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Pedigrees•Used to explore human genetics•Circles = Female•Squares = Male•Traits:
– Not Shaded = Do not have – ½ Shaded = Carrier– Full Shade = Have
Modes of Inheritance• Autosomal or Sex-Linked
– Autosomal –chromosomes other than sex chromos.
– Sex linked – X or Y
• Dominant or Recessive
Autosomal Recessive• ~equal in males & females• Often skips generations• May show carriers (half shaded)
but not always!
Autosomal Dominant•Does not skip generations•Affect crossed with unaffected = 50% of offspring are typically affected
Sex-Linked Traits–Mostly males •Mother of affected male is a carrier or affected.
–No male carriers, but can have female carriers
Pedigree FlowchartHow many males
& females areaffected?
More Males Sex Linked
Trait
Affected Males = Affected Females
Autosomal
Are carrier
s presen
t?
Yes:
Recessive
No:Does
the trait skip a
generation?
No male carriers?
Yes: Recess
ive
No: Domina
nt
Human Karyotypes• Diploid organisms• 46 Chromosomes
– 23 homologous pairs•2 sex chromos.
• Used to detected aneuploidy associated disorders
Sex Chromosomes Sex Chromosomes DisorderDisorder
•Turner’s Syndrome– Female with only one X– XO– Causes Sterility = no sex organ
development at puberty– Short stature– Webbed neck
•Klinefelter’s Syndrome–Males with an extra X –Reduced fertility–Less testosterone –1/1000 males
•XYY– Normal reproduction– Delay motor skills– temper
Y Chromosome
• Important role in sex determination
•Y presence creates a male no matter how many extra Xs–Exception : Swyer syndrome