Chapter 13 Flashcards
Discovering Chromosomes
Sutton, Boveri noted fertilization restores diploid, traits have specific loci, chromosome theory of inheritance
Thomas Morgan 1910, 1st evidence in support of CTI
worked with drosophila
wild type and mutant type
deduced eye color was sex linked
Drosophila
Fruit flies studied by Thomas Morgan
Sex linked inheritance
Non homologous across the board
X linked traits
men hemizygous (partial) for trait, inherit X from mother Y not involved
Females often carry but do not express
Sex linked recessive
few are dominant
more males affected
trait often skips generation
affected female from affected father, all sons will have the trait
Hemophilia and European royalty
lack of clotting factor
queen victoria was a carrier, queens daughters alice and beatrice carriers into russia and spain
Linked genes
proximity on chromosome
inherited together
deviate from mendel
Genetic recombination
offspring traits do not = parent
Independent Assortment
non-linked recombination
located on different chromosomes
50% recombination
Crossing over
linked recombination
located on one chromo
synapsis and exchange occurs
Autosomal inheritance
homologous chromosomes
sex does not matter
Alleles from M or F irrelevant
Sex-linked inheritance
Non-homologous chromosomes
sex of individual in cross matters
must account for each chromosome
Karyotype
view all chromosomes
any cell except RBC
Computer aligns samples
shows homologous pairs/abnormal counts
Nondisjunction
fails to separate correctly
Meiosis 1
Homologous chromosomes
Meiosis 2
Sister chromatids
Trisomy
extra chromosome
down syndrome
trisomy 21
Patau syndrome
change to autosomal number
13th chromosome appears three times
trisomy
Edwards syndrome
slow growth before birth
fatal before birth within one year
extra copy of chromosome 18
change to autosomal number
trisomy
Down syndrome
extra chromosomes
short stature/mental impairment
trisomy 21
Monomsomy
missing a copy of chromosome
turner syndrome
monosomy, physical abnormalities
one or both X chromosomes missing or partially deleted
poly x females
XXX
may be tall/thin
trisomy
Klinefelter syndrome
males; 2 Xs
XXY
speech/language delays
trisomy
Jacobs Syndrome
males; 2 Y
XYY
taller than average
Deletion
removes a segment of DNA
Duplication
repeats a segment of DNA
Inversion
180 degree rotation of DNA segment
Translocation
one segment on chrome one to segment chrome two
