Week 8 lecture notes
Week 8 lecture notes BIO102
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Popular in Biology
This 9 page Class Notes was uploaded by Danielle Kelly on Friday March 6, 2015. The Class Notes belongs to BIO102 at Washington State University taught by Dr. Strofer in Spring2015. Since its upload, it has received 66 views. For similar materials see Biology 102 in Biology at Washington State University.
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Date Created: 03/06/15
Week 8 Lecture Notes March 2nd 2015 Inheritance 0 Human phenotypes genotypes 0 Genetic variation 0 Meiosis 0 How are traits inherited O Mendel s law of segregation O Mendel s law of independent assortment Traits 1 Widow s peak dominant trait 2 Detached earlobes dominant trait 3 Attached earlobes recessive trait So Phenotype is a description of physical appearance Genotype is the genetic basis for appearance and other unseen traits What do Dominant and Recessive mean First we have to look at a cell 0 Chromosomes are found in the nucleus 0 Human chromosomes are in pairs we are diploid 0 One pair of chromosomes homologous 0 Locus location of a particular gene on a chromosome 0 Alleledifferent forms off a gene at a locus 0 Homozygous 2 copies same allele eg blueblue 0 Heterozygous 2 copies different allele egredgreen Meiosis causes variation 0 Sexual reproduction causes variation in offspring 0 New chromosomes combinations from parents Inheritance Meiosis division of gametes 0 Produces gametes egg and sperm 0 Key just like mitosis but 2 cellular divisions 0 Before second division DNA does NOT replicate 0 Major difference from mitosis 0 End up in 1 copy of chromosome haploid in eggs and sperm 0 Versus 2 copies diploid from mitosis in rest of somatic cells 0 Results in 4 daughter cells Meiosis causes variation 0 Sexual reproduction fusion of gametes causes variation in offspring 0 New chromosome combinations from parents 0 Variation also caused by crossing over 0 Homologous chromosome switch sections creating new combinations W 0 Dominant allele one dominant allele present in the genotype automatically expressed in the phenotype masks recessive 0 Recessive allele both copies on homologous chromosome must be same for recessive to be expressed Example I can roll my tongue dominant but my mom can t recessive 0 Let s say now R is the allele for rolling and r is allele for not 0 Can my dad roll his tongue 0 YES 0 What s my mom s genotype 0 Has to be rr 0 What s my dad s genotype 0 Could be Rr or RR Gregor Mendel 18221884 0 Augustinian Monk Austria 0 Studies of plant hybridization inheritance 0 Laid foundation for modern genetics 0 Results published in 1865 0 But ignored until 1900 Mendel s fire experiment pea plants with purple and white owers 1 trait 1 Removed stamens from purple owers prevent selffertilization Transferred pollen from white to purple ower Plants made seeds Planted seeds and observed offspring F1 phenotypes Bred Fls together Observed F2 grandchild phenotypes Results F1 generation were all purple F2 generation was 34 purple and IA white purple osnagts gt was dominant and white was recessive 0 These experiments resulted in Mendel s Principle of Segregation 0 Pairs of alleles segregate separate during gamete formation when eggs and sperm are made fusion of gametes of fertilization created alleles pairs again March 4th 2015 Mendel s second experiment dihybrid cross green or yellow peas and round or wrinkled peas 2 traits 0 F1 generation got all yellow round peas so yellow and round were dominant 0 F2 generation not 31 ratio as in purple white pea ower experiments 0 Got 9331 ratio 9 yellowround 3 yellow wrinkled 3 greenround 1 greenwrinkled O This is because there are 2 different loci chromosomes sort independently so all possible gametes are formed 0 These experiments resulted in Mendel s principle of independent assortment 0 He knew something other than segregation was going on 0 Each pair of alleles segregates independently of one another during gamete formation Other important experiments concepts 0 Codominance O In heterozygotes both traits are expressed O Illustrated in Mendel s third experiment w snapdragons I White red parental owers made pink offspring 0 Polygenic 0 But most traits are not coded for by single genes 0 Traits in uenced by many genes are polygenic I Eg Skin color arm length eye color etc Codominance example ABO Blood Types 0 Gene that controls ABO type codes for enzyme that dictates structure of a glycolipid on blood cells 0 Two alleles IA and IB are codominant when paired 0 Third allele i is recessive to others Incomplete Dominance 0 Mendel s 3rd experiment with snapdragons 0 When mixed red and white snapdragons F1 generation was pink intermediate 0 F2 generation has 121 ratio 0 Check of homozygous red 0 Check to heterozygous pink 0 Check to homozygous white Wm 0 Polygenic traits in uenced by multiple genes 0 E g skin color arm length eye color etc 0 Human skin color is codominant and in uenced by 3 genes 0 The greater the number of genes and environmental factors that affect a trait the more continuous thee variation in versions of that trait Genetic Disorders 0 Inherited conditions that cause mild to severe medical problems 0 Why don t they disappear 0 Mutation introduced new rare alleles 0 In heterozygotes harmful allele can be masked so it can still be passed on to offspring 0 Medicine can keep people with severe conditions