Chapter 14: The Human Genome

By Tianna Diaz and Sarah Dudas

Human Chromosomes The average human has 46 chromosomes: 23 from

each parent 2 of the 46 are sex chromosomes and the other 44

are autosomes All women have 2 X chromosomes and all men have

1 X chromosome and 1 Y chromosome

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Biologists analyze chromosomes by arranging them in a karyotype

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Human Traits

A pedigree chart shows the relationships of an inherited trait within a family.

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Polygenic traits are traits controlled by many genes

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Human Genes

The human genome is the complete set of genetic information, containing tens of thousands of genes.

Human blood is divided into groups: ABO blood groups and the Rh blood group.

Alleles, which are a number of the different forms of a gene, are either recessive or dominant.

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Sex-Linked Genes

Sex-linked genes are genes located on the X and Y chromosome that determine an individual’s sex.

Because males have only one X chromosomes, all X-linked alleles show up in males even if they’re recessive.

For the recessive alleles to show up in females, there must be one recessive allele on each X chromosome.

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Chromosomal Disorders

Nondisjunction is an error in meiosis where homologous chromosomes do not separate.

If nondisjunction happens, you may end up with an abnormal number of chromosomes, resulting in a chromosomal disorder.

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DNA Testing/Analysis

DNA testing is used to predict and check for genetic disorders.

DNA testing can be done through gel electrophoresis or DNA fingerprinting.

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The Human Genome Project

The Human Genome Project is an attempt to sequence all human DNA.

It was completed in June 2000.

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Gene Therapy

Gene therapy is the replacement of a faulty or absent gene with a normal gene that works.

There have been many cases where gene therapy has been successful, but it doesn’t always cure genetic disorders.

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