Transcript Document

Ch.9
 How are purebreeds
different from mixed
breeds?
 Purebreeds are from
parents who share
the same genes
while mixed breeds
are not
 Gregor Mendel is
known as the father
of modern genetics
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What process is illustrated on
the right?
The purple flower is being
fertilized by the pollen of the
white flower (crossfertilization).
What do we call the parental
generation?
The P generation
What do we call the
offspring?
F1
 Mendel looked at
several traits.
Which is dominant
yellow pea seed or
green pea seed?
 Yellow
When you make a cross for
one trait like flower color
it is called a _______
cross
Monohybrid - mono for one
hybrid for different
 Why are all the F1
purple?
 Because purple is
dominant to white each
F1 flower has a P allele
and a p allele.
 Why is the F2 different
from the F1?
 Because in the F2
generation two pp can
occur in the offspring
Purple flower crossed to White Flower
Possible
Gametes
Purple
P
Flower
P
White
p
Pp
Purple
heterozygote
Pp
Purple
heterozygote
Flower
p
Pp
Purple
heterozygote
Pp
Purple
heterozygote
F1 crossed to F1
Gametes
Purple
P
Heterozygote
p
Purple
P
PP
Purple homozygote
Pp
Purple heterozygote
Heterozygote
p
Pp
Purple heterozygote
pp
White homozgote
 What does loci
mean?
 Location of a gene
 Define homozygous
and heterozygous
 Homozygous - same
alleles PP or pp
 Heterozygous different alleles Pp
 When two traits are crossed
it is called a _________
cross
 Dihybrid
 Why doesn’t a dihybrid cross
produce the same outcome
as a monohybrid cross?
 Independent assortmentwhere the alleles for pea
shape go, have nothing to do
with the alleles for pea color.
 What is the ratio of
phenotypes, coat color
and vision?
 9 both dominant
 3 One dominant, one
recessive
 3 One recessive, one
dominant
 1 both recessive
Gametes
BN
Bn
bN
bn
BN
BBNN
BBNn
BbNn
BbNn
Bn
BBNn
BBnn
BbNn
Bbnn
bN
BbNN
BbNn
bbNN
bbNn
bn
BbNn
Bbnn
bbNn
bbnn
 What do you think is the
purpose of a testcross?
 To determine the genotype
of a dominant individual
 Why cross the unknown
individual to a homozygous
recessive?
 If any recessives show up in
the offspring we know the
unknown carries the
recessive trait.
 What is the chance
of getting two Bb in
a row?
 2/4 x 2/4 = 4/16 =
1/4
 Does dominant
mean more
common?
 No freckles are not
necessarily more
common.
 What is this diagram
called?
 Pedigree chart
 Why can’t we predict
Abigail Lambert’s
genotype?
 We don’t know about
her offspring and she
possesses the
dominant trait so she
could be Dd or DD
 Why do you think we
call Dd a carrier?
 They carry the trait, but
since it is recessive you
can’t see it.
 What type of disorder is
this?
 A recessive disorder
like Cystic Fibrosis
 Achondroplasia, a type of
dwarfism, is a __________
trait.
 Dominant
 Huntington’s is also
dominant but doesn’t usually
take effect until after the age
of 30. What is the potential
problem with that?
 They have already had
children and passed it on.
 What are two ways
to test for inherited
disorders in a fetus?
 Amniocentesis and
Chronic villus
sampling.
 When red and white
make pink offspring
it is called _______
dominance?
 Incomplete
 What is the ratio of
the F2 generation?
 1red:2pink:1white
 In blood type A is
dominant to O and B
is dominant to O but
A and B arre equally
dominant. What do
we call this type of
inheritance?
 Codominance
 If Maria is type O and
her sister is type AB
blood and they know
there mother’s
grandparents are type
A. What are the
genotypes of their
parents?
 Mother is Iai and dad is
I Bi
Normal red blood cells and
sickle cells
 This picture illustrates
pleiotropy, what do you
think that means?
 One gene can have an
affect on many different
things in the body sickle cell shaped cells
can cause heart failure,
kidney failure etc.
 How many different
genes are involved in
skin color?
 3
 When many genes
cause a trait like skin
color it is called
_______
 Polygenic inheritance
 What does this
picture illustrate?
 Independent
assortment - shape
and color line up
separately.
 When two genes are
on the same
chromosome like purple
flower and long pollen
or red hair and freckles,
it is called _________.
 Linked - they tend to
travel together because
the are close together
and are rarely
separated by crossing
over.
 What would you expect to be
the outcome of the cross
GgLl and ggll
 1GgLl:1Ggll:1ggLl:1ggll =
equal numbers of each type.
 Is that what was observed?
 No - most were like either
parent
 What is the chance that
crossing over will happen?
 17%
 The crossing over
frequency can be used
to calculate the distance
between genes on the
chromosome. What is
the distance between
body color and wing
shape in fruit flies?
 17
 Many organisms
have chromosomes
that determine sex,
humans have ___
and ____
 X and Y
 In chickens it is ___
and ____
 Z and W
 Where is the eye
color gene located?
 X
 What is the only way
to get a female that
has white eyes?
 The dad must have
an X with white eyes
 When a gene is on the
sex chromosome it is
called sex linked.
Red/green
colorblindness is sex
linked.
 How would this test for
colorblindeness?
 A colorblind person
would not see the
seven in the middle
 Queen Victoria
passed on a sex
linked trait to her
family, what was it?
 Hemophilia
 Duchenne muscular
dysytrophy is also
sex linked