Microbio. Exam 1

Microbes

Life forms to small to see with the naked eye

Divided into two groups: Acellular (prions, viruses), cellular (prokaryotes, eukaryotes)

Genus, species

Escherichia (_______); coli (______)

Sp.

One unspecified species in a genus

Spp.

Multiple species in a genus

Leeuwenhoek

Figure of microbiology discovery

Described microrganisms using microscopes

Pasteur

Figure of microbiology discovery

“Pasteurizing” means getting rid of harmful microbes

Koch

Figure of microbiology discovery

Linked specific microbes to specific diseases

Infectious disease

Illness caused by pathogen itself

Microbial intoxication

Illness caused by toxin the pathogen released

Indigenous microbiota

Coexists during normal human life

Can cause disease when normal conditions change - sterile site compromised

Weakened defense

Colon/GI Tract

Where in the body is there the most microbes?

Contamination

Introducing unwanted, foreign microbes to a new environment

Colonization

Microbes living and multiplying in host

No signs or symptoms

Positive screen, but infection can still be avoided

Antagonism

Microbe versus microbe relationship

Synergism

Microbes interact that positively combine affects

Vagina microbes help one another grow

Magnification

How big can you make an image appear?

Resolution

Determines how clearly details can be distinguished

Simple lens - Low

Compound microscope - High

Transmission electron microscope (TEM)

Electron microscope used to see through microbes

Scanning electron microscope (SEM)

Electron microscope used for external detailing

Light microscope

Can produce colored images unless artificially stained

Lower resolution

No, No, Smaller, Not in Nucleus, Binary Fission

Prokaryotes

True nucleus: _____
Membrane bound organelles: _______

Ribosomes: __________

DNA: ___________

Reproduction: __________

Yes, Yes, Bigger, In nucleus, Mitosis/meiosis

Eukaryotes

True nucleus: _____
Membrane bound organelles: _______

Ribosomes: __________

DNA: ___________

Reproduction: __________

Peptidoglycan

Found in prokaryotic cell wall

Prevents lysing and provides shape, selective barrier

Microbacteria disrupts ______

Gram-positive bacteria

Thick peptidoglycan layer, one inner cell membrane

Gram-negative bacteria

Thin peptidoglycan layer, both an inner and outer membrane layer

Prokaryotic capsule

Part of bacterial

Allows bacteria to live longer in cells

Resists phagocytosis

Highly organized

Plasmid

Hold extrachromosal DNA

May carry antimicrobial genes

MRSA

A drug‑resistant staph bacterium that often causes skin infections but can also lead to serious invasive disease.

Methicillin-Resistant Staphyloccocus Aureus

Fimbriae

Allows bacteria to adhere and invade different parts of the body

Peritrichous bacteria

Identify this flagellar arrangement

Amphitrichous bacteria

Identify this flagellar arrangement

Lophotrichous bacteria

Identify this flagellar arrangement

Monotrichous bacterium

Identify this flagellar arrangement

Sex pilus

Role: Transfers DNA and spreads microbacterial resistant genes

Spreads virulence factors

Increases genetic diversity in bacteria

Helps bacteria adapt quickly to environmental pressures

Endospores

Highly resistant survival structures that fight disinfectants and conditions

Not a reproductive structure, but helps bacteria persist in environments

Ex. C dificile. B anthracis

Slime layer

Loosely attached to glycocaylyx

Forms biofilm which allows bacteria to attach to medical devices - catheters, endotracheal tube

Leads to contamination

DNA replicates, cell divides, two daughter cells

Three steps of binary fission

Probiotics

Healthy microbes

Support gut, immune system, microbial balance

Diarrhea

C. Difficile infection causes _____

Week 1 takeaways

1. Microbes include cellular organisms and acellular agents; not

all microbes are pathogens.

2. Microbiota vary by body site; microbial presence does not

automatically mean infection.

3. Interpret microbiology findings using the organism, body site,

patient findings, and specimen quality.

4. Magnification enlarges an image; resolution determines how

clearly details can be distinguished.

5. Prokaryotic/eukaryotic differences and bacterial structures

influence identification, disease, treatment, and prevention.

Physiology

Explains how microbes either survive or die in certain conditions; virulence changes and supports lab identification.

Phototroph

Uses light as an energy source (e.g., algae, cyanobacteria).

Chemotroph

Uses chemicals as an energy source (most human pathogens fall into this category).

Autotroph

Uses CO₂ as a carbon source; environmental producers

Heterotroph

Uses organic compounds as a carbon source (e.g., animals, fungi, protozoa).

Chemoheterotrophs

Human infectious agents are…

Catabolism

Breakdown of large molecules to make/release ATP.

Anabolism

Building up molecules, requiring energy.

