Warm up
• Complete the punnet square for a Tall pea
plant. T= tall t=short.
– The parents are Tt x tt
– What are the genotypes and phenotypes?
– What are the genotype and phenotype ratios?
Types of Inheritances
Pp 237, 242-245
Types of Inheritance
•
•
•
•
•
•
Complete Dominance
Incomplete Dominance
Codominance
Sex-linked
Polygenic
Epistasis
You will be
responsible to
complete punnett
squares for the
types bolded
Complete Dominance
•
•
•
•
One allele is completely dominant over the other
Only two phenotypes exist
One phenotype is masked
The heterozygous phenotype shows dominant trait
–
–
–
–
Ex: Tall peas are dominant to short peas
TT= tall
Tt= tall
tt=short
Complete Dominance
Autosomal Genetic Disorders.
Carrier: A heterozygote for a recessive disorder
(ex/ Cc).
• Carrier does not show symptoms but can pass
recessive allele to offspring
• Affected person must inherit two recessive alleles
• Example Cystic Fibrosis, Tay-sachs, sickle-cell
anemia
• CC &Cc = unaffected
• cc = affected
Incomplete Dominance
• Neither allele is completely dominant over the
other
Incomplete Dominance
• Neither allele is completely
dominant over the other
• Three phenotypes exist
• The heterozygous phenotype
shows blended trait
Incomplete Dominance
• Neither allele is completely dominant over the
other
• Three phenotypes exist
• The heterozygous phenotype shows blended
trait
• Ex: Flowers can be pink, red, or white.
– RR=red
– rr= white
– Rr=pink
Incomplete Dominance
• Cross two pink flowers
– Draw Punnet Square
• What percent of their offspring will have white
flowers?
Incomplete Dominance
• Cross two pink flowers
• What percent of their offspring will have white
flowers?
• Fish can be green (GG), blue (BB), or teal
(GB)
Green (GG)
Teal (GB)
Blue (BB)
Codominance
•
•
•
•
Both alleles are dominant
Three phenotypes exist
Neither phenotype is masked
The heterozygous phenotype shows both traits
at once
Codominance
•
•
•
•
Both alleles are dominant
Three phenotypes exist
Neither phentoype is masked
The heterozygous phenotype shows both traits
at once.
X
red (RR)
=
white (WW)
Codominance
•
•
•
•
Both alleles are dominant
Three phenotypes exist
Neither phentoype is masked
The heterozygous phenotype shows both traits
at once. (Not a blend)
X
red (RR)
=
white (WW)
red & white(WR)
Codominance
EX: In Smileys, eye shape can be starred,
circular, or a circle with a star.
Write ALL the phenotypes and genotypes that
exist.
Codominance
EX: In Smileys, eye shape can be starred,
circular, or a circle with a star.
Write ALL the phenotypes and genotypes that
exist.
• CC = circle
SS = star
SC = circle-star
Homework
• Incomplete Dominance WS
– 3 pages
– Must be colored for credit.
Warm-up 12/11
• A Blue flower is crossed with a Yellow flower.
– What are the offspring colors and their predictided
ratios if: (Show Punnet squares)
• Blue is codominant with Yellow
• Blue and Yellow exhibit incomplete dominance
• Blue is completely dominant over Yellow
• Quiz Friday on Genetics
• Study Guide Due Thursday 12/19/13
Sex Linked
• Disorder/trait found on the “X” chromosome
• Which gender has more instances of having an
x-linked disorder?
• Men-Males have no second copies of X-linked genes
(XY).
• Females have two X chromosomes (XX) so if one has
a defect they can use the other normal X chromosome.
Sex-Linked
•
•
•
•
EX: color blindness
Punnett square determines sex and trait
First, Use X and Y to show gender
Second, use a letter on the X chromosome to
show which allele they inherited.
• “Y” has to come from father
• “XR or Xr” vs just “R or r”
Sex-Linked
•
•
•
•
EX: color blindness
Punnett square determines sex and trait
First, Use X and Y to show gender
Second, as a letter on the X chromosome to show which allele they
inherited.
