Microbiology Study Guide Exam 1 Flashcards
Decomposition
Definition- The process by which organic substances are broken down into simpler organic or inorganic matter.
Role- Both positive (nutrient recycling) and negative (food spoilage)
Types of Microbes- Bacteria, fungi
Produce Food
Definition- Microorganisms are used in the production of various foods.
Role- Positive
Type of Microbes- Yeast (bread, beer), bacteria (yogurt, cheese)
Medicine Production
Definition- Microorganisms are used to produce antibiotics vaccines, and other pharmaceuticals.
Role- Positive
Type of Microbes- Bacteria (penicillium for penicillin), fungi.
Normal Microbiota
Definition- The community of microorganisms that live on and in our bodies
Role- Positive
Type of Microbes- Bacteria, Fungi
Pathogens/ Infectious Diseases
Definition- Microorganisms that cause disease
Role- Negative
Type of Microbes- Bacteria, viruses, fungi, protozoa
Photosynthesis
Definition- The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll
Role- Positive
Type of Microbes- Algae, cyanobacteria
Bacteria
Properties- Prokaryotic, unicellular, can be beneficial or pathogenic
Archaea
Properties- Prokaryotic, unicellular, often found in extreme environment
Fungi (Yeast &Molds)
Properties- Eukaryotic, can be unicellular (yeast) or multicellular (Molds), decomposers
Protozoa
Properties- Eukaryotic, can be unicellular or multicellular, perform photosynthesis
Helminths
Properties- Eukaryotic, multicellular, parasitic worms
Viruses
Properties- Acellular, requires a host to replicate, can be pathogenic
Decomposition
Definition- The breakdown of dead organic matter
Photosynthesis
Definition- The process by which plants and some microorganisms convert light energy into chemical energy
Cellular
Pertaining to cells
Acellular
Not consisting of, divided into, or containing cells
Unicellular organisms
Consisting of a single cell
Multicellular
Consisting of multiple cells
Prokaryotic Cells
Definition- A cell lacking a true nucleus and membrane-bound organelles
Eukaryotic Cells
Definition- A cell with a true nucleus and membrane- bound organelles
Animal
Definition- A multicellular, eukaryotic organism that is typically motile and heterotrophic (can’t make its own food)
Punishment from God for sin
Definition- Punishment from God/ the gods for sinful behavior
Historical ex: Leprosy was often seen as a punishment for sins in medieval Europe
Miasma Theory
Definition- The theory that disease was caused by “ bad air” or miasmas emanating from decomposing organic matter
Historical ex: Cholera was believed to be caused by miasmas before the germ theory was accepted
Germ Theory
Definition- The theory that specific disease is cause by specific microorganisms
Historical ex: Tuberculosis, caused by Mycobacterium tuberculosis, was one of the diseases that helped establish germ theory
Leprosy
Areas Affected: Skin, nerves, respiratory tract
Spread: Prolonged close contact with an infected person
Plague
Areas Affected: Lymph nodes(bubonic), bloodstream (septicemic), lungs (pneumonic)
Spread: Flea bites, contact with contaminated fluid or tissue, inhalation of respiratory droplets
Smallpox
Areas affected: Skin, internal organs
Spread: Direct contact with infected bodily fluids or contaminated objects
Cholera
Affected areas: Intestines
Spread: Contaminated water or food
Polio
Affected areas: Nervous system
Spread: Fecal-oral route
Leprosy Impact
Impact: Led to social stigma and isolation of affected individuals
Justinian Plague Epidemic
Impact: Contributed to the decline of the Byzantine Empire and caused significant population loss
European Plague Epidemics (1300s-1600s)
Impact: The Black Death killed an estimated one-third of Europe’s population, leading to economic and social changes
European syphilis Epidemics (1500s)
Impact: Caused widespread fear and led to the development of early public health measures
Smallpox Impact
Impact: Decimated indigenous population in the Americas and led to the first successful vaccination campaign
Cholera Epidemics (1800s)
Impact: Spurred improvements in water and sanitation infrastructure
Childbed Fever (1800s)
Impact: Led to the adoption of antiseptic techniques in childbirth significantly reducing maternal mortality
Polio Epidemics (1900s)
Impact: Led to the development of the Salk and Sabin vaccines, drastically reducing the incidence of the disease
Smallpox Vaccine
Development: Created by Edward Jenner using cowpox to confer immunity to smallpox
Impact: Led to the eventual eradication of smallpox
Pasteur’s Vaccines & Sabin Polio Vaccine
Development: Louis Pasteur developed vaccines for rabies and anthrax; Albert Sabin developed the oral polio vaccine
Impact: Pasteur’s work laid the foundation for modern immunology; Sabin’s vaccine helped control polio globally
Salk Polio Vaccine
Development: created by Jonas Salk using inactivated poliovirus
Impact: Provided effective immunity against polio and was a major public health breakthrough
Edward Jenner
Contribution: Developed the first successful smallpox vaccine using cowpox
Antonie Van Leeuwenhoek
Development: Improved the microscope and was the first to observe and describe microorganisms.
