Transcript Genetic Mutations

Genetic Mutations
Unit 2-2 Notes
Mr. Hefti – Pulaski Biology
1. Genetic Mutations
“a change in the DNA of a gene”
–Mutations in gametes can be
passed on to offspring
–Mutations in body cells affect only
the individual in which they occur
2. Categories
• Point Mutations
– Change in one or just a few bases in a gene
• Frameshift Mutations
– Cause genes to be read in the wrong threenucleotide sequence
Three nucleotide sequences are
called “codons”
New rule: when referring to the
amino acids that DNA codes for, T still
goes with A, but now A goes to U
(which stands for Uracil).
See if you can find the amino acid
that these DNA sequences code for
using the Universal Codon Chart…
CAT
GUA
T T A
= valine
A AU
= asparagine
Read from the top
second.
Read
from
this
side
first!
Then
read
from
this
side
third.
2A. Point Mutations
• Substitution
– One nitrogenous base is replaced with a
different one
–C T A G G A
–G A U C A U
• GAU = ? / CAU = ? / CCU = ?
–Aspartate / Histidine / Proline
2B. Frameshift Mutations
• Insertion
– One or more bases are added to a gene
–T A G C C T
–A G U C G G A
• AGU = ? / AUC = ? / CGG = ?
–Serine / Isoleucine / Arginine
2B. Frameshift Mutations
• Deletion
– One or more bases are deleted from a
gene
–C G A T A G
– __C U A U C
• GCU = ? / AUC = ?
–Alanine / Isoleucine
• CUA = ? / UC = ?
–Leucine / “Nothing”
3. Sources of Mutations
• X-rays
• UV rays
• Radiation
• Asbestos
• Alcohol
• LSD
• Marijuana
• Benzene
• Formaldehyde
4. Genetic Diseases
• Some genetic diseases are caused by
inherited mutations
– Sickle cell anemia
– Tay-Sach’s disease
– Cystic fibrosis
– Hemophilia
– Huntington’s disease
Sickle cell anemia
• Recessive
• Causes for the abnormal development of
rbc’s
• Sickle shape causes cells to break apart
or get jammed in blood vessels
Tay-Sach’s disease
• Recessive
• Causes infants’ nervous systems to break
down
– Death in early childhood
Cystic Fibrosis
• Recessive
• Causes for the overproduction of mucus
• Mucus clogs organs, especially lungs
making breathing difficult
Hemophilia
• Sex-linked recessive
• Blood clotting disorder
Huntington’s disease
• Dominant
• Causes brain to gradually deteriorate
• Usually goes unnoticed until adulthood