BIOL212 W2-1

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary shape of bacilli in prokaryotic cells?

Tightly coiled

Spherical

Curved

Cylindrical (correct)

Which term refers to the arrangement of cocci that resembles clusters of grapes?

Sarcina

Staphylococcus (correct)

Streptococcus

Coxiella

Which bacterial morphology is characterized by a twisted appearance?

Coccus

Bacillus

Spirillum (correct)

Vibrio

What is the significance of cell morphology in prokaryotic cells?

It does not predict physiology, ecology, or phylogeny. Signup and view all the answers

Which of the following bacterial arrangements is correctly matched with its description?

Staphylococcus - Grapelike clusters Signup and view all the answers

Which prokaryotic cell shape is described as ovoid?

Coccus Signup and view all the answers

Which arrangement refers to a unique bacterial morphology of tightly coiled organisms?

Spirochetes Signup and view all the answers

Which describes the shape of Vibrio bacteria?

Curved Signup and view all the answers

What does the term 'appendaged bacteria' refer to in microbial morphology?

Bacteria with extended appendages Signup and view all the answers

What is the origin of the prefix 'strepto' as used in Streptococcus?

Twisted Signup and view all the answers

What component is primarily found in the S-layers of archaea?

Lipid-modified glycoprotein subunits Signup and view all the answers

What is the primary function of capsules and slime layers in prokaryotic cells?

Assisting in attachment to surfaces Signup and view all the answers

Which of the following bacteria is characterized by the presence of teichoic acid?

Streptococcus pneumoniae Signup and view all the answers

What describes the relationship between the S-layer and the outer membrane in Gram-negative bacteria?

The S-layer is closely associated with the lipopolysaccharide of the outer membrane. Signup and view all the answers

What happens during the process of autolysis in colonies of Streptococcus pneumoniae?

The central portion dissolves, creating a dimpled appearance. Signup and view all the answers

What role do polysaccharide layers in capsules and slime layers play in prokaryotic cells?

They act as virulence factors to prevent phagocytosis. Signup and view all the answers

Which is true regarding the S-layer's structure in Gram-positive bacteria?

S-layers are bound to secondary cell wall polymers. Signup and view all the answers

What type of organisms typically have pseudomurein as an intermediate layer?

Methanogenic archaea. Signup and view all the answers

Which respiratory disease is most commonly caused by Streptococcus pneumoniae?

Pneumococcal pneumonia Signup and view all the answers

Which aspect of capsules differentiates them from slime layers?

Capsules are more resistant to environmental changes. Signup and view all the answers

What property of S.pneumoniae is primarily responsible for its virulence?

Complex polysaccharide capsule Signup and view all the answers

Which of the following vaccines contains capsular polysaccharides from seven serotypes?

Prevnar (PCV7) Signup and view all the answers

Which structure enables bacteria like Salmonella enterica to adhere to surfaces?

Fimbriae Signup and view all the answers

What is the primary function of type IV pili in bacteria?

Enable twitching motility Signup and view all the answers

What distinguishes conjugative/sex pili from fimbriae?

Size and number present per cell Signup and view all the answers

What is the total number of recognized serotypes of S.pneumoniae?

90 Signup and view all the answers

Which property of capsular polysaccharides is essential for their use in vaccines?

Complex structure Signup and view all the answers

What is CRM197 linked to in the Prevnar vaccines?

Capsular polysaccharides Signup and view all the answers

Which of the following best describes the pellicle formed by certain bacteria?

A thin sheet of cells on liquid surface Signup and view all the answers

What is the significance of the $5.95 billion sale of Prevnar 13 in 2020?

It positions Prevnar 13 as the highest selling vaccine (except COVID-19 vaccines). Signup and view all the answers

What is a major component of the gram-positive cell wall?

Peptidoglycan Signup and view all the answers

Which type of bond is found in the pseudomurein of Archaeal cell walls?

β-1,3 glycosidic bonds Signup and view all the answers

What component is covalently bound to the peptidoglycan in gram-positive bacteria?

Teichoic acids Signup and view all the answers

Which statement about S-layers in Archaeal cell walls is true?

They consist of protein or glycoprotein. Signup and view all the answers

Which of the following is NOT a characteristic of teichoic acids?