Aerobic Respiration

Oxygen is the final electron acceptor; produces high ATP.

Fermentation

Occurs without oxygen; produces low ATP and characteristic end products that help in lab identification.

Lysogenic Conversion

A temperate bacteriophage (a non-living, acellular virus) introduces phage genes into a bacterium, changing its phenotype (e.g., increased virulence).

Transduction

A bacteriophage accidentally transfers DNA from one bacterium to another.

Transformation

Bacterial cells incorporate free ("naked") DNA from disintegrated cells into their own genotype.

Conjugation

A donor bacterium makes direct contact with a recipient bacterium; a plasmid is transferred from one cell to another and may carry antimicrobial resistance genes.

Factors Affecting Microbial Growth

Nutrients

Moisture — Dry conditions decrease growth.

Temperature

pH — Affects enzyme function.

Osmotic Pressure — Increased solute concentration decreases growth.

Atmosphere — O₂ and CO₂ needs vary by organism.

Psychrophiles

Prefer cold temperatures; environmental organisms.

Psychrotrophs

Grow at refrigerator temperatures; pose a food spoilage risk. (Refrigeration slows but does not inhibit all growth.)

Mesophiles

Prefer moderate/body temperature; human pathogens.

Thermophiles

Prefer high temperatures; found in hot springs and heat-tolerant environments.

Water

_____ is required for metabolism and growth

Endospores, protozoan cysts

___________ and __________ survive in dry environments better than other cells

Plasmolysis

Cytoplasm and cell membrane shrinks away from the cell wall in a hypertonic environment; explains why high salt/sugar environments inhibit growth.

Enriched, selective, differential, selective-differential

Four types of culture media

Lag Phase

Cells adjust to the environment.

Log Phase

Rapid, exponential growth.

Stationary Phase

Growth rate equals cell death rate.

Death Phase

Cells die faster than they grow.

Sterilization

Removal of all microbial life, including endospores.

Disinfectant

Reduces pathogens on inanimate objects.

Antisepsis

Reduces microbes on living tissue.

Sanitation

Reduces microbes to public health standards.

Aseptic Technique

Prevents contamination and maintains asepsis (absence of disease-causing microorganisms).

Autoclaving, pasteurization

Two heat inhibition methods (one that sterilizes, then one that inhibits)

Desiccation

Dry inhibition method.

Radiation

Damages microbial DNA.

Filtration

Physically removes microbes from fluid or air.

Time, temperature, concentration, type of microbe (presence of spores), organic matter

Factors Affecting Growth-Control Effectiveness

-Cidal

Suffix that means kills the target microbe

-Static

Suffix that means inhibits microbe growth

Chemotherapy

A chemical/drug used to treat disease.

Antimicrobial Agent

Medication used to treat infection.

Antibiotic

Antibacterial drug used to treat bacterial infections.

Selective Toxicity

Targeting the pathogen while minimizing harm to human cells. Requires:

Proper site

Effective concentration for extended time

Best when targets differ between pathogen and host

Cell wall, ribosomes

What two structures of bacteria cell are used as targets for antimicrobials?

Weakens bacterial cell-wall formation

Damages membrane integrity

Blocks DNA/RNA production

Blocks ribosomes

Blocks essential metabolism steps

Name 5 Antimicrobial Agent Mechanisms

Can harm indigenous microbiota

Why can broad-spectrum antibiotics be negative?

Intrinsic resistance

Inherent resistance characteristic of a microbial species

Acquired Resistance

Develops through gene transfer or mutation. (Note: patients don't become antibiotic resistant — microorganisms do.)

Altered drug-binding site

Method of bacterial resistance

Drug doesn’t fit target

Reduced permeability

Method of bacterial resistance

Ineffective drug entry.

Drug-inactivating enzyme

Method of bacterial resistance

Drug destroyed/modified

Efflux pump

Method of bacterial resistance

Drug pumped out of the cell

New gene acquisition

Method of bacterial resistance

Resistance trait spreads through gene transfer.

B-lactamase

Enzyme that inactivates antibiotics via enzymatic deactivation; break the β-lactam ring.

Empiric Therapy

Treatment starts before the exact pathogen is identified; therapy is reassessed and adjusted once lab tests identify the pathogen.

Susceptibility Testing

Determines how vulnerable a microbe is to specific antimicrobial drugs (Susceptible or Resistant).

Negative Effects of Antimicrobial Drugs

Allergic reactions and drug toxicities

Broad-spectrum agents disrupt indigenous microbiota

Resistant organisms survive and repopulate

Viruses don't have the organized structures that antibiotics target.

Why would you not use antibiotics on influenza virus?

Prions

Infectious proteins; not cells, but infectious particles/agents