Test 1 Notes and Study Guide
Test 1 Notes and Study Guide 85033 - GEN 3000 - 002
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Date Created: 08/31/15
GENETICS 3000 Introduction to Genetics y E O as 3 a f 65gt H H t K r tug I Business Office 151 PampA also 057 LSF Email ktsaiclemsonedu Phone 6564696 Office hours M 2304pm T 24pm By appointment FREE Tutoring is available through the Academic Success Center ll lg Business 0 Textbook Klug et al Essentials of Genetics 0 8th Edition N Mrquot I 0 2 Exams 4 inclass exams 1 final Homework lVIasteringGenetics Assignments due on Tuesday Ii 39 Computers will be allowed unless they I become a distraction l Gene cs Experimental science of heredity The study of heredity and the variation of inherited characteristics The branch of biology that deals with heredity especially the mechanisms of hereditary transmission and the variation of inherited characteristics among similar or related organisms The study of the patterns of inheritance of specific traits relating to genes and genetic information Also known as heredity Gene cs Blueprint of life Central Dogma A I I I I I 1 DNA replication Transcription l Translation WW Molecular genech Population gene cs 019pr Ipv OO Concepts in Genetics Eukaryotes vs Prokaryotes Genes are the fundamental unit of heredity Alleles one of several forms of a gene Phenotype vs Genotype Traits not inherited but reflect genotype environment phenotype DNA and RNA carry genetic info Genes are located on chromosomes Evolution is genetic change a Modern Society depends on Fuel amp Fiber Gene Modern Medicine and Genetics b Laron I dwarfism Susceptibility Lowtone to diphtheria deafness Limb girdle muscular dystrophy Chromosome 5 Healthcare Costs Are Over 2 trillionyr 8608 person in US 2007 or 179 of GDP 2011 Princess Victoria Edwar Key of SaxeCoburg Duke of K t CI Carrier of 1786 1 861 1767 182 x hemophilia trait W 39bert J Affeaed person Queen of England 18 186i 1819 1901 I I I I I I Victoria Edward V L0U395 Alfred He na Louise Arthur Leopold Henry 4 l39 King of England of Hesse Alfonsoxm m King of Spain Nicholas II Alice Czar of Russia of Athlone mlm Wilhelm Sophie CEOFQEV m IAlexandra of Greece King of England I George VI Prince Sigmund m Olga Gonzalo Juan Maria King of England of Prussia Tatania Prussian Royal Family Mane Anastasna Russian Royal Family JUan Car390 Sophia Princess Elizabeth II Prince ng 0f Spam 0f Greece Margaret Queen of England Philip I l Elena Cristina Felipe l l l l Princess Prince Prince Prince Anne Charles Andrew Edward Spanish Royal Family British Royal Family Model Organisms Used to Study Human Diseases Organism E coli S cerevisiae D melanogaster C elegans D rerio M muscuus 2012 Pearson Education Inc Canis lupus familiaris Human Diseases Colon cancer and other cancers Cancer Werner syndrome Disorders ofthe nervous system cancer Diabetes Cardiovascular disease Lesch Nyhan disease cystic brosis FragileX syndrome and many other diseases C Genetics through the Ages Principles of heredity first demonstrated 1012000 years ago omestioation Artificial fertilization 2880 years ago Assyrians Hindu writings 2000 years ago suggest avoiding spouses wundesirable traits Genetics grew out of a historical need at 000 AD J tcci393 8000 BC quot3 ID as 80001000 BC domestication of animals 5000 BC Plant cultivation 500 BC300 BC Aristotle 18561859Darwin amp Mendel v Ideas on Human Reproduction and Heredity 2 Pangenesis specific particles gemmules carry information l 1 from body to reproductive organs which are passed to embryo at 0V conception Very early concept yo Inheritance of acquired characteristics Greeks proposed traits acquired in life incorporated into hereditary info and passed on Ex Artist would pass on art skills to offspring a Pangenesis concept Robert Hooke 1665 discovered cell using the microscope Two early ideas l Preformationism inside egg or sperm is a tiny version of an adult homunculus 39 V Blending inheritance offspring are a blend of parents Schwann and Schleiden Proposed the cell theory 1839 Cells are the basic unit of all living things Cells arise from preexisting cells Library of Cong ress Charles Darwin 1 8091 882 Theory of evolution through natural selection 0n the Origin of Species 1856 heredity was the fundamental of evolution Gregor Mendel 18221884 Discovered basic principles of heredity 1866 Crossed pea plants and analyzed patterns of transmission We will visit with Mendel later Walter Flemming observed N division of chromosomes 1879 V V l l0 1885 hereditary information contained in the nucleus W 39 i C I August Weismann i Cut off the tails of mice for 22 generations tail length of On descendants did not change 1 E i Purposed Germplasm theory cells of the reproductive system carry compete set of information 0 Kr WY 3 PaHQENESiS concept b Germ plasm theory n U w Sperm 1l Sperm K zygote Zygote K Egg Egg 1 0 Modern Genetics 1902 Sutton proposed genes are on chromosomes 1953 James Watson Francis Crick and Rosalind Franklin 3D structure of DNA 1966 the chemical structure of DNA resolved Early 1970s recombinant DNA technology 1977 Gilbert and Sanger developed DNA seq Techniques 1983 PCR 1995 complete sequence of an organism quot o 2003 human genome project is completed Chromosomes and Cellular Reproduction Prokaryote Ce wall Eubacterium Plas ma 39 membrane Archaebacterium Ri b0 5 O m e S gt 7 45 if quot 5 DNA f Eubacterla true bacterla 3 maj or groups 0f lifelt Archaea shares some traits with euks Eukaryotes Eu true 55 99 Pro pre Karyote nucleus Prokaryotic cells Eukaryotic cells Nucleus Absent Cell diameter Genome DNA Amount of DNA Relatively small Membranebounded Relatively small from 1 to 10 um Usually one circular DNA molecule Not complexed with histones in eubacteria some histones in archaea Present Relatively large from 10 to 100 um Multiple linear DNA molecules Complexed with histones Relatively large organelles Absent Present Cytoskeleton Absent Present Genome Size Genome Size E coli Tiger Salamander T rypanosama brucei Marbled Lung sh Human Gonganlax polyedm The Microscope opened our eyes to the world of Cell physiology Zacharias J anssen Robert Hooke Antoni van Leeuwenhoek D Nahanal thlrarg39 cut ruledlclne Antoni van Leeuwenhoek 116321723 9 A u u o u 35 w I tJv quot39 539 Monster Soup commonly called