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Genetics. Incomplete Dominance Where neither the dominant or recessive allele is truly dominant over the other, both are dominant.

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Presentation on theme: "Genetics. Incomplete Dominance Where neither the dominant or recessive allele is truly dominant over the other, both are dominant."— Presentation transcript:

1 Genetics

2 Incomplete Dominance Where neither the dominant or recessive allele is truly dominant over the other, both are dominant

3 Incomplete Dominance The heterozygote will “blend” the two traits into an intermediate third trait RED Flower x WHITE Flower ---> PINK Flower

4 Incomplete Dominance Because neither allele is dominant over the other, we use a large base letter indicating the character and a capital superscript showing trait C R C R for red flower C W C W for white flower One allele from each parent is passed on. A cross would produce C R C W which is pink phenotype.

5 It’s important to know when you’re dealing with incomplete dominance *notice that the offspring is showing 3 rd phenotype *notice that the trait in offspring is a blending of parental traits

6 Codominance Similar to incomplete dominance because it too creates a 3 rd phenotype, different from parents. Parental traits don’t blend, instead the two traits appear together in a hybrid red and white --> red & white spotted

7 Here’s an example of a codominant flower showing both parental pink and white traits.

8 X ROAN COW

9 Human Blood Types Antigen- molecules that can trigger an immune response A carries A antigen B carries B antigen AB has both antigens O carries neither antigen Rh Factor; Rh+ carry this antigen, while Rh- individuals don’t. In transfusions, a new antigen cannot be introduced into the body of recipient

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11 How common is your blood type? 46.1% 38.8% 11.1% 3.9%

12 Who can give you blood? People with TYPE O blood are called Universal Donors, because they can give blood to any blood type. People with TYPE AB blood are called Universal Recipients, because they can receive any blood type. Rh +  Can receive + or - Rh -  Can only receive - Universal Recipient Universal Donor

13 Polygenic Inheritance When multiple genes affect a single character, variation Height, weight, eye color, skin color Suppose ABC were 3 “TALL” alleles and abc were 3 “short” alleles Someone with genotype AABBCC would be very tall, while someone with genotype AaBBCC would be slightly less tall

14 ABAbaBab ABAABBAABbAaBBAaBb AbAABbAAbbAaBbAabb aBAaBBAaBbaaBBaaBb abAaBbAabbaaBbaabb AB: Dark Red plants ab: white plants Wide RANGE of phenotypes

15 Environment Influence on Phenotype Sometimes an organisms phenotype depends on their environment regardless of genotype For example, hydrangea flowers of the same genotype range from blue-violet to pink, depending on soil acidity

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17 An enzyme responsible for dark fur is only active at cooler temperatures like cat’s extremities

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19 Gene Linkage Genes on separate chromosomes assort and separate independently from each other Genes located on SAME chromosome and close together (close gene-loci) tend to be inherited together. * Genetic linkage If genes are far apart, but on the same chromosome, crossing over could separate them

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21 Sex-Linked Genes Any gene located on an sex chromosome is a sex-linked gene In humans, most of these are on the X chromosome (much bigger than Y)

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24 Hemophilia: X-linked genetic RECESSIVE disorder hHh

25 Mother is a carrier hhH HH hHH H

26 FATHER IS A CARRIER hHH hHH

27 Red-green color blindness X-linked color blind allele is recessive Heterozygous females have normal vision Males who get recessive allele in their only X chromosome are affected.

28 X-linked recessive disorders are more common in men than women Women need 2 recessive alleles on each of her X chromosomes to be affected Men only need 1 recessive allele on his only X chromosome to be affected


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