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Chapter 10 Notes

Genes and Chromosomes

Links !

A single gene disorder, Cystic Fibrosis

Why we look like we do (Homeotic genes), they tell how body parts develop in different areas of the body

Overview of the proteins that determine blood type

a "jumping gene" on chromosome 16, a discussion of Insertion Polymorphism

HUMAN GENOME project, 35,000 genes for anyone to look at.


Chapter 10 Notes

 Genes and Chromosomes

I.                    Mutations

A.  Changes in the hereditary message of the DNA, which then changes the gene or chromosome.

B.  Types of mutations:

1.      Chromosome

A.  Non-disjunction- failure of a whole chromosome t separate during meiosis.

B.  Polyploidy- more than one chromosome failing to separate during meiosis.

C.     Deletion/Duplication- loss or addition of a chromosome segment.

2.      Gene

A.  Point mutations- smallest changes affects one amino acid.

B. Frameshift mutations- single base is inserted or deleted, changing polypeptide product.

II.                 Regulation of Gene Expression

A.  Incomplete Domination or Codominance

1.      The dominant allele is not full expressed or is equally dominant with the other allele.

a. Some flowers display Incomplete Dominance.

1.      Red Flower genotype=RR

2.      White flower genotype=rr

3.      F1 offspring are all=Rr

4.      Rr phenotype is Pink!

b.  Cattle color displays Codominance

1.        Red cattle genotype=  HR HR

2.      White cattle genotype=HwHw

3.      Genotype of F is HR Hw which is roan color.

b.      Human blood types show Codominance.

1.  Blood types are controlled by multiple alleles. (IA, IB, and i)

2. Allele IA is codominant with allele IB.

3.  Allele i is recessive to both IA and IB.

4.  The i gene (isoagglutinogen) produces the antigens on the RBC.  Antigens are cell surface markers for cells to recognize each other.

5.  The genotypes for blood types are as follows:

            Type A- IA IA or IAi

            Type B-IB IB or IBi

Type AB-IAIB (codominance)

Type O- ii

B.     Polygenic Inheritance

1.      Traits that are controlled by several genes.

a.  Shape of your nose, eye color, skin color etc.

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