THAMES WATER 1827 Caricature showmg public reaction to what were I I probably shocklng I r revelations about mucrotlal a v contamunants in the Thames A Jnmonu vf39r ranquot 91 Natlanal thnraru at lutedlline quotThe HL tcrug39 o Bacternzulcqu bJ 39Hh39nllia m E Ullni39li39h Bacteria as drawn by Leeuwenhoek iiaw Delv 1 353l l 3 a Ile 3939f39v39 39Ll 53ch by quot en 5 age Eu karyote Animal cell Plant cell Nucleus i Nuclear envelope Endoplasmic reticulum Ribosomes Mitochondrion Vacuole Chloroplast Golgi apparatus Plasma membrane Cell wall 4 Bacterial DNA red Chromosome of Eukaryote the result of DNA complexed to proteins Histone proteins 4 n t m 0 r In C Viruses Are NOT Cells 7Viral protein OK Adenovirus 0 Can only reproduce inside of a host cell 0 Most closely related evolutionarily to host Cell Reproduction Prokaryote A prokaryotic cell contains a single circularchromosome attached to 9w lt Q j the plasma membrane 60 Lra Bacterium DN A l The chromosome replicates 3 As the plasma membrane grows the two 1 b chromosomes separate acterla Divides quot A A 11111 The cell divides Each new cell has an identical copy of the original chromosome 10 bllllon Al bacteria in lt ij gt 10 hours Cell Reproduction Prokaryote 7 I I 3xquot HLI quot 3 quot 5 3 o X i Cell Reproduction E ukaryote Eukaryotes typically have 2 sets of chromosomescell as a result of sexual reproduction 0 One set from mother one from father called homologous pairs 2 sets of genetic info eX most eukaryotic cells 1 set eX reproductive cells 390 Allele A I i Allele a Gene for hair color red Gene for hair color Brown pairs of chromosomes alike in structuresize carry genetic info for the same characters humans have 23 homologous pairs 2 meters endtoendD Chromosome Structure Telomere Centromere Kinetochore Two sister Spindle chromatlds mlcrotubules Telomere Y One One chromosome chromosome 39 xv 39 Aquot Kinetoc h Ore The Four Major Types of Chromosomes Metacentric l k l Acrocentric 3amquot 139 ME N is 3 L Telocentric arm arm The Cell Cycle 6 Cytokinesis G0 arreseted nondividing stage M or Spindle G1 cell growth assembly ch 62M checkpoint M phase nuclear and CS checkpoint cell division Beyond this point cell can divide Beyond this point Interphase cell is committed to cell growth divide S DNA synthesis CANCER AND THE CELL CYCLE TihE Eeiilli Diviiun Eycla and it Ewntrl 7 J ny li 3 Elli E F l p 5 r b Q A E is Also can be means of ANTIcancer therapy Example G0G1 arrest and S phase inhibition of human cancer cell lines by inositol hexaphosphate IP6 Time in each stage lnterphase Miu lnterphase Nucleus Centrosomes Nuclear envelope DNA Synthesis G1 S G2 occur Cannot see chromosomes With light microscope Prophase Developing spindle V Prometaphase Disintegrating nuclear envelope Chromatids of a chromosome Chromosomes condense Remember DNA is already replicated Mitotic spindle forms from centrosomes animals mostly feW plants the exception Mitotic spindle Nuclear envelope disappears starts in prophase Microtubules contact chromatids Telophase r Metaphase Metaphase plate 39 Spindle pole j Chromosomes arrange in single plane metaphase plate 7 Anaphase Daughter chromosomes 5 gt k j Sister chromatids move toward opposite poles after separation chromatids chromosomes Chromosomes arrive at spindle poles Nuclear membrane reforms 2 nuclei Chromosomes disappear from View The stages of mitosis a Interphase b Prophase c Prometaphase 9 Late telophase d Metaphase f Early telophase e Anaphase How do chromosomes move Tubulin subunhs Kinetochore Spindle 5 g I microtubulesg Chromosome The Force to Move Chromosomes Comes from Two Sources C h ro m o s o m e Tubulin subunits V Ki n etoc h 0 re Motor protein I w 39 39 Mlcrotubule Illj 633 l 3979 v gt Ce ntrosom e I Iquot a 9 Ill1 1quot Ce n t r0 5 o m e j 1 Depolymerization of tubulin at end microtubules shorten 2 Molecular motors 3 Taxol stabilizes microtubules 4 Nocodazole causes depolymerization of microtubulues gt3 f 21H 2 Efrany 35 gr 5 3 a 3 593 M g lt X Super Md rrrrrr 33 if a 3 r a 52 M rag lt 19 20 21 22 x These metaphase chromosomes have been through S and are arranged With their homologous pair Counting Chromosomes Me and Mr Jones Number of chromosomes per ceH 8 Number of DNA 4 molecules per ceH Brief moment of double because chromatids are seperated and Without nuclear envelope What Regulates the Cell Cycle a Interphase gt21 lnterphase Interphase 5 8 S 3 s 7 q S b Levelof c clin B y Level of active MPF Mphase promoting factor Cyclin Dependent Kinase CDK MPF cyclin B CDK Proteins Breakdown of nuclear envelope b chromosome condensation spindle assembly I Active Cyclin B MPF 0 7 degradation CDK j 13 5quot CZM checkpoint Activating factors M phase CI5 ChECkPOint phosphorylation7 quotdefquot a d cell dIVISIOII Inactive 0 Dephosphorylation MPF CDK Increasing cyclin B 9 lnterphase cell growth CDK Of Note 1 Bcell lymphoma can be caused by mutation in cyclin 2 Overexpression of cyclin found in breast and esophageal cancer 3 Many other examples MEIOSIS H 3mm 3132215 2quot n 4 Mitosis MEiOSiS gametes 1 Single nuclear division 2 Results in the same number of chromosomes 3 Yields genetically identical cells 1 2 divisions 2 Newly formed cell has half the number of starting chromosomes 3 Genetically variable cells Meiosis Middle Prophase I Chromosomes begin to condense Spindle forms Late Prophase l Pairs of homologs Homologous chromosomes pair Synapsis very close association j Late Prophase I 4 J 2 39W 65quotquot i if 2 Bivalent2 homologous pairstetrad 4 different chromatids Crossing over Chiasma area of crossing over physical breakage Nuclear membrane break down What would happen if crossing over occurred between 2 sister chromatids Metaphase I Metaphase plate Homologous pairs of chromosomes align along metaphase plate Microtubules attach to one pair from each pole Anaphase I Homologous pairs of chromosomes are separated 1 Telophasel Cytoplasm divides after chromosomes arrive at spindle poles lnterkinesis nuclear membrane reforms DNA relaxes Propha se 3quot Mia phasequot Anapha s e Ill Equatorial plate sister chromatids are pulled apart now chromosome Chromosomes recondense Like metaphase of mitosis Nuclear envelope breaks down Chromosomes align on metaphase plate Te lop h a se II Produ cts J j Chromosomes arrive at spindle 4 diffCI GIlt p 39e