They are found only in gram-negative bacteria. Signup and view all the answers

What type of cell wall polymer is absent in Archaea?

Peptidoglycan Signup and view all the answers

Which polysaccharide substitutes N-acetylmuramic acid in pseudomurein?

N-acetyltalosaminuronic acid Signup and view all the answers

Which characteristic describes the S-layer structure found in many bacteria and archaea?

Paracrystalline structure Signup and view all the answers

How do S-layers contribute to the overall structure of cell walls?

They are usually the outermost layer. Signup and view all the answers

What is the function of teichoic acids in gram-positive bacteria?

Binding metal ions Signup and view all the answers

What is the key structural characteristic of hami in SM1 Archaea?

They have a barbed terminus for surface attachment. Signup and view all the answers

Which function do carbon storage polymers primarily serve in prokaryotic cells?

Act as energy reserves. Signup and view all the answers

What role do gas vesicles play in planktonic cells?

Confer buoyancy. Signup and view all the answers

Which component is primarily found in the polyphosphate granules in prokaryotic cells?

Inorganic phosphate. Signup and view all the answers

How do magnetosomes assist prokaryotic cells?

Aid in magnetotaxis. Signup and view all the answers

What is a significant characteristic of the structure of gas vesicles?

Impermeable to water and solutes. Signup and view all the answers

What type of energy reserves do sulfur globules represent in prokaryotic cells?

Elemental sulfur as a fixed energy source. Signup and view all the answers

Where are carbonate minerals typically found in prokaryotic cells?

In cell inclusions as biomineralization products. Signup and view all the answers

What are poly-β-hydroxyalkanoates (PHAs) primarily composed of?

Polymers of β-hydroxybutyric acid. Signup and view all the answers

What is the major function of cell inclusions in prokaryotic cells?

Store surplus metabolites and reduce osmotic stress. Signup and view all the answers

What are endospores primarily designed for in bacteria?

Long-term survival under unfavorable conditions Signup and view all the answers

What characteristic is unique to Archaella compared to bacterial flagella?

They are half the diameter of bacterial flagella Signup and view all the answers

Which arrangement of flagella is characterized by a single flagellum at one end of the bacterium?

Polar Signup and view all the answers

What is a distinctive feature of gliding motility in bacteria?

Typically occurs away from the colony Signup and view all the answers

Which type of cells are capable of forming endospores?

Gram-positive bacteria including Bacillus and Clostridium Signup and view all the answers

What is the primary component of bacterial flagella?

Flagellin Signup and view all the answers

How does the swimming speed of bacteria with flagella typically change?

It increases with the strength of the proton motive force Signup and view all the answers

What type of bacterial motility is characterized by smooth, slow movement?

Gliding motility Signup and view all the answers

What is the primary advantage of endospores in bacteria?

Resistance to extreme environmental conditions Signup and view all the answers

Which factor does NOT influence the arrangement of flagella in bacteria?

The presence of endospores Signup and view all the answers

Which behavior describes the movement of E. coli during chemotaxis?

Run and tumble Signup and view all the answers

What type of rotation do flagellar motors use to create a 'run' in bacterial movement?

Counterclockwise Signup and view all the answers

Which of the following describes the role of chemoreceptors in bacteria?

They monitor chemical concentration differences Signup and view all the answers

How does Rhodobacter manage its movement in response to environmental conditions?

By fully reversing flagellar rotation Signup and view all the answers

What allows phototrophic organisms to optimize their position for light harvesting?

Photoreceptors Signup and view all the answers

What describes the motility feature of certain eukaryotic microbial cells?

Cilia or flagella Signup and view all the answers

Which process describes the behavior of bacteria when entering darkness to avoid harmful conditions?

Scotophobotaxis Signup and view all the answers

Which bacteria are noted for their collective movement toward a light source?

Rhodospirillum centenum Signup and view all the answers

What distinguishes the response of bacteria to chemical gradients compared to spatial gradients?

Bacteria respond to temporal differences Signup and view all the answers

What is a key structural feature of eukaryotic cells mentioned?

Presence of a membrane-enclosed nucleus Signup and view all the answers

What is the primary difference between mitosis and meiosis in terms of chromosome sets produced?

