Biology 101: Intro to Biology Ch 12. Types & Effects of Genetic Mutations

Mutation

• any change in the nucleotide sequence of an organism’s DNA

• a permanent change in a DNA sequence

Point Mutations

• changes in the genetic sequence that occur at a specific point along the DNA strand

• base substitutions

• insertions & deletions

• smaller mutations and typically affect one or two bases

Base Substitutions

• point mutations in which one nitrogenous base is substituted by a different base

• transitions

• transversions

Transistions

base substitutions that swap a purine for another purine or a pyrimidine for another pyrimidine

Purines

adenine and guanine

Pyrimidines

thymine and cytosine

Transversion

base substitutions that swap a purine for a pyrimidine, or vice-versa

Insertion

a point mutation in which one or more base pairs is added to a DNA sequence

Deletion

a point mutation in which one or more base pairs is removed from a DNA sequence

A type of point mutation that alters the length of the DNA strand is _____.

1. A base substitution

2. A transition.

3. A deletion.

4. An transversion.

A deletion.

The best term to describe the incorporation of a random mistake into the DNA sequence at a specific point is _____.

1. A base deletion

2. A base insertion

3. A chromosomal mutation

4. A point mutation

A point mutation

An example of a transversion mutation is _____.

1. A cytosine substituted for a thymine.

2. An adenine substituted for a guanine.

3. A thymine substituted a cytosine.

4. A guanine substituted for a thymine.

A guanine substituted for a thymine.

Based on the original sequence, ACTTGAC, which of the following answer choices includes a transition mutation?

1. ACTTTAC

2. ACTTCAC

3. ACTTGGC

4. ACTTGTC

ACTTGGC

_____ mutations result in a longer DNA strand.

1. Deletion

2. Transition

3. Insertion

4. Transversion

Insertion

Missense Mutation

a point mutation that changes a codon to indicate a different amino acid

Nonsense Mutation

early termination of a polypeptide

Silent Mutation

a point of mutation that has no overall effect on a protein’s function

A mutation in DNA can affect the amino acid sequence because it affects the code found in _____.

1. mRNA

2. tRNA

3. the nucleus

4. rRNA

mRNA

Which type of mutation does NOT change the overall function of the protein?

1. missense

2. nonsense

3. insertion

4. silent

silent

Which type of mutation results in an incomplete polypeptide because of an early stop signal?

1. missense

2. silent

3. nonsense

4. insertion

nonsense

The eleventh amino acid of protein X should be serine, however, due to a mutation it now has the amino acid alanine in that position. Which type of mutation could have caused this change?

1. Silent

2. Nonsense

3. Translocation

4. Missense

Missense

What kind of mutation causes sickle-cell anemia?

1. nonsense

2. missense

3. silent

4. insertion

missense

Mutagen

• environmental agent that causes a mutation

• any chemical or physical agents that cause a mutation’s in an organism’s DNA

DNA polymerase

proofreads after DNA replication

Mutagens are typically found _____.

1. in the air

2. in an organism's food

3. in an organism's environment

4. in the ground

in an organism's environment

How do mutagens cause mutations?

1. By increasing the likelihood of a replication error

2. By decreasing the likelihood of finding food

3. By increasing vulnerability to predators

4. By decreasing the immune response

By increasing the likelihood of a replication error

When can a genetic mutation get passed down through successive generations?

1. When it makes the organism faster

2. When it makes the organism stronger

3. When it doesn't cause significant harm to the organism's ability to survive and reproduce

4. When it makes the organism healthier

When it doesn't cause significant harm to the organism's ability to survive and reproduce

Why do people try to protect their skin from ultraviolet radiation?

1. UV radiation is a mutagen.

2. UV radiation comes from the environment.

3. UV radiation causes tanning.

4. UV radiation always causes mutations.

UV radiation is a mutagen.

Which enzyme checks DNA for errors?