Possible genotypes and phenotypes:
XR XR = Female, normal vision
XR Xr = Female, normal vision
Xr Xr = Female, color blind
XR Y = Male, normal vision
Xr Y = Male, color blind
•
Sex Linked
What percentage of offspring would be color
blind if a female carrier and a male who has
normal vision had children?
Sex Linked
What percentage of offspring would be color
blind if a female carrier and a male who has
normal vision had children?
Step 1: Determine genotype of parents
____________ x ____________
Sex Linked
Step 2: set up and complete punnett square.
What percent of their children would be
colorblind?
XR
Y
• Possible genotypes and phenotypes:
XR XR = normal vision
XR Xr = normal vision
XR
Xr
Xr Xr = color blind
XR Y = normal vision
XRY XrY
Xr Y = color blind
XRXR XRXr
Single gene traits
• controlled by only one gene
- complete, incomplete, and codominant
EX. Huntington Disease (D/d), Sickle Cell
Anemia (N/S) , Cystic Fibrosis (R/r)
Polygenic traits
• controlled by additive effects of two or more
genes
EX. Skin color (controlled by 3-6 genes), eye
color
- each gene is responsible for adding
pigment
Polygenic
• Many genes may interact
to produce one trait
• Ex: Skin color result of
four genes that interact to
produce range of colors
Epistasis
• One gene controls many traits
• EX: Albinism
• Albinos are unable to synthesize melanin, the
pigment molecule responsible for most human
coloring
Multiple allele trait
• controlled by more than two
alleles in one gene
• Still only inherit one copy from
each parent for a total of two
alleles but have a few to
combine
EX. Blood type:
Homework
• Sex Linked Traits
– In Packet
Warm up 12/12
• Liking Brussels Sprouts is a recessive
characteristic.
– What are the possible genotypes for an individual
who:
• likes Brussels sprouts.
• hates Brussels sprouts.
– A man who hates Brussels sprouts wants to find
out if he is heterozygous or homozygous. Should
he find a mate who likes Brussels sprouts or one
who hates Brussels sprouts. Explain your answer
with a punnet square!
Test Cross
• Used to determine if a
dominant parent’s genotype is
Bb or BB
• Cross with homozygous
recessive (bb)
• If in the offspring, there are
bb, then the parent had to be
Bb
Blood Typing
Trait controlled by multiple alleles, with two that
are codominant and one “null”
Dominant Allele: I
2 Dominant Alleles:
A: IA B:IB
Recessive Allele: i
1 Recessive Allele:
O= i
• Trait controlled by multiple alleles, with two
that are codominant and one “null”
• Trait controlled by multiple alleles, with two
that are codominant and one “null”
• Example: Blood Types
• Trait controlled by three
alleles, with two that are
codominant and one
recessive
IA : produces A antigens
on surface of cell
IB : produces B antigens
i: does not produce
antigens
Practice Problem
• What possible blood types could the children
of a homozygous A female and a male with
AB blood have?
• Parents Genotype
_______X ________
• Someone with AB blood can receive blood
from A, B, AB, and O because it doesn’t have
antibodies to clump cells. However it can only
be giving to AB because all other blood types
have antibodies that can cause clumping with
the AB cell.
• Use serums that contain these antibodies to test
blood type
Testing Blood Type
• Use anti-A serum and anti-B serum
• If you use anti-A serum and it clumps then it
has A antigens (proteins), if you use anti-B
serum and it clumps then it has B antigens
• No clumping = no antigens
What blood type would this be?
Homework
• Blood Type Problems
• Friday: Quiz
– Genetics
• Punnet Squares, Complete, Incomplete &
Codominance
– Mitosis & Meiosis
• Know Phases, Haploid, Diploid, Nuclear
State
• Exam: Friday Dec. 20th
– Intervention: Wednesday 12/18 @ 2:45-3:30 pm
& Thursday 12/19 @ 6:50 -7:35 am
Homework
• Read 237 -242
• Problems p 240 #1-6
• P 251 # 1, 4, 5, 6