Used single lens microscopes to discover microbes are ubiquitous & diverse
Ignas Semmelweis
Developed: Handwashing to prevent childbed fever
Joseph Lister
Developed: antiseptic Surgery using carbolic acid (phenol) to clean surgical dressings & instruments
to control infections
Florence Nightingale
Developed: Collected health data causes of deaths in British field hospitals during the Crimean war
EX: Hygiene, sanitation, & nutrition reduced diseases
Louis Pasteur
Developed: Linked microbes to spoilage of beer and wine. Heat treatment can kill microbes and prevent spoilage, pasteurization is still used today
created vaccines for rabies and anthrax
John Snow
Developed: Mapped distribution of cholera cases to find cause by surveyed population to find common factors.
Snow identified the link between cholera and water, allowing prevention of the disease
Robert Koch
Developed: Techniques to isolate & grow bacteria: Bacillus anthracis bacteria cause anthrax evidence supporting Germ theory of disease
Jonas Salk
Developed: Developed the first effective polio vaccine using inactivated poliovirus
Albert Sabin
Developed: Developed the oral polio vaccine using live attenuated virus
Alexander Fleming
Developed: Discovered penicillin, the if antibiotic
Chain and Florey
Developed: Purified and mass-production penicillin for clinical use
Sanitation
Definition: Measures to maintain cleanliness and prevent disease
Impact: Improved waste disposal and clean water supply reduced the spread of infectious diseases
Hygiene
Definition: Practices to maintain health and prevent disease especially through cleanliness
Impact: Personal and public hygiene practices, such as handwashing, reduced disease transmission
Vaccines
Definition: Biological preparations that provide immunity to specific diseases
Impact: Mass vaccination campaigns eradicated or controlled many infectious diseases
Antibiotics
Definition: Drugs that kill or inhabit the growth of bacteria
Impact: Antibiotics like penicillin treated bacterial infections effectively, reducing mortality rates
Emerging Diseases
Definition: Disease that are newly identified or previously unknown
Ex: HIV/AIDS, COVID-19, Zika virus
Reasons for Emergence: Changes in human behavior environment changes, and increased global travel
Stigmatization
Definitions: The act of treating someone negatively based on a distinguishing characteristics or condition
Re-emerging Diseases
Definition: Diseases that were previously under control but are now increased in incidence
Ex: Tuberculosis, malaria, measles
Reasons for Emergence: Antibiotic resistance, reduced vaccination rates, and change in public health measures
Isolation
Definitions: Separating infected individuals to prevent the spread of disease
Vaccine
Definitions: A biological preparation that provides immunity to a specific disease
Barriers
Definitions: Physical or biological measures to prevent disease transmission
Eradicated
Definitions: Completely eliminated from a population
Eliminated
Definitions: Reduced to zero causes in a specific area
Ubiquitous
Definitions: Present everywhere
Asepsis
Definitions: The absence of bacteria, viruses, and other microorganisms
Epidemiology
Definitions: The study of the distribution and determinants of health-related states in populations
Koch’s Postulates
Definitions: Criteria to establish a causative relationship between a microbe and a disease
Spontaneous Generation
Definitions: The disproven theory that life can arise from no-living matter
Iron Lung
Definitions: A mechanical respirator used to assist breathing in polio patients
Antibiotic
Definitions: A drug that kills or inhabits the growth of bacteria
Physical Therapy
Definitions: treatment to restore movement and function
Penicillin
Definitions: The first antibiotic discovered by Alexander Fleming
Antibiotic Resistance
Definitions: The ability of bacteria to resist the effects of an antibiotic
Prevention
Definitions: measures taken to prevent disease
Bacteria
Definition: Unicellular, prokaryotic organisms that are ubiquitous and diverse.
