Alternative Patterns of Inheritance

Incomplete Dominance• Heterozygote creates a

new phenotypic trait that is in between the dominant and the recessive ( i.e. middle)• ex. Snap dragon flowers

can be Red (RR), Pink(RW, or white(WW) with different allele combinations

• Ex. Hair texture • Curly , wavy, straight ( C, S)

Lets practice

1. Predict the genotypes and phenotypes of a cross between a red snapdragon and a pink snap dragon

2. Predict the genotype and phenotypes of a cross between 2 individuals with wavy hair.

Co- Dominance • In the heterozygote,

both alleles are expressed at the same time.• Example: Coat color in

the horses can be red ( RR), white (WW), or Roan ( RW).

• Roan = both red and white hairs in the coat color at the same time

Lets practice

1. Predict the genotypes and phenotypes of a cross between a White cow and red cow.

2. Predict the genotype and phenotypes of a cross between 2 individuals from the F1 generation from question #1

Multiple Alleles• Traits are controlled by more than 2 alleles• Ex Blood type uses 3 alleles (IA, IB, i)

• Which alleles do you think are dominant?• Which alleles are recessive?• Would any of theses alleles demonstrate an

alternative pattern of inheritance?

What are the different blood types?

Type A Type BType ABType O

• What would be the genotypes for those phenotypes?

• IAIA or Iai• IB IB or Ibi• IAIB

• ii

Let’s Read about how blood type influences some cultures… And answer the questions.

Make sure your blood type article is complete so that we can grade

• Also Make sure that your practice punnett squares worksheet is complete .

• We will go through both of these… today and take more notes

ABO SYSTEM is NOT THE ONLY ONE

Rh+ Rh-

MOM is _____& BABY is ____

OTHER BLOOD TYPES____________________ IF:

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MOM is _____& BABY is _____

Rh+

Rh+ Rh+

Rh-

NO PROBLEMS

Can be a ___________ IF: Mom is _____ Baby is _____

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1st baby OK but few baby cells entering mom’s bloodstreamput mom’s immune system on alert for + cells.

Next + baby, mom’s immune system can attack baby as it isgrowing

Mom given shot after 1st birth prevents this

Rh+

PROBLEM

Rh-

Homework• Complete the punnett squares practice work sheets

WARM UP• COMPLETE THE INCOMPLETE AND CO-DOMINANCE

WORKSHEET• Only answer #s 6-9, 11, 14, 19 • Complete the problems on a separate piece of paper.

Sex Linked Traits

• Sex linked traits – when genes are carried on the X chromosome

• Nothing is really on the Y chromosome

• The evolution of the Y chromosome is a GOOD thing because it ensures that the human population is always ½ male and ½ female • (CONTINUATION OF

SPECIES)

Some Examples of sex-linked traits…- Colorblindness- Baldness- Hemophilia

When setting up a punnett square…• The sex linked trait is written as a lowercase letter because they are

recessive and also a super script

• Example Xb

• The phenotypes for sex linked crosses must include the gender of the offspring and whether or not they have the trait

• Phenotypes for baldness traits..• XB XB = normal female

• XB Y = normal male

• XB Xb = carrier female

• XbXb = bald female

• XbY = bald male

There are NO male carriers

Let’s Practice

• A bald man marries a normal female. Determine the phenotypic ratio for the offspring.

- A bald male marries a carrier female. What are the chance that all the children will be bald?

Polygenic Traits• Traits are controlled by several genes. Ex. Skin, eye, and hair

color are controlled by more than one gene.

Pedigree – shows patterns of inheritance• Individuals either have the trait, do

not have the trait, or are a carrier for the trait

• Carrier = individual who has ONE copy of a recessive allele

DRAW and LABEL THE PEDIGREE ACCORDING TO THE FOLLOWING SCENARIO:Han Solo, son of Owen, and Leia, daughter of Anikin, both have freckles, but their son Jedd does not. Queen Amadala, died giving birth to twins, Luke and Leia. Leia has freckles, but her brother does not. Han’s brother, Chewie, and his sister, Padme, like their mother, Peru, do not have freckles.