cells Nuclear envelope reforms Cytoplasm divides Consequences of Meiosis 1 Each cell produces 4 cells generally 2 Chromosome number is halfhaploid 3 Cells produced from meiosis are genetically variabledistinct Distinct for two reasons 1 Crossing over yields sister chromatids that are NOT identical 2 Random distribution of chromosomes in Anaphase I DNA synthesis b A Aa B 317 Ila Nb b A Aa a Crossing over B B b39 39 b Prophase l c A aA B Bb a Meiosis Iandll b d wt w 21gt C I va a on Random Distribution of Chromosomes in Anaphase l d Metaphase I i Anaphase I d Telophase I i I A 1 Metaphase plate V xix xix b c Cametes A In xlp I I I lm Ilm mm I I I lm um IIIm r gt IlmNNIIp m H m wnp mm mp I lp up mp I I I Ip up IIIp 39 I r w pl lp IIp np r lmx ID I I I Im um IIIp I I I Im llm IIIp W um up E lllp mm I I I Ip up mm I I up up IIIm of possible 39mxx39p I I I 39m p 39p I I 39m quotp Ip combinations quot quotan W39m 2n n number of Inpnnmm I I Ip llm mm I I ID um mm hgirmsologous lmx ID I I I m up mm I I Im p m p up um Humans 23 chromosomes I m 8388608 combinations m n p I I I lp m IF I I I Ip Ilm mp Parent cell 2n Prophase Metaphase Anaphase Two daughter cells each 2n Liquot 3 390 cells each n P Anaphase II Four daughter gt gt n n L L i 4 Mitosis Meiosis 1 Single nuclear division 2 Results in the same of chromosomes 3 Yields 2 genetically identical daughter cells 1 Two cell divisions yields 4 cells usuaHy 2 Newly formed cell has 12 of starting chromosomes Anaphasel 3 Genetically variable cells cross overrandom dist of chromosomes Faren1 EEII hwia ma si xtwp baf r nhmm ma repfli tium rn afinrg r Pmphase upligme ghmmuaumg 39 39 mu Eigtar chrmatida Mel apham nanhase Talaphasa zanapha5e auhter cells uniquot m mla yrighi Piaimam E umtl n IHL EHJHIEHIHQ 33 Benjamin ummmgs Ehmmasnma quot I Epli ti n 5 Eimar ch mmatidg separate during MEIDEIE I J Fru hase 1 M Tatrad frmed by gynap i 13f hIJTJ39IJDIjFQUE nihmmusmes Ehr m sma rapllicatiinni TEtrEIE Elfin at the mataph e plate etaphase i Humal ua chwm V iI m EHquotIEE 13 Er t during r mpih m slime Ehr matjids rmiin tagge har Hamid 2 a gh iErsfl I r gall Hf Ir 1 main i Eli l39I C39I El l u fr REE x 7 A r n n mills nil malnils El Hui u her hjmmnsa maj mglliaatilunjg sister ahmmatida Bantams during pih II a Male gametogenesis spermatogenesis b Female gametogenesis oogenesis M Mitotic C0 Spermatogonium 2n C Oogonium 2n V V 0 Primary spermatocyte 2n Primary oocyte 2n Meiosis I Meiosis I unequal cytokinesis o 0 Secondary spermatocytes Secondary oocyte First polar body In In Meiosis ll unequal cytokinesis Meiosis ll 0 0 o Spermatids In ovum in Second polar body 0 ll J l 391gt39I J 1 J N I Zygote 2n 1 Sperm K Microsporangium produces microspores Zngte Megasporangium produces megaspores Sorophyte Diploid 2n Fertilization Meiosis Haploid n Megaspore n E99 Female 5 gametophyte perm embryo sac Microspore n Male gametophyte pollen grain Mendelian Genetics Johann Gregor Mendel Likely read Darwing s On the origins of species by means of natural selection or the preservation of favoured races in the struggle for life 18561863 breeding experiments 1865 Presented results at meeting 35 years prior to Garrodg s work April 9 1865 1866 paper published largely unnoticed 1900 Mendelp s work recognized Mendel s Pea Plants a good choice Seed endosperm Seed shape Seed coat color color fFlower position Gtem length 1 W Axial Yellow Green Round Wrinkled Gray White along stem 5 P God color kfpod shape 4 Terminal at tip of stem Ta lenflated Constricted 39jk Short Mendel s effectiveness was due to 1 Choice of subjects easy to grow grows rapidly 1 yeargeneration produces many offspring 2 Had genetically pure stocks of different types of peas to start studies 3 Avoided characters that exhibited variation 4 Used experimental approach hypothesis driven research also thorough record keeper Table 31 Term Gene Allele Locus Genotype Heterozygote Homozygote Phenotype or trait Character or characteristic Summary of important genetic terms Definition A genetic factor region of DNA that helps determine a characteristic One of two or more alternate forms of a gene Specific place on a chromosome occupied by an allele Set of alleles that an individual possesses An individual possessing two different alleles at a locus An individual possessing two of the same alleles at a locus The appearance or manifestation of a character An attribute or feature 4 1909 Johannsen from pangenesis 4 Round seed vs wrinkled loci plural 4 Genotype environment Only GENOTYPE IS INHERITED Different Alleles occupy the same locus on Homologous chromosomes Allele R I Allele r Y J Homologous chromosomes Geed endosperm Geed shape Geed coat Flower position Gtem Ien th color color 0 0 J3 k Yellow Greenj Round Wrinke9 G F od color od shape 4 Terminal at tip of stem h Inflated Tall V Short Constricted Monohybrid Cross parents differ in a single characteristic What is it called if you cross the other direction Reciprocal cross Using one plant as the female and then the other To make sure that the results are the same for both parents Character Contrasting traits F1 results F2 results F2 ratio 5474 round Seed Shape roundwrinkled a 0 all round 1850 wrinkled 2961 Seed color ellow reen all ellow 6022 yeuow 3 01391 y 9 0 J y 2001 green 39 39 882 full Pod shape fullconstricted M all full 299 constricted 2951 428 green Pod color greenyellow all green 1 52 yellow 2821 Flower 705 violet color VlOletWhlte all VlOlet 224 white 3151 Flower 651 axial position axuaItermlnal all axnal 207 terminal 3141 Stem 787 tall height talldwarf I i all tall 277 dwarf 2841 2012 Pearson Education Inc Mendel s first experiment P generation Homozygous round seeds wrinkled seeds axe Homozygous J F generation Selffertilized experiment r I i l 1 J 000 Mendel s second F2 generation Results k j l 2quot Fraction of progeny seeds 5474 Round seeds y 34 Round Cl 1850 Wrinkled seeds I4 Wrinkle J All 7 characteristics Mendel studied yielded this 31 ratio in the F2 generation grandkidspeas Mendel concluded 1 Unit factors in pairs each trait has 2 different unit factors that result in different traits gives 3 possible combinations 2 DominanceRecessive traits that were observed in F1 dominant Those that disappeared recessive 3 Segregation Two alleles separate When gametes are formed one allele to each