Roles: Decomposition, nutrient cycling, disease causation, food production, and biotechnology.
Flagellum/Flagella
Composition: Protein (flagellin).
Appearance: Long, whip-like structures.
Function: Motility.
Advantage: Allows bacteria to move towards favorable environments (chemotaxis).
Axial Filaments (Spirochetes)
Composition: Protein.
Appearance: Internal flagella wrapped around the cell.
Function: Motility.
Advantage: Enables corkscrew motion, allowing movement through viscous environments.
Pilus/Pili
Composition: Protein (pilin).
Appearance: Hair-like appendages.
Function: Conjugation (DNA transfer between bacteria).
Advantage: Facilitates genetic exchange and increases genetic diversity.
Fimbria/Fimbriae
Composition: Protein.
Appearance: Short, bristle-like structures.
Function: Attachment to surfaces.
Advantage: Helps bacteria adhere to host tissues and surfaces, aiding in colonization.
Capsule
Composition: Polysaccharides or proteins.
Appearance: Gelatinous outer layer.
Function: Protection against desiccation and immune system evasion.
Advantage: Enhances bacterial survival and pathogenicity.
Cell Membrane
Types of Bacteria: All bacteria.
Composition: Phospholipid bilayer with embedded proteins.
Function: Selective permeability, transport, and communication.
Advantage: Maintains homeostasis and allows nutrient uptake.
Cell Wall
Types of Bacteria: Most bacteria (Gram-positive and Gram-negative).
Composition: Peptidoglycan.
Function: Structural support and protection.
Advantage: Prevents osmotic lysis.
Mycolic Acid
Types of Bacteria: Mycobacteria.
Composition: Long-chain fatty acids.
Function: Provides a waxy, protective layer.
Advantage: Increases resistance to desiccation and chemical damage.
Teichoic Acid
Types of Bacteria: Gram-positive bacteria.
Composition: Polymers of glycerol or ribitol.
Function: Structural support and ion regulation.
Advantage: Contributes to cell wall rigidity and surface charge.
Endotoxin
Types of Bacteria: Gram-negative bacteria.
Composition: Lipopolysaccharides (LPS).
Function: Elicits strong immune responses.
Advantage: Can cause fever and inflammation in hosts, aiding in bacterial survival.
Outer Membrane
Types of Bacteria: Gram-negative bacteria.
Composition: Lipopolysaccharides, phospholipids, and proteins.
Function: Protection and selective permeability.
Advantage: Provides an additional barrier against harmful substances.
Gram-Positive
Components: Peptidoglycan: Thick layer.
Teichoic Acids: Polymers of glycerol or ribitol.
Lipoteichoic Acids: Anchored to the plasma membrane.
Advantages: Provides structural support and rigidity.
Retains crystal violet stain, appearing purple under a microscope.
Identification Gram staining results in a purple color
Gram-Negative
Components: Outer Membrane: Contains lipopolysaccharides (LPS).
Peptidoglycan: Thin layer.
Periplasmic Space: Between the outer membrane and plasma membrane.
Plasma Membrane: Inner membrane.
Advantages: Provides an additional barrier against harmful substances.
LPS can trigger strong immune responses.
Identification: Gram staining results in a pink or red color
Mycobacterial
Components: Mycolic Acid: Long-chain fatty acids.
Arabinogalactan: Polysaccharide layer.
Peptidoglycan: Linked to arabinogalactan.
Mycomembrane: Outer membrane.
Advantages: Provides resistance to desiccation and chemical damage.
Protects against host immune responses.
Identification: Acid-fast staining due to mycolic acid
Ribosomes
Composition: Protein and RNA.
Function: Protein synthesis
Cytoplasm
Composition: Contains 70-80% water, proteins, carbohydrates, and ions.
Function: Site of metabolic activities.
Chromosome
Composition: DNA.
Function: Stores genetic information.
Cytoskeleton
Composition: Protein filaments
Function: Maintains cell shape, aids in cell division.
Plasmids
Composition: Circular DNA molecules.
Function: Provides genetic advantages such as antibiotic resistance.
Advantage: Can be transferred between bacteria, increasing genetic diversity.
Inclusions
Composition: Various substances (e.g., glycogen, poly-β-hydroxybutyrate).
Function: Storage of nutrients.
Advantage: Provides reserves for times of nutrient scarcity
Proteins
Composed of amino acids.
Carbohydrates/Sugars
Composed of carbon, hydrogen, and oxygen.
