UNCW BIO 246: Microbiology Final Exam

The Metric System

Microbial size is measured using micrometers ($\mu m$) and nanometers ($nm$).

Limit of Resolution

This is defined as the minimum distance two points can be apart and still be distinguished as separate entities.

Light Microscopy

Utilizes visible light and glass lenses to magnify specimens.

SEM (Scanning Electron Microscopy)

Optimized for viewing 3D surface details of a specimen.

TEM (Transmission Electron Microscopy)

Optimized for viewing internal ultrastructures, such as organelles or viral cores.

Robert Hooke

Established early cell theory after observing cork 'cells'.

Antonie van Leeuwenhoek

The first to describe living microbes, which he called 'animalcules'.

Louis Pasteur

Disproved spontaneous generation via biogenesis using swan-neck flasks, pioneered fermentation research, and identified microbes as the cause of food spoilage.

General Features of Prokaryotes

These organisms lack a nucleus and membrane-bound organelles.

Prokaryotic Genetics

They contain circular DNA and extrachromosomal plasmids.

Ribosomes in Prokaryotes

They possess a 70S structure, which is a common target for antibiotics.

Prokaryotic Reproduction

Occurs through binary fission.

Gram-Positive Bacteria

Features a thick peptidoglycan layer and teichoic acids.

Gram-Negative Bacteria

Features a thin peptidoglycan layer and an outer membrane containing LPS (Lipopolysaccharide/Endotoxin).

Acid-Fast Bacteria

Contains waxy mycolic acids that require a specialized acid-fast stain for identification, such as in Mycobacterium tuberculosis.

Flagella

Used for motility.

Fimbriae

Used for attachment to host surfaces.

Pili

Specifically the sex pilus used for conjugation, which is the transfer of DNA/plasmids between cells.

Capsule/Slime Layer

Glycocalyx used for adherence and protection from host phagocytosis.

Endospores

Dormant, highly resistant structures produced by Bacillus and Clostridium to survive extreme environmental stress.

Common Shapes of Prokaryotes

Common shapes include Bacillus (rod), Coccus (sphere), and Spirochete (spiral); arrangements include Strepto- (chains) and Staphylo- (clusters).

Endosymbiosis

Explains how mitochondria and chloroplasts originated from engulfed prokaryotic cells.

Eukaryotic Organelles

Include the nucleus, RER/SER, Golgi, lysosomes, mitochondria, and chloroplasts.

Ribosomes in Eukaryotes

They possess an 80S structure.

Fungi

Includes yeasts (which reproduce via budding) and molds (which consist of filamentous hyphae and spores).

Protists

Includes protozoa (which move via pseudopods, flagella, or cilia and often form cysts for survival) and Algae (which can cause HABs/Harmful Algal Blooms).

Helminths

These are parasitic worms and are classified as animals.

Acellular Nature of Viruses

Viruses are obligate intracellular parasites that lack cellular structure.

Structure of Viruses

Consist of a capsid and nucleic acid; some are Enveloped (lipid bilayer) while others are Naked.

Spikes in Viruses

Surface proteins used for host cell tropism and attachment.

Nucleic Acids in Viruses

Can be composed of either DNA or RNA.

Bacteriophage

Viruses that specifically infect bacteria.

Retrovirus

Uses reverse transcriptase to convert viral RNA into DNA.

Oncovirus

Viruses capable of causing cancer.

Viral Replication Cycle

Adsorption $

ightarrow$ Penetration (Endocytosis or Fusion) $

ightarrow$ Uncoating $

ightarrow$ Synthesis $

ightarrow$ Assembly $

ightarrow$ Release (Lysis for naked viruses, Budding for enveloped viruses).

Crucial Viral Enzymes

Include reverse transcriptase, integrase, and protease.

Prions

Acellular proteinaceous infectious agents that cause conversion of normal host proteins into misfolded prions, leading to spongiform encephalopathy.

Sterilization

Destroys all viable life forms, including highly resistant endospores.

Disinfection

Reduces pathogen levels on inanimate surfaces.

Antisepsis

Chemicals applied directly to living tissue to reduce microbes.

Sanitization

Mechanical removal of microbes to reach safe public health levels.

Degermation

Manual reduction of microbes on a specific area of the skin, such as a surgical scrub.

Cidal vs. Static

Cidal agents kill microbes, while static agents inhibit their growth.

Narrow vs. Broad Spectrum Antibiotics

Refers to the range of different microbial species a drug can target.

Superinfection

Occurs when broad-spectrum antibiotics destroy protective normal flora, allowing an opportunist to overgrow.

Peptidoglycan Target

Inhibited by Beta-lactams (like Penicillins) which target the transpeptidase enzyme.

Mycolic Acid Target

Synthesis is inhibited by INH (Isoniazid).

Ergosterol Target

Fungal membranes are targeted by Azole antifungals.

Beta-lactamase

An enzyme produced by bacteria to destroy the beta-lactam ring of certain antibiotics.

