6.7 Mutations

• Mutations can occur during DNA replication or through exposure to external agents called mutagens
• Match the point mutation type with its description:

  Substitution ↔️ One nucleotide is replaced by another

  Insertion ↔️ One or more nucleotides are added

  Deletion ↔️ One or more nucleotides are removed
• A chromosomal mutation where a section of the chromosome is repeated is called duplication
• In a chromosomal translocation, a segment from one chromosome moves to a non-homologous chromosome
• What is the result of a chromosomal duplication?

  ABC → ABCABC
• Mutations can only occur during DNA replication.

  False
• What are the two main causes of mutations?

  DNA replication errors and mutagens
• In a substitution mutation, one nucleotide is replaced by another
• What are mutations in DNA sequence called?

  Changes
• What is a point mutation?

  Single nucleotide change
• Chromosomal mutations involve changes in large segments of chromosomes.


  True
• What happens in a chromosomal inversion?

  A section is flipped
• Give an example of a substitution mutation.

  ATG → ACG
• In a chromosomal inversion, the sequence ABC is flipped to CBA
• Classify the different types of mutations based on whether they are point mutations or chromosomal mutations:

  1️⃣ Point mutations

  2️⃣ Substitution

  3️⃣ Insertion

  4️⃣ Deletion

  5️⃣ Chromosomal mutations

  6️⃣ Duplication

  7️⃣ Inversion

  8️⃣ Translocation
• What is a point mutation?

  Change at a single nucleotide
• An insertion mutation adds nucleotides to a DNA sequence.


  True
• In a duplication mutation, a section of the chromosome is repeated
• What occurs in a translocation mutation?

  A chromosome segment moves
• What is the primary cause of DNA replication errors?

  Mistakes during replication
• What is the effect of a neutral mutation?

  No effect on gene function
• What is the effect of a beneficial mutation?

  Enhances gene function
• A frameshift mutation occurs when nucleotides are inserted or deleted, altering the reading frame of the DNA sequence.


  True
• During proofreading, DNA polymerase can detect and correct mismatched nucleotides
• What does nucleotide excision repair remove from DNA?

  Damaged DNA segments
• Steps of DNA repair mechanisms

  1️⃣ Proofreading by DNA polymerase

  2️⃣ Mismatch repair recognizes errors

  3️⃣ Nucleotide excision repair removes damaged segments

  4️⃣ Base excision repair corrects individual bases
• What happens in a deletion mutation?

  Nucleotides are removed
• Steps of an inversion mutation

  1️⃣ A section of the chromosome is identified

  2️⃣ The section is flipped

  3️⃣ The flipped section is reattached
• Match the type of mutation with its description:

  Point Mutation ↔️ Changes at a single nucleotide

  Chromosomal Mutation ↔️ Changes in large chromosome segments

  Mutagen ↔️ External agent that causes mutations
• Mutagens can cause both point and chromosomal mutations.


  True
• A harmful mutation can lead to a non-functional protein
• Match the mutation type with its potential effect:

  Substitution ↔️ Neutral, harmful, or beneficial

  Insertion ↔️ Often harmful, causing a frameshift

  Duplication ↔️ Beneficial by increasing gene expression
• What determines the specific impact of a mutation?

  Mutation location and gene function
• Mismatch repair replaces incorrectly paired nucleotides.

  True
• Base excision repair detects and removes damaged individual DNA bases