Phospholipid bilayer
Composed of phospholipids, forms cell membranes.
Peptidoglycan
Composed of sugars and amino acids, forms bacterial cell walls.
DNA
Deoxyribonucleic acid, stores genetic information.
Mycolic Acid
Long-chain fatty acids found in mycobacterial cell walls.
Protein/RNA
Ribosomes are composed of these, essential for protein synthesis.
Contains 70-80% Water
Cytoplasm’s water content.
Motility
Movement of the cell (e.g., via flagella).
Chemotaxis
Movement towards or away from chemical stimuli.
Concentration
The amount of a substance in a given area.
Attractants
Substances that attract cells.
Repellants
Substances that repel cells.
Conjugation
Transfer of genetic material between bacteria.
Attachment
Adherence to surfaces (e.g., via fimbriae).
Avoid Phagocytosis
Mechanisms to evade immune cells.
Selectively Permeable Barrier
Allows certain substances to pass while blocking others (e.g., cell membrane).
Protection from Lysis in Hypotonic Environment
Prevents cell bursting (e.g., cell wall).
Cell Support
Structural integrity (e.g., cytoskeleton).
Cell Shape
Determined by the cell wall and cytoskeleton.
Storage of Information for Cell Structures And Functions
DNA
Make Proteins
Ribosomes
Storage of Abundant Nutrients
Inclusions
Move to Favorable Environments
Function: Motility (e.g., flagella).
Advantage: Avoids death or increases multiplication by moving towards nutrients or away from harmful conditions.
Move to certain tissues in host
Function: Chemotaxis.
Advantage: Establishes disease by reaching specific tissues.
Attachment
Function: Fimbriae, pili.
Advantage: Helps establish disease by adhering to host cells.
Biofilm Formation
Function: Extracellular polymeric substances (EPS).
Advantage: Protects bacteria from environmental stresses and antibiotics.
Avoid removal by host phagocytes
Function: Capsule.
Advantage: Establishes/maintains disease by evading the immune system.
Survival outside of the host
Function: Endospores.
Advantage: Allows bacteria to survive harsh conditions.
Tigger inappropriate host defenses
Function: Endotoxins.
Advantage: Causes high fever and massive inflammation, aiding in bacterial survival.
Protect from certain antibiotics/disinfectants
Function: Outer membrane (Gram-negative bacteria).
Advantage: Provides an additional barrier against harmful substances.
Transfer of abilities
Function: Plasmids.
Advantage: Transfers antibiotic resistance and other traits.
Components present in All Bacteria
- Cytoplasm
- Cell Membrane
- Ribosomes
- Nucleoid (Chromosomal DNA)
- Cell Wall (in most bacteria)
Binary Fission
Process: One bacterium splits into two genetically identical daughter cells.
Steps: DNA replication, cell elongation, septum formation, cell separation.
Components and function differences from Vegetative Cells
Components: DNA, ribosomes, dipicolinic acid, calcium ions, spore coat.
Function: Dormant, highly resistant structure.
Function of Endospore
Function: Survival in extreme conditions (e.g., heat, desiccation, radiation).
Generation Time
Definition: The time it takes for a bacterial population to double.
Calculation: ( N_t = N_0 \times 2^n )
( N_t ): Number of cells at time ( t )
(N_0 ): Initial number of cells
(n ): Number of generations
Factors Influencing:
1.Nutrient availability
2. Temperature
3. pH
Advantage of Endospore Formation
Advantage: Allows bacteria to endure unfavorable conditions for extended periods.
Bacteria Genera that form endospores
Ex: Bacillus, Clostridium.
Sporulation and Germination
Sporulation: Process of endospore formation triggered by nutrient depletion.
Germination: Return to vegetative state when conditions become favorable.
Genus and Species Names
Definition: The binomial naming system assigns each organism a two-part name: the genus and the species.
Formatting:
- Typed: Italicized (e.g., Escherichia coli).
-Handwritten: Underlined (e.g., Escherichia coli)
Bacillus
Shape: Rod-shaped.
Example: Bacillus subtilis.
Coccus
Shape: Spherical.
Example: Staphylococcus aureus.
Vibrio
Shape: Comma-shaped.
Example: Vibrio cholerae.
Spirillum
Shape: Spiral-shaped, rigid.
Example: Spirillum minus.
Spirochete
Shape: Spiral-shaped, flexible.
Example: Treponema pallidum.
