Chapter 13.3

What are mutations?

They are changes in DNA that affect genetic information.

What is a point mutation?

It is a change in one or a few nucleotides.

What kinds of point mutations are there?

Substitution and inversion.

What is a frameshift mutation?

It is a mutation that shifts the reading frame.

What kinds of frameshift mutations are there?

Insertion and deletion.

What are chromosomal mutations?

They are mutations that involve changes in whole chromosomes.

How many codons does substitution affect?

It affects only a single codon.

Are the effects of substitution serious?

Generally, they are not serious unless they affect an amino acid that is essential for the structure and function of the finished protein molecule.

Is it possible for a mutation to have no effect on the phenotype?

Yes, it is possible for a mutation to have no effect on the phenotype. Changes in the third base of a codon often have no effect, for example.

Do inversion mutations affect a small part or a large part of the gene?

They only affect a small part of the gene.

Why do frameshift mutations cause the entire genetic code to shift?

They cause the entire genetic code to shift because they insert/delete whole nucleotides rather than changing one codon alone.

Is it possible for frameshift mutations to render proteins unable to perform their function?

Yes, it is possible for them to render proteins unable to perform their function since they shift the entire reading frame of the genetic message.

What is the difference between a chromosomal mutation and a genetic mutation?

The difference is that genetic mutations only affect one gene while chromosomal mutations change the number and structure of entire chromosomes.

What are the 4 kinds of chromosomal mutations?

Deletion, duplication, inversion, and translocation.

What of the 4 kinds of chromosomal mutations is exclusive to chromosomal mutations (and doesn't appear in genetic mutations)?

Translocation.

What happens when a chromosomal mutation involves deletion?

When a chromosomal mutation involves this, this means that a part of the chromosome is deleted.

What happens when a chromosomal mutation involves duplication?

When it involves duplication, this means that a part of the chromosome is duplicated.

What happens when a chromosomal mutation involves inversion?

When it involves inversion, this means that the chromosome twists and inverts the piece of DNA (chromosome); a segment breaks off the chromosome and reattaches, but it's backwards.

What happens when a chromosomal mutation involves translocation?

When it involves translocation, this means that genetic information is traded between non-homologous chromosomes.

What are the two ways in which DNA can become mutated?

The first way is through inheritance and the second is through acquiring them.

How can mutations be acquired?

They can be acquired through environmental agents (mutagens) or mistakes when DNA is copied.

What are the environmental agents (mutagens) that cause mutations?

Pesticides, tobacco, UV radiation, and nuclear radiation.

True or false: Most mutations are neutral and have no effect on the organism, but some can be harmful or beneficial as well.

True: Most mutations are neutral and have no effect on the organism, but some can be harmful or beneficial as well.

What are some examples of neutral mutations?

Eye color and birthmarks.

What are some examples of harmful mutations?

Sickle cell anemia (a point mutation).

What are some examples of beneficial mutations?

People with sickle cell anemia being immune to malaria, evolution causing genetic variation, and polyploidy crops.

What is gene expression?

It is building a protein based on the instructions of a gene (section of DNA).

What is gene regulation in prokaryotes?

It is when prokaryotes only transcribe genes for proteins they need. This is to conserve energy.

How does gene regulation in prokaryotes relate to gene expression?

Gene regulation in prokaryotes makes sure that gene expression is only done for the proteins that the organism needs, and not unnecessary ones whose production process would waste energy.

What is an operon?

It is a group of genes that determine if a protein is transcribed. (On and off switch.)

What is a lactose operon?

It is a group of genes that code for the enzymes (lactase) needed to digest lactose, the sugar in milk.

What is it called when a substitution changes the amino acid?

It is called a missense mutation.

What is it called when a substitution does not change the amino acid?

It is called a silent mutation.

What is it called when a substitution changes the amino acid to a stop codon?

It is called a nonsense mutation.

Which mutation outcome is responsible for new variations of a trait?

The mutation outcome is missense (substitution).

Which mutation outcome does not result in an abnormal amino acid sequence?

The mutation outcome is silent (substitution).

Which mutation outcome stops the translation of an mRNA molecule?

The mutation outcome is nonsense (substitution).