Video Notes - Immunology, Microbiology, and Genetics Vocabulary Flashcards

A comprehensive set of vocabulary terms and concise definitions drawn from the lecture notes to aid exam preparation.

MHC (Major Histocompatibility Complex)

Cell-surface molecules that display antigen fragments to T cells for immune recognition.

HLA (Human Leukocyte Antigen)

Gene complex on chromosome 6 encoding MHC proteins involved in immune function.

MHC Class I

Found on all nucleated cells; presents endogenous antigens to CD8+ T cells; not on red blood cells.

MHC Class II

Found on antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells; presents exogenous antigens to CD4+ T cells.

Antigen-presenting cells (APCs)

Cells (e.g., dendritic cells, macrophages, B cells) that process and present antigens with MHC II to T cells.

NK cells

Natural killer cells regulated by MHC; detect stressed or abnormal cells lacking MHC I.

Genetic drift

Random mutations in pathogens that can make them unidentifiable by the immune system.

Genetic shift

Hybridization between viruses leading to new, often more virulent strains.

Immune evasion

Pathogens employ strategies to avoid detection or destruction by the immune system.

Dengue/Zika immune disruption

Pathogens can produce molecules that interfere with cytokine signaling.

HIV

Human immunodeficiency virus; destroys CD4+ T helper cells, compromising immunity.

CD4+ T helper cells (TH cells)

Key orchestrators of the immune response; their loss increases susceptibility to infections.

HAART

Highly Active Antiretroviral Therapy used to manage HIV infection.

HIV retinopathy

HIV-related microangiopathy with hemorrhages and cotton-wool spots; dilated exam recommended.

Vaccination

Immunization to stimulate protective neutralizing antibodies and adaptive immunity.

Edward Jenner

Pioneer of vaccination using cowpox to confer protection against smallpox.

Herd immunity

Protection of a population when a sufficient proportion is immune, reducing spread.

Vaccine types

Live attenuated, killed (inactivated), subunit/extract, recombinant, and DNA/RNA vaccines.

Primary immune response

Initial activation and clonal expansion of T and B cells after first exposure.

Secondary immune response

Faster, stronger response upon re-exposure due to memory cells.

IgG

Major serum antibody providing long-lasting and systemic protection.

IgA

Antibody mainly protecting mucosal surfaces (secretions).

Hypersensitivity

Exaggerated immune responses causing tissue damage; categorized into four types.

Type I hypersensitivity

IgE-mediated immediate reactions (e.g., allergies, anaphylaxis, hay fever) involving mast cell degranulation.

Mast cells

Cells loaded with IgE that release histamine when cross-linked by antigen.

Basophils

Circulating cells that release histamine during allergic reactions.

Histamine

Mediator of inflammation causing vasodilation, edema, and itching.

Type II hypersensitivity

Antibody binding to cell membranes or extracellular matrix (e.g., transfusion reactions, hemolysis).

Hemolytic transfusion reaction

Incompatible blood type triggers IgM/IgG antibodies and destruction of donor red cells.

Erythroblastosis fetalis

Rh incompatibility causing fetal red cell destruction by maternal antibodies.

Goodpasture syndrome

Autoantibodies attack lungs and kidneys, with complement involvement.

IgM/IgG with epitopes

Antibody classes that bind to cell surfaces and promote phagocytosis or cytotoxic effects.

Complement activation

Proteins that enhance opsonization and cell lysis as part of Type II/III responses.

Type III hypersensitivity

Immune complex-mediated reactions causing inflammation and vasculitis (e.g., RA, lupus).

Rheumatoid arthritis

Autoimmune disease with immune complex involvement causing joint inflammation.

Lupus (systemic lupus erythematosus)

Autoimmune disease with immune complexes causing widespread inflammation.

Immune complex

Antigen–antibody complexes that activate complement and recruit inflammation.

Type IV hypersensitivity

Delayed-type hypersensitivity mediated by T cells (not antibodies); 48–72 hours.

Contact dermatitis

T cell-mediated skin reaction to allergens or metals.

ABO blood group antigens

Carbohydrate antigens (A and B) on RBCs that determine blood type.

Naturally occurring antibodies

Preexisting antibodies against A/B antigens without prior exposure.

Rh factor

Rhesus antigen on RBCs; Rh- mothers can form anti-Rh antibodies against Rh+ fetus.

Rhogam

Rho(D) immune globulin given to prevent maternal antibodies against Rh+ fetus.

Bone marrow transplant (hematopoietic stem cell transplant)

Transplant of stem cells to treat anemia, leukemia, or immunodeficiency.

Graft-versus-host disease (GVHD)

Donor immune cells attack recipient tissues; minimized by T cell removal.

Ocular GVHD

GVHD effects on lacrimal gland and ocular surface causing dry eye and inflammation.

Cancer immunity

Immune system surveillance and response to tumor cells.

Carcinoma

Malignant tumors arising from epithelial tissues (skin, glands, etc.).

