the allele that is regarded as dominant completely masks the effect of the allele that is recessive Dominant alleles are written with capital letters and recessive alleles are written with lower case letters ID: 907988
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Slide1
Complete Dominance
Complete dominance: the allele that is regarded as dominant completely masks the effect of the allele that is recessive. Dominant alleles are written with capital letters and recessive alleles are written with lower case letters.
For example, purple flowers are dominant to white flowers. A homozygous white flower is crossbred with a homozygous purple flower. What are the phenotypes of the offspring?
Slide2Incomplete Dominance
Incomplete Dominance:
Both alleles are capitals because the alleles are not dominant or recessive
**neither one takes over or hides ….not dominant or recessive…they MIX TOGETHER! Like mixing paint! The outcome is in-between!!
R=Red Flowers
B=Blue FlowersRR=Red Flowers BB=Blue FlowersRB=Purple FlowersHere’s one where red and white make pink
Slide3Try These Punnett Squares…please
Cross a
Blue flower with a
red flower
.
Cross a red flower with a purple flower.Cross two purple flowers.
Slide4Codominance
Same deal with the alleles…all letters will be capital.This time they are both being dominant.
It’s like splattering one color on another-they both show up equally dominant.For example, you have a homozygous black feathered chicken who mates with a homozygous white feathered chicken. Their offspring will have BOTH white and black feathers.
Results in a third phenotype: speckled.
Slide5So…Codominant Alleles
R=Red Fish B= Blue FishRR=Red Fish BB=Blue Fish
RB=
Red
and
Blue Fish (like spots or stripes)
Slide6Now Try These Punnett Squares…please
Cross a Blue fish
with a red fish
.
Cross a
red fish with a red and blue f
i
s
h
.
Cross two
red
and
blue
f
i
s
h
.
Slide7Blood Type is also Codominant
Blood types A and B are codominant.When present, they are both expressed.However, Blood type O is recessive.When present with dominant alleles, it is masked.
Slide8Blood Type Examples
A man with AB blood is married to a woman with AB blood. What blood types will their children be and in what proportion?A woman with type A blood (genotype: AO) is married to a type B person (genotype: BO). What blood types will their children have?
Slide9Can You Pick Out the Co-dominant and Incompletely dominant Example?
Silly Question…of course you can
Slide10See…You Did it
Slide11Sex-linked
Sex-linked traits are carried on the sex chromosomes.The sex chromosomes are 23 pair.XX = femaleXY = male
Because, males only have one X chromosome, they have a much greater chance of having sex-linked traits.
Slide12Examples of Sex-Linked Traits
Colorblindnessa problem with the color-sensing cones in the retina of the eye.
You can’t see certain colors
Red/Green-most common
Blue Yellow
Achromatopsia-see greys onlyHemophiliaBlood lacks clotting factor, most of which are produced in the liver.
Slide13Colorblindness Example
Colorblindness is a recessive disorder carried on the X-chromosome.A female carrier of colorblindness and a normal male want to have children. What is the probability they will have a child who is colorblind?