Download lab 10 - genetics

Agenda
• DO NOT TURN IN PRE-LAB YET!! We’ll go over
it.
• Lab Quiz #9
• Turn in Microworlds
• Show me or turn in Lab 10 w/ your name
when you finish it. If you show me it, do not
leave until I record your pts for it.
Punnett Squares
• Show possible
combinations of alleles
demonstrating
Mendel’s Laws
• We’ll go thru an
example with:
– Purple flower allele: P
– White flower allele: p
In a mating between two Pp
heterozygote parents
P
P PP
p
Pp
Pp
pp pp
p Pp
Punnett Square Problems
1. Heterozygous (Pp) x white (pp)
When it’s not so simple
• INCOMPLETE DOMINANCE: heterozygotes have
a unique or intermediate phenotype
When it’s not so simple
• INCOMPLETE DOMINANCE: heterozygotes have
a unique or intermediate phenotype
Genotypes:
HH
Homozygous
for ability to make
LDL receptors
Hh
Heterozygous
hh
Homozygous
for inability to make
LDL receptors
Phenotypes:
LDL
LDL
receptor
Cell
Normal
Mild disease
Severe disease
When it’s not so simple
• CODOMINANCE: both alleles are expressed
equally in the phenotype of a heterozygote
•RR = red hair
•rr = white hair
•Rr = red hairs and
white hairs
Codominant Alleles - Bloodtype
• Three alleles for blood type
–A
–B
–O
• This allele is for a protein (blood antigen) on
the outer surface of red blood cells
Codominant Alleles - Bloodtype
ANTIGENS
• A gene  A protein
• B gene  B protein
• O gene  no protein
ANTIBODIES
• Your body produces
antibodies to any protein
that you don’t have the
gene for
Codominant Alleles - Bloodtype
Blood Type & Multiple Alleles
Sex Linkage
• Remember that I said that everyone has two
alleles, one from the mother and one from the
father?
• Well, there is an exception. Any guesses as to
what it is called?
Sex Linkage
• Sex Chromosomes = X
and Y
• What do you notice
about the X and the Y
chromosomes?
• X chromosome has
many genes
• Y chromosome has few
Riddle me this…
• Hemophilia is a
recessive sex-linked
disease. Are boys or
girls more likely to
suffer from hemophilia?
WHY?
XH
Xh
H
X
XHXH XHXh
Y
XHY
XhY
Ex. 1-3: Punnett Squares & Probability
• In Ex1. Question #1 you need to
keep track of both the color (or fill
state) & capitalization of A & a on
the chromosomes!
• Show me #1 when finished.
• Skip the 3rd example of X-linked
Recessive (at end of Ex.2).
• Show me or turn in Lab 10 w/ your
name when finished, 10 pts!