Unit 3 & 4: GeneticsUnit 3:Macro genetics – Meiosis Mitosis • Somatic cells (cells that are NOT...
Transcript of Unit 3 & 4: GeneticsUnit 3:Macro genetics – Meiosis Mitosis • Somatic cells (cells that are NOT...
Unit3&4:Genetics
Unit3:Macro- Genetics
Unit4:Micro- Genetics
Whatwecanseesuchasour
physicalfeatures
WhatwecannotseesuchasDNA
Unit3:Macrogenetics– Geneticsthatwecansee
Liger?
Unit3:Macrogenetics– Geneticsthatwecansee
Glofish realorfake?
Unit3:Macrogenetics– Geneticsthatwecansee
Glowinthedarkmice?
Unit3:Macrogenetics– Geneticsthatwecansee
Belgianbluebull
Unit3:Macrogenetics– Geneticsthatwecansee
Leading questions:
1. What is genetics? 2. What evidence do
YOU know that makes genetics exist?
Unit3:Macrogenetics– Geneticsthatwecansee
Watch this:https://www.youtube.com/watch?v=0vAAf4g5iF8
Gregor Mendel –Why was his research so significant?
Unit3:Macrogenetics– Geneticsthatwecansee
Gregor Mendel: 1822 – 1884
• Studied garden peas (ok what’s so important about it?)
What he observed was:
• There was a MATHETMATICAL relationship of traits being passed down into the next generation!
Unit3:Macrogenetics– Geneticsthatwecansee
What does this mean?
• If there is a mathematical relationship, then that means that genetics is NOT random!
• You can ’calculate’ the probability of traits being passed down.
Unit3:Macrogenetics– Geneticsthatwecansee
Lookattheratios!
Theyarenearlya3to1ratio!
Unit3:Macrogenetics– Geneticsthatwecansee
Howdoesthis“genetics”stuffallwork?
Unit3:Macrogenetics– Geneticsthatwecansee
Let’sreview
Mitosis Meiosis
• Whenanorganismgrows,itundergoesmitosis.
• Mitosisissimplycellsdividingbycopying thegeneticmaterial(DNA).
• Everyresultisthesameasbefore.
Unit3:Macrogenetics– Geneticsthatwecansee
Let’sreview
Mitosis
Thecellls willgrowbycopyingoldcells.TheDNAwillbethesame.
Unit3:Macrogenetics– Geneticsthatwecansee
Let’sreview
Mitosis Meiosis
• InMeiosis,thisistheprocessthatleadstoourgeneticdiversity.
• Let’stakeacloserlook.
Unit3:Macrogenetics– Geneticsthatwecansee
Let’sreview
Meiosis
Everysexcellsproducedwillbedifferent
Meiosis
Unit3:Macrogenetics– Meiosis
“The process that’s saving our humanity, maybe. ”
Yeung
Leadingquestion• Howcomeyouandyoursibling(s)donotlookexactlyalike?
JessicaSimpson AshleeSimpson
Unit3:Macrogenetics– Meiosis
Meiosis• Meiosisistheprocessinwhichsperm andegg cellsareproduced.
• Sperm andegg cellsarecalledreproductive cells(sexcells)incomparisontosomatic cells (anyotherbodycell.• Whatmakessexcellsdifferentthansomaticcellsisthateverysexcellwillcontaintraitsfromthemotherandfatherrandomly!
Unit3:Macrogenetics– Meiosis
Unit3:Macrogenetics– Meiosis
Insidethetestis,spermisproduced.Theprocessspermisproducedisviameiosis.
Unit3:Macrogenetics– Meiosis
Whatdoesmeiosislooklike?
ThisismeiosisYepthere’salotofstuffhappening
Unit3:Macrogenetics– Meiosis
Keythingstonoteformeiosis:
1. Meiosisiscelldivision(fromonecellto4cells)
2.Youstartoffwithacellwithtraitsfrombothparents(pairofchromosomescalleddiploid=2n) butendsupwithjust1copy(singlechromosomethathasbeenmixed.Haploid=1n)
3.Crossingoveroccursinmeiosiswhichallowsthe
exchangeofgeneticmaterial.
Unit3:Macrogenetics– Meiosis
Unit3:Macrogenetics– Meiosis
Mappingoutmeiosis
KeyTermstoknowforMeiosis
Chromosomes:• Humanshave46chromosomesor
22pairshomologouschromosomes.• Chromosomesarelargestrandsof
DNAHomologousChromosomes
• Apairofchromosomesthataresimilarinlengthandgenes.(1fromdadand1frommom).
SisterChromatids• Eachindividualchromosomethat
hasbeenreplicatedduringmeiosis
Unit3:Macrogenetics– Meiosis
Unit3:Macrogenetics– Meiosis
Note the differencesbetween the terms.
Homologouschromosomes arechromosomes that aresimilar with genes/traitssuch as hair colour fromdad and hair colour frommom NOT hair colourand genes for big toe.
Unit3:Macrogenetics– Meiosis
Thischromosomeaccountsfor“brownhair”
Thischromosomeaccountsfor“blondehair”
Crossingoverhappensat“Chiasma”whereDNAisexchangedfromonechromosometotheotherhomologue
Resultsingeneticvariationbetweensperm/eggcells
Unit3:Macrogenetics– Meiosis
Mitosis• Somaticcells(cellsthatareNOTsexcells)• Noexchangeofmaterial(resultingcellsaresameasparent)• Occursin1phase• Resultingcellsarediploid(2N)orhavebothsetsofchromosomes• 2cellsareformed
Meiosis• Onlyinsexcells(gametes• Exchangeofgeneticmaterial• Occursin2phases• Resultingcellsarehaploid(1N)orhave1halfsetofthechromosomes• 4sexcellsareformed(eggcellsdegeneratetoresultin1)
Unit3:Macrogenetics– Chromosomes
Let’stalkaboutourchromosomes
Unit3:Macrogenetics– Chromosomes
• Chromosomesarestructuresfoundinsidethenucleusofthecell.
• ItisbasicallyastructurethatisalongspoolofDNAwrappedaround.
• Itcarryallofourgenes
• Humanshave46chromosomesor23pairs.
Unit3:Macrogenetics– Chromosomes
• 22ofthe23pairsareautosomes,whicharechromosomesforallofourtraitswhilethe23rd pairofchromosomes(xandy)determinethesexoftheorganism.
• XX=females• XY=males
Unit3:Macrogenetics– Non-disjunctiondisorders
Non-disjunctiondisorders
Unit3:Macrogenetics– Non-disjunctiondisorders
Whathappenswhenyouhaveanextrachromosomeor
missingchromosome?
Unit3:Macrogenetics– Non-disjunctiondisorders
Non-disjunctiondisorder
Non-disjunctiondisorderiswhenchromosomesfailtoseparateduringmeiosisleavinganextraormissingchromosomeinthesexcell.
Unit3:Macrogenetics– Non-disjunctiondisorders
Asaresult,thespermoreggcellwillnothaveorwillhaveanextrahomologouschromosome.
Unit3:Macrogenetics– Non-disjunctiondisorders
Whenfertilizationoccurs,thezygote(sperm+egg)willhaveanunevennumberofchromosome.
Unit3:Macrogenetics– Non-disjunctiondisorders
Herearesomenon-disjunctiondisorders:
1. DownSyndrome– trisomy21(extrachromosomeonchromosome#21).
2. Klinefelter syndrome– ExtraXchromosomeinmalesresultinginXXY.
3. Turnersyndrome– MissingXchromosomeinfemalesresultinginjustX.
Unit3:Macrogenetics– Non-disjunctiondisorders
Refertothereadingsforeach.
Unit3:Macrogenetics– Non-disjunctiondisorders
Klinefelter’s syndrome
Unit3:Macrogenetics– Non-disjunctiondisorders
Turner’ssyndrome
Unit3:Macrogenetics– Non-disjunctiondisorders
Trisomy18– Edward’ssyndrome
Extrachromosomeon#18
Lessthan10%willseetheir1st birthday
Unit3:Macrogenetics– Non-disjunctiondisorders
Trisomy13– Patau syndrome
Extrachromosomeon#13
Only5– 10%willseetheir1st birthday.Mostwilldiewithinfirstdaysorweeksoflife.
Unit3:Macrogenetics– Non-disjunctiondisorders
Sohowdowedetermineifafetushasanon-disjunctiondisorder?
Unit3:Macrogenetics– Amniocentesis
Amniocentesis• Takessampleof
amnioticfluid(theliquidthefetusgrowsin)fromthemother
• Inthefluid,therearecellswherethebabyhasshedfromhis/herskinandbladder
Unit3:Macrogenetics– Karyotyping
Thecellsarethenanalyzedforthenumberofchromosomespresent.
ThismethodiscalledKaryotyping.
Unit3:Macrogenetics– Karyotyping
Karyotyping pairsupallofthehomologouschromosomesandlabeled1to21
Unit3:Macrogenetics– Karyotyping
Male Female
Unit3:Macrogenetics– Karyotyping
Downsyndrome (Trisomy21)
Kleinfelter SyndromeXXY
Unit3:Macrogenetics– Karyotyping
TurnerSyndrome(X)
Unit3:Macrogenetics– Karyotyping
Summary• Inthissetofnotes,youshouldhavelearntthefollowing:• Mitosis• Meiosisandtheirimportance• Chromosomesinhumans• Non-disjunctiondisorders• Karyotyping
Unit3:Macrogenetics– Summary