12.1 Mutations Reading Questions

What is nondisjunction?

• Failure of genes to be passed on to future generations

• A mutation caused by the environment

• Failure of chromosomes to separate properly

• A duplication of genes on a chromosome

Mutations in DNA molecules can occur when —

• replication of DNA is exact

• a DNA enzyme attaches to an RNA codon

• RNA codons are replaced by DNA nucleotides

• a change occurs in DNA nucleotide bases

Which of the following changes would be expected in the amino acid chain if the following mutation occurred?

(use the codon chart)

ACG GUC CCG - ACG GCC CCG

• The amino acid sequence would be shorter than expected.

• The identity of one amino acid would change

• The amino acid sequence would remain unchanged.

• The identities of more than one amino acid would change.

Which part of DNA provides instructions for how to produce a protein?

• The sequence of nitrogen bases

• The sugar molecules

• The phosphate groups

• The bonds that hold the sugar and bases together

Substitutions, insertions, and deletions are known as “point” mutations because they

• change the genetic information of DNA

• affect the structure of a chromosome

• involve only a single nucleotide

• change the amino acid that is inserted into a protein

Which of the following can be a mutagen?

• an inversion

• a toxic chemical

• a nucleotide

• a random mutation

The DNA sequence TTT codes for the amino acid lysine. The DNA sequence TTC also codes for lysine. What can you conclude from this information?

• a deletion in the genetic instructions may not be significant

• adding a nucleotide to a genetic sequence has no effect

• any substitution that changes the genetic code affects a trait

• this kind of substitution in the genetic code may go unnoticed

Which two types of biomolecules are directly affected by a mutation?

• nucleic acids and lipids

• nucleic acids and carbohydrates

• proteins and nucleic acids

• proteins and carbohydrates

Any permanent change in a gene is called a

When can a mutation be passed on to offspring?