Download Mutations

Mutations
What is a mutation?

Changes in the DNA
sequence that affect genetic
information.
Gene Mutations

Result from changes in a
single gene.

3 Types:
Substitution
 Insertion (Frame-shift)
 Deletion (Frame-shift)

Point Mutations

Substitution

One nucleotide replaces another.

Usually changes one amino acid in
the sequence of the protein.

Ex: sickle cell anemia
Point Mutation (Substitution)
Frame Shift Mutations

Insertion/Deletion




Insertion - the addition of a
nucleotide.
Deletion - the removal of a
nucleotide.
Bases are still read in groups of
three (codons).
Changes many amino acids in the
sequence of the protein
Frame Shift Mutation (Insertion)
Frame Shift Mutation (Deletion)
Which
would
you
rather
have?
What Causes Mutations?

May occur spontaneously
during cell division/meiosis.
X-rays
 Asbestos
 Insecticides
 UV light
 Radioactive substances

How Are Mutations Passed On?

The mutation must happen in
a sex cell (gamete).
Chromosomal Mutations



Involve changes in whole chromosomes.
chromosomal mutations
5 types:
1. Translocation
2. Duplication
3. Deletion
4. Inversion
5. Nondisjunction
Chromosomal Mutations
Deletion, Inversion, Translocation, Duplication
https://www.youtube.com/watch?v=FgMKGIED4Yo
Chromosomal Mutations
https://www.youtube.com/watch?v=FgMKGIED4Yo
Nondisjunction

An error that occurs during meiosis
in which homologous chromosomes
fail to separate properly.

One gamete may receive two of the
same type of chromosome and
another gamete receives no copy.
Ex- down syndrome

Down Syndrome (Trisomy 21)



Trisomy: having three copies of one
chromosome.
Down Syndrome is caused by a trisomy on the
21st chromosome.
Likelihood of this disorder increases with the
increasing age of the mother.
Age of Mother vs. Down Syndrome
Ways to Detect Genetic Disorders

Karyotyping- prepared enlarged
photograph showing paired homologous
chromosomes from a cell.

May show chromosomal abnormalities
such as an extra or missing chromosome.
Testing for Down Syndrome
https://www.youtube.com/watch?v=Juq4OnBtNU
http://www.bmhvt.org/healthmatters/prosand-cons-of-genetic-screening-duringpregnancy
Medical Genetic Research

Generates knowledge used to design
ways of diagnosing, preventing,
treating, controlling, or curing
diseases of plants and animals.
Genetic Counseling

Discussions between physician and
the family which may include
inheritance patterns, prediction of
genetic disorders, and family
planning.
 Screening
 Karyotyping
 Amniocentesis
Screening

Chemical analysis of body fluids such
as blood and urine. Analysis may
indicate the presence of chemicals
associated with genetically-related
disorders.
Amniocentesis


Involves the removal of amniotic
fluid for chemical analysis.
This technique can show the
chromosome content of the cells of
the embryo.
Amniocentesis
https://www.yout
ube.com/watch?v
=bZcGpjyOXt0
Genetic Disorders



PKU (Phenylketonuria):
individuals lack the enzyme that is
needed to break down phenylalanine.
If a newborn has PKU, phenylalanine
may build up in the tissues during
the child’s first years of life and
cause severe mental retardation.
https://www.youtube.com/watc
h?v=XKSoMi4U-1k
Genetic Disorders: PKU
Genetic Disorders


Tay-Sachs Disease:
lipid
accumulation in the brain cells,
mental deficiency, blindness, death
in early childhood.
https://www.youtube.com/watc
h?v=RzEpkBU-ITA