Things you should know and understand for the test:

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• Things you should know and understand for the
  test
• - Basic vocabulary necessary to speak genetics
• Steps of mitosis and meiosis
• Basics of Gametogenesis
• Mendels 4 postulates (laws)
• Expected Mendelian ratios for mono-, di-, and
  tri-hybrid crosses
• How to use Chi-square analysis to determine
  whether observed is
• different from expected for breeding
  experiments
• How to set up and interpret Punnett squares
• How to set up and interpret fork line diagrams
• Understand how modifications (lethal alleles,
  epistasis, co-dominance,
• incomplete dominance, etc) can alter
  phenotypic ratios
• - Understand that the basic Mendelian ratios may
  be modified, but the
• underlying laws still govern the inheritance
  pattern
• Be able to interpret human pedigrees
• Know what pedigrees can and cannot tell us
• Understand the role of the Y chromosome in sex
  determination
• Understand and be able to interpret sex-linked
  traits

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Sex Determination
Why do we come in two different models?
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Gametogenesis
What differences do you notice between
spermatogenesis and oogenesis?
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Sex Determination Versus Sex Differentiation
Sex determination is generally a genetic event
that leads the indifferent gonad to develop into
a testis or an ovary.
Sex differentiation is the development of the
male or female phenotype based on the type of
gonad present and is largely hormone dependant.
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Drosophila Sex Determination
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Determination of Gonadal Sex
Human
Mouse
Ovary
Ovary
XX
Streak
Ovary
X0
Testis
Testis
XY
XXY
Testis
Testis
The presence or absence of the Y chromosome
determines the sex of the gonad.
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The Sex Chromosomes
X
Y
p
p
q
q
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Karyotype Human Male
46, XX male
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Sex Reversal in Mice
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The Sex Chromosomes
X
Y
p
p
q
q
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Mechanisms for Transferring Y DNA to the X
Chromosome
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Transgenic Mice with SRY
XY
XX, SRY
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Gonadal Determination
SRY
-SRY
All gonads start out indifferent, i.e.the same in
both the male and female and its development as
either a testis or ovary is determined by the
presence or absence of SRY.
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Temperature Sensitive Sex Determination
Dont worry about temperature sensitive sex
determination, just be aware that it does exist
and may be important if global warming persists.