mutation

any change that occurs in the DNA sequence of a chromosome.

mutagens

environmental conditions that cause mutations and are avoidable

Karyotypes

used to identify mutations are a photographic display of the chromosomes from a cell

Amniocentesis

15th to 20th week of pregnancy- a needle is inserted into the uterus to obtain fetal cells. This allows for karyotypes

Chorionic villus sampling (CVS)

8th week of pregnancy- a suction tube is inserted vaginally to obtain fetal cells. This allows for karyotypes

Deletion Mutations of chromosome structure

removal or loss of a piece of a chromosome.

Duplication Mutations of chromosome structure

When a segment is repeated twice within one chromosome

Inversion Mutations of Chromosome Structure

is when a segment of a chromosome is removed, rotated 180° and reinserted in the opposite direction

Translocation Mutations of Chromosome Structure

when there is an exchange of genetic material between two non-homologous chromosomes

Aneuploidy Mutations of Chromosome Number

An abnormal chromosome number

Monosomy disorders Mutations of Chromosome Number

disorders that result due to a missing chromosome

Trisomy disorders Mutations of Chromosome Number

disorders that result due to an extra chromosome

Nondisjuction--the reason for aneuploidies Mutations of Chromosome Number

The failure of tetrads to separate into dyads during Anaphase I. OR The failure of dyads to separate into individual chromatids during Anaphase II = results in the wrong # of chromosomes in gametes

Autosomes

chromosomes that have nothing to do with an individual’s gender

Monosomies of any autosomes Mutations of Chromosome Number

lethal

Trisomies of autosomes Mutations of Chromosome Number

= may be lethal --*3 examples

Trisomy #13 Mutations of Chromosome Number autosomes

Patau’s syndrome has a cleft palate and hair lip Death occurs a few days after birth

Trisomy #18 Mutations of Chromosome Number autosomes

Edward’s syndrome Defects in multiple body systems Dies a few months after birth

Trisomy #21 Mutations of Chromosome Number autosomes

Down syndrome survive beyond 40 years of age

Monosomies of the sex chromosomes

Lethal in Males

YO Monosomies of the sex chromosomes

missing second sex chromosome X --> Lethal

XO Monosomies of the sex chromosomes

Missing second sex chromosome = female with Turner's syndrome

Turner’s syndrome (XO) Monosomies of the sex chromosome

Short, Web neck, underdeveloped ovaries = sterile A constriction of her aorta, she will ultimately have heart and kidney problems

XXY Trisomies of the sex chromosomes

extra sex chromosome Y = male with Klinefelter's syndrome

XXX Trisomies of the sex chromosomes

extra sex chromosome X = female with Metafemale syndrome/ Triplo-X

XXY Trisomies of the sex chromosomes

extra sex chromosome Y = normal male

Klinefelter’s syndrome (XXY) Trisomies of the sex chromosomes

excessively tall, have slight breast development, poor body hair growth, have underdeveloped testes -->will be sterile may have mild mental retardation.

Triplo-X (Metafemale) syndrome Trisomies of the sex chromosomes

physically normal female sterile due to under developed ovaries and uterus