Mitosis results in two diploid daughter cells, while meiosis results in four haploid gametes. Signup and view all the answers

Which organelle is crucial for ATP production in anaerobic eukaryotic microorganisms?

Hydrogenosomes Signup and view all the answers

What structural feature distinguishes flagella from cilia?

Cilia are shorter and arranged in rows, while flagella are longer. Signup and view all the answers

What is the main biochemical reaction that occurs within hydrogenosomes?

Oxidation of pyruvate to produce acetate. Signup and view all the answers

What type of motion is utilized by cilia to provide cellular motility?

Whipping Signup and view all the answers

Which of the following components is responsible for driving the motility of flagella?

Dynein Signup and view all the answers

How do meiosis and mitosis differ in terms of genetic variation in the resulting cells?

Meiosis creates genetically varied gametes, while mitosis produces identical daughter cells. Signup and view all the answers

What is the characteristic structural arrangement of cilia?

Nine doublet microtubules surrounding a single central pair Signup and view all the answers

What type of daughter cells does mitosis produce?

Diploid cells Signup and view all the answers

Which statement best describes the role of histones in relation to chromosomes?

Histones help package and organize DNA into chromatin. Signup and view all the answers

Study Notes

Prokaryotic Cell Morphology

Prokaryotic cells have diverse shapes, referred to as morphology.
The major morphologies include:
- Coccus (cocci): Spherical or ovoid.
- Rod/bacillus: Cylindrical.
- Spirillum: Curved or spiral.
Prokaryotic cells can remain grouped after cell division, forming characteristic arrangements such as:
- Chains: Streptococcus
- Cubes: Sarcina
- Grapelike clusters: Staphylococcus
Other types of prokaryotic cells include:
- Spirochetes: Tightly coiled
- Appendaged bacteria: Bacteria with specialized structures
- Filamentous bacteria: Long, thread-like bacteria.
Morphology typically does not predict a prokaryotic cell's physiology, ecology, phylogeny, or other properties.
Some examples of morphologies include:
- Coccus: Coxiella burnetii
- Rod: Prosthecobacter dejongeii
- Spirillum: Treponema pallidum
- Vibrio: Curved rod
- Spirochete: Tightly coiled, helical structure
The term staphyl comes from the Greek word "staphylē" meaning "bunch of grapes," while strepto comes from the Greek word "streptos" meaning "twisted."
These arrangements reflect bacterial growth patterns and cell division.

Gram-positive Cell Wall

Composed of up to 90% peptidoglycan
Peptidoglycan forms "cables"
Teichoic acids are covalently bound to peptidoglycan
Teichoic acids bind divalent metal ions like Ca+2 and Mg+2 for transport
Lipoteichoic acids are teichoic acids covalently bound to membrane lipids

Archaeal Cell Walls

Do not contain peptidoglycan
Contain pseudomurein (pseudopeptidoglycan)
- Found in certain methanogenic Archaea
- Similar to peptidoglycan
- Composed of N-acetylglucosamine and N-acetyltalosaminuronic acid
- Contains β-1,3 glycosidic bonds
- Contains only L-stereoisomer amino acids
Cannot be destroyed by lysozyme or penicillin
Some Archaea lack pseudomurein and have other polysaccharide polymers

S-Layers

Most common type of archaeal cell wall
Made of protein or glycoprotein
Have a paracrystalline structure
Present in many organisms in addition to other cell wall components
Always the outermost layer

Cell Surface Structures

Capsules and slime layers are not part of the cell wall because they do not provide structural strength
They are composed of polysaccharide layers
Can be thick or thin, rigid or flexible
Capsules are tightly attached, form a tight matrix, and are visible with India ink
Slime layers are loosely attached, easily deformed, and are found in organisms like Leuconostoc

Capsule and Slime Layer Functions

Assist in attachment to surfaces
Play a role in biofilm development and maintenance
Important virulence factors: protect against phagocytosis
Prevent dehydration/desiccation

Streptococcus pneumoniae

Gram-positive cocci, arranged in pairs (diplococci) and short chains
Encapsulated
Fastidious growth
Cell wall includes teichoic acid rich in phosporylcholine (C polysaccharide)
C polysaccharide is required for the activity of an autolytic enzyme, amidase

