Genetic Code and Mutation - An Overview

Mutations and genetic code are closely linked. Mutations are changes in the DNA sequence that can change the genetic code. It can lead to variations in traits or genetic disorders. The genetic code is the set of rules by which DNA or RNA sequences are translated into proteins. Mutations can occur naturally or due to environmental factors and may affect protein synthesis. Mutation and the genetic code are key parts of the molecular basis of inheritance.

This Story also Contains

1. What is Mutation and Genetic Code?
2. Genetic Code
3. Mutation
4. Types of Mutations
5. Relationship Between Mutation and Genetic Code
6. Importance of the Mutation and Genetic Code
7. Recommended video for Genetic Code and Mutation
8. MCQs on Genetic Code and Mutation

The genetic code is made of codons. A mutation can change these codons. Mutation and the genetic code impact gene interaction. Some mutations are silent, others harmful. Mutations may be inherited or random. In this article, mutation and genetic code, types of mutations, and the importance of the mutation and genetic code are discussed. Genetic code and mutations lead to variations and play a role in evolution.

What is Mutation and Genetic Code?

The genetic code is considered the set of rules by which the information in the DNA sequence is translated into amino acids that form proteins. It is important in the structure and function of cells. The process is known as protein synthesis. It is the foundation of molecular biology. The genetic code guides all cell functions.

The genetic code is important in biology because it outlines the mechanisms at the molecular level in life. The genetic code is universal and specific. It helps transfer information across generations. It supports research in genetics, biotechnology, and medicine.

Mutation is a change in the DNA sequence. It may be natural or environmentally induced. Mutations can be helpful, harmful, or silent. They affect gene regulation and gene expression. Mutation is key to evolution and diseases. It plays a role in genetic variation.

Genetic Code

The genetic code is the sequence of nucleotides—adenine, cytosine, guanine, and thymine—in DNA or RNA that specifies the amino acid sequence in a protein. The decoding of the genetic code was one of the high points of molecular biology. It was the discovery of a universal shared language of all living creatures.

Genetic code is the instructions by which information contained in the DNA or RNA molecules is used to build a protein by cells of living organisms with the help of sets of three molecules of nucleotides known as codons. The codons are referred to as triplets of nucleotides that specify particular amino acids and several types of RNA molecules (mRNA, tRNA, and rRNA) that make the process of transcription-translation possible.

Mutation

A mutation is generally defined as any permanent change in the DNA sequence coding for a gene. This can add a change in the sequence of just a single DNA building block—a nucleotide—or several nucleotide pairs. It can be added to or removed from the DNA molecule. Mutagens are agents that increase the rate of mutations by altering the DNA structure. It involves large-scale chromosomal changes at the level of genes, including gene duplications and deletions, and chromosomal rearrangements. Any change in the genetic code and mutation can lead to altered or faulty proteins in the body. A genetic mutation is a change in the DNA sequence that can affect how genes function.

Types of Mutations

The change in the DNA sequence affects the amino acid composition of proteins, with eventual changes in their structure and function.

• Point Mutations

A point mutation is when a single nucleotide base changes in the DNA. These changes might mostly arise during replication of DNA or repair processes and may or may not have serious effects on protein synthesis.

• Silent Mutations

These are mutations that do not alter the amino acid sequence of the protein. One of the reasons is the redundancy or degeneracy in the genetic code: more than one codon may code for an amino acid. Hence, such a mutation might happen in the non-coding region of the gene or the coding region but without bringing a change in the amino acid encoded.

• Missense Mutations

In a missense mutation, one amino acid is replaced with another. This can change the shape or function of a protein. The impact depends on how important that part of the protein is. Some may cause diseases, while others have no effect.

• Nonsense Mutation

A nonsense mutation introduces a stop codon into the mature mRNA sequence. Such nonsense mutations result in protein truncation, which cuts short the length of the protein, rendering it nonfunctional because the premature process of translation stops. Nonsense mutations typically result in a loss-of-function mutation: the earlier such a mutation occurs within the sequence, the more drastically different the size of the peptide produced is from that of the wild type encoded for by the normal mRNA.

