Mutations
Explore how changes in DNA affect organisms.
Learn
Types of Mutations
- Substitution: One base is replaced by another
- Insertion: Extra base(s) added to the sequence
- Deletion: Base(s) removed from the sequence
- Frameshift: Insertion or deletion shifts reading frame
- Causes: UV radiation, chemicals, copying errors
- Effects: Can be harmful, neutral, or beneficial
Practice
Question 1: What is a mutation?
Answer
A mutation is a change in the DNA sequence that can alter the genetic information.
Question 2: If the original sequence is ATG-GCA-TTT and becomes ATG-GTA-TTT, what type of mutation occurred?
Answer
Substitution mutation - the C was replaced by T.
Question 3: Why are frameshift mutations often more harmful than substitutions?
Answer
Frameshift mutations change every codon after the mutation, affecting many amino acids, while substitutions only affect one.
Question 4: Name two environmental factors that can cause mutations.
Answer
UV radiation and certain chemicals (mutagens) can cause mutations.
Question 5: What is a deletion mutation?
Answer
A deletion mutation occurs when one or more nucleotide bases are removed from the DNA sequence.
Question 6: Can mutations be beneficial? Give an example.
Answer
Yes, some mutations provide advantages. Example: bacteria can develop antibiotic resistance through beneficial mutations.
Question 7: What type of mutation adds extra nucleotides to DNA?
Answer
Insertion mutation adds extra nucleotides to the sequence.
Question 8: If a mutation occurs in a body cell (not a sex cell), can it be inherited?
Answer
No, mutations in body cells (somatic cells) cannot be passed to offspring. Only mutations in sex cells (gametes) are heritable.
Question 9: The sequence CAT-CAT-CAT becomes CA-TCA-TCA-T after a mutation. What happened?
Answer
A deletion of one T caused a frameshift mutation, changing how the sequence is read.
Question 10: Why might some mutations have no effect on an organism?
Answer
Silent mutations don't change the amino acid produced, or the mutation may occur in non-coding DNA regions.