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Lecture 17

BIOL 1201 Lecture Notes - Lecture 17: Synapsis, Prophase, Sister ChromatidsPremium


Department
Biological Sciences
Course Code
BIOL 1201
Professor
Moroney, James
Lecture
17

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BIOL1201Lecture17CellDivision
Cancer
● Cancertreatmentstrategy:Killcellsthatarerapidlydividing
● Onetypeofanticancerdrugpreventsmicrotubulesfromelongating(polymerizing)
○ Vicristineandvinblastine
● Anothertypeofdrugpreventsmicrotubulesfromdepolymerizing
○ ExampleTaxol
○ Thedevelopmentofcoloncancerischaracterizedbyawellorderedseriesof
mutations
Genes
Homologouschromosomesarephysicallysimilar
● Humanspossess22pairsofautosomesand2sexchromosomes
● Humansomaticcellscontain46chromosomesandarediploidcells(2n)
● Humanreproductivecellshave23chromosomesandarehaploidcells(n)
Meiosis
Consistsoftwodivisions,MeiosisIandMeiosisII
InMeiosisI,homologouschromosomespair,DNAcrossoveroccurs,andthenthe
chromosomesseparate,celldivides
Consistsof:
○ INTERPHASEI:DNAsynthesized(duplicated),similartomitosis
PROPHASEI:Example:Startwithacellthatis2n=4.Chromosomalcrossover
(pairingandcrossingoverofhomologouschromosomes)occurs
<IMPORTANT!>
DuringPROPHASEI,crossingovercanoccurbetweenhomologous
chromosomes
○ SynapsisorpairingoccursduringprophaseI
○ METAPHASEI:Pairedchromosomesalignonthemetaphaseplate
○ ANAPHASEI:Homologouschromosomesseparate 
○ TELOPHASEI:Chromosomesreachpoles,2,newnucleiform
InMeiosisII,sisterchromatidsseparate,cellsdivide
FiG.13.9
**clickerquestions**
Whatistheresultwhenadiploidcellundergoesmitosis?2diploidcells
Yourlivercellsaretheresultofmitosis
Thestageofthecellcyclethatoccursimmediatelyaftercytokinesisis:G1
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