Strepto- (Cocci or Bacilli)
Arrangement: Chains.
Example: Streptococcus pyogenes (streptococci).
Diplo- (Cocci or Bacilli)
Arrangement: Pairs.
Example: Neisseria gonorrhoeae (diplococci).
Staphylococci
Arrangement: Clusters.
Example: Staphylococcus aureus.
Osmosis
Definition: Movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration.
Simple Diffusion
Definition: Movement of molecules from an area of high concentration to low concentration without the use of energy.
Facilitated Diffusion
Definition: Movement of molecules across a membrane via transport proteins, from high to low concentration, without energy use.
Active Transport
Definition: Movement of molecules against their concentration gradient using energy (ATP).
Phagocytosis
Definition: The process by which a cell engulfs large particles or cells.
Composition
Definition: Biofilms are composed of microbial cells and extracellular polymeric substances (EPS).
Cell structures used to help establish biofilms
Fimbriae: Aid in initial attachment to surfaces.
Capsules: Provide protection and help in the formation of the biofilm matrix.
Impact
Why Hard to Treat: Biofilms protect bacteria from antibiotics and the immune system, making infections difficult to eradicate.
Organelles
Definition: Organelles are specialized subunits within a cell that perform specific functions, often enclosed within their own lipid bilayers
Flagellum/ Flagella
Types of Eukaryotic Microbes: Some protozoa, algae.
Appearance: Long, whip-like structures.
Function: Movement.
Advantage: Enables motility to find nutrients or escape predators.
Cilia
Types of Eukaryotic Microbes: Some protozoa.
Appearance: Short, hair-like structures.
Function: Movement and feeding.
Advantage: Allows for locomotion and helps in capturing food particles.
Cell Membrane
Types of Eukaryotic Microbes: All eukaryotic cells.
Composition: Phospholipid bilayer with embedded proteins.
Function: Selectively permeable barrier.
Advantage: Controls the movement of substances in and out of the cell.
Cytoplasm
Composition: 70-80% water, proteins, carbohydrates, ions.
Function: Site of metabolic activities.
Glycocalyx/Capsule
Types of Eukaryotic Microbes: Some fungi, protozoa.
Appearance: Gel-like outer layer.
Function: Protection and adherence.
Advantage: Protects against desiccation and helps in attachment to surfaces.
Cell Wall
Types of Eukaryotic Microbes: Fungi, algae, plants.
Composition: Polysaccharides (e.g., cellulose in plants, chitin in fungi).
Function: Structural support and protection.
Advantage: Provides rigidity and protection against osmotic pressure.
Cytoskeleton
Composition: Protein filaments (e.g., actin, microtubules).
Function: Maintains cell shape, aids in cell division and intracellular transport.
Chromosomes
Composition: DNA.
Function: Stores genetic information.
Ribosomes
Composition: Protein and RNA.
Function: Protein synthesis.
Organelles
Examples: Nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes.
Function: Perform specific cellular functions.
Nucleus
Composition: DNA, nucleoplasm, nuclear envelope.
Function: Houses genetic material and controls cellular activities.
Mitochondria
Composition: Double membrane, own DNA.
Function: ATP production through cellular respiration.
Endoplasmic Reticulum (ER) & Golgi Apparatus
Composition: Membrane-bound structures.
Function: ER synthesizes proteins and lipids; Golgi apparatus modifies, sorts, and packages proteins and lipids.
Lysosomes (not all eukaryotic cells)
Composition: Membrane-bound vesicles containing digestive enzymes.
Function: Digestion of engulfed microbes, injured cells, or old organelles.
Components Present in All Eukaryotes
- Plasma Membrane
- Cytoplasm
- Ribosomes
- Nucleus
- Mitochondria
House and Multiply Information
Organelle: Nucleus.
Function: Stores and replicates DNA.
Make Energy (ATP)
Organelle: Mitochondria.
Function: Produces ATP through cellular respiration.
Process and Transport Molecules
Organelle: Endoplasmic Reticulum (ER) and Golgi Apparatus.
Function: Synthesizes, modifies, and transports proteins, lipids, and sugars.
Mitosis
Definition: A process of nuclear division in eukaryotic cells that results in two genetically identical daughter cells.
Phases:
Prophase: Chromatin condenses into chromosomes; nuclear envelope breaks down.
Metaphase: Chromosomes align at the cell’s equator.
Anaphase: Sister chromatids separate and move to opposite poles.