Pneumococcal Disease

Typically occurs when the immune system is weakened
Can occur after other diseases, such as influenza infection
Pneumococcal pneumonia is the most common serious form
Symptoms:
- Fever and chills
- Cough
- Rapid breathing or difficulty breathing
- Chest pain

Disease Mechanism

Virulent strains of S. pneumoniae are covered with a complex polysaccharide capsule
Capsular polysaccharides are used for serologic classification of strains
Currently, 90 serotypes are recognized
Purified capsular polysaccharides are used in a polyvalent vaccine

Polyvalent Pneumococcus Vaccine

Prevnar (PCV7) and Prevnar 13 (PCV13)
- Contain bacterial capsule sugars (capsular polysaccharides) from 7 or 13 serotypes
- Linked to CRM197, a nontoxic recombinant variant of diphtheria toxin

Salmonella enterica

Possesses fimbriae
- Filamentous protein structures
- ~2-10 nm wide
- Enable organisms to stick to surfaces or form pellicles

Pili

-  Typically longer than fimbriae
-  Fewer pili than fimbriae per cell
-  Conjugative/sex pili facilitate genetic exchange between cells (conjugation)
-  Type IV pili adhere to host tissues (bacterial virulence) and support twitching motility

Chemotaxis

E. coli is often used to study chemotaxis.
E. coli is peritrichous, meaning it has flagella distributed around its cell.
E. coli exhibits "run and tumble" behavior.
- Runs are smooth forward movements with flagella rotating counterclockwise.
- Tumbles occur when the flagellar motor rotates clockwise, causing the flagellar bundle to come apart and the cell to stop and jiggle.
Many bacteria, like Pseudomonas, can fully reverse flagellar rotation, avoiding tumbling and reversing direction.
Some bacteria, like Rhodobacter, stop and are affected by Brownian motion.
Bacteria respond to temporal, not spatial, differences in chemical concentration.
Chemoreceptors monitor and sample the environment for attractants and repellents.
Sensory information is transmitted through a complex cascade of proteins that ultimately influence the direction of flagellar motor rotation.

Phototaxis and Other Taxes

Phototaxis involves using photoreceptors to optimize light harvest for phototrophic organisms.
Scotophobotaxis is the response of entering darkness, causing cells to tumble and reverse direction to return to light.
Other taxes include aerotaxis, osmotaxis, and hydrotaxis.

Eukaryotic Microbial Cells

Eukaryotic cells have a membrane-enclosed nucleus.
Other organelles include mitochondria, Golgi complex, lysosomes, endoplasmic reticula, microtubules, and microfilaments.
Some eukaryotes have motility structures like flagella or cilia.
Some eukaryotes have cell walls.
Eukaryotic cell membranes contain sterols that provide structural strength.

Features of the Nucleus and Cell Division

The nucleus contains chromosomes and histones.
Cell division occurs through mitosis and meiosis.
- Mitosis is the normal form of nuclear division in eukaryotic cells resulting in two diploid daughter cells.
- Meiosis is a specialized form of nuclear division resulting in four haploid gametes.

Mitochondria, Chloroplasts, and Hydrogenosomes

These organelles specialize in energy metabolism.
Hydrogenosomes are present in anaerobic eukaryotic microorganisms that lack mitochondria.
Hydrogenosomes oxidize pyruvate to H2, CO2, and acetate, producing ATP and sometimes CH4.
Examples of organisms with hydrogenosomes include human parasites and various protists found in the rumen of ruminant animals.

Flagella and Cilia

Flagella and cilia are organelles of motility allowing cells to swim.
Cilia are short flagella.
Flagella and cilia are structurally distinct from prokaryotic flagella and do not rotate; they whip (flagella) or beat in synchrony (cilia).
These structures consist of a bundle of nine pairs of microtubules surrounding a central pair of microtubules.
Dynein, attached to the microtubules, uses ATP to drive motility.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the diverse shapes and arrangements of prokaryotic cells. This quiz covers the major morphologies, including coccus, bacillus, and spirillum, as well as unique forms like spirochetes and filamentous bacteria. Challenge yourself to identify the structure and classification of these microorganisms.