high-yield midterm exam notes
Unit 1: Cell Membranes & Transport
Cell Structure
Q: What is the fluid mosaic model?
A: The plasma membrane is a flexible phospholipid bilayer with embedded proteins.
Q: What makes up the plasma membrane?
A: Phospholipids, proteins, cholesterol, and carbohydrates.
Q: Which part of a phospholipid is hydrophobic?
A: Fatty acid tails.
Q: Which part of a phospholipid is hydrophilic?
A: Phosphate head.
Q: What is selective permeability?
A: The membrane allows some substances to pass while restricting others.
Passive Transport
Q: What is diffusion?
A: Movement of molecules from high concentration to low concentration.
Q: Does diffusion require ATP?
A: No.
Q: What is osmosis?
A: Diffusion of water across a selectively permeable membrane.
Q: What is facilitated diffusion?
A: Passive movement through membrane proteins.
Tonicity
Q: What happens to a cell in a hypotonic solution?
A: Water enters the cell; it swells.
Q: What happens to a cell in a hypertonic solution?
A: Water leaves the cell; it shrinks.
Q: What happens in an isotonic solution?
A: No net water movement.
Active Transport
Q: What is active transport?
A: Movement against a concentration gradient using ATP.
Q: What is the sodium-potassium pump?
A: A transport protein that moves Na⁺ out and K⁺ into the cell using ATP.
Vesicular Transport
Q: What is endocytosis?
A: Bringing substances into the cell via vesicles.
Q: What is phagocytosis?
A: "Cell eating."
Q: What is pinocytosis?
A: "Cell drinking."
Q: What is exocytosis?
A: Releasing substances from the cell.
Unit 2: Infection & Disease
Symbiotic Relationships
Q: What is mutualism?
A: Both organisms benefit.
Q: What is commensalism?
A: One benefits, the other is unaffected.
Q: What is parasitism?
A: One benefits while the host is harmed.
Q: What is amensalism?
A: One organism is harmed while the other is unaffected.
Microbiome
Q: What is resident microbiota?
A: Permanent microorganisms normally found in the body.
Q: What is transient microbiota?
A: Temporary microorganisms present for short periods.
Q: What is an opportunistic pathogen?
A: A normally harmless microbe that causes disease under certain conditions.
Disease Terms
Q: What is a pathogen?
A: A disease-causing microorganism.
Q: What is contamination?
A: Presence of microbes.
Q: What is infection?
A: Successful invasion and growth of microbes.
Q: What is morbidity?
A: Disease or illness.
Portals of Entry
Q: What is the most common portal of entry?
A: Respiratory tract.
Q: What is the parenteral route?
A: Direct deposition through skin into deeper tissues.
Adhesion
Q: What are adhesins?
A: Molecules that allow pathogens to attach to host cells.
Q: What happens if bacteria lose adhesins?
A: They often become avirulent.
Biofilms
Q: What is a biofilm?
A: A community of microorganisms embedded in a sticky matrix attached to a surface.
Virulence
Q: What is pathogenicity?
A: Ability to cause disease.
Q: What is virulence?
A: Degree of pathogenicity.
Toxins
Q: What is an exotoxin?
A: A toxin secreted by living bacteria.
Q: What is an endotoxin?
A: Lipopolysaccharide (LPS) from Gram-negative bacteria.
Q: What is the toxic part of endotoxin?
A: Lipid A.
Disease Stages
Q: What is the correct sequence of infectious disease stages?
A: Incubation → Prodromal → Illness → Decline → Convalescence.
Signs and Symptoms
Q: What is a symptom?
A: Subjective complaint felt by the patient.
Q: What is a sign?
A: Objective finding observed by others.
Transmission
Q: What is direct contact transmission?
A: Person-to-person physical contact.
Q: What is indirect contact transmission?
A: Transmission through fomites.
Q: What are fomites?
A: Contaminated inanimate objects.
Q: What is droplet transmission?
A: Spread by respiratory droplets traveling less than 1 meter.
Q: What is airborne transmission?
A: Spread through aerosols traveling more than 1 meter.
Q: What is a biological vector?
A: A vector that also serves as a host.
Q: What is a mechanical vector?
A: A vector that carries but does not host the pathogen.
Epidemiology
Q: What is incidence?
A: Number of new cases.
Q: What is prevalence?
A: Total number of cases.
Q: What is an endemic disease?
A: Constantly present in a population.
Q: What is an epidemic?
A: More cases than expected.
Q: What is a pandemic?
A: An epidemic affecting multiple continents.
Healthcare-Associated Infections
Q: What is a healthcare-associated infection (HAI)?
A: Infection acquired in a healthcare setting.
Q: What is an iatrogenic infection?
A: Infection caused by medical treatment or procedures.
Unit 3: Innate Immunity
Lines of Defense
Q: What are the first two lines of defense called?
A: Innate immunity.
Q: What is the third line of defense?
A: Adaptive immunity.
First Line of Defense
Q: What enzyme in tears and saliva destroys bacterial cell walls?
A: Lysozyme.
Q: What are defensins?
A: Antimicrobial peptides.
Q: What does sebum do?
A: Lowers skin pH and inhibits microbes.
Q: Which cells secrete mucus?
A: Goblet cells.
Q: What is competitive inhibition?
A: Normal microbiota competing with pathogens.
Leukocytes
Q: What are the three granulocytes?
A: Neutrophils, eosinophils, basophils.
Q: What are the two agranulocytes?
A: Monocytes and lymphocytes.
Q: What do monocytes become in tissues?
A: Macrophages.
Q: Which WBC is the first responder to infection?
A: Neutrophil.
Q: Which WBC releases histamine?
A: Basophil.
Q: Which WBC fights parasitic worms?
A: Eosinophil.
Q: Which cells kill virus-infected and cancer cells?
A: Natural killer (NK) cells.
Phagocytosis (Very High Yield)
Q: What is the correct sequence of phagocytosis?
A: Chemotaxis → Adhesion → Phagosome → Phagolysosome → Destruction.
Q: What is chemotaxis?
A: Movement toward chemical signals.
Q: What is opsonization?
A: Coating pathogens to enhance phagocytosis.
Complement
Q: What are the three complement pathways?
A: Classical, alternative, and lectin.
Q: What activates the classical pathway?
A: Antibodies.
Q: What activates the alternative pathway?
A: Microbial surfaces.
Q: What activates the lectin pathway?
A: Mannose on microbial cells.
Q: What is the membrane attack complex (MAC)?
A: Complement proteins that form holes in pathogen membranes.
Interferons
Q: Which interferons are released early in viral infection?
A: IFN-α and IFN-β.
Q: What does IFN-γ do?
A: Activates macrophages and neutrophils.
Inflammation
Q: What are the four classic signs of inflammation?
A: Redness, heat, swelling, pain.
Q: Which chemical is released by basophils and mast cells during inflammation?
A: Histamine.
Q: What is diapedesis?
A: Movement of leukocytes through vessel walls.
Q: What is margination?
A: Leukocytes sticking to vessel walls before diapedesis.
Fever
Q: What are pyrogens?
A: Fever-producing chemicals.
Q: Which part of the brain controls body temperature?
A: Hypothalamus.