Problem 1 What are the three main types of... [FREE SOLUTION]

Chapter 12: Problem 1

What are the three main types of point mutations? What change occurs in each?

Short Answer

Expert verified

The three main types of point mutations are substitution, insertion, and deletion. Substitution replaces one nucleotide with another, insertion adds an extra nucleotide, and deletion removes a nucleotide.

Step by step solution

Define Point Mutation

A point mutation is a genetic mutation where a single nucleotide base is changed, inserted, or deleted from a DNA sequence.

Identify the Three Main Types

The three main types of point mutations are substitution, insertion, and deletion.

Explain Substitution

In a substitution mutation, one nucleotide is replaced by another. For example, if adenine (A) is replaced by cytosine (C), it can change the resulting protein.

Explain Insertion

Insertion mutations occur when an extra nucleotide is added into the DNA sequence. This addition can shift the reading frame of the genetic code, potentially altering the function of the resulting protein.

Explain Deletion

In a deletion mutation, a nucleotide is removed from the DNA sequence. Similar to insertion, this can shift the reading frame and change the function of the resulting protein.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Genetic Mutation

A genetic mutation is a change that occurs in the DNA sequence of an organism. These changes can happen due to errors during DNA replication, or as a result of environmental factors like UV rays and chemicals. Mutations are essential for evolution as they introduce genetic diversity. They can be broadly categorized into point mutations and chromosomal mutations.

Point mutations affect a single nucleotide base in the DNA. These small changes can have a variety of effects, from negligible to significant, depending on where they occur and how they alter the genetic code.

Substitution Mutation

In a substitution mutation, one nucleotide is replaced by another in the DNA sequence. This is a type of point mutation. For example, if a cytosine (C) is replaced by a guanine (G), this changes the DNA message at that specific spot.

Substitutions can be divided into two main types:

**Silent Mutations**: These do not change the resulting protein, as the new codon still codes for the same amino acid.
**Missense Mutations**: These change one amino acid in the protein, which can affect its function.
**Nonsense Mutations**: These create a stop codon, leading to a truncated, usually nonfunctional protein.

Insertion Mutation

Insertion mutations add extra nucleotides into the DNA sequence. This can dramatically affect the genetic code because it may shift the reading frame (frameshift mutation).

For instance, if a guanine (G) is added to a sequence, the grouping of codons downstream from the insertion changes. This can result in different amino acids being added to the protein, possibly altering its structure and function.

Frameshift mutations usually result in nonfunctional proteins or truncated proteins, which can lead to diseases or disorders.

Deletion Mutation

Deletion mutations occur when a nucleotide is removed from the DNA sequence. Similar to insertions, deletions can also cause frameshift mutations because they shift the reading frame of the genetic code.

For example, if a thymine (T) is deleted, the codons downstream will be read incorrectly, potentially resulting in a malfunctioning protein.

Deletions can have severe consequences, often leading to genetic disorders or diseases due to the loss of essential protein function.

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What are the three main types of point mutations? What change occurs in each?

Short Answer

Step by step solution

Define Point Mutation

Identify the Three Main Types

Explain Substitution

Explain Insertion

Explain Deletion

Key Concepts

Genetic Mutation

Substitution Mutation

Insertion Mutation

Deletion Mutation

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