Unit 2A - Mutations - 9th Grade

Mutation (definition)

A permanent change that occurs in a DA sequence

What is one major reason for mutations?

Due to mistakes when the DNA is copied

What is another major reason for mutations?

As the result of environmental factors such as UV light and cigarette smoke

What are three environmental reasons for mutations?

Radiation (ex.: UV Radiation and X-Rays), Chemicals (ex: Cigarette smoke, Nitrates/Nitrites, Barbecuing, and Benzoyl Peroxide), and Infectious Agents (ex.: HPV and Helico. pylori)

Mutations fall into two basic categories:

Gene mutations and Chromosomal mutations

What is the main difference between gene mutation and chromosomal mutation?

Gene mutation is an alteration of the nucleotide sequence of a gene whereas chromosomal mutation is an alteration of the structure of number of chromosomes.

Some mutations cause a single ___ base (A, T, C, or G) to change to another and result in different ___ being coded for

nucleotide; amino acid

Types of Gene Mutations:

Silent mutations, Missense mutations, Nonsense mutations, and Frameshift mutations

Silent mutations (definition)

The mutated sequence codes for the same amino acid

Missense mutations (definition)

Changes one amino acid to another

Nonsense mutations (definition)

Result in a STOP codon; this results in a shorter protein

Frameshift mutations (definition)

The two types are deletion and insertion. In both cases all the following amino acids change

What are 2 types of frameshift mutations?

Insertion mutation and Deletion mutation

Insertion mutation (definition)

When a single extra base is added into the code

Deletion mutation (definition)

When a single base is removed from the code