Transcript File - Down the Rabbit Hole

Mutations are a result in a change in DNA
sequence

›
A protein with a different AA sequence could be
produced.
›
Germ Cell - If mutations occur in sex cells they may
be passed on to the next generation.
›
Somatic- A mutation occurring only in body cells
may be a problem for the individual but will not be
passed on to the offspring.
Mutations may be classified as chromosomal
alterations or gene mutations

›
Chromosomal alterations are generally more severe
because many genes are usually involved.
Significance of Mutations
Most are neutral
• Eye color
• Birth marks
• Some are harmful
• Cystic Fibrosis
• Down Syndrome
• Some are beneficial
• Sickle Cell Anemia to Malaria
• Immunity to HIV
•
What Causes Mutations?

There are two ways in which DNA can become
mutated:
– Mutations can be inherited.
 Parent to child
– Mutations can be acquired.
 Environmental damage
 Mistakes when DNA is copied
Silent mutation

›
any mutation that is not expressed
because it does not cause a
change in amino acid chain.
Point mutation

base-pair substitution
› 1 base is replaced by a different base
›
• Point mutation
• Only one nucleotide
changes, but it makes a
different protein
Gene Mutations

Point Mutations – changes in one or a
few nucleotides
– Substitution
 THE FAT CAT ATE THE RAT
 THE FAT HAT ATE THE RAT
– Insertion
 THE FAT CAT ATE THE RAT
 THE FAT CAT XLW ATE THE RAT
– Deletion
 THE FAT CAT ATE THE RAT
 THE FAT ATE THE RAT
•
Frameshift
• Causes every codon in the DNA sequence to
be changed after the mutation:
• Insertion- one or more bases are added
• Deletion- one or more bases are removed
A
Deletion - part of chromosome is left out.
Duplication - part of chromatid breaks off
add attaches to the sister chromatid
creating a duplication of genes on the
same chromosome.


›


Deletion and duplication mutations are errors
that occur during crossing over in Meiosis I.
Translocation - when part of one
chromosome breaks off and is added to
a different chromosome.
Inversion - when part of a chromosome
breaks off and is reinserted backwards.
Chromosome Mutations
Changes in number and structure of entire
chromosomes
 Original Chromosome ABC * DEF
 Deletion
AC * DEF
 Duplication
ABBC * DEF
 Transposition
ACB * DEF
 Inversion
AED * CBF
 Translocation
ABC * JKL
GHI * DEF

Chromosomal Deletion
A dinky Y chromosome
and the hairy ear gene
on the Y chromosome