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Dominance

RR. rr. Dominance. Objective 3.04 Interpret and predict patterns of inheritance. Incomplete Dominance. Also called Partial Dominance. Results in the blending of traits Happens due to a weak (less active )gene The heterozygous phenotype appears intermediate (in between).

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Dominance

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  1. RR rr Dominance Objective 3.04 Interpret and predict patterns of inheritance

  2. Incomplete Dominance • Also called Partial Dominance. • Results in the blending of traits • Happens due to a weak (less active )gene • The heterozygous phenotype appears intermediate (in between). Red + White = Pink

  3. Co-Dominance • Co-dominant alleles result in the expression of both traits. • Red + White = Both Red & White together!

  4. Multiple Alleles • When there are two or more possible allele pairs for one locus. (more than just 2 options) • ABO Blood typing (I, i) is an example. • There are 4 possible combinations (blood types) A B AB O

  5. Polygenic Traits • When traits are controlled by more than one pair of genes. • Provides a wide range of phenotypes! • Ex. Hair Color, Skin Color, Height, Weight. • Think of bell peppers! • 3 different genes play a role in the color: • *Y - timing of chlorophyll elimination (Y - early; y - normal)  * R - color of carotenoids (R - red; r - yellow)  * C - regulation of carotenoid deposition   (C - normal; c1, c2 - lowered concentration)

  6. o Y- rr c1c2 - pale yellow o Y- rr Cc2 - darker yellow o yyrr CC – green o Y- R- CC – red o yyRr CC – purple o Y- Rr Cc2 - pale yellow

  7. Karyotypes • A profile (picture) of an individual’s chromosomal setup. • Doctors are able to use a karyotype to: • Check for 46 chromosomes • 22 pairs of autosome • 1 pair of sex chromosomes (XX or XY) • Determine the sex of an unborn baby

  8. Autosomal Disorders • Autosomal tells us that the gene for the disorder is on one of the first 22 pairs of chromosomes, so both men and women are affected equally. • These disorders are recessive, which means that you would need to get a recessive gene from both mom AND dad to have the disorder. So, Mom & Dad are carriers and probably don’t know it (Dd x Dd = 1:4 chance of dd) • Ex. Sickle cell anemia , cystic fibrosis, & Huntington’s disease.

  9. Sex Linked Traits • Found on the 23rd (last) pair of chromosomes X and Y. • The X chromosome is bigger than the Y, so it has many more genes. • Boys (XY) get an X from mom and a Y from dad. Because they only have one X, if there is a defective gene, they will have the disease. • Girls (XX) get an X from mom and an X from dad. Because they have two X’s, if there is a defective gene on one of the X’s, they have another X (that is probably “healthy” and won’t have the disease…will only be a carrier. • Therefore, sex linked traits are much more common in males than in females. • Ex. Hemophilia & Color Blindness

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