chapter 15 the chromosomal basis of inheritance. mendelian inheritance has its physical basis in the...
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Chapter 15The Chromosomal Basis of Inheritance
Chapter 15The Chromosomal Basis of Inheritance
Mendelian inheritance has its physical basis in the behavior of chromosomes during meiosis.
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt Morgan
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganIn the early 1900’s, he was the first scientist to want different varieties of fruit flies to study.
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganA white-eyed mutation showed up in his laboratory.
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganHe bred his white-eyed fruit flies with “wild type” red-eyed fruit flies.
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganF1: all offspring had red eyes
(therefore red is dominant)
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganF2: red:white = 3:1
(as expected)
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganF2: red:white = 3:1
But all the white-eyed flies were male. (very surprising)
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganF2 red:white = 3:1
But all the white-eyed flies were male. (very surprising)
F2♀ red = 100%
F2♂ red:white = 1:1
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganTherefore the gene for white eyes is on the X chromosome.
Chapter 15The Chromosomal Basis of Inheritance
Thomas Hunt MorganXX = red-eyed female
XX = red-eyed femaleXY = red-eyed male
XY = white-eyed male
Chapter 15The Chromosomal Basis of Inheritance
Recombination
Chapter 15The Chromosomal Basis of Inheritance
RecombinationLinked genes tend to be inherited together because they are on the same chromosome.
Chapter 15The Chromosomal Basis of Inheritance
RecombinationIndependent assortment of chromosomes and crossing over produce genetic recombinations.
Chapter 15The Chromosomal Basis of Inheritance
RecombinationRecombination can be used to map genes on the chromosome.1 centimorgan = 1% recombination
Chapter 15The Chromosomal Basis of Inheritance
Sex Chromosomes
Chapter 15The Chromosomal Basis of Inheritance
Sex ChromosomesSeveral patterns exist.
XX vs. XY
XX vs. X
ZW vs. ZZ
diploid vs. haploid
Chapter 15The Chromosomal Basis of Inheritance
Sex ChromosomesSeveral patterns exist.
XX vs. XY
XX vs. X
ZW vs. ZZ
diploid vs. haploid
Chapter 15The Chromosomal Basis of Inheritance
Barr Bodies
Chapter 15The Chromosomal Basis of Inheritance
Barr BodiesA mammalian cell needs only one active X chromosome.
In females, one of the two X’s is inactivated
Chapter 15The Chromosomal Basis of Inheritance
Genomic Imprinting
Chapter 15The Chromosomal Basis of Inheritance
Genomic ImprintingIndividual genes may also be inactivated. Often this is done preferentially to the maternal or to the paternal copy of the gene.
REPRODUCTIVE COMPETITION BETWEEN MALES AND FEMALES
DAD DAD
MOM MOM MOM
KID KID KID KID KID KID
Easygoing kids make mom’s job easier. Mom has more kids.
DAD DAD
MOM MOM MOM
KID KID KID KID KID KID
Difficult kids make mom’s job harder. Moms have fewer kids. Dad’s kids do better.
DAD DAD
MOM MOM MOM
KID KID KID KID KID KID
Genomic imprinting allows genes to have different effects based on whether they are passed through mom or through dad.
DAD DAD
MOM MOM MOM
KID KID KID KID KID KID
Chapter 15The Chromosomal Basis of Inheritance
Chromosomal Mutations
Chapter 15The Chromosomal Basis of Inheritance
Chromosomal MutationsAlterations in chromosome number or structure cause some genetic disorders.
Chapter 15The Chromosomal Basis of Inheritance
Chromosomal MutationsAneuploidy
Abnormal chromosome number
Chapter 15The Chromosomal Basis of Inheritance
Chromosomal MutationsPolyploidy
More than two complete sets of chromosomes
Chapter 15The Chromosomal Basis of Inheritance
Chromosomal MutationsDeletion
Duplication
Inversion
Translocation
Chapter 15The Chromosomal Basis of Inheritance
Extranuclear Genes
Chapter 15The Chromosomal Basis of Inheritance
Extranuclear GenesMitochondria and chloroplasts contain some genes
Chapter 15The Chromosomal Basis of Inheritance
Extranuclear GenesMitochondria and chloroplasts contain some genes.
These exhibit non-Mendelian inheritance (mother line only).
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