Exam 1 Study Guide
Exam 1 Study Guide Biol 180
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This 5 page Study Guide was uploaded by Arielle Menn on Tuesday October 13, 2015. The Study Guide belongs to Biol 180 at University of Washington taught by Scott Rider Freeman in Summer 2015. Since its upload, it has received 63 views. For similar materials see Introductory Biology in Biology at University of Washington.
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Date Created: 10/13/15
Exam 1 Study Guide Monday ctober 12 Z 15 1139 PM Housekeeping 0 Exam is in Kane 130 at the normal lecture time on 101615 0 There are short answers experimental designs graphs and drawings 0 There are multiple versions of the exam 0 It39ll cover everything through Thursday 1015 with an emphasis on lecture O Calculators are allowed but not provided the only other things we need are pencils and erasers 0 There will be exam review Thursday 10 15 530720 in Bagley 131 0 It39s important to sit in your assigned section because you can only hand in the exam to your TA 0 No phones Outline 0 General Experimental Design 0 General Concepts and Vocabulary 0 Theory of Special Creation 0 Theory of Lamarckian Evolution 0 Theory of Evolution by Natural Selection 0 Mendelian Experiments 0 Punnett Squares and Basic Laws of Inheritance 0 Genetic Diseases to be added we haven39t learned this yet 0 Data Analysis and Statistics to be added we haven39t learned this yet General Experimental Design 0 It39s important to only be testing one dependent variable at a time and only manipulating one independent variable at a time Control as many other factors as possible Anything that could possibly impact the outcome should be controlled or averaged out between groups When a factor is difficult or impossible to control use large sample size and random distribution to make sure the average state for each group in terms of the controlled variables is uniform Design experiments to support the null hypothesis which is the negation not the reverse of your hypothesis 0 Eg If the hypothesis is that there39s a positive correlation between two factors the null hypothesis is NOT that there39s a negative correlation but that there isn39t a correlation at all General Concepts and Vocabulary O A theory usually has a pattern and a process component 0 Pattern component What is happening What pattern is being observed 0 Process component Whyhow is this happening What is the mechanism Uniformitarianism The concept that the basic way the world works now is the way it works in the past allows us to assume that phenomena like soil erosion existed in the past and to collect data based on those assumptions Homologous traits and species species or traits that have similarities in both function and underlying structuregenetics evolved from the same place Homoplasy Analogous Traits in contrast with homologous traits analogous traits look similar or serve a similar function but have different geneticstructural backgrounds which suggests they evolved separately Theory a hypothesis that applies to a larger field a collection of hypotheses that relate to each other to explain a larger system Fitness an individual39s ability to survive and reproduce as efficiently and effectively as possible Adaptation a species39 change over time in response to environmental factors this adaptation is a gradual process resulting from the death or decreased fertility of those less adapted to surviving in the Biology 180 Page 1 environment Model Organism A relatively simple organism cheap easy to work with en masse preferably with a short generation time and quick turnover specifically for genetic studies and with easily observabletrackable phenotypes across generations 0 Whatever we study in model organisms should be applicable as directly as possible to other organisms so that findings can be extended as far across the biological spectrum as possible Replicating an experiment requires keeping all the variables the same and doing the exact same experiment It is important both to replicate experiments to make sure original results weren39t a fluke and to do similar experiments with a variety of controlled settings and characters to supportrefute the hypothesis Gene a factor that influences for our purposes so far a phenotype of a particular trait and is passed on to offspring O Allele a version of a gene In genotypes and phenotypes ratios deal with whole numbers eg 121 whereas frequencies deal with fractions or decimals that need to add up to 1 eg 025 05 025 Theory of Special Creation 0 O 0 Pattern component species are unchanging unrelated and perfectly suited to their environments Process component species were created as they are now by a higher power or deity quot6000 years ago Evidence to look for well adapted species constant and unchanging population a point of genesis for all life forms etc Lamarckian