Question

Alternative forms of the same gene are ______ a. gametes b. homologous c. alleles d. oncogenes

Short answer

The correct answer is 'c. alleles.'

Step-by-step solution

Understand the Question

We need to identify the term used to refer to different forms of the same gene.

Define the Term 'Alleles'

Alleles are different forms of the same gene. They can occur due to mutations or variations in the sequence of DNA in gene loci.

Evaluate the Options

- **Gametes** are reproductive cells. - **Homologous** refers to chromosomes that make up a pair. - **Alleles** are indeed different forms of the same gene. - **Oncogenes** are genes that have the potential to cause cancer. Therefore, the correct answer is 'alleles.'

Confirm the Correct Choice

All other options do not fit the definition of different forms of the same gene. Therefore, 'alleles' is the correct choice.

Key concepts

Gene Mutations

Gene mutations refer to any change in the DNA sequence that makes up a gene. These changes can be as small as a single DNA base pair being altered, or as large as a section of a chromosome being duplicated or deleted. Mutations can occur spontaneously or as a result of environmental factors.

Some mutations have no effect, while others can result in changes in the form or function of the organism—sometimes these changes can lead to disease or notable traits. For instance, a single gene mutation may change one allele into another, altering the genetic expression and potentially introducing genetic variation within a population.

Mutations play a vital role in evolution by providing new alleles that might be selected for or against in a population. They are just one of several sources introducing genetic diversity, making life so varied and fascinating.

Genetic Variation

Genetic variation is the diversity found within a species' genetic makeup. This variation is crucial for a species' survival as it allows for adaptation to changing environments.

There are several mechanisms that contribute to genetic variation, including:

• Mutations, which introduce new alleles into a population.
• Sexual reproduction, which combines alleles from two parents, leading to a unique genetic combination in the offspring.
• Gene flow, which is the exchange of genes between populations, allowing for diversity to spread across different groups.

Genetic variation is the raw material for natural selection. It allows some individuals to possess traits that are better suited to their environment, enabling them to survive and reproduce more effectively.

Chromosomes

Chromosomes are long, thread-like structures made of DNA and protein. They are located in the nucleus of eukaryotic cells. Each chromosome is composed of many genes, which are specific sequences of DNA that code for proteins. Humans typically have 23 pairs of chromosomes in their cells.

Each chromosome pair consists of one chromosome inherited from the mother and one from the father. This pairing is partly what contributes to genetic diversity, as the mixing of parental chromosomes ensures that offspring are genetically unique.

Chromosomes play a crucial role in cell division, ensuring that DNA is accurately copied and distributed in cellular processes like mitosis and meiosis. During meiosis, homologous chromosomes exchange genetic material in a process known as crossing over—this increases genetic variation within a population.

DNA Sequence

A DNA sequence is the order of nucleotides in a strand of DNA. These nucleotides include adenine (A), thymine (T), cytosine (C), and guanine (G). The specific order of these bases determines the genetic information carried by a segment of DNA, akin to letters forming words in a sentence.

This sequence is fundamental to the process of gene expression, as it dictates the order in which amino acids are assembled to make proteins. Proteins, in turn, carry out various structural and functional roles within organisms.

Understanding a DNA sequence comes down to understanding its unique code that dictates cellular processes. Any change in this sequence can result in a gene mutation, potentially altering protein function, which may have wide-ranging effects on an organism, driving genetic variation within a population.

Overall, the study of DNA sequences allows scientists to understand and manipulate genetic information for the betterment of health and science.