Question

Why is a random mutation more likely to be deleterious than beneficial?

Short answer

Answer: A random mutation is more likely to be deleterious than beneficial because the complexity of the genome and its proteins make it more probable for a mutation to cause harm rather than provide an advantage to the organism. The protein structure is highly sensitive to changes, and most proteins perform essential functions. Also, the interactions between different genes and proteins are complex, making it difficult for random mutations to result in improvements.

Step-by-step solution

Define random mutations

Random mutations are changes to an organism's genetic material (DNA) that occur spontaneously without any specific cause. They can either be beneficial, neutral, or deleterious (harmful) to the organism depending on how the mutation affects the specific gene or DNA sequence.

Explain the complexity of the genome

The genome of an organism is a highly complex and finely tuned system. It contains thousands of genes that interact with one another, with many sequences essential for proper functioning. The genes contain information for the production of proteins, which carry out different functions. Hence, any change in the DNA sequence (mutation) can potentially affect the structure or function of the gene products, that is, proteins.

Discuss probabilities of random mutations

Since random mutations can occur at any point in the DNA sequence without any specific cause, the likelihood of a mutation having a beneficial, neutral, or deleterious consequence is primarily due to chance. The probabilities of a mutation being beneficial or harmful depend on various factors such as the complexity of the protein, the function it performs, and its interaction with other proteins.

Explain why most random mutations are likely to be deleterious

There are several reasons why a random mutation is more likely to be deleterious than beneficial: 1. The protein structure is highly sensitive to changes in the amino acid sequence, and even minor alterations can lead to loss of function or even harmful effects. Since random mutations occur by chance, it is less likely that a mutation will result in an improvement rather than a detrimental change. 2. Many proteins perform essential functions in an organism, and a loss or modification of these functions could lead to severe consequences, such as a disease or loss of fitness. Beneficial mutations, on the other hand, would require the mutation to improve an existing protein function or produce a new one, which is less likely to occur. 3. The interactions between different genes and proteins are complex, and unfavorable gene combinations can lead to adverse effects. Consequently, even if a mutation on a specific gene is not directly harmful, it can still be deleterious because it can disrupt the overall balance of the organism. In conclusion, a random mutation is more likely to be deleterious than beneficial because the complexity of the genome and its proteins make it more probable for a mutation to cause harm rather than provide an advantage to the organism.