Evolution 0 Pattern component Species get larger and more complex over time progressively they climb up the Ladder of Evolution Process component Individuals adopt traits throughout their lifetimes that are more advantageous to their survival and pass those traits down to their offspring Evidence to look for individuals that change over time traits that are shared between individuals and their offspring change in species over time creatures becoming more complex Evolution by Natural Selection O 0000 What are the four postulates of Natural Selection 1 Individuals within populations are variable 2 Some of these variations are passed on to offspring 3 Not all individuals produce the same number of offspring 4 Individuals with certain heritable traits produce most offspring To summarize Heritable variation leads to differential reproductive success Key Point Evolution is a result of the differential reproductive success Individuals do not evolve evolution only happens on the level of an entire population What39s the key difference between Lamarckian evolution and Natural Selection Lamarckian evolution is progressive whereas natural selection is randomresponsive but doesn39t strive to change the species in any particular direction Evidence species that change over time individual variation in fertility of offspring within a species deathlower fitness of individuals within a species that possess traits less suited for their environment Mendelian Experiments 0 At the turn of the 20th century Darwin was confused evolution had been commonly accepted by the sci community but natural selection seemed to have some issues in the logic 0 According to the theory of blending inheritance an offspring of two parents with different versions of a trait should yield an average phenotype eg A red and a white flower would make a pink flower a tall and a short plant would make a medium height plant 0 BUT if this were true then entire populations should be homogenized over time into a uniform phenotype Biology 180 Page 2 and scientists weren39t observing this in nature 0 A monk named Mendel decided to look into genetics and blending inheritance by experimenting on some pea plants 0 These pea plants had seven observable traits in which a plant could exhibit one of two phenotypes and for each trait Mendel could get two purebreeding lines where 100 of the offspring in every generation had the phenotype he wanted 0 Mendel crossed tall plants with short plants and found that all of the resulting plants were tall but when he allowed the offspring to selffertilize and produce a second generation 25 were short 0 He repeated this experiment and did analogous experiments with the other six traits to make sure he saw a pattern 0 These experiments disproved blending inheritance because offspring were either short or tall but the traits of the parents never blended to produce medium height plants 0 Now Mendel knew O Inheritance is particulate blending doesn39t occur When we crossed two parents with different phenotypes we didn39t get a hybrid phenotype 0 Each individual pea plant has two alleles of each gene Because traits that disappeared in F1 reappeared in F2 so an extra copy of that recessive allele must have been saved somewhere 0 Individuals can be homozygous both alleles are the same or heterozygous the two alleles are different 0 Some alleles are dominant to others others are recessive I Note Dominance and recessiveness are defined ONLY in terms of the appearance of heterozygotes I Note most alleles are neither dominant nor recessive 0 During gamete formation in a parent pairs of alleles segregate separate and go into different gametes I Each gamete contains one allele of each gene 0 Male and female gametes fuse during fertilization to form a zygote I Each offspring then has two alleles one from each parent Punnett Squares and Basic Laws of Inheritance In the Punnett Square to the left the yellow highlighting represents the phenotype of the A allele and the blue highlighting represents the phenotype of the a allele 0 What about a dihybrid cross Do two genes act under dependent assortment where both alleles from the mother are inherited together and there are no cases with one allele from one parent and the other allele from the other parent or independent assortment where each allelegene sorts completely separately and any combo is possible 0 The answer is independent assortment see notes from 107 for more details 0 When the two genesalleles are on different chromosomes they sort completely independently 0 When the two genes are on the same chromosome they have a higher chance of being sorted together into the same gamete see Meiosis and Recombination below for more info 0 Eg If Parent 1 and Parent 2 are both AaBb genotypes then they can each produce the gametes AB Ab a8 and ab under independent assortment Therefore their offspring would look