Sarcoma

Malignant tumors arising from connective tissues like bone or cartilage.

Leukemia

Cancer of hematopoietic/blood-forming cells; systemic disease.

Lymphoma

Cancer of lymphoid tissue forming solid tumors.

Proto-oncogene

Normal growth-promoting gene that can become an oncogene when mutated.

Oncogene

Mutated/abnormally activated gene driving uncontrolled cell growth.

Tumor suppressor gene

Gene that protects against cancer; loss leads to unchecked growth.

Tumor-specific antigens (TSAs)

Antigens uniquely expressed on tumor cells that can be targeted by immunity.

Immune surveillance theory

Idea that immune system detects and eliminates developing tumors.

Innate immunity

Immediate, non-specific defense, including NK cells and macrophages.

Natural killer (NK) cells and MHC I

NK cells detect reduced MHC I on tumor cells and mediate cytotoxicity.

Interferon

Cytokine with antiviral and antitumor activities that activates immune responses.

Opsonization

Antibody-mediated marking of pathogens to enhance phagocytosis.

Biofilms

Structured microbial communities protected by a glycocalyx layer; can be beneficial or harmful.

Glycocalyx

Gelatinous external layer of polysaccharides/proteins aiding attachment and protection.

EPS (extracellular polymeric substance)

Matrix produced by biofilms that facilitates adherence to surfaces.

Capsule

Organized, firmly attached glycocalyx that enhances virulence and immune evasion.

Slime layer

Unorganized, loosely attached glycocalyx, less protective but aids attachment.

Gram-positive bacteria

Bacteria with thick peptidoglycan layer and teichoic acids; stain purple.

Gram-negative bacteria

Bacteria with a thin peptidoglycan layer and an outer membrane containing LPS; stain pink/red.

Peptidoglycan (PGN)/murein

Disaccharide polymers cross-linked by peptides forming the bacterial cell wall.

Lipopolysaccharide (LPS)

Outer membrane component in Gram-negatives; Lipid A acts as endotoxin.

Pili (fimbriae)

Hair-like appendages used for adhesion and, in many Gram-negatives, for conjugation.

Periplasm

Space between outer membrane and plasma membrane in Gram-negative bacteria.

Teichoic acids

Negatively charged polymers in Gram-positive cell walls aiding ion transport.

Lysozyme

Enzyme that damages peptidoglycan; found in body secretions and tears.

EDTA

Chelating agent that weakens outer membrane and enhances lysozyme access in Gram-negatives.

Protoplast

Gram-positive-like cell wall-removed cell; membrane intact, vulnerable to lysis.

Spheroplast

Partially cell wall-deficient cell; lacks peptidoglycan fully, still has outer membrane.

Mycoplasma

Bacteria with no cell wall; plasma membrane contains sterols for stability.

Archaea

Organisms with cell walls lacking peptidoglycan; distinct biochemistry from bacteria.

Mycolic acid

Hydrophobic waxy lipid in mycobacterial cell walls; resists staining and decolorization.

Acid-fast stain

Stains waxy cell walls (e.g., Mycobacterium) red due to mycolic acids.

Endospore

Durable, dormant bacterial structure with thick coat; Gram-positive typically.

Sporogenesis

Formation of endospores within a bacterial cell.

Germination

Exit from dormancy when conditions become favorable.

Prokaryote vs Eukaryote structure

Prokaryotes lack a nucleus; eukaryotes have membrane-bound organelles and a nucleus.

Plasma membrane (prokaryotes)

Phospholipid bilayer controlling movement of substances.

Group translocation

Active transport unique to prokaryotes that chemically modifies transport substrates to trap them inside.

Nucleoid

Region containing a single circular bacterial chromosome, no true nucleus.

Plasmids

Small, extra circular DNA that carries accessory genes (e.g., resistance).

Ribosomes (70S)

Bacterial ribosomes (30S+50S); targets for many antibiotics.

Inclusions

Stored nutrients within the cytoplasm for later use.

Endospores (dormancy)

Resistant, dormant form enabling survival in harsh conditions.

Nucleus (eukaryotic)

Largest organelle with double membrane; contains chromosomes and nucleolus.

Ribosomes (80S in eukaryotes)

Protein-synthesizing organelles composed of 40S and 60S subunits.

Chloroplasts and mitochondria (70S ribosomes)

Endosymbiotic organelles with bacterial-type ribosomes.

Cytoskeleton, cytosol, cytoplasmic streaming

Components of the cytoplasm; cytoplasmic movement and organization.

Endocytosis (receptor-mediated)

Selective uptake of substances by inward folding of the cell membrane.

Nucleolus

Nuclear region where ribosomal RNA is synthesized.

Capnophiles

Organisms that require higher CO2 levels for growth.

Aerobe vs anaerobe

Organisms requiring oxygen (aerobe) vs those killed or inhibited by it (anaerobe).

Facultative anaerobe

Can grow with or without oxygen, using respiration or fermentation.