeding population to another by migration, possibly leading to allele frequency changes Genetic drift: changes in allele frequency in small breeding populations due to chance fluctuations Genotype: the genetic constitution (gene makeup) of an organism HardyWeinberg equilibrium: a situation in which allele and genotype frequencies in an ideal population do not change from one generation to the next, because the population experiences no selection, no mutation, no migration, no genetic drift, and random mating. Heterozygous: unlike members of any given pair or series of alleles that consequently produces unlike gametes Homozygous: identical members of a given pair or series of alleles that consequently produces identical gametes Natural selection: differential survival and reproduction in nature that favors individuals that are better adapted to their environment; elimination of less fit organisms Phenotype: the observable characteristics of an organism Recessive: a term applied to one member of an allelic pair lacking the ability to manifest itself when the other or dominant member is present Hardyweinberg equilibrium (5 violations) 5. Population size must be is extremely large (nearly infinitely so) 6. There cannot be any gene flow (no genetic mixing with other populations) 7. There are no mutations 8. Mating is random (no assortative mating) 9. There is no natural selection (survival and reproduction are equal among individuals in the population)
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