like Lb bb Biology 180 Page 3 g AABB Emilio A0812 7amp6 pg mp0 mob mac my QED Mfg Qag lm g Rw b oxb mgr lam aq b More Mitosis and Meisosis O Mitosis The process responsible for asexual reproduction and growth in multicellular organisms O Meiosis Sexual reproduction O Mitosis How does it work 1 Prophase DNA is replicated into two sister chromatids from each chromosome 2 Metaphase chromosomes line up along the middle of the cell metaphase plate 3 Anaphase sister chromatids separate and travel toward opposite ends of the cell 4 Telophase cell starts to pinch in towards the middle resembling more of a peanut shape than a bubble 5 Cytokinesis the cell separates into two separate but identical cells 0 Notation Haploid Number vs Ploidy 0 We use n to indicate the number of diff types of chromosomes found in a species this is known as the haploid number 0 We use a numeral before n to indicate the number of each type present this numeral represents ploidy ex Humans are diploid because we produce two copies of each chromosome horses are triploid O A chromosome is an unreplicated collection of DNA represented as a strand 0 A chromatid is a replicationcopy of a chromosome that is created during mitosismeiosis to help create multiple identical copies of the same DNA 0 A chromosome that is replicated looks like two chromatids side by side still counts as one chromosome 0 Meiosis How does it work FR 7 lla oid xg ltgt Meiosis 1 is a ploidy reduction Plbldg 3 C1 gt Each chromosome replicates but the ploidy number stays the 6 same b Homologs synapse which means sister chromosomes find each other so it looks like four copies bound in a bundle because there d are two chromatids corresponding to each of the two sister chromosomes at least in a diploid cell b Crossing over occurs so the copies of the sister chromosomes exchange information in this little bundle of four chromatids gt Then the sister chromosomes separate and travel to opposite ends of the cell so even though you see two strings going to each side o t e ce t ose two strings represent t e two c romatl s or Md f h ll h 39 h h 39d f HO VOK 4 only ONE chromosome Therefore at this phase the cells go from 90 a sm39x diploid to haploid with each individual chromosome still in its W W n 39ch we replicated chromatid state 0 Meiosis 2 is stays in a haploid state J I You have one of each chromosome sitting in a haploid daughter VA cell in a replicated state so it looks like two identical chromatids V V The chromatids line up on the metaphase plate down the middle of the cell and separate again Each daughter cell how has only one chromatidreplica of one L 17 chromosome it39s still haploid 4 At this point there are ready gametes and the cell will only Innhnmn Ainlninl nixaha nFInv IFnrllnnn Inllnnn nhnn I nnnIInnv Biology 180 Page 4 V V chromosome it39s still haploid b At this point there are ready gametes and the cell will only become diploid again after fertilization when it joins with another person39s haploid gamete 0 Now we have the Chromosome Theory of Inheritance O O 0 Pattern component Mendel39s observations from his pea plant experiments Process component Meiosis This theory includes the principle of segregation Where homologous chromosomes synapse and separate in Meiosis 1 so each gamete eventually gets one parental allele not a blend It also covers the principle of independent assortment which is when chromosomes line up separately on the metaphase plate during Meiosis 2 so genes on separate chromosomes sort completely independently 0 Genes are linked when they are on the same chromosome genes are sexlinked when they are on an X or Y chromosome together 0 Recombination happens during Meiosis 1 homologs synapse which means sister chromosomes meet up in the middle of the cell and then swap matching sections of their DNA 0 This means that even if two genes are on the same chromosome they are not guaranteed to end up in the same gamete because the section with one of the genes could be swapped out into the sister chromosome If two genes are on the same chromosome the probability of them getting swapped away from each other during recombination is directly proportional to the distance between them along the chromosome 0 If the two genes are on opposite ends of the chromosome anywhere that the chromosome recombines will be between the two genes so one of them will definitely get swapped over 0 If two genes are right next to each other on the chromosome the chances that the recombination point will be right between them are super slim so they39ll probably end up on the same chromosome and eventually in the same gamete O The distance between two genes on a chromosome is measured in centiMorgans and the distance is the same as the percentage change that they39ll be recombined small distance small chance and vice versa Biology 180 Page 5
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