Microbiology Flagella and Capsule Quiz

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Questions and Answers

What is the primary function of flagella in bacteria?

To facilitate cellular mobility (correct)

To perform photosynthesis

To protect the cell from environmental stress

To assist in DNA replication

Which component distinguishes Gram-negative bacteria from Gram-positive bacteria?

Thick peptidoglycan layer

Presence of an outer membrane (correct)

Lipid A

Teichoic acids

What is the role of fimbriae in bacterial cells?

To provide structural rigidity

To transfer nutrients between cells

To allow attachment to host cells (correct)

To enable movement through liquid environments

Which of the following correctly describes the difference between prokaryotic and eukaryotic flagella?

Eukaryotic flagella are longer and fewer in number compared to prokaryotic flagella. Signup and view all the answers

What is a key feature of a biofilm?

It is a complex community of multiple microbial species. Signup and view all the answers

What prevents bacterial cells from over-expanding when water enters?

Peptidoglycan cell wall Signup and view all the answers

What characteristic of Gram-positive bacteria leads to a different immune response compared to Gram-negative bacteria?

Thick peptidoglycan layer with teichoic acids Signup and view all the answers

What is the primary component of the bacterial envelope?

Cell wall and cytoplasmic membrane Signup and view all the answers

Which structure is characteristic of prokaryotic cells that have lost their cell wall?

Two distinct membrane layers. Signup and view all the answers

What is the main characteristic of mutualism in symbiotic relationships?

Both organisms benefit from the relationship. Signup and view all the answers

What is quorum sensing?

A system of communication that depends on population density. Signup and view all the answers

What is a characteristic feature of commensalism?

One organism is unaffected while the other benefits. Signup and view all the answers

How do microorganisms in a biofilm interact with each other?

They secrete a matrix that helps them adhere to surfaces. Signup and view all the answers

What type of relationship is described as synergism?

A relationship that produces results only when organisms are together. Signup and view all the answers

What significant finding was highlighted by the Human Microbiome Project?

Identifying the role of microorganisms in both healthy and diseased humans. Signup and view all the answers

What is the primary reproductive method of bacteria?

Binary fission. Signup and view all the answers

What is the primary function of ribosomes in a eukaryotic cell?

Protein synthesis Signup and view all the answers

Which structure is responsible for the synthesis of rRNA?

Nucleus Signup and view all the answers

Which of the following describes a function of lysosomes?

Intracellular digestion Signup and view all the answers

What type of ribosomes are found in mitochondria and chloroplasts?

70S Signup and view all the answers

What type of transport does endocytosis belong to?

Active transport Signup and view all the answers

The endosymbiotic theory proposes that mitochondria and chloroplasts originated from which type of organisms?

Prokaryotes Signup and view all the answers

Which component of the cytoplasm is primarily responsible for maintaining cell shape and structure?

Cytoskeleton Signup and view all the answers

What is the role of the Golgi apparatus within a cell?

Post-translation modification and packaging of proteins Signup and view all the answers

Which step in the Gram staining procedure is responsible for setting the dye in the bacteria?

Mordant Signup and view all the answers

What is a key component that acid-fast bacteria have in their cell walls?

Mycolic acid Signup and view all the answers

What is the ultimate purpose of the decolorizer in the Gram staining process?

To remove the outer membrane lipids from Gram-negative bacteria Signup and view all the answers

In the context of mycoplasma, which statement is true about their cell wall?

They possess a plasma membrane that contains sterols. Signup and view all the answers

Which type of bacteria is characterized by having a cell wall made of quasi-peptidoglycan?

Archaea Signup and view all the answers

What color does a Gram-negative bacterium appear after the counter-stain step in the Gram staining process?

Pink Signup and view all the answers

What is the primary stain used in the acid-fast staining procedure?

Carbol fuchsin Signup and view all the answers

What defines a virion?

A complete infectious viral particle Signup and view all the answers

Which step in the Gram staining procedure involves fixing the bacteria to the slide?

Heat fix Signup and view all the answers

Which characteristic is NOT typical of a virus?

Contains ribosomes for protein synthesis Signup and view all the answers

Which of the following refers to the specific types of cells that a virus can infect?

Tissue tropism Signup and view all the answers

How do non-enveloped viruses specifically differ from enveloped viruses?

Non-enveloped viruses have a protein coat only Signup and view all the answers

What occurs during the lytic cycle of a bacteriophage?

Host cell is lysed, releasing new virions Signup and view all the answers

What is a key step in the lysogenic cycle after the bacteriophage penetrates the host cell?

Integration of viral genome into the host cell genome Signup and view all the answers

Which process describes how an animal virus enters a host cell?

Active transport via endocytosis or fusion Signup and view all the answers

What distinguishes viral infections that can affect multiple host types?

Host range Signup and view all the answers

Study Notes

Bacterial Structures and Functions

Slime Layer: A less dense capsule that diffuses into surrounding environments.
Flagella: Whip-like structures on the cell wall aiding mobility; consists of proteins (H antigens), rotating hook, and basal body for anchorage.
Fimbriae: Short, hair-like appendages that enable attachment to host cells.
Pili: Thin, filamentous structures that facilitate DNA transfer during bacterial conjugation.
Prokaryotic Flagellum: Stationary cork-like structure powered by basal motor for rotation.
Eukaryotic Flagellum: Moves in a whipping motion.
Eukaryotic Cilia: Shorter structures that enable diverse movement types.

