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Mutations
Let’s review what we previously learned about Nucleic Acids and Protein Synthesis
• DNA codes for mRNA,
• mRNA carries the information
needed for the synthesis of
coded proteins in the ribosomes.
• tRNA is the go-for that brings the
amino acids to the ribosomes to
make the protein).
• Does this process ever make a mistake?
• Have you ever had to copy a large amount
of information?
• What is the likelihood of you making a
mistake or more?
• What could cause these changes?
Changes in genetic material
1. Gene Mutations:
alters one or more genes
2. Chromosomal Mutations:
alter the entire chromosome or a
portion of it.
GENE MUTATIONS
a. Point Mutations – affect only one
amino acid
b. Frameshift mutations – May affect an
entire amino acid sequence.
Point mutation
• involves a change in one or a few
nucleotides.
• Influences a single amino acid in the
polypeptide change. Caused by a
substitution of a Nitrogen base.
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THE FAT CAT ATE THE RAT
Take out “C” in Cat & substitute a “B”
THE FAT BAT ATE THE RAT
Does not really change the meaning to
the sentence or the protein formed
• If DNA reads: A T G G T C G A T T G G CAA
• mRNA:
U A C C A G C U A AC C GUU
• Amino Acid:
Tyrosine - Glutamine – Leucine -Threonine – Valine
• But if mRNA: U A C C A G C A A AC C GUU
• The AA:
Tyrosine – Glutamine – Glutamine – Threonine – Valine
Frameshift mutation
• involves a change in the entire protein
formed or a large portion of it.
• Caused by insertions (additions) or
deletions of Nitrogen bases.
• THE FAT CAT ATE THE RAT
• Take out “E” in THE & group into
3’s
• THF ATC ATA TET HER AT_
This makes no sense at all!!
• If DNA reads: A T G G T C G A T T G G CAA
• mRNA:
U A C C A G C U A AC C GUU
• AA:
Tyrosine - Glutamine – Leucine -Threonine – Valine
• BUT if mRNA: U A C C A G U A A C C G U U _
• THEN Amino Acid: Tyrosine - Glutamine – STOP!!!!
• The entire sentence makes no sense.
The protein formed would be totally
different
So which form of a mutation
would be more severe?
• Frameshift mutation …
since an entirely new protein would
be formed
CHROMOSOMAL MUTATIONS
• involve changes in number and
structure of the chromosomes.
• Could change location of genes on the
chromosomes or the number of copies
of some of the genes.
• Deletions – part of a chromosome is missing
Duplications – Extra copies of genes are
inserted
• Inversions – Reverse direction of parts of the
chromosome
Chromosomal Mutations animation
Translocations
Parts of one non-homologous chromosome
breaks off and attached onto another nonhomologous chromosome