gamete upon fusion at fertilization zygote gets one allele from both male and female parent separate With equal probability into gametes Principle of Segregation Mendel s rst laW each individual diploid organism possesses two alleles for any particular characteristic Two alleles segregate into gametes and this occurs randomly and in equal proportions 6 generation Homozygous Homozygous round seeds wrinkled seeds x x 0 RR F1 should always I I Gamete formation Camete formation be hEtETOZngUS i Ci as long as the Cametes Q J parents are both km pure RR and n F1 generation Round seeds J Rr Camete formation 1 b 4 generation Round seeds J Rr Camete formation i Cametes L J S Iff t39r t39 b e er I Iza Ion c F2 generation Round Round 34 Round 39 l4Wrinked 0 J V4 RR V4 Rr V4 rR Wrinkled 0 V4 rr Camete formation fJ7 m L Cametes of L LYJ J on Selffertilization If the F1 generation of Rr selffertilizes then the offspring should have an equal chance at every combination of genotype However the Rr and rR are the same so there are 3 genotypes to get the round phenotype and one genotype to get wrinkled F2 generatlon Round Round Wrinkled 34 R0 U n d r 14 Wrinkled O 9 14 RR 14 Rr 14 1R 4 W I I Gamete formation Cametes c Selffertilization h A RoundrRound Wrinkled Wrinkled J a 0 kd Rr rR F3 generation Backcross heterozygous Tt i Cametes tt Homozygou i p Fertilization recessive v F1 generation 39 R C Punnett 1917 T1 Genotypic and phenotypic ratios 1quot Short Conclusion Genotypic ratio 1 Tt1 tt Phenotypic ratio 1 tall 1 short 6 generation 1 5 q Icfo a Q Fertilization TEST CROSSES Cross individual of unknown genotype with homozygous recessive Tall pea plant either Tt or TT how can we gure out which one T2 X tt will tell us If the plant is TT Then all F1 generation should Tt tall However if plant is Tt then F1 generation will be Tt tall and tt short in 11 ratio Testcross results a b m gtlt m m gtlt m Homozygous Homozygous Heterozygous Homozygous tall dwarf tall dwarf l l 1 all tall Table 34 Genotypic ratios for simple genetic crosses crosses for a single locus Genotypic Genotypes Genotypes Ratio of Parents of Progeny 121 AaXAa 1I4AA l2Aa l4aa 1 1 Aa X aa 1I2 Aa 1I2 aa Aa X AA 12 Ad 1l2 AA Uniform progeny AA X AA All AA aa X aa All an AA X aa All Aa Table 33 Phenotypic ratios for simple genetic crosses crosses for a single locus with dominance Phenotypic Genotypes Genotypes Ratio of Parents of Progeny 31 Aa gtltAa 3I4A l4 aa L 1 A X 1 2Aa12 m Uniform progeny AA X AA All AA aa gtlt aa All aa AA gtlt aa AllAa AA X Aa All A Crosses of organisms that differ in two characteristics P generation Round yellow Wrinkled green seeds seeds 9 gtlt c RR YY rryy Cametes Fertilization k J Fl generation Round yellow seeds 1 J Self fertilization K F 2 generation RRYY RrYy RRYy RrYY o u a o Rr Yy rryy Rryy rr iy a a o RR Yy Rryy RR yy Rr Yy J J gts rConclusion Phenotypic ratio 9 round yellow3 round green 3 wrinkled yellow 1 wrinkled green Mendel always got a 93 3 1 ratio in dihybrid crosses Principle of Independent Assortment Mendel is Second Law Alleles at different loci separate independently of one another NOTE The characters must be located on Different chromosomes as assortment is related to chromosome separation at Anaphase I P1 cross P1 cross yellow round gtlt green wrinkled yellow wrinkled gtlt green round 0 All yellow round o 0 0 F1 Q 1 F1 gtlt F1 yellow round gtlt yellow round F2 0 916 yellow round 316 green FOUHd 0 o 316 yellow wrinkled 116 green wrinkled 0 2012 Pearson Education Inc Dihybrid Cross 0 Punnett square More than 2 loci becomes dif cult U P RR yY round green wrinkled yellow Gametes R y x O rr YY rY Kgd l1 Rr Yy round yellow U x U l1 391 r i 5 gametes F2 R Y R y r y r Y 1 1 1 1 4 4 4 4 RR YY RR Yy Rr Yy Rr WY 3 7 V 1 1 1 1 1 16 16 16 16 4 U U U U RR Yy RR yy Rr yy Rr Yy R W 1 1 1 1 v 1 16 16 16 16 m 1 1 3 4 U U U U E Rr Yy Rr yy rr yy rr Yy g quot W 1 l l l 1 16 16 16 16 0 4 0 U I O Rr YY Rr Yy rr Yy rr YY FY 1 1 1 1 1 16 16 16 16 4 O U 0 D 9 3031 U round yellow 0 roundgreen wrinkled yellow 53 wrinkledgreen What is the probability of of rolling the die twice and getting 4 both times a The multiplication rule l in 6 or 16 AND m l in 6 or 16 RollZ 47 339 Therefore 16 X 16 136 To use this rule events must be independent Branch diagram Can obtain both genotypic and phenotypic ratios By setting out the proportions of genotypes or phenotypes for each allele pair and connecting these to proportions of the other allele pairs a branch or web of genotypes or phenotypes can be constructed will be yellow of the F2 is round lt 1A will green will be yellow 14 ofthe F2 is wrinkled lt 1A will be green Applying probability to dihybrid crosses cake Round yellow Round yellow quot4 X J Rr Yy Rr Yy Expected Expected Expected proportions proportions proportions for first for second for both trait shape trait color traits f Rr gtlt Rr Yy gtlt Yy C RrYyXRrYy D H4 Cross Cross 34 R 34 Y H Round Yellow V4 rr V4 yy 3931 Wrinkled Green J k 34 R Round V4 rr Wrinkled gt34 Y V4 W Green 34 Y gt Yellow V4 W Green Tl l Yellow 39 K R Y gt 34 X 34 916 3 Round yellow Ryy 34 X I4 316 Round green rrY gt I quot 4 X 34 316 19 Wrinkled yellow quotW x gt V4 gtlt I4 16 Wrinkled green Round yellow Wrinkled green Dihybrid Test Cross X x Rr Yy rryy Expected Expected Expected proportions for proportions for proportions for rst character second character both characters K Rrer39Yyny RrYerryy H Cross Cross l l 12 Rr V2 Yy Round C Yellow u V2 rr SX V2 yy KWrinkled Green I 4 W V2 Yy Rr Yy gtYellow 12 X V2 M 0 V2 Rr Roundyellow Round D V2 yy Rr yy gtGreen I V2 X V2 V4 J Roundgreen V2 Yy rr Yy gtYellow 12 X V2 V 3 12 Wrinkled yellow Wrinkled 12 I gtrryy Green V2 X V2 V K J l 4 kWrInkledgreen W X RRYYCC rryycc Rr Yy Cc I lSelffertilization Expected proportions Expected proportions Expected proportions Expected proportions for for first character for second character for third character all three characters Rrgtlt Rr Yy X Yy Cc X Cc C RrYyCc X RrYyCc Cross 34 R Round 0 34 YYelow w 34 CGray I4 rr Wrinkled 14 yyCreen II l4 cc White J j j K W W 34 C Cray R Y C 34 X 34 X 342764 w 34 Y YEI39OW Round yellow gray I4 cc White RY cc 1 3 gtlt 3 gtlt V49e4 3 R R d 4 4 4 4 Gun 0 Round yellow white gt 34 C Gray gt R y C 34 X V4 gtlt 34 964 I g 1 V4 Green 5 Round green gray U gt I4 cc White gt Ryycc 34 X V4 gtlt V4 364 7 Round green white gt 34 C Gray gt rr Y C 14 x 34 x 34 964 7 34 Y Ye39low Wrinkled yellow gray J r I4 cc White gt rrY cc 7 39 Wr39nkled 1333 4 V4 X 34 X V4 364 r 39 UJ Wrinkled yellow white gt 34 C Cray gt rryyC V4gtltV4gtlt34364 39 quot V4 Y Green II Wrinkled green gray gt 14 cc White gt rryycc 39 a V4 X quot4 X quot4 V64 Wr39nkled reen white j x J x j x 39 9 J Generation of F2 trihybrid phenotypes Combined proportion 34 B 39 34 C gt343434 ABC 2764 ABC 34 A 14 C gt343414 ABC 964 ABC 14 b 34 C gt341434Abc 964 AbC 14C gt341414Abc 364 Abc 34 B 34 C gt143434aBC 964 ch 140 14C 14341463c 364 ch 14 bw 34 C gt141434abc 364 abC 14C gt141414abc 164 abc 2012 Pearson Education Inc HoW are Pea plant crossing related to Chromosomes 1900s Walter Sutton studied insects Discovered that homologous pairs of chromosomes consists of one maternal one paternal Developed Chromosome Theory of heredity Homologous pairs segregate independently at meiosis Two alleles segregate during anaphase I or anaphase II depends on Whether or not crossing over has occurred Homologous chromosomes in pairs G G g 9 W WW w Genes are part of chromosomes Homologs segregate during meiosis or W w W Each pair separates Nquot 39v 39 r quot39 39 39 quot hymns v 39 quot V 391 7 5 v quot 39 39I r vrvi v yr 39 1N r T quot 39 quot quot 14 14 All possible gametlc combinations are formed with equal probability 2012 Pearson Education Inc What is the probability of of rolling the die twice and getting 4 both times a The multiplication rule l in 6 or 16 AND m l in 6 or 16 RollZ 47 339 Therefore 16 X 16 136 To use this rule events must be independent Probability will Make your life easier this is not a gambling tip Consider this genetic cross T tall t recessive short allele Tt X Tt What is the prob of getting TT offspring Prob of T from one parent 12 Prob of T from second parent 12 You need T AND T so 12 X 12 14 b The addition rule K The probability of one of two or more mutually exclusive events is calculated by adding the probabilities of the two events 5 9 either or O O O VW d K Roll dice once What is prob of getting either 5 or 6 16 of getting 5 16 of getting 6 Therefore 16 16 26 or 13 Probability will Make your life easier this is not a gambling tip Consider this genetic cross Tt X Tt What is the prob of each genotype TT 14 Tall Tt 14 Tall tT 14 Tall tt 14 short What is the prob of a Tall plant Tall is TT 0r Tt OR addition 14 for TT 14 for Tt 14 for tT 34 A Tough One What is the prob of the cross AaBbchdEe X AaBchddEe Yielding aabbccddee Break down crosses to singlelocus crosses AaXAa aal4 Bb X Bb bb 14 cc X Cc cc 12 Dd X dd dd 12 Ee X Ee ee 14 Since these are and then multiply them all together 1256 Binomial Expansion and Probability Albinism occurs if you are homozygous at the A locus with mutant a Consider this cross Aa X Aa normal hets Offspring AA 1A1 Aa 14 Normal phenotype aA 14 aa 1 Binomial Expansion and Probability What is the prob of these parents Aa having 3 kids With albinism aa 1st child AND 2nd child AND 3rd child 14 X 14 X 14 164 What about the prob of these parents have 3 kids lwith albinism and 2 Without If the rst has it Multlple events Use W1th 1A X X 964 and quotWithin each child s If the second and 01 fOI X X 964 combining the probability If the third of all three kids XXWM Because either of these schemes yields 1 child With albinism 2 Wo 964 964 964 2764 What do we do when observed ratios differ from what we expected Goodness of t Cross two roaches Yy brown X yy yellow Expected 11 if Y is dominant So a total of 40 offspring should yield 2020 brown to yellow What if we get 2218 Remember chance is at work Chi squareX2 Test Used to determine the probability that the difference between the observed and the expected values is due to chance If P 2 005 Differences likely caused by chance random P lt 005 Assume chance is NOT responsible and a significant difference eXists Goodness of Fit Using the Chisquared test Remember 1 This test cannot tell if a cross has been done correctly 2 This test does not tell us if the results are correct 3 All it does is indicate the probability that the difference between observed and expected is due to chance Cross Bb X Bb Where B is black is expected to yield BB 14 Bb 12 bb 14 So if 50 individuals 34 are black 375 black individuals 14 or 125 are gray BUT WHAT IF WE GOT 30 AND 20 IS THIS DUE TO CHANCE OR SOMETHING ELSE Obs Exp2 X2 for all classes Expected Class Obs Exp ObsExp2 ObsExp2Exp Black 30 375 5625 15 Gray 20 125 5625 45 Total X2 60 compare to critical values at specific P 005 and df degrees of freedom 45 deviation due to chance Table 34 Critical values of the 13 distribution P df 995 975 9 5 1 05 025 01 005 1 000 000 0016 0455 2706 3841 5024 6635 7879 2 0010 0051 0211 1386 4605 5991 7378 9210 10597 05 is usually used 3 0072 0216 0584 2366 6251 7815 9348 11345 12838 4 0207 0484 1064 3357 7779 9488 11143 13277 14860 5 0412 0831 1610 4351 9236 11070 12832 15086 16750 6 0676 1237 2204 5348 10645 12592 14449 16812 18548 7 0989 1690 2833 6346 12017 14067 16013 18475 20278 8 1344 2180 3490 7344 13362 15507 17535 20090 21955 9 1735 2700 4168 8343 14684 16919 19023 21666 23589 10 2156 3247 4865 9342 15987 18307 20483 23209 25188 11 2603 3816 5578 10341 17275 19675 21920 24725 26757 12 3074 4404 6304 11340 18549 21026 23337 26217 28300 13 3565 5009 7042 12340 19812 22362 24736 27688 29819 14 4075 5629 7790 13339 21064 23685 26119 29141 31319 15 4601 6262 8547 14339 22307 24996 27488 30578 32801 P probability df degrees of freedom Degrees of freedom dD nl n is Number of different phenotypes df 2 2 phenotypes black or grey 1 1 Our value 60 is between probability of 0025 and 001 so less than 25 probability that deviation that we observed is due to Chance so Chance probably did not produce deviation any explanations KP generation 1 Purple X White flowers 7 flowers L J T Cross l KFI generation Purple g flowers x 3 l Intercross F2 generation 105 Purple 45 White Degrees of freedom 2 1 1 Probability from Table 34 1 ltPlt5 Phenotype Observed Expected Purple 105 34gtlt150 1125 White 45 14gtlt150 375 Total 150 k j 0 E2 x2 2 E 2 105 11232 45 3752 1125 375 5625 5625 2 X quot 1125 375 2 X 05 15 20 k KDegrees of freedom n 1 5T0 0 62 b 6 b m dgt a a 39 Introduction to Tecfigree mowysis O 6 r bi Pedigree