Chapter 14- Human Genome

Section 1: Human Heredity

I. Human Heredity

A. Human chromosomes 

1. A picture of chromosomes arranged in a picture is called a karyotype.

2. A normal human has 46 chromosomes, 23 pairs.

22 pairs of autosomes1 pair of sex chromosomes

 3. A female chromosomes is XX, a male is XY.

eggs carry XSperm carry either X or Y

**Males determine the sex of the offspring!!

B. Human Traits

1. Human genes are inherited according to the same principals that Mendel discovered.

 2. A pedigree chart shows relationships within a family.

3. Genetic counselors analyze pedigree charts to infer the genotypes of family members.

 4. Many traits are strongly influenced by environmental, or non-genetic factors, including nutrition and exercise.

C. Human Genes

1. The human genome- our complete set of genetic information includes tens of thousands of genes.

 2. Some of the very first genes to be identified were those that control blood type.

BLOOD GROUPS

Phenotype Genotype Antigen

A IAIA or IAIo A

B IBIB or IBIo B

AB IAIB A and B

O IoIo --------

E. Recessive Alleles

Many human genes have become known through the study of genetic disorders.

  In most cases genetic disorders are

USUALLY recessive. 

See page 345 to see some disorders

Albinism ( Recessive )

Cystic Fibrosis ( Recessive)

CF is most common among people with Northern Europe ancestors.

People with CF have serious digestive problems in addition they produce thick, heavy mucus that clogs their lungs and breathing passageways.

F. Dominant Alleles

Not all genetic disorders are caused by a recessive allele.

  Two examples of a genetic disorder

caused by autosomal dominant alleles are Acondroplasia (dwarfism) and Huntington’s disease.

Dwarfism ( Dominant)

Huntington’s disease

G. Codominant alleles

Sickle cell disease is caused by a codominant allele.

Sickle Cell Disease (Codominant)

Sickle cell is a disease found in African American’s.

Sickle cell disease produces physical weakness, and damage to the brain, heart, and spleen.

H. From Gene to molecule

In both cystic fibrosis and sickle cell disease, a small change in the DNA of a single gene affects the structure of a protein, causing a series genetic disorder.