NVCC BIO 150 Test 1 Fall 2025 Questions with expert curated solutions with 100% Accuracy (PASSED)

Obligate Aerobes

only aerobic growth, oxygen required. Contains enzymes catalase and SOD(superoxide dismutase) which neutralizes toxic forms of oxygen. Growth only where high concentrations of oxygen have diffused into the medium

How are endospores useful to a bacterial cell? Outline the endospore formation process

Resting cells found in certain bacterial species.

Resistant to desiccation, heat and chemicals

Can be viable for centuries

Sporulation: process of endospore formulation. NOT REPRODUCTION

1.) Spore septum begins to isolate newly replicated DNA and a small portion of cytoplasm

2.) Plasma Membrane starts to surround DNA, cytoplasm and membrane isolated in step 1

3.) Spore septum surrounds isolated portion, forming forespore

4.) Peptidoglycan layer forms between membranes

5.) Spore coat forms

6.) Endospore is freed from cell

Characteristics of Microorganisms

1.) Microbes as a group show diversity, multiple domains

2.) Microbes are Ubiquitous! They're everywhere

3.) Structure=Function

Are all microbes dangerous?

NO ONLY 1% OF ALL MICROBES ARE DANGEROUS TO HUMANS

What is the importance of Microbial Life on earth?

1.) Major part of food chain of all organisms

2.) Waste breakdown/nitrogen cycling in plants

3.) Food Production

4.) Drug Production

Beneficial Uses of Microbes

1.) Microbial Ecology

2.) Bioremediation

3.) Pest Control

4.) Biotechnology

Who developed the system of naming organisms and whats it called?

Carl Linnaeus, Binomial Nomenclature

What are the three domains of life and who developed it?

Bacteria, Archaea, Eukarya. Developed by Dr. Carl Woes

What characteristics are used to classify life into three domains?

Ribosomal RNA, Single Cell/multicellular, Transferral RNA Structure

Prokaryote Bacteria

1.) Single-Celled Organisms

2.) Bacteria exist in different shape, have cell wall made of Peptidoglycan

3.) Asexual Reproduction, Binary Fission

4.) Modal or Non-Modal, Flagella allows it to move

Prokaryote Archaea

1.) Present in most extreme environments

2.) Methanogens, high methane environment

3.) Extreme Halophiles, high salt environment

4.) No Peptidoglycan, different cell wall

Fungi

1.) Multicellular or Unicellular

2.) Most engage in sexual reproduction, some in asexual reproduction and some can do both

3.) Mycellea made up of filaments called Hyphae

4.) Cell wall made of Kiatin

5.) Absorb organic chemicals for nutrients

Protozoa

1.) Unicellular

2.) Free living or parasitic

3.) Some are Photosynthetic

4.) sexual or asexual reproduction

5.) May be Modal, can use flagella, massive Cillia or a pseudopod "false foot" to move in environment

6.) Disease causing agents

Algae

1.) Water Plants

2.) Cellulose Cell walls

3.) Uni or multicellular forms

Helminths

1.) Parasitic flatworm/roundworm

2.) Microscopic

3.) Cysts/egg/larvae are way from going host to host

Viruses

1.) Extremely small, Acellular. Neither Prokaryote or Eukaryote

2.) Can be seen with Electron Microscope

3.) Consist of nucleic acid core either DNA or RNA

4.) Nucleic acid surrounded by protein coat, sometimes by lipids as well

5.) Parasites, only replicate in a host cell

Anton Van Leuwenhoek (1673) (Early Year Major Event)

(Animalcules) Created first Microscope to look at animal cells

Robert Hooke(Early Year Major Event)

coined the term "cell" and redesigned microscope with light source

Edward Jenner(Early Year Major Event)

(vaccination) First to start idea of vaccines with cowpox. Exposed maids to cowpox before working with them

Louis Pasteur(Early Year Major Event)

Refutes Spontaneous Generation with beef broth experiment

Spontaneous Generation Theory

the theory that living organisms can rise from nonliving things

Rudolf Virchow(Golden Age of Microbio)

Theory of biogenesis- If there are cells, they will settle and continue to multiply

Robert Koch(Golden Age of Microbio)

Postulates of Disease/Germ theory of disease- Postulates determine how germs can cause disease

Ignaz Semmelweis (Golden Age of Microbio)

advocated hand washing to prevent transmission of puerperal fever from one OB patient to another. First started idea of Aseptic Technique

Joseph Lister

Began using disinfectants and antiseptics during surgery. Continued Semmelweis' idea of aseptic technique

Chemotherapy

Using chemical drugs to defeat disease (NOT CANCER CHEMO)

Paul Erlich and Chemotherapy

coined the term antibiotics for the "magic bullet" antimicrobials he pursued

Alexander Fleming

discovered penicillin, Penicillum inhibits growth of colonies

What are the 5 branches of Microbiology?