1. DNA polymerase

2. RNA primase

3. RNA polymerase

4. DNA helicase

DNA polymerase

Reading Frame

a way of dividing the mRNA into codons and focusing on one codon at a time

Frameshift Mutation

a mutation caused by an insertion or deletion, which causes a shift in the translation reading frame

How does a frameshift mutation in the gene coding for the enzyme, hexosaminidase A, result in Tay-Sachs disease?

1. The mutation results in incorrect synthesis of the enzyme.

2. The mutation does not alter production of the enzyme.

3. The mutation prevents synthesis of the enzyme.

4. The mutation results in over production of the enzyme.

The mutation results in incorrect synthesis of the enzyme.

How would a shift in the reading frame likely alter the resulting protein?

1. The protein would be not be altered because the reading frame does not affect the resulting protein.

2. Any alteration to the reading frame would prevent the protein from being formed.

3. The protein would be only slightly altered because a single amino acid would be miscoded.

4. The protein would be greatly altered because multiple amino acids would be miscoded.

The protein would be greatly altered because multiple amino acids would be miscoded.

Which type of mutations can result in a frameshift?

1. Nonsense and missense

2. Missense and deletions

3. Nonsense and insertions

4. Insertions and deletions

Insertions and deletions

Which of the following modifications of this DNA sequence, ACTGAC, would be considered a frameshift mutation?

1. ACAGAC

2. ACTGAT

3. ACCTGAC

4. AGTGAC

ACCTGAC

The deletion of a base in the DNA strand will _____.

1. Not alter the mRNA strand but will result in a modification to the subsequent amino acid.

2. Result in the deletion of a base in the mRNA strand and the removal of the subsequent amino acid.

3. Result in the deletion of a base in the mRNA strand and a modification to the subsequent amino acid.

4. Not alter the mRNA but will result in the removal of the subsequent amino acid.

Result in the deletion of a base in the mRNA strand and a modification to the subsequent amino acid.

DNA

the unit of heredity in all organisms

Nucleotides

the repeating units of a DNA sequence

Genes

sequences of DNA that code for proteins

_____ is used to describe a mutation in which one nitrogenous base is replaced by another.

1. Insertion

2. Base substitution

3. Frameshift

4. Deletion

Base substitution

In point mutations, there are changes in one or a few nucleotides at a single location in a DNA sequence.

Which of the following is NOT a nucleotide?

1. Guanine

2. Thymine

3. Ribose

4. Adenine

Ribose

Part of a normal DNA sequence is TACCGG. If this sequence undergoes a base substitution, out of the possibilities given identify the sequence that could be a possible result.

1. TACAGG

2. TACGG

3. TACCGG

4. TACCGGA

TACAGG

What are mutations that result in DNA sequences that are slightly too long or too short called?

1. Point mutation

2. Sickle cell mutation

3. Frameshift mutation

4. Codon mutation

Frameshift mutation

How are the Tay Sachs and the Duchenne Muscular Dystrophy diseases different?

1. Tay Sachs is caused by a nucleotide base substitution of the hexosaminidase gene while the Duchenne Muscular Dystrophy is caused by addition of a nucleotide base to the dystrophin gene.

2. Tay Sachs is caused by a nucleotide base substitution of the hexosaminidase gene while the Duchenne Muscular Dystrophy is caused by deletion of a nucleotide base from the dystrophin gene.

3. Tay Sachs is caused by the deletion of a nucleotide base from the hexosaminidase gene while the Duchenne Muscular Dystrophy is caused by addition of a nucleotide base to the dystrophin gene.

4. Tay Sachs is caused by insertion of a nucleotide base into the hexosaminidase gene while the Duchenne Muscular Dystrophy is caused by deletion of a nucleotide base from the dystrophin gene.

Tay Sachs is caused by insertion of a nucleotide base into the hexosaminidase gene while the Duchenne Muscular Dystrophy is caused by deletion of a nucleotide base from the dystrophin gene.