pictorial representation of a family history Male Female Sex unknown or unspecified Unaffected individual O ltgt Individual affected with trait I Obligate carrier carries the gene but 0 does not have the trait Asymptomatic carrier unaffected at this time but may later exhibit trait Multiple individuals 5 5 amp 9 0 Q ltgt e lt9 9 Deceased individual Male Proband first affected family member coming to attention of geneticist P Family history of individual unknown Family parents and three children one boy and two girls in birth order Adoption brackets enclose adopted individuals Dashed line denotes adoptive parents solid line denotes biological parent Female Sex unknown or unspecified 0 P ltgt 0 l 2 Male Female Sex unknown or unspecified Identical Nonidentical Unknown Twins A A 39 ltgt i 2 Consanguinity quot 39 mating between 39 related individuals 2 3 Ill i 2 Indicates consanguinity a IV Generation 8 9 IO H 12 13 1415 Birth order V a Autosomal Recessive Trait u dgt ltgt M Either I3 or l4 must be 3 4 heterozygous Recessive traits typically skip generations 6 7 5 Recessive autosomal traits appear equally in both sexes 5 6 2012 Pearson Education Inc H O I 0 4 D 6 1x v 91 w Gi y e 9 14 15 16 17 18 19 20 21 22 23 24 25 E 1 11 16 17 18 19 20 21 22 10 ll 131111111 9 10 11 12 l3 14 15 Autosomal Reeessive disorders are more common in eonsanguineous interbreeding families Autosomal Dominant Traits 6 39 m lt73 1 l 2 6 7 8 9 10 12 13 39V F T E l 2 3 4 5 Appear equally in Males and Females Unaffected individuals do not transmit to offspring affected have at least one affected parent a IV 4 5 8 9 10 10 d H 12 I H 12 13 I4 14 15 15 Purity Ward O I Harmony R n Stillborn Abby Mickie Gunny o l m Justice SCOtty Co ey Lily Rose 0 Maus39 Basil Shane Kyi Dusty Layla Diamond 7 I Keeper 4443 quotFEVFPEUHJ Dusty Maus Tank 39quotquot 344 HA Stan F3415 2395 33 43 53 0004449 owmmmm EB quot1 H32 393 4T 5 5 1E OObOO KB 239 37 4 5739 6 7 B1 939 10711 h 111151111 41 11 E5172 a1 41 51 m ttw 57 13111 211 311 bbb dbl 51039 EDI 7 12112111150915 160151111111113111 023141 29 19 1491 54 w 19 431121 11 41 51 61 11 B11 91 bOODOO 52 E12 IDE12 22 32 142 2 62 9 2 I 1 I a Greyhound 1 I Labrador Retxrlever OEI Pedigree Didi EH 1 1 1 And WE5E O OUU g y 1415 25 3539 45 1513 1231 331 4a 53 13 I1 Pal ux Pow m i Anubis M4 Castor Ester Ilsis Sue Who i B4 quot I MEI V 4 1r 39 1 1 I FWE 25 35 46 I mtoeomtuu bomumm mm 25 3 5 45 55 BE 76 BE 95 1 434139s 25 35 4s 54 8111 s 125 351 45 55 55 15 85 1951 bbbb m sm 31115 211 35 41a 55 BE 15 I Ii i i 1i i i f nww w 114114114 124444444 11 wt14 391 1 39 39 39 39 1331121 11 41 51 51 11 B 91 1111 OOOb 521F115 23 33 4395 58 55 78 EB oooooboonnn DBVTI39Q 2939 39 d9 59 59 1399 5539 99 11091119 31056315 ifll i5 E1 H318 211 4a 53 53 HE 4111 OO HIE I39B RE 48 53 63 BE Em 31311 211 31 471 571 61 1222 32 43 66 Deciphering genotypes in pedigrees Unaffected Unaffected carrier carrier father mother l I I LEGEN o RECESSIVE DOMINANT GENE GENE Unaffected chlld Unaffected Unaffected Affected child carrier child carrier chlld on mm mum mu AUTOSOMAL RECESSIVE What is probability that they Will 15 20 have an affected child D Does 20 have a family history of the disease No Assume her genotype is DD Probability O Yes Have to determine her probability of being a carrier Probability of baby being affected Probability of father being a carrier AND Probability of mother being a carrier AND Probability of baby receiving both recessive alleles from carrier parents Pdd PDad Dd X PMom Dd X Pdd in hybrid cross EX If 20 has an affected sibling Pdd 23 X 23 X 1A 19 Study Guide Exam I Ch 14 I Ch 1 a Model organisms importance b Early theories of hereditary transmission i Principles of heredity first demonstrated 1012000 years ago domestication ii Artificial fertilization 2880 years ago Assyrians iii Hindu writings 2000 years ago suggest avoiding spouses wundesirable traits iv V Pangenesis specific particles gemmules carry information from throughout the body to the reproductive organis which are passed to embryo at conception very early concept vi Acquired quotinheritance of acquired characteristicsquot Greeks proposed that traits are acquired in life incorporated into hereditary info and passed on 1 EX Artist would pass art skills to offspring vii Preformationism inside an egg or sperm is a tiny adult homunculus viii Blending inheritance offspring are a blend of parens c Important people amp their contributions i Schwann and Schleiden proposed cell theory 1839 1 Cells are the basic unit of all living things 2 Cells arise from preexisting cells ii Darwin 18021882 theory of evolution through natural selection 0n the Origin of Species 1856 hereditary was the fundamental of evolution iii Mendel 18821884 discovered basic principles of heredity 1866 1 Crossed pea plants and analyzed patterns of transmission 2 We will visit with Mendel later iv Flemming observed division of chromosomes 1879 1 1885 hereditary information contained in the nucleus v Weismann cut off the tails of mice for 22 generations but the tail length didn t change with descendants 1 Purposed Germplasm theory cells of the reproductive system carry complete set of information vi Sutton 1 1902 Sutton proposed genes are on chromosomes 11 1953 James Watson Francis Crick and Rosalind Franklin 3D structure of DNA 111 1966 the chemical structure of DNA resolved IV Early 1970s recombinant DNA technology V 1977 Gilbert and Sanger developed DNA seq Techniques VI 1983 PCR V11 1995 complete sequence of an organism VIII 2003 human genome project is completed IX Ch 2 a Pro vs eukaryote i Prokaryotes cell reproduction leads to another cell that s identical has same original chromosome ii Eukaryotes typically have 2 sets of chromosomes due to sexual reproduction from mom and dad homologous pairs Prokaryotic cells Eukaryotic cells Absent Nucleus Present Cell diameter Relatively small from I to l0 um Relatively large from ID to 100 um Genome Usually one circular DNA molecule Multiple linear DNA molecules DNA Not complexed with histones in Complexed with histones eubacteria some histones in archaea Amount of DNA Relatively large Membranebounded Relatively small Absent Present organelles Cytoskeleton Absent Present 1 b Ploidy i Meiosis creates cells that the chromosome number is halfhaploid ii In both mitosis and meiosis the parent cell is diploid 2n4 iii However mitosis yields identical daughter cells that are also diploid iV But in meiosis there are 4 daughter cells that are haploid and all variable c Chromosome structure 3 Telomere Centromere Kinetochore Two sister dl chromatids 5939quot e microtubules Telomere U w I a 1 One One chromosome chromosome ii Metacentric Submetacentric Acrocentric Telocentric d Cell cycle Phases Interphase G1 S G2 and Mitosis Most of time is spent in interphase Mitosis is quick the main goal is to make sure that the daughter cells get everything that they need Cytokinesls M phase nuclear and cell division Interphase cell growth s o The Cell Cycle is very controlled and regulated G1 Gap 1 Growth 1 Some cells stop here others continue with the cell cycle so that they grow and then divide Example neuron cells They stop at G1 S checkpoint most of the time But if cells pass through the checkpoint they are COMMITTED and now they have to divide In S phage the DNA is synthesized copied At the G2 M checkpoint this checkpoint is to try to catch errors in replication Here it makes sure it s ready to divide Mitosis i Phases amp important events 1 Interphase DNA synthesis G1 S G2 occur cannot see chromosomes with light microscope Mitosis begins with prophase chromosomes condense mitotic spindle forms from centrosomes Prometaphase the nuclear envelope disappears completed it started in prophase microtubules contact chromatids Metaphase chromosomes arragen in single plane metaphase plate random alignment Anaphase sister chromatids move toward the opposite poles once they start moving and the sister chromatids are separated they are now chromosomes ii Spindle fibers 1 2 3 Telophase chromosomes arrive at spindle poles Nuclear membrance reforms around both nuclei The chromosomes unwind disappear from view Form in prophase from centromeres In prometaphase the microtubules contact chromatids Spindle pulls sister chromatids apart in anaphase o Spindle fibers are made up of tubulin subunits f Meiosis i Vs mitosis Mitosis single nuclear division results in same number of chromosomes yields genetically identical cells Meiosis 2 divisions newly formed cell has half the number of starting chromosomes yields genetically variable cells Meiosis 11 looks similar to Mitosis because sister chromatids separate ii Phases amp important events iii 1 W 9quot 10 Crossing over 1 Prophase I a Middle chromosomes begin to condense and spindle forms b Late homologous chromosomes pair synapsis very close association bivalent 2 homologous pairs tetrad 4 different chromatids c Late crossing over chiasma area of crossing over physical breakage nuclear membrane breaks down Metaphase I homolous pairs of chromosomes align along metaphase plate while microtubules attach to one pair from each pole Anaphase I homologous pairs of chromosomes are separated Telophase I cytoplasm divides after chromosomes arrive at spindle poles Interkinesis nuclear membrance reforms and DNA relaxes Prophase 11 chromosomes recondense and nuclear envelope breaks down Metaphase 11 chromosomes align on metaphase plate like metaphase of mitosis Anaphase II sister chromatids are pulled apart now they are chromosomes Telophase 11 chromosomes arrive at spindle poles nuclear envelope reforms cytoplasm divides Products 4 genetically variable daughter cells Occurs in late prophase 1 physical crossing over iv Genetic variability 1 3 v Unequal division Occurs in Due to crossing over of the diploid chromosomes two different sets of information You can calculate the number of possible combinations 2n n is the number of homologous pairs And also due to random distribution of chromosomes reproduction organs This unequal division occurs in females in both Meiosis 1 and 2 when eggs are made o In meiosis I the cell division pushes almost all of the cytoplasm over to one half of the cell The larger cell portion will be known as a secondary oocyte But the smaller portioned cell will be a first polar body that will NOT continue to meiosis II and will most likely dissolve 0 After the secondary oocyte goes through meiosis II it is now an ovum a haploid mature gamete 0 But sometimes the secondary oocyte does not go through meiosis II it will also make second polar bodies that usually dissolve g Counting chromosomes You can count chromosomes by counting centromeres i Counting the number of chromosomes per cell the only time that the amount doubles is during anaphase because the chromatids are separated to form 2 chromosomes and both sets of chromosomes are within the same cell without a nuclear envelope yet thus double the number of chromosomes in a cell ii Counting the number of DNA molecules per cell 1 Well the DNA amount doubles during S phase when the DNA is copied The DNA amount is not halved until telophasecytokinesis when the cell separates and then the DNA amount is normal X Ch 3 a Mendel ii iii iv b Definitions 1 ii iii iv V vi vii viii Likely read Darwin s Orgin of Species Breeding experiments 18561863 1866 paper published largely unnoticed 1900 Mendel s work recognized Effectiveness 1 Good choice of subjects because the pea plants are easy to grow and grow rapidly produces many offspring Had genetically pure stocks of different types of peas Avoided characteristics that exhibited variation 4 Used quotexperimental approachquot hypothesis drived researched also through record keeper wsv Gene a genetic factor that helps determine a characteristics Allele one of two or more alternate forms of a gene Locus specific place on a chromosome occupied by an allele Genotype set of alleles that an individual possesses Heterozygote an individual possessing two different allele at a locus Homozygous an individual possessing two different alleles at a locus Phenotype or trait the appearance or manifestation of a character Character or characteristic an attribute or feature c Mendel experiments i ii iii Crosses 1 Reciprocal cross when you cross the other direction 2 Backcrosscross the f1 generation with one of the parents Dominance traits that were observed in F1 dominant Those that disappeared recessive Principle of segregation two alleles separate when gametes are formed one allele to each gamete upon fusion at fertilization zygote gets one allele from both male and female parent