Key Terms in Immunology and Molecular Genetics

Key Terms in Immunology and Molecular Genetics

Immunology: Defense Mechanisms of the Body

The immune system protects organisms from pathogens through a variety of mechanisms. Understanding the types of immunity and the roles of different immune cells is essential for studying how organisms resist disease.

• Pathogen: A foreign organism (such as a virus, bacterium, or parasite) that causes disease.

• Innate Immunity: Fast, non-specific immune defense you are born with. It provides the first line of defense against pathogens.

• Adaptive Immunity: Specific, acquired immunity that develops after exposure to antigens. It involves memory and specificity.

• Antigen: A molecule that triggers an immune response, often found on the surface of pathogens.

• Antibody: A protein made by B cells that binds to antigens, helping to neutralize or eliminate them.

• B Cell: A type of white blood cell that produces antibodies.

• T Cell: A type of white blood cell involved in cell-mediated immunity. T cells can directly kill infected cells or help regulate other immune responses.

• Cytotoxic T Cell: A T cell that kills infected or cancerous cells.

• Helper T Cell: A T cell that activates and directs other immune cells.

Molecular Genetics: DNA, RNA, and Protein Synthesis

Molecular genetics explores how genetic information is stored, transmitted, and expressed in living organisms. Key processes include the flow of genetic information from DNA to RNA to protein.

• Genotype: The genetic makeup of an organism; the set of genes it carries.

• Phenotype: The observable characteristics of an organism, such as appearance, behavior, and physiology.

• Gene: A segment of DNA that codes for a protein or functional RNA.

• Allele: Different versions of a gene that may produce variations in a trait.

• DNA (Deoxyribonucleic Acid): The molecule that stores genetic information in all living organisms.

• RNA (Ribonucleic Acid): A molecule involved in the expression of genetic information and protein synthesis.

• Transcription: The process of copying a gene's DNA sequence into messenger RNA (mRNA).

• Translation: The process by which the sequence of an mRNA is used to build a protein.

• Mutation: A permanent change in the DNA sequence, which can affect gene function and phenotype.

Central Dogma of Molecular Biology

The central dogma describes the flow of genetic information within a biological system:

• DNA → RNA → Protein

This process involves two main steps:

• Transcription: $\text{DNA} \xrightarrow{\text{transcription}} \text{RNA}$

• Translation: $\text{RNA} \xrightarrow{\text{translation}} \text{Protein}$

Examples and Applications

• Example of Innate Immunity: Skin acts as a physical barrier to pathogens.

• Example of Adaptive Immunity: Vaccination stimulates the production of specific antibodies against a pathogen.

• Example of Mutation: Sickle cell anemia is caused by a mutation in the gene encoding the beta chain of hemoglobin.