I. Types of Chromosomes
A. autosomes-22 pairs per somatic cell
B. sex chromosomes-1 pair, pair #23
C. Y chromosome is responsible for maleness characteristics.
II. Sex-Linked Genes
A. Genes are located on the X sex or Y chromosome. x-linked
1. Females are often carriers
2. Occurs most often in men
3. ex: Normal vision=C (dominant)
Colorblindness = c (recessive)
Problems: Normal male X carrier female.
C. Hemophilia- clotting factor is missing in blood.
D. Muscular Dystrophy- progressive wasting away of muscle tissue due to genetic defect of gene.
III. Sex Influenced Traits
A. Gene located on autosomes that differs when expressed in a male or female.
B. Baldness: B= normal hair, b=baldness
1. bb=male and female bald
2. Bb-male bald only
Problem: Hetero. Male X hetero. Female
IV. Chromosomal Abnormalities
A. Nondisjunction- failure of a chromosome pair to separate during meiosis.
1. Downs Syndrome- (Trisomy 21)
a. Extra #21 chrom.
2. Klinefelters Syndrome
a. 47 chromosomes-XXY
3. Turners Syndrome
a. 45 chromosomes-XO
V. Genetic Diseases
A. Huntington disease- H h=normal
1. single dominant allele is responsible
2. slow destruction of nervous system. The only way 2 not have Huntingtons is hh.
B. Sickle Cell Anemia
1. abnormal shape of red blood cells
2. normal allele is codominant with sickle allele.
3. heterozygous genotype is partially resistant to malaria.