1. Chapter 14
The Human Genome

2. 14-1 Human Heredity Human Chromosomes
karyotype: a grouping of chromosomes made from the chromosomes cut out from a photograph of a cell in mitosis

3. 14-1 Human Heredity Human Chromosomes
karyotype: a grouping of chromosomes made from the chromosomes cut out from a photograph of a cell in mitosis
sex chromosomes: the pair of chromosomes that determine the individual’s sex (XX for females and XY for males)
all eggs carry a single X chromosomes
sperm carry either an X or a Y (50/50 chance…)
This, male sperm cells determine if the newborn will be a boy or a girl…
autosomes: all other chromosomes

4. Human traits
pedigree: a chart showing the relationships within a family that can be used to study how a trait is passed from generation to generation
many traits are polygenic (controlled by more than one gene)
many traits are strongly influenced by environment (nutrition and exercise)
genes that reach full expression in one generation may not in the next if denied the proper environment

5. A square represents a male.
A circle represents a female.
A vertical line and a bracket connect the parents to their children.
A horizontal line connecting a male and female represents a marriage.
A half-shaded circle or square indicates that a person is a carrier of the trait.
A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait.
A completely shaded circle or square indicates that a person expresses the trait.

6. Human Genes blood group genes Rh factor: single gene with two alleles,
Rh+ (dominant) and Rh- (recessive)
ABO blood group: single gene with three alleles (IA, IB, i)
“IA” and “IB” are codominant alleles and “i” is a recessive allele

7. Safe Transfusions
Phenotype
(Blood Type)
Antigen on
Red Blood Cell
Genotype To
From

8. recessive allele disorders
phenylketonuria: lack the enzyme necessary to break down phenylalanine (amino acid found in milk and other food)
recessive allele on chromosome 12
Tay-Sachs: causes breakdown of central nervous system and death in first few years
caused by autosomal recessive gene
found mostly in Jewish families in central and eastern Europe
dominant allele disorders
achondroplasia: form of dwarfism caused by autosomal dominant allele
Huntington’s disease: nervous system disorder that causes a loss of muscle control and mental function
codominant allele disorder
disorder in 1 out of 500 African Americans with sickle cell anemia

9. From Gene to Molecule cystic fibrosis (CF) sickle cell anemia
Fatal genetic disease among people from Northern Europe causing digestive problems and thick mucus in lungs (half survive until their 20s)
a 3 base change causes deletion of an amino acid in a protein and improper folding to transport chloride ions
sickle cell anemia
common genetic disorder among African Americans producing sickle-shaped red blood cells that tend to get stuck in capillaries producing weakness and damage to brain, heart, and spleen
caused by a one base change in DNA
heterozygous individuals are immune to malaria
dominant or recessive?
one normal CF allele is dominant over a recessive CF allele