• Frameshift Mutation

The frameshift mutation is a mutation that consists of nucleotide insertion or deletion, changing the reading frame of the sequence during expression. The reading frame changes; that is, the codons are regrouped, and, hence, a different sequence of amino acids is formed downstream of the mutation.

• Insertions Mutation

Insertion mutations add extra bases into the DNA. This extra DNA can change the reading frame. The protein made is often very different and does not work. If the insertion happens in a key gene, it can cause a disorder.

• Deletions Mutation

Deletions remove one or more nucleotide base pairs from the DNA sequence. As with insertions, this change disrupts the reading frame of the codons downstream from that site. Such an alteration in sequence can then greatly alter the amino acid sequence of the resulting protein, usually causing the protein to be nonfunctional or severely impaired in function.

Relationship Between Mutation and Genetic Code

The genetic code is a set of instructions found in DNA that tells the cell how to build proteins. A mutation is a change in the DNA sequence. When a mutation occurs, it can alter the genetic code and may affect how proteins are made. Some mutations are harmless, while others cause disease. These changes also create genetic variation in populations. This relationship is important in understanding genetic variation, evolution, and diseases.

Importance of the Mutation and Genetic Code

Mutation and genetic code play a vital role in biology and genetics. The genetic code controls how traits are expressed, while mutations introduce changes in this code. These changes can lead to new traits, diseases, or adaptations.

• Medical Applications: Genetic disorders; treatment and diagnosis; medical practice based on an individual's genetic profile.

• Agriculture Application: Improvement of plant variety through genetic engineering to increase yield, resistance to pests, and improvements in nutrition.

• Evolutionary Biology: The role of mutation in generating genetic variation; Adapting to changing environments and driving the process of evolution.

Recommended video for Genetic Code and Mutation

MCQs on Genetic Code and Mutation

Question: What is not true for genetic code?

1. It is nearly universal

2. It is degenerate

3. It is unambiguous

4. A codon in mRNA is read in a non-contiguous fashion

Answer: DNA or mRNA sequences and amino acid sequences are connected through the genetic code, where each triplet of nucleotides, called a codon, encodes one of the 20 amino acids (e.g., glutamic acid, methionine, phenylalanine, serine, tryptophan, tyrosine, etc.). There are 64 codons in total, and the genetic code is read in a continuous and non-overlapping manner. The statement that codons are read in a "non-contiguous manner" is false, as codons are read sequentially without any spaces or interruptions between them. This continuous reading ensures that each codon is translated directly into an amino acid without any punctuation or gaps.

Hence, the correct answer is option 4) A codon in mRNA is read in a non-contiguous fashion

Question: A Transition or transversion mutation could result due to

1. Base pair mutation

2. Silent mutation

3. Nonsense mutation

4. Missense mutation

Answer: Mutations are changes in the DNA sequence that can affect gene expression and function. In addition to base-pair substitutions, mutations include insertion (addition of one or more nucleotides) and deletion (removal of nucleotides), which can cause frameshifts. Mutations can also be classified as silent, missense, or nonsense based on their impact on protein synthesis. These changes are significant in evolution, genetic disorders, and the understanding of cellular processes. Base-pair substitution is of two types:

• Transition mutation: When one purine is replaced by another purine or one pyrimidine is replaced by another pyrimidine.

• Transversion mutation: When one purine is replaced by a pyrimidine and vice versa.

Hence, the correct answer is option (1) Base pair mutation. .

Question: Which of the following is a type of gene mutation

1. Deletion

2. Addition

3. Substitution

4. All of these

Answer: Type of gene mutation:

• Deletion: This is a type of mutation where one or more nucleotide bases are removed from the DNA sequence.

• Addition: This is when one or more nucleotide bases are added to the DNA sequence.

• Substitution: This occurs when one nucleotide base is replaced by another in the DNA sequence.

Hence, the correct answer is option 4)All of these

Also Read-

• MCQ on types of Mutation

• RNA Processing

• RNA Splicing