MRSA

Resists methicillin by utilizing an alternative transpeptidase that the drug cannot bind to.

Commensal Microbes

Microbes that do no harm.

Opportunistic Microbes

Microbes that harm if the host is compromised.

Parasites

Microbes that harm the host.

Pathogenesis Factors

Requires an infectious dose, adherence (often via capsules), and evasion/damage mechanisms including coagulase, cytotoxins, neurotoxins, enterotoxins, and endotoxins.

Transmission Factors

Include reservoir, carrier, vector, fomite, and vertical transmission.

Epidemiology

John Snow's study of cholera founded this field; metrics include Incidence (new cases) and Prevalence (total existing cases).

First Line Barriers of Innate Immunity

Includes the skin, mucus flow, cilia (respiratory escalator), and stomach acid.

Hematopoiesis

The process of blood cell production in the bone marrow.

Neutrophils

The primary phagocytes.

Basophils/Mast Cells

Release histamine.

Macrophages and Dendritic Cells

Perform antigen presentation.

Pattern Recognition Receptors (PRRs)

Detect microbial PAMPs (Pathogen-Associated Molecular Patterns).

Inflammation

Triggered by histamine; characterized by vasodilation, edema, and fever induced by pyrogens.

Complement System

A system of blood proteins that can form a MAC (Membrane Attack Complex) to lyse target cells.

MHC Molecules

MHC I is found on all nucleated cells (presents endogenous antigens); MHC II is found on APCs (presents exogenous antigens).

Helper T (CD4)

Recognizes MHC II and coordinates the immune response via cytokines.

Cytotoxic T (CD8)

Recognizes MHC I and induces apoptosis in infected or abnormal cells.

B-Cells

Activate and differentiate into plasma cells to secrete specific antibodies.

IgG

The most abundant antibody; capable of crossing the placenta.

IgM

The first antibody produced during a primary immune response.

IgA

Secretory antibody found in tears, saliva, and breast milk.

Functions of antibodies

Include neutralization, opsonization (tagging for phagocytosis), and agglutination.

Immunity Types

Active (body makes its own antibodies via vaccine or infection) vs. Passive (transfer of pre-formed antibodies, e.g., breast milk).

S. aureus

Arrangements are in clusters; they are Catalase positive (produce bubbles with $H_2O_2$).

S. pyogenes

Arrangements are in chains; they are Catalase negative.

Impetigo

A superficial epidermis infection featuring honey-colored crusts, pustules, and skin peeling.

Cellulitis

An infection extending into the dermis and subcutaneous tissues.

Necrotizing Fasciitis

Rapid destruction of the fascia by S. pyogenes, known as 'flesh-eating' disease.

SSSS

Staphylococcal Scalded Skin Syndrome: A systemic condition in infants where skin peels due to staphylococcal toxins.

Measles

A viral infection causing a maculopapular rash and Koplik spots in the oral mucosa.

Chickenpox/Shingles

Caused by the Varicella-Zoster virus; can remain latent in nerves.

Conjunctivitis

Commonly called 'pink eye,' involving redness and discharge.

Neonatal Conjunctivitis

Vertical transmission of gonorrhea or chlamydia during birth; newborns receive erythromycin drops as prevention.

Trachoma

A bacterial infection by C. trachomatis; the leading cause of infectious blindness globally.

Keratitis

Typically viral; the leading cause of infectious blindness in the U.S.

Meningitis

Infection of the meninges; symptoms include stiff neck, fever, headache, and photophobia.

Neisseria meningitidis

The most serious form of meningitis; often causes petechiae (small purple spots).

Streptococcus pneumoniae

Common etiology of meningitis; 70% of the population are carriers.

Poliomyelitis

An acid-stable enterovirus transmitted via the fecal-oral route (contaminated water); 1% of cases result in paralytic disease.

Toxoplasmosis

Subacute encephalitis; poses a high risk for pregnant women due to vertical transmission.

Tetanus

Caused by C. tetani; produces spastic paralysis (lockjaw).

Botulism

Caused by C. botulinum; produces flaccid paralysis (often from foodborne toxins).

Endocarditis

Acute: Typically S. aureus; colonization of healthy heart valves via a parenteral route.

Plague

Caused by Yersinia pestis; transmitted by a flea vector; results in swollen necrotic lymph nodes called buboes.

Lyme Disease

Caused by Borrelia burgdorferi; transmitted by a tick vector; distinguished by a bulls-eye rash (erythema migrans).

HIV/AIDS

A viral infection that specifically depletes CD4 Helper T-cells.

Malaria

Caused by Plasmodium (protozoan); transmitted by an Anopheles mosquito vector.

Otitis Media

A middle ear infection causing ear pain and a bulging eardrum; common in children.

Strep Throat

Caused by S. pyogenes; potential complications include Scarlet Fever and Rheumatic Fever.

Tuberculosis

Caused by M. tuberculosis; an acid-fast bacterium that forms granulomas in the lungs; noncompliance with treatment is a major cause of drug resistance.