Question

A(n) ________ is a sudden, permanent change in a sequence of DNA. a. allele b. chromosome c. epigenetic d. mutation

Short answer

d. mutation

Step-by-step solution

Analyze the options

Go through each of the available answer choices and discard any that do not accurately match the description given of a sudden, permanent change in a DNA sequence.

Select the appropriate answer

Mutation is the term that best fits this description. A mutation is a change that occurs in our DNA sequence, either due to errors when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.

Key concepts

DNA Sequence

The DNA sequence is the unique code of genetic instructions within every living organism, which determines all biological traits and functions. It is comprised of a series of nucleotides, designated as the letters A (adenine), T (thymine), C (cytosine), and G (guanine). These nucleotides arrange themselves in specific sequences to form genes, which in turn guide the production of proteins, enzymes, and other crucial components necessary for life.

Understanding DNA sequences is fundamental to genetics, as they underlie heredity and variation of organisms. Even minor changes in this complex code can have significant effects on an organism's physical attributes or health, leading to genetic disorders or increased susceptibility to diseases. It is these changes, or mutations, to the DNA sequence that can alter the function of a gene and its associated traits.

Environmental Factors on DNA

Environmental factors can have profound impacts on DNA, potentially inducing mutations that can be inherited by future generations. Such factors include exposure to certain chemicals, radiation, and lifestyle choices. For example, ultraviolet (UV) light from the sun can cause mutations by creating thymine dimers, resulting in skin cancers. Other chemicals, like those found in tobacco smoke, can lead to base substitutions or insertions in DNA, heightening the risk of lung cancer.

Moreover, not all interactions between environment and DNA are negative. Some environmental factors can trigger positive changes in gene expression, a field known as epigenetics, without altering the underlying DNA sequence. These can include modifications such as methylation of DNA or acetylation of histones, influencing how genes are turned on or off, which can contribute to an organism's ability to adapt to changing environments.

Mutation Types

There are several types of genetic mutations, each with unique characteristics and implications for an organism. Point mutations involve a change at a particular point in the DNA sequence, such as a single nucleotide substitution. This includes missense mutations that result in a different amino acid in a protein, nonsense mutations that create a premature stop codon, and silent mutations that do not change the amino acid sequence due to the redundancy of the genetic code.

Other mutation types include insertions and deletions, which refer to the addition or loss of nucleotides in the DNA. These can result in frameshift mutations, leading to a completely altered amino acid sequence downstream of the mutation. Larger scale mutations affecting whole chunks of chromosomes, like duplications, inversions, and translocations, can disrupt gene functions or regulatory elements, sometimes leading to conditions like cancer or developmental disorders.