Chapter 7

Down Syndrome

A condition of retardation and associated physical disorders caused by an extra copy of chromosome 21.

Genetic Disease (disorder)

A disease caused by an inherited mutation in a gene passed down from parent to child.

Gene therapy

Attempting to correct defective genes using Genetic Engineering. Cells are collected A virus is used to inject a healthy gene into blood cells Corrected cells are re injected into patient Hopefully new cells produce new protein

Autosomal recessive disorder?

Both sexes can be affect equally because both have copies of autosomal chromosomes and identical odds. EX: Cystic fibrosis -caused by one or more mutations

4 Changes that can occur in chromosome structure(DITD)

Deletion-a segment breaks off and is lost from the chromosome Inversion-a segment breaks off and is reattached in reverse order Translocation-a segment breaks off one chromosome and becomes attached to a different nonhomologous chromosome Duplication-a chromosome becomes longer after acquiring an extra copy of one of its chromosome segments

Dr. Klein Gene Therapy

Mice had same symptoms as WAS, and he if didn't work mice would die not Felix

Carrier for a genetic disorder

One copy of a recessive allele - they can pass on the disorder allele, but they do not have the disease.

SRY Gene

Sex determining region of Y, is the "Master sex switch" that determines that the growing embryo will be male - otherwise remains female. When present - SRY causes genes on some autosomes to produce male characteristics When absent - autosomal genes produce femal characteristics

X linked disorder Autosomal recessive Autosomal dominant

WAS Cystic Fibrosis Dwarfism

WAS gene

Wiskott - Aldrich Syndrome: Located on X chromosome multiple immune system issues

Why are x linked disorders more common in males?

Y chromosome does not have copy of that gene. need to inherit only a single copy of the disorder allele to exhibit the disorder.

Can women be affected by X linked disorders?

Yes but must have two copies in order to be affected

Karyotype

a picture of a cells chromosomes during meiosis that have been sorted and matched in pairs

Problems with Gene therapy

in many cases, gene therapy has not worked, few patients developed leukemia, at least two patients died by immune response to vector used, scientists working to correct problems, need to develop new approaches to use genes for treatment of genetic diseases

Autosomes

paired homologous chromosomes, alike in length, shape, and loci of genetic traits. Humans have 22 pairs

Locus

the location of a physical gene on a chromosome

Genetic Engineering

the permanent introduction of one or more genes into a cell, tissue, or organ