separate with equal probability into gametes 1 Each individual diploid organism possesses two alleles for any particular characteristic Two alleles segregate into gametes and this occurs randomly and in equal proportions iv Principle of Independent assortment alleles at different loci separate independently of one another d Punnett is a diagram that is used to predict an outcome of a particular cross or breeding experiment e Monohybrid cross Dihybrid cross RA Ra rA ra RA RRAA RRAa RrAA RrAa f Ra rA ra RRAa RrAA RrAa RRaa RrAa Rraa RrAa rrAA rrAa Rraa rrAa rraa Phenotypic and Genotypic ratios g Branch diagram i ii iii h Probability i Multiplication rule when the independent events are quotandquot i j ii Addition rule when the independent events are quoteither Can obtain both genotypic and phenotypic ratios By setting out the proportions of genotypes or phenotypes for each allele pair and connecting these to proportions of the other allele pairs a branch or web of genotypes or phenotypes can be constructed 34 will be yellow 3A of the F2 is round 11 will green 34 will be yellow 11 of the F2 is wrinkled 1 will be green 1 When you re saying quotandquot for both independent possibilities to occur you multiply the chances U H U 01 Chisquare used to determine the probability that the difference between the observed and the expected values is due to change 1 ii iii iv pr is less than 05 then you can assume chance is NOT responsible for difference X2 sum of observedexpected2 expected Degrees of freedom n1 1 N number of phenotypes First determine X2 value and then find it on the chart What probability is it closest to or between Convert those probabilities into percentages Pedigree Analysis Pedigree pictorial representation of a family history Male Female Sex unknown or unspecified Unaffected individual D O ltgt Individual affected with trait I Obligate carrier carries the gene but E does not have the trait Asymptomatic carrier unaffected at this time but may later exhibit trait ecao ltwgt ltgt Multiple individuals 5 Deceased individual JZf Q Identification ii Pedigree is built around proband first person who goes to the geneticist Male Female Sex unknown or unspecified Proband first affected family member coming to 1 P1 P1 attention of geneticist P Family history of 7 lt7gt individual unknown 6 Family parents and three 1 2 children one boy and two girls quot in birth order Adoption brackets enclose adopted individuals Dashed line denotes adoptive parents solid line denotes biological 39 parent Male Female Sex unknown or unspecified Identical Nonidentical Unknown Twins 7 Consanguinity mating between related individuals I 2 Indicates consanguinity iii Determining genotypes 1 If you don t know anything about person assume they are heterozygous dominant iv Autosomal recessive indicated by skipping generations First generation parents must be heterozygous carriers or express the homozygous recessive 1 More common in consanguineous interbreeding families like dogs XI Autosomal dominant trait once it disappears it s gone because it doesn t skip and come back a Like autosomal recessive it appears equally in males and females b Unaffected individuals do not transmit to offspring affected have at least one affected parent XII Ch 4 a Alleles ii iii iv vi vii viii ix xi xii xiii xiv xv b Symbols ii iii Allele different forms of a gene as in D or d Same gene among individuals but different alleles combinations Lossoffunction mutation The allele isn t doing what it s supposed to be doing sometimes not always Null allele Complete loss of function Gainoffunction mutation Supposed to make pink But it makes red It s overachieving Neutral mutation May not change the phenotype but at genetic level you can see the different in alleles As in you have red Still making red And making red doesn t change But you can see some sort of different in the alleles at genetic level Gene interaction We can also have two genes that interact with each other to create a product Something depends on two genotypes Xlinkage On sex chromosomes How does it change what we seeexpect to see in the next generation Capital vs lowercase 1 Usually capital is dominant Lowercase is recessive Wildtype vs mutant vs 1 Wildtype normal 2 2 Anything that deviates mutant or just without and no Superscripts can be placed on labelling the alleles c Incomplete dominance i Example 1 Purple dominance 2 White recessive 3 If parents are Pp and Pp both dominant purple the F1 generation would be PP Pp Pp and pp So the genetic ratio is 1 PP 2 Pp 1pp but the phenotype is 1 purple 2 violet 1 white 4 This is NOT COMPLETE DOMINANCE because that would look like 3 purple 1 white d Codominance i ii iii iv MN blood types antigens on red blood cells Two alleles LM and LN Possible Genotypes LMLM LMLN LNLN Phenotypes 1 LMLM Only produce M antigen 2 LNLN Only produce N antigen 3 LMLN Produce BOTH M and N antigen i j Differences between dominance incomplete dominance and codominance Table 51 Type of Dominance Definition Phenotype of the heterozygote is the same as the phenotype of one of the homozygotes Dominance Phenotype of the heterozygote is intermediate falls within the range between the phenotypes of the two homozygotes Incomplete dominance Phenotype of the heterozygote includes the phenotypes of both homozygotes Codominance Table 51 Genet3A uncepluaiAerour h Fourth Edition V 2012 W H Freeman and Company vi Another example is dealing with sickle cells There will be both Wild type and recessive sickle forms of RBC It will look like a simple heterozygous genotype but it will act like BOTH for phenotype Pleiotropy one gene that impacts several aspects of the overall phenotype Multiple alleles can be many different alleles for one gene in the general population i Sometimes dominant effects color but then the recessive is lethal ii Example blood types ABO blood groups Lethal alleles dominant lethal one copy causes death i Example Huntington s disease Epistasis i a phenomenon that consists of the effect of one gene being dependent on the presence of one or more 39modifier genes39 genetic background Similarly epistatic mutations have different effects in combination than individually Complementation Penetrance and Expressivity k Temperature Effect
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