Telophase: Nuclear envelopes reform around each set of chromosomes.
Phagocytosis and Digestion
Organelle: Lysosomes.
Function: Digests engulfed microbes, injured cells, or old organelles.
Cytokinesis
Definition: The division of the cytoplasm to form two separate daughter cells after mitosis.
Process:
Animal Cells: A cleavage furrow forms, pinching the cell into two.
Plant Cells: A cell plate forms, leading to the separation of the two cells.
Organelles
Eukaryotes: Possess membrane-bound organelles (e.g., nucleus, mitochondria).
Prokaryotes: Lack membrane-bound organelles.
Cell Walls
Eukaryotes:
Plants and Algae: Cellulose.
Fungi: Chitin.
Prokaryotes: Peptidoglycan (in bacteria).
Cell Membranes
Eukaryotes: Phospholipid bilayer with sterols (e.g., cholesterol).
Prokaryotes: Phospholipid bilayer without sterols (except in some Mycoplasma).
Chromosomes Structure
Eukaryotes: Linear chromosomes associated with histone proteins.
Prokaryotes: Circular chromosomes without histones.
Chromosome Location
Eukaryotes: Phospholipid bilayer with sterols (e.g., cholesterol).
Prokaryotes: Phospholipid bilayer without sterols (except in some Mycoplasma).
Multiplication Processes
Eukaryotes: Mitosis (for somatic cells) and meiosis (for gametes).
Prokaryotes: Binary fission
Mold Characteristics
Multicellular: Composed of long, thread-like structures called hyphae.
Hyphae Cell Shape: Tubular.
Multiplication: Can occur by sporulation (production of spores).
Fungi; Cell Walls
Composition: Chitin.
Function: Provides structural support and protection.
Roles of Fungi
Decomposition: Break down dead organic matter.
Recycle nutrients in ecosystems.
Yeast Characteristics
Unicellular: Single-celled organisms.
Oval Cells: Typically, oval-shaped.
Beneficial Symbiotic Relationships:
Lichens: Symbiosis between fungi and algae or cyanobacteria.
Mycorrhizae: Symbiosis between fungi and plant roots.
Diseases
Human: Infections (e.g., athlete’s foot), allergies, or toxins (e.g., aflatoxins).
Plant: Infections (e.g., rusts, smuts).
Algae Characteristics/ Roles
Unicellular: Many are single-celled.
Motility: Many are motile, using flagella or other structures.
Photosynthesis: Produce oxygen and serve as the base of aquatic food webs.
Toxins: Some produce toxins that can cause diseases (e.g., paralytic shellfish poisoning).
Food & Medicine Production:
Used in the production of bread, beer, and antibiotics (e.g., penicillin).
Normal Microbiota
Can be opportunistic pathogens looking for opportunities to cause disease.
Types of Motilities
Flagella: Long, whip-like structures.
Cilia: Short, hair-like structures.
Amoeboid: Movement through pseudopodia.
None: Some protozoa are non-motile.
Protozoa Characteristics/Roles
Unicellular: Single-celled organisms.
No Cell Walls: Lack rigid cell walls.
Moist Environment: Require moist environments to survive.
Motility: Most are motile.
Phagocytes: Have lysosomes for digesting engulfed particles.
Zooplankton: Part of the aquatic food web.
Disease: Some protozoa cause diseases (e.g., malaria, amoebiasis).
Cell Form
Trophozoites: Active, multiplying form.
Cysts: Dormant, protected form that can survive harsh environmental conditions.
Cysts (Protozoa)
Type: Dormant and protected.
Resistance: High resistance to harsh conditions.
Endospores (Bacteria)
Type: Dormant and highly resistant.
Resistance: Extremely high resistance to harsh conditions.
Hyphae (Fungi)
Type: Active and multiplying.
Resistance: Moderate resistance.
Spores (Fungi)
Type: Dormant and resistant.
Resistance: High resistance.
Trophozoite (Protozoa)
Type: Active and multiplying.
Resistance: Low resistance
Vegetative Cells (Bacteria)
Type: Active and multiplying.
Resistance: Low resistance.
Yeast (Fungi)
Type: Active and multiplying.
Resistance: Moderate resistance.
Characteristics of Enzymes
Definition: Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process.
Activity: Enzyme activity is provided by the enzyme’s active site, where substrates bind, and reactions occur.
Specificity: Enzymes are highly specific to their substrates due to the unique shape of their active sites
Protein
Large molecules composed of amino acids, essential for various biological functions.