1.) Bacteriology- Study of Bacteria

2.) Mycology-Study of Fungi

3.) Parasitology-Study of Parasites

4.) Immunology- Study of immune system

5.) Virology- Study of Viruses

Biofilm

A surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation.

normal human microbiota

Populations of mutualistic and commensal microbes that live on and in the bodies of healthy individuals, about 100 trillion bacteria in total, representing hundreds of species

emerging infectious diseases

A new disease or one that reemerges, coronavirus

Primary Differences between Prokaryote and Eukaryote cells

1.) Prokaryotes are smallest organisms/unicellular with circular DNA in nucleoid region, Eukaryotes are larger and multicellular, have enclosed nucleus with strands of DNA

2.) Prokaryotes have cell wall for structure/protection, Eukaryotes have cytoskeleton for support

3.) Prokaryotes do Asexual Reproduction(Binary Fission), Eukaryotes do Sexual Reproduction

Baccillus Cell Shape(Rods)

SingleBaccillus- Single rod

Diplobaccillus- Two rods

Streptobaccillus- Chain of rods

Coccobaccillus-rounded rod, square shape

Coccus Cell Shape (Round/spherical)

Diplococci- Two cocci, one plane of division

Streptococci-Chain of cocci, one plane of division

Tetrad- Four cocci in a quad, two planes of division

Sarcinae- Two tetrads stacked

Staphylococci- Clump of Cocci, looks like grapes

Spiral Cell Shape

Vibrio- Comma shaped, flagella present

Spirillum- Corkscrew Shape

Spirochete- Spiral shaped, wormlike, longer than spirrilum, corkscrew movement

Describe structure and function of Glycocalyx(outer layer of bacteria)

Two types Capsule and Slime Layer

1.) Capsule is sticky, made of "sugar coat", protects the bacteria from dehydration/loss of nutrients. Ability to attach to host cell, AND WILL STOP PHAGOCYTOSIS

2.) Slime Layer is loose/unorganized. Can attach to host or other bacteria and protects it from dehydration.

Prokaryotic Flagella parts, structure and function

1.) Made of three parts: Filament(Actual Tail), Hook(Attaches filament to Basal Body and plasma membrane) and Basal Body(Motor)

2.) Rotates 360 degrees to allow bacteria to "run" and "tumble"

3.) Bacteria move in response to Stimuli (Taxis)

How do Prokayotic and Eukaryotic Flagella movement differ?

Prokaryotic flagella rotate to allow them to run and tumble. Eukaryotic flagella are composed of microtubules in a 9 pairs + 2 array that allow it to bend and grappling hook twitching motility

peritrichous flagella(arrangement of flagella)

flagella all over

Monotrichous Flagella(arrangement of flagella)

One flagella on polar end

Lophotrichous Flagella (arrangement of flagella)

Tuft(several) flagella on polar end

Amphitrichous Flagella (arrangement of flagella)

One Flagella on both polar ends (2 Total)

axial filaments (endoflagella)

Found ONLY in spirochetes.

Anchored at one end of the cell

Rotation of Axial Filament rotates the cell in the opposite direction (similar to corkscrew)

Differentiate the functions of Pili and Fimbriae. Describe how Pili are used for motility

Fimbriae allow for attachment.

Pili facilitate transfer of DNA from one cell to another during conjugation. Have both gliding and twitching motility

Twitching motility of Pili act like a grappling hook, moves in jerking motion towards Pillus

Describe function of bacterial cell wall

Made of Peptidoglycan, sugar protein cell wall

Combats lysis, osmotic lysis

Provides strength to resist rupturing due to osmotic pressure

good antibiotic target

List the Components of Peptidoglycan and describe how these components interact. (GRAM POSITIVE CELL WALL)

Repeating framework of long glycan(sugar)chains cross linked by peptide/protein fragments.

NAG and NAM form sugar chains while amino acids held together by peptide bonds serve as bridge/cross chain.

Wall Techoic Acid links and holds cell wall components together

Lipotechoic Acid- Anchors components of cell wall to plasma membrane, negative charge.

Structurally how does a gram positive cell wall and gram negative cell wall differ?

A gram negative cell wall contains no Teichoic acid.

Composed of thin layer of Peptidoglycan and outer membrane

Lipopolysaccharide on outer membrane has three parts, O Polysaccharide, Core Polysaccharide(provides structure stability), and Lipid A (endotoxin)

Explain the gram stain procedure

Developed by Hans Christian Gram

1.) Primary stain of crystal violet

2.) Use mordant of Iodine to allow for primary stain to stick. Intesifies the affinity of a stain to a structure

3.) Decolorizing agent of Alcohol-Acetone, determines whether gram pos or neg. Dehydrates the cell and pores in cell wall will seal. Will seal the mordant and primary stain. Gram pos cells stay purple while gram neg cells turn colorless.

4.) Counterstain of Safranin. Will turn the gram neg bacteria from colorless to red. However gram pos cells will stay purple even with counterstain.

What happens to cell walls when they become damaged? What are some examples of cells that can disrupt or breakdown cell walls

We hope to kill the cell when damaging the cell wall but some cells have the ability to survive without it.

Protoplasts are wall-less gram positve cells

Spheroplasts are wall-less gram negative cells

L Forms are wall-less cells that swell into irregular shapes

Lysozome digests disaccharide in peptidoglycan

Penicillins are cell wall inhibitors by interfering with peptide bonds

Describe the Structure of the Plasma Membrane and its components

Plasma membrane contains a phospholipid bilayer, peripheral proteins, and Integral and Transmembrane proteins penetrate the membrane

selectively permeability and what are some processes that move materials across the plasma membrane

a property of cell membranes that allows some substances to pass through, while others cannot

Simple diffusion through the lipid bilayer

Facilitated diffusion through a nonspecific transporter

Facilitated diffusion through a specific transporter

Osmosis through the lipid bilayer and an aquaporin

Osmosis and the effect of hypertonic, hypotonic and isotonic solutions on a bacterial cell

Osmosis is the movement of water particles through a semipermeable membrane going from a high to low concentration until equilibrium is reached on both sides.

If a cell is placed in a hypotonic solution, water moves into the cell and if the cell wall is not strong enough it will burst (osmotic lysis)

If a cell is placed in a hypertonic solution, water moves out of the cell and its cytoplasm begins to shrink (plasmolysis)

If a cell is placed in an isotonic solution no net movement of water occurs

Describe the structure of bacterial ribosomes. Why are bacterial ribosomes good targets for antibiotics?

Prokayotes: 70s (svedburg unit)

50s+30s subunits, 30s is the small subunit and 50s is the large subunit. Together they make the complete 70s ribosome

unbound in bacterial cells

Eukaryotes: 80s

40s+60s subunits. 40s is the small subunit and 60s is the large subunit. Together they make the complete 80s subunit

Membrane bound: Attached to ER and free in cytoplasm

Ribosomes are targets for antibiotics because of the size difference in Prokaryotes (70s). Antibiotics can target specific ribosomes to stop them from creating proteins.

Microbial Growth

an increase in number of cells/population, not in cell size

Effects of temperature, pH, osmotic pressure and oxygen on microbial growth

Temperature is the range of temperatures ideal for microbial growth

pH has a varied range based on microbe type. Most 6.5-7.5 pH, acidity and alkalinity inhibit growth.

osmotic pressure, cell in a hypertonic solution is plasmolysed and inhibit growth. Prefer isotonic solutions.

Oxygen byproducts can have a toxic effect on bacteria if they don't have the means of expelling it

facultative anaerobes

both aerobic and anaerobic growth; greater growth in presence of oxygen. Presence of both catalase and SOD to dispel toxic oxygen. Growth is best where most oxygen is present but can occur throughout the test tube.

obligate anaerobes

carry out fermentation or anaerobic respiration and cannot survive in the presence of oxygen. Lacks both enzymes that can dispel toxic oxygen.

aerotolerant anaerobes

can tolerate oxygen and grow in its presence even though they cannot use it, anaerobic growth only. Only has SOD to dispel toxic oxygen.

Microaerophiles

Aerobes that require Oxygen levels from 2-10% and have a limited ability to detoxify Hydrogen Peroxide and Superoxide Radicals

quorum sensing

Communicate and cooperate in the formation and function of biofilms. Quorum sensing allows the microbes in a biofilm to communicate with each other even though they may not be in the same species for the survival of the biofilm.

chemically defined media

exact chemical composition is known

complex media

extracts and digests of yeasts, meat, or plants. Undetermined chemical composition, exact chemical compositon varies from batch to batch.

Describe Methods to grow microbes aneorbically and under high CO2 conditions

Reducing Media: Chemically combines with dissolved O2 and depletes O2 in the media

Anaerobic jar/anaerobic chamber

CO2 incubator/candle jar

Biosafety levels

BSL-1: no special precautions

BSL-2: lab coat, gloves, eye protection

BSL-3: biosafety cabinets to prevent airborne transmission

BSL-4: sealed, negative pressure

Exhaust air is filtered twice

Biosafety levels act as a guide on how dangerous certain microbes are

selective media

suppress growth of unwanted bacteria and encourage growth of desired microbes

differential media

allows growth of several types of microbes and displays visible differences among those microbes

enrichment culture

Selects and encourages growth of desired microbes.

Increases very small numbers of organisms to detectable levels

Streak Plate Method

Used to isolate pure cultures. 4 streaks done on a single plate, streak 1 touches streak 2, streak 2 touches streak 3, streak 3 touches streak 4 but streak 4 does not touch streak 1. Amount of colonies goes down with each streak. You want to form colony forming units (CFUs)

What are the three ways microbes are preserved?

1.) Refrigeration (short term)

2.) Deep Freezing:-50 degrees C to-95 degrees C

3.) Lyphophilization (Freeze Drying): Frozen (-94 degrees C to -72 degrees C) and dehydrated in a vaccum.

List and Define Methods of Reproduction in prokaryotic cells

Binary Fission: Asexual reproduction

Budding: Yeast cells

Condiospores(actinomycetes)

Fragmentation of Filaments

generation time

the time it takes for a population to double in number

What are the 4 phases of the bacterial growth curve

1.) Lag Phase: Intense activity preparing for growth but no increase in population size

2.) Log Phase: Logarithmic or exponential increase in population, highest metabolic activity.

3.) Stationary Phase: Period of equilibrium, microbial deaths balance new production of cells

4.) Death Phase: Population is decreasing at a logarithmic scale

Whats the difference between direct and indirect measures of microbial growth

Direct methods give an almost exact number Microbial growth by processes like plate counts or filtration.

Indirect methods give you an approximate amount of microbial growth by processes like turbidity, metabolic activity and dry weight.

Sepsis

The presence of significant contamination of microbes

Asepsis

absence of significant contamination of microbes

Sterilization

The process that completely destroys all microbial life, including spores.

Disinfection

Destruction of vegetative pathogens on inanimate objects

Antisepsis

destruction of vegetative pathogens on living tissue

Degerming

removal of microbes from a limited area

sanitation

intended to lower microbial growth on eating/drinking utensils to safe public health levels.

biocide/germicide

treatments that kill microbes

Bacteriostasis

inhibiting, not killing, microbes

What factors influence the effectiveness of antimicrobial treatments? What cellular structures are targeted by the microbial control agents?

Microbial Characteristics/ Types

Environmental influence/temperature

Presence of Organic matter

Nature of suspending medium

Time of exposure

Targets include: Alteration of membrane permeability, damage to proteins, damage to nucleic acids.

What is the decimal reduction time?

Minutes to kill 90% of a population at a given temperature

How is moist heat sterilization performed and why is it more effective than dry heat sterilization

Boiling and producing steam under pressure using an autoclave are ways to perform moist heat sterilization.

Moist Heat is more effective because heat is more easily transferred than dry heat

What is pasteurization and the method of Pasteurization. How are dairy products tested to ensure proper pasteurization?

Pasteurization eliminates pathogens and reduces spoilage organisms which increases quality. For milk, process of pasteurization includes High Temp Short Time(HTST): 72 degrees C for 15 sec and Ultra High Temperature (UHT): 140 degrees C for less than 4 seconds.

Phosphotaste Test is used to see if enzyme is inactivated in dairy pasteurized.

examples of dry heat sterilization,

flaming, incineration, hot-air sterilization. Kills by oxidation

have to use a higher temperature for longer if using a dry heat sterilization technique compared to a moist heat sterilization technique.