2.4.1 Types of Mutations

• Genetic mutations are changes in the sequence of DNA
• Chemical mutagens like base analogs can cause mutations by mimicking DNA bases
• Match the type of mutation with its description:

  Point Mutations ↔️ Change in a single nucleotide base pair

  Frameshift Mutations ↔️ Insertion or deletion of nucleotides that shift the reading frame

  Chromosomal Mutations ↔️ Changes in chromosome structure or number
• What type of mutation occurs when a codon changes from $GUU$ to GUC</latex>?


  Synonymous
• A missense mutation results in a change to a different amino acid.
• A nonsense mutation always results in a shortened protein
• What is an example of a point mutation in DNA sequence?

  $A$ to $T$
• Point mutations involve a change in a single nucleotide
• What type of point mutation results in no change in the amino acid sequence?

  Synonymous
• A nonsense mutation changes a codon to a stop codon.
• The synonymous mutation example shows a change from $GUU$ toGUC</latex>, both coding for valine
• Match the mutation type with its description:

  Point Mutations ↔️ Change in a single nucleotide

  Frameshift Mutations ↔️ Insertion or deletion of nucleotides

  Chromosomal Mutations ↔️ Changes in chromosome structure
• Effects of a frameshift mutation on the reading frame

  1️⃣ Insertion or deletion of nucleotides not in multiples of three

  2️⃣ Shift in the reading frame

  3️⃣ Change in the amino acid sequence

  4️⃣ Production of non-functional protein
• What is the effect of a frameshift mutation on the amino acid sequence?

  Alters amino acid sequence
• Frameshift mutations typically result in functional proteins.

  False
• If the original sequence $ATC - GAT - CGA$ has an $A$ inserted after $ATC$, the new sequence becomes $ATC - A - GAT - CGA$, altering the codons
• Match the chromosome mutation type with its description:

  Deletion ↔️ Loss of a chromosome segment

  Duplication ↔️ Extra copy of a chromosome segment

  Inversion ↔️ Reversal of a chromosome segment

  Translocation ↔️ Transfer of a segment to another chromosome
• What are numerical changes in chromosomes called?

  Aneuploidy and polyploidy
• Down syndrome is an example of aneuploidy caused by an extra copy of chromosome 21
• Polyploidy refers to having multiple complete sets of chromosomes.
• What are the two main categories of chromosome mutations?

  Structural and numerical
• A deletion in chromosome structure involves the loss of a chromosome segment
• An inversion in chromosome structure reverses a chromosome segment.
• What is an example of aneuploidy in humans?

  Down syndrome
• Polyploidy refers to having multiple sets of chromosomes
• Down syndrome is caused by an extra copy of chromosome 21.
• What are the structural changes in chromosome mutations?

  Deletions, duplications, inversions, translocations
• An inversion in chromosome structure results in a changed gene order
• Match the numerical change with its description:

  Aneuploidy ↔️ Extra or missing chromosomes

  Polyploidy ↔️ Multiple sets of chromosomes
• Genetic mutations can be caused by chemical mutagens.
• Point mutations involve a change in a single nucleotide base pair
• What type of mutation shifts the reading frame of DNA?

  Frameshift mutation
• Match the cause of mutation with its example:

  UV radiation ↔️ Thymine dimers

  Base analogs ↔️ Incorporation into DNA
• What are the three types of point mutations based on their effects?

  Synonymous, missense, nonsense
• A missense mutation results in a change to a different amino acid.
• A synonymous mutation changes the codon but not the amino acid.
• What is the effect of frameshift mutations on the reading frame?

  Shifts the reading frame
• An example of a frameshift mutation is the insertion of an A
• Match the mutation type with its description:

  Frameshift ↔️ Insertion or deletion of nucleotides

  Point ↔️ Single nucleotide base substitution
• What is the example of aneuploidy provided in the study material?

  Trisomy 21