LIFESCI 7B Study Guide - Spring 2018, Comprehensive Midterm Notes - Natural Selection, Reading Company, Evolution
12 Oct 2018
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Department
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LIFESCI 7B
MIDTERM EXAM
STUDY GUIDE
Fall 2018
WEEK I
-gene :segment of DNA that influences one or more Phenotypes
-allele :particular form of agene
-diff alleles have diff DNA sequences -causes trait variation
-locus :stretch of DNA at aParticular location on achromosome
-(every gene is technically alocus .Aheterozygous individual has 2diff alleles at
the same locus /gene ,but not every locus influences Phenotype in not always
called agene )
MEIOSIS I
pwpnaflt
PPOPHASEI
-homologous chromosomes undergo synopsis (gene -for -gene pairing )
-bivalents form (2Pairs of sister ohromatidsaka homologous chromosomes )
-each chromosome from each Parent has 2sister chromatics
t(each Parent chromosome has been duplicated )
metaphases OROSSING OVER Cin prophase I)
HOMOLOGOUS
chromosomes sister onwmatids
(IMOM ,Idad )/
t#tba
anaphase I
→→
re ¥.
OD- oniasma
µ
•
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-•age••• oooo ago
•
•••
it tr ones breakage +recombinant
tell Phase Ithis
9is adouble crossing over chwmatids
stranded DNA break
-oniasmatd also hold bivalents together
ANAPHASEI
-homologous chromosomes separate
(hands =HOMOLOGOUS .hands move apart first ,then fingers in Meiosis I)
-Centro mores don't split -sister chromatics stay together
-1of 2chromosomes at each Pole
-23 chromosomes (46 chromatics in Pairs ).
later they will separate so each
Chwmattd is called achromosome
.
Each gamete has 23 chromosomes .HAPLOID !
MEIOSIS Iresults in haploid gametes
PNPNASEI How is meiosis Idifferent from meiosis #mitosis ?
-meiosis I:homologous chromosomes Pair ,cross
over ,segregate from each other
-.meiosis I:Centro merest sister chromatics separate
ff-in the female
,the oocyte gets the majority of the
Metaphase Icytoplasm and the 3Other gametes are
"Polar bodies "
ANAPHASE I
-like anaphase of mitosis ,separated chromatics Cnow called
tfchromosomes )are Pulled toward Poles
anaphase I
⇐⇒e⇒
1tty
TOIO Phase I
→haploid gametes !
GENOTYPE to PHENOTYPE
-phenotype :observed characteristics -visible ,developmental ,behavior
-results from interaction between genotype kenvironment
-alleles :homozygous (alleles from each Parent are the same )&heterozygous (different
'"T
-effect of amutation on an organism often depends on environment
-many Polymorphisms increase susceptibility to disease (ex :lung elasticity loss ),but some are
not harmful or beneficial (ex :Protection against HIV )
-Polymorphism :Any genetic diff among individuals that would definitely occur in a
Population Of 50 individuals
MENDEL
-the breeding :Phenotype Of offspring is identical to Parents
-PI →Fl →FZ
-Fl
self
-fertilization didn't breed true →recessive trait showed up
again
-testowss :mating to ahomozygous recessive
-addition used when "either or "
,multiplication when "and
"
-9:3 :3 :1ratio may be different if genes Affect the same trait
-epistdsts :shown by genes that modify Phenotypic expression of other genes
Cex :white 1brown chicken )
