Key Terms in Immunology and Molecular Genetics

Key Concepts 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 cells and molecules is essential for grasping how the body defends itself.

• 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. Provides the first line of defense against pathogens.

• Adaptive Immunity: Specific, acquired immune defense that develops after exposure to antigens. Involves memory for faster response upon re-exposure.

• Antigen: A molecule that triggers an immune response. Usually a protein or polysaccharide on the surface of pathogens.

• Antibody: A protein made by B cells that binds to antigens, marking them for destruction by other immune cells.

• B Cell: A type of white blood cell that produces antibodies. Essential for humoral immunity.

• T Cell: A type of white blood cell involved in cell-mediated immunity. Includes helper T cells and cytotoxic T cells.

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

Molecular Genetics: Information Flow in Cells

Genetic information is stored, expressed, and transmitted through specific molecules and processes. Understanding these terms is fundamental to molecular biology.

• 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 found at the same locus on homologous chromosomes.

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

• RNA (Ribonucleic Acid): A molecule involved in gene expression and regulation. Types include mRNA, tRNA, and rRNA.

• 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. Can lead to changes in protein structure and function.

Examples and Applications

• Example of Innate Immunity: Skin and mucous membranes act as physical barriers to pathogens.

• Example of Adaptive Immunity: Production of specific antibodies after vaccination.

• Example of Mutation: Sickle cell anemia is caused by a single nucleotide mutation in the hemoglobin gene.

Key Processes and Equations

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

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