A mutation is a permanent change in the genetic material (DNA) of a cell. Mutations can occur in somatic cells (body cells) or germ cells (gametes).
There are two main types of gene mutations:
- Point mutations are changes in a single base pair of DNA. They can be caused by replication errors, exposure to radiation, or chemicals called mutagens.
- Frameshift mutations are insertions or deletions of one or more base pairs of DNA. They can disrupt the reading frame of the DNA, which changes the order of amino acids in the protein that is being coded for.
a. A silent mutation is a point mutation that does not change the amino acid sequence of the protein that is being coded for. This is because the altered base pair still codes for the same amino acid. Silent mutations are usually harmless.
b. A missense mutation is a point mutation that changes one amino acid to another. This can change the structure and function of the protein. Missense mutations can be harmful, but they are not always serious.
c. A nonsense mutation is a point mutation that changes a codon into a stop codon. This prematurely terminates the translation of the mRNA, resulting in a truncated and nonfunctional protein. Nonsense mutations are usually lethal.
a. Original DNA sequence: AGTTATTCGGCCTC
Mutated DNA sequence: A G A TAATTCGGCCTC
Type: Point mutation
Cause: Substitution
Mutation: Silent (no change in amino acid)
b. Original DNA sequence: CA ACTAGTAACCTCT
Mutated DNA sequence: C A ACTATAACCTCT
Type: Point mutation
Cause: Substitution
Mutation: Missense (change in amino acid)
c. Original DNA sequence: CTCGCAAGATTT
Mutated DNA sequence: CTCGCAACGATTT
Type: point mutation
Cause: Substitution
Mutation: Missense (change in amino acid)
See text below
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A mutated gene that interrupts the process of cell division is called a(n).
MUTATIONS:
What is a mutation?
What are the 2 types of Gene Mutations?
Define the terms (Pre-AP must define all 3):
a. Silent mutation:
b. Missense mutation:
c. Nonsense mutation:
Review the original strand of DNA and circle where the mutation occurred. Then identify if it is a Point or Frameshift Mutation and what caused the mutation-such as Substitution, Deletion or Insertion. Then state whether it caused a Silent, Missense or Nonsense Mutation.
a. Original DNA sequence: AGTTATTCGGCCTC
Mutated DNA sequence: A G A TAATTCGGCCTC
Is this Point or Frameshift?
Cause: Type:
b. Original DNA sequence: C AACTAGTAACCTCT
Mutated DNA sequence: C A ACTATAACCTCT
Is this Point or Frameshift?
Cause: Type:
c. Original DNA sequence: C T C GCAAGATTT
Mutated DNA sequence: C T C G CAACGATTT
Is this Point or Frameshift?
Cause:
Type: