Prokaryotic Cell Biology

Which of the following is NOT a characteristic of prokaryotic cells?
A. Lack of internal membranes
B. Can specialize into tissues
C. Lack of organelles
D. Do not form multicellular organisms

lack internal membranes and organelles

What shape is described as a comma-shaped bent rod?
A. Bacillus
B. Vibrio
C. Spirillum
D. Spirochete

vibrio

Which bacterial arrangement describes a group of eight cells?
A. Tetrad
B. Sarcina
C. Strepto
D. Staphylo

Sarcina

True/False

• Prokaryotes contain membrane-bound organelles.

• “Staphylo-” describes bacteria arranged in clusters.

• “Diplo-” refers to bacteria dividing into groups of four.

F T F

• The bacterial shape described as a rod is called ___________.

• “Coccus” refers to a ___________-shaped bacterium.

• ___________ describes bacteria arranged in a chain.

bacillus, circle, strepto

Match the following glycocalyx components with their descriptions:

Structure	Description
A. Capsule	1. Not well organized, loosely attached
B. Slime layer	2. Firmly attached, organized structure

A2, B1

The glycocalyx helps bacteria by:
A. Providing energy for photosynthesis
B. Protecting against phagocytosis
C. Destroying host immune cells directly
D. Serving as a genetic material storage site

protecting against phagocytosis

The crystalline layer that maintains cell shape and adhesion is the:
A. Capsule
B. S layer
C. Slime layer
D. Pili

S layer

Which pathogen’s S layer contributes to its high virulence in hospital infections?
A. Escherichia coli
B. Clostridium difficile
C. Bacillus anthracis
D. Mycoplasma pneumoniae

clostridium difficile

True/False

• The S layer protects cells from dehydration.

• Glycocalyx can act as a nutrient source under stress conditions.

T T

Describe how the glycocalyx contributes to virulence.

the glycocalyx contributes to virulence by helping bacteria evade the host immune system and adhere to surfaces. Its capsule form protects the cell from phagocytosis by white blood cells, allowing the pathogen to survive longer in the host. It also promotes the formation of biofilms, which make bacterial communities more resistant to antibiotics and immune defenses. Increases a bacterium’s ability to infect, survive, and spread within a host

Explain why a capsule might help bacteria survive inside a host.

a capsule helps bacteria survive inside a host by protecting them from the host’s immune defenses. The capsule acts as a slippery outer layer that prevents phagocytosis, making it harder for white blood cells to engulf and destroy the bacteria. It can also block desiccation, drying out, and help the bacteria adhere to host issues, giving them a better chance to multiply and cause infection

Which structure is responsible for bacterial movement?
A. Pili
B. Flagella
C. Fimbriae
D. Ribosomes

flagella

The protein that composes flagella is:
A. Tubulin
B. Actin
C. Flagellin
D. Myosin

flagellin

A bacterium with flagella on both ends is described as:
A. Monotrichous
B. Peritrichous
C. Amphitrichous
D. Lophotrichous

amphitrichous

Eukaryotic flagella move by _________, while prokaryotic flagella move by _________.
A. Twisting; waving
B. Waving; twisting
C. Rotating; sliding
D. Sliding; contracting

waving, twisting

Fill in the Blank

• ___________ are short hair-like structures used for attachment.

• ___________ are longer structures used to transfer DNA during conjugation.

• Axial filaments are found in ___________ and allow movement by twisting.

Fimbriae, pili, spirochetes

True/False

• Fimbriae are found mainly in gram-positive bacteria.

• Pili can contribute to antibiotic resistance.

• Axial filaments are also called endoflagella.

F T T

Explain how pili can contribute to the spread of antibiotic resistance.

Pili, specifically conjugation pili, contribute to the spread of antibiotic resistance by allowing horizontal gene transfer between bacteria. During this process, one bacterium transfers a plasmid, a small circular piece of DNA, to another cell through the pilus. These plasmids often contain antibiotic resistance genes, enabling the recipient bacterium to survive antibiotic treatment and pass those resistance traits on to future generations. 

• Why are axial filaments important for spirochete motility?

Axial filaments are important for spirochete motility because they allow these bacteria to movie in a corkscrew-like motion, which helps them travel through viscous environments such as mucus or tissue. These filaments are located between the cell wall and outer sheath and, when they rotate, they cause the entire cell to twist and flex. This is unique movement gives spirochetes the ability to burrow host tissues, a key factor in their ability to infect and spread

The primary component of bacterial cell walls is:
A. Peptidoglycan
B. Lipid A
C. Cellulose
D. Chitin

peptidoglycan

O-polysaccharides act as:
A. Endotoxins
B. Antigens
C. Energy sources
D. Enzymes

antigens

What is the function of iodine during Gram staining?
A. Counterstain
B. Mordant
C. Decolorizer
D. Primary stain

mordant

A bacterium lacking peptidoglycan and containing sterols in its membrane is most likely:
A. Mycoplasma
B. Archaea
C. Bacillus
D. Clostridium

mycoplasma

Matching

Type	Characteristic
A. Gram-positive	1. Thin peptidoglycan, outer membrane present
B. Gram-negative	2. Thick peptidoglycan, no outer membrane

A2, B1

Fill in the Blank

• The ___________ acts as an endotoxin in gram-negative bacteria.

• The enzyme ___________ breaks bonds in peptidoglycan and is effective against gram-positive bacteria.

• ___________ are bacteria that lack a cell wall but have sterols in their membrane.

Lipopolysaccharide, lysozyme, mycoplasmas

True/False

• All bacteria have the same type of cell wall structure.

• Acid-fast bacteria contain mycolic acid in their cell walls.

F T

Why is knowing whether a bacterium is Gram-positive or Gram-negative important in medicine?

Because it guides antibiotic selections. Gram positive have thick peptidoglycan walls and are more susceptible to antibiotics that target cell wall synthesis. Gram negative have thin peptidoglycan and an outer membrane with lipopolysaccharides, which can act as endotoxins and make them more resistant to certain antibiotics

Explain how lysozyme damages bacterial cell walls.

Lysozyme breaks the bonds in peptidoglycan, which weakens the cell wall making bacterium susceptible to osmotic lysis. more effective against gram positive bacteria because their thick peptidoglycan layer is directly exposed. Gram negative have an outer membrane that protects them

The region containing bacterial DNA is called the:
A. Nucleus
B. Nucleoid
C. Ribosome
D. Plasmid

Nucleoid

Plasmids:
A. Are essential for bacterial survival
B. Often carry helpful genes such as antibiotic resistance
C. Are part of the main chromosome
D. Are found only in eukaryotes

Bacterial ribosomes are smaller than eukaryotic ones, making them:
A. Ineffective in protein synthesis
B. Targetable by certain antibiotics
C. Useless to the cell
D. Identical to human ribosomes

Often carry helpful genes such as antibiotic resistance

Fill in the Blank

• ___________ are storage areas for materials like phosphate, lipids, and sulfur.

• ___________ inclusions allow movement up and down water columns.

• ___________ inclusions contain magnetic iron oxide, acting like a compass.

Inclusions, gas vacuoles, magnetosomes

True/False

• Plasmids are necessary for survival.

• Carboxysomes allow some bacteria to fix carbon dioxide.

• Gas vacuoles help bacteria adjust their buoyancy.

F T T

Define “selective toxicity” and explain its medical importance.

the ability of a drug to target and kill or inhibit harmful microorganisms without causing significant harm to the host’s cells. It allows antibiotics and antimicrobial treatments to effectively treat infections while minimizing damage to the patient’s own cells.

Why might inclusions be considered “survival tools” for bacteria?

Inclusions are considered survival tools because they store essential nutrients and compounds that bacteria can use when resources are limited

Endospores are produced by:
A. Gram-negative bacteria only
B. Gram-positive bacteria such as Bacillus and Clostridium
C. Archaea only
D. Fungi

gram positive bacteria such as bacillus and clostridium

What triggers endospore formation?
A. Abundance of nutrients
B. Favorable environmental conditions
C. Environmental restriction or stress
D. Genetic mutation

environmental restriction or stress

During sporulation, the newly formed spore is first called a:
A. Sporangium
B. Forespore
C. Nucleoid
D. Protoplast

forespore

Describe the steps of sporulation.

new dna separated, plasma membrane surrounds the copy of dna, forms forespore, sporangium engulfs forespore, layers of peptidoglycan and protein form around forespore and provide resistance, maturation, release

Explain why endospores are clinically important.

Because they are extremely resistant to heat, desiccation, chemicals, and radiation, making infections difficult to eliminate

You are analyzing a hospital infection caused by Clostridium difficile. Explain how the organism’s S layer and endospore formation make it highly virulent.

The S layer is a crystalline protein layer that helps maintain cell shape, adhesion, and protection. Protects the bacterium from host defenses, such as phagocytosis, allowing it to persist longer in the host. Endospores allow C. Difficile to survive harsh conditions like antibiotics, disinfectants, and dehydration. Both together enhance immune evasion, colonization, and make it difficult to treat 

A bacterial sample stains Gram-positive and forms endospores. Which genus might it belong to, and why is this clinically significant?

the bacterium likely belongs to the genus bacillus or clostridium as these are gram positive capable of forming endospores

Which of the following is present in both prokaryotes and eukaryotes?
A. Nucleus
B. Ribosomes
C. Mitochondria
D. Endoplasmic reticulum

Ribosomes

A key structural difference between prokaryotes and eukaryotes is:
A. Eukaryotes have no membranes
B. Prokaryotes lack a true nucleus
C. Prokaryotes contain lysosomes
D. Eukaryotes lack ribosomes

prokaryotes lack a true nucleus

List two similarities and two differences between prokaryotic and eukaryotic cells.

both have ribosomes for protein synthesis, both have a plasma membrane that regulates what exits and enters the cell

• Explain how bacterial flagellar movement differs from eukaryotic flagellar movement.

bacterial flagella and eukaryotic flagella move differently due to structural and mechanistic differences. Bacterial is composed of flagellin protein, move by rotating like a propeller, twisting. eukaryotic flagella is composed of microtubules, move in a wave like or whip like motion, powered by atp. Bacteria rotate to move, while eukaryotes wave their flagella. This allows bacteria to navigate their environment differently than eukaryotic cells. 

Prokaryotes lack

internal membrane bound organelles

prokaryotic cells contain

dna, ribosomes, cytoplasm, and a plasma membrane

spherical or circular

cocci

rod shaped

bacillus

comma shaped or slightly curved rod

vibrio

sprillium

rigid corkscrew shape

flexible, tightly coiled corkscrew

spirochete

tree-like filamentous shape

branching filaments

pair after one division

diplo

chain formation

strepto

group of four

tetrad

sarcina

group of eight

staphylo

irregular cluster

glycocalyx

surface coating made of polysaccharides, polypeptides, or both

types of glycocalyx

capsule and slime layer

well organized and firmly attached to cell wall

capsule

loosely organized and easily washed off

slime layer

functions of glycocalyx

nutrient source during starvation, virulence factor, protects bacteria from being eaten by immune cells, prevents dehydration by retaining water, reduces material loss from the cell, forms biofilms

crystalline layer of protein or glycoprotein

s layer

s layer functions

maintains cell shape and rigidity, aids in adhesion to surfaces and host cells

Clostridium difficile uses an S layer that

contributes to its pathogenicity and persistence in hospitals

Any feature that helps a pathogen interact with/or persist in a host _____ disease likelihood

increases

external appendages made of the protein flagellin

flagella

structure of flagella

filament, hook, basal body (anchor), anchoring differs between gram positive and gram negative bacteria

monotrichous

single flegellum

peritrichous

flagella covering entire surface

lophotrichous

tuft/cluster of flagella at one end

amphitrichous

flagella at both ends

Prokaryotic flagella movement:

rotate like a propeller, twisting motion

eukaryotic flagella movement:

move in a whip like or wave motion, sperm cells

virulence, regarding flagella

the motility aids bacteria in colonization and infection, increasing pathogenic potential

Found in spirochetes

axial filaments/endoflagella

where is endoflagella found

inside the outer sheath but outside the cell wall

What do endoflagella allow

bacterium to corkscrew through viscous environments such as tissue or mucus

Endoflagella is important for

pathogenicity

Pili function

DNA transfer during conjugation 

Conjugation

a process in which one bacterium transfers genetic material to another through cell to cell contact

Conjugation process

donor cell form a pilus, pilus attaches to a recipient cell that lacks plasmid, a copy of the plasmid dna is transferred through pilus into cell, the recipient becomes a new donor

Why does conjugation matter

one of the main ways bacteria share genes, including antibiotic resistance genes

What is longer, pili or fimbriae

pili

May carry toxin or antibiotic resistance genes, which can spread to other bacteria

pili

pili are important for

genetic diversity and antimicrobial resistance

short, thin, hair like appendages made of protein

fimbriae

where are fimbriae mostly found

in gram negative bacteria

fimbriae function

attachment to surfaces, hosts, and other cells, not movement

what does the peptidoglycan structure do

provides shape, strength, and protection from osmotic pressure

what has thick peptidoglycan layer

gram positive

what has thin peptidoglycan layer plus an outer membrane

gram negative

O-polysaccharides act as

antigen surface identifiers

Lipopolysaccharides function as

endotoxins in gram negative bacteria

list the steps of a gram stain by reagent

crystal violet, iodine, alcohol, safranin

list the steps of a gram stain by function

primary stain, mordant/stain fix, decolorizer, counter stain

which bacteria retain the purple crystal violet-iodine complex

gram positive