Gene

Definition

A gene is a basic unit of heredity in living organisms, composed of DNA and responsible for the transmission of traits from parents to offspring. Genes encode instructions for making proteins, which perform various functions in the body, influencing physical characteristics, behavior, and overall health.

5 Must Know Facts For Your Next Test

1. Genes are located on chromosomes, which are structures within cells that organize and carry genetic material.
2. Each gene can exist in multiple forms called alleles, which can lead to variations in traits among individuals.
3. Humans have about 20,000 to 25,000 genes, and each person inherits two copies of each gene—one from each parent.
4. The expression of genes can be influenced by environmental factors, leading to changes in traits without altering the underlying DNA sequence.
5. Mutations in genes can result in changes to an organism's traits and can be beneficial, harmful, or neutral depending on the context.

Review Questions

• How do genes function in heredity and what role do they play in determining an organism's traits?
  • Genes function as the fundamental units of heredity by carrying the information necessary for producing proteins that dictate various traits. Each gene contains specific instructions encoded in DNA sequences that influence physical characteristics and biological functions. When organisms reproduce, they pass their genes to their offspring, ensuring that traits are inherited according to patterns determined by dominant and recessive alleles.
• In what ways can environmental factors influence gene expression and phenotypic outcomes?
  • Environmental factors such as diet, temperature, and exposure to toxins can significantly impact gene expression, leading to variations in phenotypic outcomes. This phenomenon is known as epigenetics, where external influences modify how genes are turned on or off without changing the underlying DNA sequence. These changes can affect an organism's appearance, behavior, and health over its lifetime and may even be passed on to future generations.
• Evaluate the implications of gene mutations on evolutionary processes within populations over time.
  • Gene mutations introduce new genetic variations into populations, which are essential for the process of evolution. These mutations can result in new traits that may offer advantages or disadvantages in a given environment. Over time, beneficial mutations may become more common through natural selection as individuals with favorable traits have better chances of survival and reproduction. This ongoing process contributes to the diversity of life and the adaptation of species to changing environments.

Related terms

DNA: Deoxyribonucleic acid, the molecule that carries genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms.

allele: A variant form of a gene that can produce different traits or characteristics in an organism.

genotype: The genetic constitution of an individual organism, representing the specific alleles present for a given gene.