Bacterial Envelopes and Cell Walls

Bacterial Envelope: Comprises the cell wall and cytoplasmic membrane, with glycocalyx outside the cytoplasm.
Cell Wall Functions: Determines shape, provides structural support, and prevents excessive expansion.
Gram-positive Bacteria: Thick peptidoglycan, no outer membrane, contains teichoic acids for rigidity and immune response variation.
Gram-negative Bacteria: Thin peptidoglycan and outer membrane with lipopolysaccharides (LPS) acting as endotoxins; porins allow specific transport.
Acid-fast Bacteria: Contain mycolic acid layered within peptidoglycan structures.
Archaea Cell Wall: Can be wall-less or consist of pseudopeptidoglycan.
Mycoplasmas: Lack cell walls but possess sterols in the plasma membrane.

Gram Staining Process

Gram Stain Purpose: Differential staining technique distinguishing bacterial types by their cell walls.
Staining Procedure:
- Heat Fixation: Adheres bacterial cells to the slide, preserving their structure.
- Primary Stain (Crystal Violet): Stains all bacteria purple.
- Mordant (Iodine): Forms a complex with crystal violet, trapping it within the cell walls of Gram-positive bacteria.
- Decolorization (Acetone Alcohol): Removes outer membrane lipids from Gram-negative bacteria, allowing them to lose their purple color.
- Counter-Stain (Safranin): Stains exposed Gram-negative peptidoglycan pink, while Gram-positive blijft purple.

Acid-Fast Bacteria (AFB) and Staining Methods

Definition: AFB exhibit PPG stacks similar to Gram-positive bacteria with waxy lipids (mycolic acid).
Acid-Fast Staining Procedure:
- Heat Fixation: Ensures bacterial adherence and preservation.
- Primary Stain (Carbol Fuchsin): Stains acid-fast cells red by penetrating the waxy lipid.

Eukaryotic Cell Structures and Functions

Flagella/Cilia: Enable movement with side-to-side undulation.
Cytoplasm: Contains cytosol (fluid) and cytoskeleton (microfilaments, intermediate filaments, microtubules).
Ribosomes: Composed of 80S subunits, involved in protein synthesis.
Endoplasmic Reticulum:
- Rough ER: Synthesizes and transports proteins.
- Smooth ER: Synthesizes lipids.
Golgi Apparatus: Modifies and packages proteins for secretion.
Lysosomes: Membrane-bound sacs containing digestive enzymes for cellular digestion.
Mitochondria and Chloroplasts: Organelles involved in ATP production and photosynthesis, respectively, with their own DNA and 70S ribosomes.

Endosymbiotic Theory

Concept: Explains the origins of eukaryotic cells from prokaryotic ancestors through symbiotic relationships.
Supporting Evidence:
- Circular chromosomes and 70S ribosomes in mitochondria and chloroplasts.
- Binary fission as a replication method.
- Double-membraned structures similar to Gram-negative bacteria.

Types of Symbiosis

Commensalism: One organism benefits while the other is unaffected.
Mutualism: Both organisms benefit from the interaction.
Parasitism: One organism benefits at the expense of the other.
Synergism: Interaction where two organisms achieve outcomes together that they could not achieve separately.

Biofilms

Definition: Complex communities formed by microorganisms sticking to surfaces and encased in material they produce.

Human Microbiome and Project

Definition: Collection of microorganisms associated with healthy and diseased humans.
Human Microbiome Project: Aims to characterize microbial communities and their biological properties over time.

Microbial Ecology

Study of Interactions: Focuses on how microorganisms interact with each other and their environments.

Bacterial Communication

Mechanisms: Microorganisms secrete chemical signals, have corresponding receptors, and respond when a certain threshold of signal concentration is reached.
Quorum Sensing: Enables microorganisms to coordinate gene expression based on local population density.

Virions and Virus Characteristics

Virion: Complete infectious viral particle.
General Characteristics:
- Composed of either DNA or RNA with a protein coat (capsid).
- May be enveloped or non-enveloped.
- Host-specific, often targeting certain cell types.

Bacteriophages and Viral Life Cycles

Bacteriophage: Viruses infecting bacteria; specific bacteriophages target specific bacterial strains.
Lytic Cycle Steps:
- Absorption, penetration, replication, assembly, maturation, and lysis of host cell.
Lysogenic Cycle: Viral DNA integrates into the host genome after adsorption and penetration.

Animal Virus Multiplication Steps

Absorption/Attachment: Virus binds to specific receptors on host cell.
Penetration: Entry via endocytosis or fusion into the host cell membrane.

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Description

Test your knowledge of the microbial structures such as the slime layer, flagella, and fimbriae. This quiz covers their functions, composition, and importance in mobility and attachment to host cells. Understand the basic concepts associated with these components of cell biology.