Enzyme
A type of protein that acts as a catalyst in biochemical reactions.
Activity: The rate at which an enzyme catalyzes a reaction.
Active Site: The region on an enzyme where substrate molecules bind and undergo a chemical reaction.
Substrate: The reactant that an enzyme acts upon.
Product: The molecules produced from the enzymatic reaction.
Activity
The rate at which an enzyme catalyzes a reaction.
Active Site: The region on an enzyme where substrate molecules bind and undergo a chemical reaction.
Substrate: The reactant that an enzyme acts upon.
Product: The molecules produced from the enzymatic reaction.
Active Site
The region on an enzyme where substrate molecules bind and undergo a chemical reaction.
Substrate
The reactant that an enzyme acts upon.
Product
The molecules produced from the enzymatic reaction.
Metabolism
Definition: Metabolism encompasses all chemical reactions that occur within a living organism to maintain life.
Catabolism vs. Anabolism
Catabolism: The breakdown of complex molecules into simpler ones, releasing energy (e.g., cellular respiration).
Anabolism: The synthesis of complex molecules from simpler ones, requiring energy (e.g., protein synthesis)
Factors Influencing Enzyme Activity
Temperature: Optimal temperature increases activity; too high or too low temperatures can denature the enzyme.
pH: Each enzyme has an optimal pH range; deviations can reduce activity.
Substrate Concentration: Increased substrate concentration increases activity until the enzyme is saturated.
Enzyme Concentration: More enzyme molecules increase the reaction rate, provided there is enough substrate.
Inhibitors: Molecules that decrease enzyme activity.
Activators: Molecules that increase enzyme activity
Role of ATP:
ATP (adenosine triphosphate) is the primary energy carrier in cells, providing energy for various metabolic processes
Classifications by Optimal/Required Environment:
Psychrophiles: Thrive in cold environments (0-15°C).
Psychrotrophs: Can grow at low temperatures but prefer moderate temperatures (20-30°C).
Mesophiles: Prefer moderate temperatures (20-45°C), including human body temperature
Key Temperatures
4°C: Refrigeration temperature, slows microbial growth.
37°C: Human body temperature, optimal for many human pathogens.
Temperature
Above Optimum: Causes enzyme denaturation and cell death.
Below Optimum: Causes dormancy or death due to slowed metabolic processes.
pH Scale
Acidic: pH 0-6.
Neutral: pH 7.
Alkaline (Basic): pH 8-14
Classifications
Acidophiles: Thrive in acidic environments.
Acid Tolerant: Can survive in acidic conditions but prefer neutral pH.
Neutrophiles: Prefer neutral pH.
Alkaline Tolerant: Can survive in alkaline conditions but prefer neutral pH.
Alkaliphiles: Thrive in alkaline environments.
Effect of pH on Microbial Growth
Outside Optimum Range: Can cause death of microorganisms.
Optimal Water Content
Cytoplasm: 70-80% water is optimal for cellular functions.
Effect of Dehydration
Dehydration: Causes dormancy or death of cells.
Isotonic Environment
Definition: Solute concentration is equal inside and outside the cell.
Effect on Cells: No net movement of water; cells remain stable.
Hypotonic Environment
Definition: Solute concentration is lower outside the cell.
Effect on Cells: Water enters the cell, causing it to swell and potentially burst (lysis).
Hypertonic Environment
Definition: Solute concentration is higher outside the cell.
Effect on Cells: Water leaves the cell, causing it to shrink (plasmolysis)
Cell Component for Survival in Hypotonic Environments
Cell Wall: Provides structural support and prevents lysis.
Classifications
Halophiles: Thrive in high salt concentrations.
Halotolerant: Can tolerate high salt concentrations but do not require them for growth
Aerobic vs. Anaerobic Environment
Aerobic: Requires oxygen for growth.
Anaerobic: Does not require oxygen; may be harmed by it
Roles of Oxygen and Reactive Oxygen Species (ROS)
Oxygen: Essential for aerobic respiration.
ROS: Reactive molecules that can damage cellular components.
Degradation of ROS: Enzymes like catalase and superoxide dismutase help degrade ROS.
Obligate Aerobes
Require oxygen to grow.
Microaerophiles
Require low levels of oxygen
Aerotolerant Anaerobes
Do not use oxygen but can tolerate its presence.
Obligate Anaerobes:
Cannot tolerate oxygen
