Download Dna Mutations

• Point mutations (only affect one base
in a codon)
• Frameshift mutations—alter the way
the codons are read
• Substitution: a mutation that exchanges one base for
another
• Causes:
• change to a codon to one that encodes a different
amino acid and cause a small change in the protein
produced
• change a codon to one that encodes the same amino
acid and causes no change in the protein produced.
These are called silent mutations.
• change an amino-acid-coding codon to a single "stop"
codon and cause an incomplete protein. This can have
serious effects since the incomplete protein probably
won't function.
• Frameshift mutation: changes that can alter
a gene so that its message is no longer
correctly expressed
•Insertions: mutations in which extra bases
are inserted into a new place in the DNA
• Example:
•Deletions: mutations in which a section of
DNA is lost, or deleted.
• Example:
• Sickle cell anemia is the result of a type of
mutation in the gene that codes for part of the
hemoglobin molecule. Recall that hemoglobin
carries oxygen in your red bloods cells. The
mutation causes these red blood cells to
become stiff & sickle-shaped when they release
their oxygen. The sickled cells tend to get stuck
in blood vessels, causing pain and increased risk
of stroke, blindness, damage to the heart &
lungs, and other conditions.
• Analyze the DNA strands below to determine which
amino acid is changed
• Normal hemoglobin DNA
• ACGTAGACTGAGGACTCC
• Normal hemoglobin mRNA
• Normal hemoglobin AA sequence
• Sickle cell hemoglobin DNA
• ACGTAGACTGAGGACACC
• Sickle cell hemoglobin mRNA
• Sickle cell hemoglobin AA sequence
• What type of mutation is this? Please explain why.