alive to reproduce Genetic disorders tVDes 1Single gene mutations a gt6000 known disorders b 1 in 200 births inherited predictably c E g cystic fibrosis sickle cell anemia Huntington s disease 2 Multifactorial or polygenic a Combinations of environmental factors amp mutations in multiple genes b Eg breast cancer associated genes found on chromosomes 6 11 13 14 1517 and 22 c Nature of complex gene interactions make very complicated 3 Chromosomal a Duplication b Inversion c Translocation d Deletion e Nondisjunction 4 Mitochondrial a Relatively rare Inheritance patterns 0 Autosomal in nonsex chromosomes recessive If parents are both heterozygous the child will have a 25 chance of being affected 0 E g CF 0 Autosomal Dominant trait often appears in every generation 0 E g Achondroplasia 39Homozygotes usually stillborn 39Heterozygotes display a type of dwarfism 39Have short arms and legs relative to other body parts 0 Xlinked recessive carried on X chromosome only 0 Males show disorder more than females 0 Son cannot inherit disorder from his father 0 Examples of Xlinked traits 39Color blindness L Inability to distinguish among some or all colors 39Hemophilia LBloodclotting disorder L 17000 males has allele for hemophilia A 393 Was common in European royal families Bio 102 Spring 2015 Practice Exam 11 these are the types of questions I ask The exam will be 50 multiple choice questions a bonus I may use one or a few of the exact questions below 1 A true breeding plant that produced yellow seeds is crossed with a truebreeding plant that produces green seeds all of the seeds in the offspring are yellow why a yellow allele is recessive to green allele b all offspring are homozygous yellow c yellow is easier to produce d yellow allele is dominant to green allele e yellow and green alleles are codominant 2 Attached earlobes are recessive to free earlobes If you father has attached earlobes and your mother is heterozygous for free earlobes what is the probability you will have attached earlobes a 0 b 25 c 50 d 75 e 100 3 An individual who is homozygous a expresses the dominant b carries two different alleles of a gene c is a carrier of a genetic disorder d carries two copies of the same allele for a gene e expresses the recessive 4 Which is the most important type of immune cells that HIV attacks leading to AIDS a macrophages b B cells c cytotoxic T cells d natural killer cells e helper T cells 5 Why do vaccines help prevent future infection and illness a they stimulate memory B and T cell production which provides future adaptive immunity b they stimulate macrophages that have memory c you generally become stronger after each pathogen you fight off d they stimulate production of natural killer cells e vaccines contain bacteria or viruses that compete with new infectioncausing ones 6 Which of the following is not part of a second line of immune defense a phagocytic white blood cells b defensive proteins c in ammatory response d fever e skin and mucous 7 Approximately what percentage of new emerging infectious diseases are transmitted from animals to humans a 10 b 25 c 33 d 50 e 75 8 The golgi apparatus is the site of a sorting and shipping station of the cell b energy production for the cell c the place where wastes are packed up and sent out of the cell d protein synthesis e all of the above 9 Why does HIV undergo reverse transcription a so it can enter a cell membrane b so it can enter a nuclear membrane c so it can become DNA and take over cellular machinery d so it can assemble new buds in the cytoplasm e so that it can break down its nuclear envelope 10 Cancer can be caused by a damage to tumor suppressor genes b damage to protooncogenes c cells dividing out of control d DNA damage that causes a cell to constantly signal that it should divide e all of the above 11 Movement of materials into a cell against a concentration gradient is most likely a diffusion b osmosis c facilitated diffusion d active transport e none of the above 12 Nondisjunction in a human egg that results in an extra copy of chromosome 21 would result in which of the following genetic disorders a Turner syndrome b Down s syndrome c Kleinfelter s syndrome d Spina bifida e Jacob Syndrome 13 If both parents are carriers for an autosomal genetic disorder what s the chance that any one of their offspring will have the disorder a 0 b 25 c 50 d 75 e 100 14 The spread of Darwin s finches among the Galapagos Islands from a mainland ancestor has resulted in several different species each with different beak shapes that matches their main food source The process that led to these different species is known as a homologous traits b adaptive radiation c artificial selection d sympatric speciation e sexual selection 15 Which is the most diverse group of organisms in terms of numbers of species a insects b reptiles c bacteria d fungi e trees 16 Water moves in and out of a cell via the process of a facilitated diffusion b active transport c cell pumping d osmosis e all of the above 17 Which stage of mitosis is the one Where you can see the chromosomes lined up along the center of the cell a prophase b metaphase c anaphase d telophase e cytokinesis 18 A cell that is hypertonic relative to its solution Will a burst b shrivel c do nothing d first shrivel than burst e lose its nucleus Answer key ppOQQMPWNP ngtmmgtmunu 10 11 12 13 14 15 16 17 18 gtZUgtUUUUUUUD1
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