Bacteria Classification & Structure

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Questions and Answers

Prokaryotes have a much simpler design than eukaryotes.

True

What are the traits of eukaryotic cells?

Fungi, Parasites
Larger than prokaryotes
Membrane-bound true nucleus
More than 1 diploid strand
Membrane-bound organelles
Bigger ribosomes
Sterols in membrane
Cell wall in fungi is chitin
Respiration via mitochondria
Sexual/Asexual reproduction

What are the traits of prokaryotic cells?

Bacteria
Smaller than eukaryotes
No membrane-bound nucleus
1 chromosome, haploid circular
No membrane-bound organelles
Smaller ribosomes
No sterols in the membrane
Peptidoglycan cell wall
Respiration via cytoplasmic membrane
Binary fission reproduction

What is the clinical significance of peptidoglycan?

Since it is unique to bacterial cell walls, it is a good target for antibiotics. Signup and view all the answers

What are the classifications of bacteria?

<ol> <li>Macroscopic/Microscopic Appearance</li> <li>Growth/Metabolic Properties</li> <li>Antigenicity</li> <li>Genetic Properties</li> </ol> Signup and view all the answers

What is macroscopic appearance in bacteria?

Growth characteristics on nutrient and selective media including colony morphology. Signup and view all the answers

What are the three basic bacterial shapes?

<ol> <li>Coccus - round spheres</li> <li>Bacilli - rods</li> <li>Spirillum - spirals</li> </ol> Signup and view all the answers

What are the bacterial arrangements?

Coccus, Bacillus, Spirochete <ol> <li>Pairs and singles/PandS/Borrelia</li> <li>Chains/Chains/Treponema</li> <li>Clusters/Flagellated Bacilli/Spirilla</li> </ol> Signup and view all the answers

What is the purpose of the Gram staining technique?

Separates bacteria into two major groups based on differences in cell wall structures. Signup and view all the answers

Which organisms cannot be classified by Gram stain?

<ul> <li>Mycobacterium (waxy outer coat)</li> <li>Mycoplasma (no peptidoglycan)</li> <li>Chlamydia (spore-like)</li> <li>Treponema (very thin)</li> </ul> Signup and view all the answers

What are the steps of Gram staining?

<ol> <li>Crystal Violet</li> <li>Iodine</li> <li>Decolorizer (Alcohol/Acetone)</li> <li>Safranin Red</li> </ol> Signup and view all the answers

How does E. coli typically appear visually?

Short rods (bacilli) that lightly stain. Signup and view all the answers

How does S. aureus typically appear visually?

Groups of cocci that stain darkly. Signup and view all the answers

What is the clinical significance of Gram staining?

Important in determining proper therapy for treatment of an infection. Signup and view all the answers

What are growth/metabolic properties?

<ul> <li>Oxygen requirements (aerobic vs anaerobic)</li> <li>Substrate utilization (lactose vs nonlactose fermenter)</li> <li>Production of specific enzymes (catalase)</li> </ul> Signup and view all the answers

What is antigenicity?

Presence of characteristic surface antigens. Signup and view all the answers

What is serotyping?

Distinguishing strains of bacteria by using antibodies that can detect specific antigens. Signup and view all the answers

What are genetic properties in bacteria?

<ul> <li>Highly conserved sequences identify genus</li> <li>Highly variable sequences identify species/subspecies</li> <li>Methods (DNA hybridization, PCR, ribotyping, microarray)</li> </ul> Signup and view all the answers

In prokaryotes, a mutation in the mother cell may or may not be expressed in daughter cells.

False Signup and view all the answers

Where is the round chromosome found in the prokaryotic cell?

In the cytoplasm; no membrane-bound organelles. Signup and view all the answers

What characterizes the cytoplasmic membrane in prokaryotic cells?

Similar to eukaryotes but no sterols in prokaryotes; responsible for many functions. Signup and view all the answers

What are the characteristics of the bacterial cell wall?

<ul> <li>Outermost component to all bacteria (except Mycoplasma)</li> <li>Distinguishes Gram + and -</li> <li>Prevents osmotic lysis</li> <li>Determines/maintains cell shape</li> <li>Contains peptidoglycan</li> </ul> Signup and view all the answers

What are PAMPs?

Pathogen-Associated Molecular Patterns; repetitive patterns on bacteria that the innate immune system can respond to. Signup and view all the answers

Study Notes

Prokaryotes vs. Eukaryotes

Prokaryotes have a simple design and are generally smaller than eukaryotes.
Eukaryotic cells include fungi, animals, and plants, characterized by membrane-bound organelles and a true nucleus.

Eukaryotic Traits

Larger than prokaryotes with complex structures, including multiple diploid chromosomes.
Membrane-bound organelles present, including mitochondria for respiration.
Cell walls in fungi contain chitin; capable of sexual and asexual reproduction.

Prokaryotic Traits

Bacteria that are smaller and simpler than eukaryotic cells.
Lack a membrane-bound nucleus; possess a single haploid circular chromosome.
Contain peptidoglycan in their cell walls, crucial for maintaining structure.

Clinical Significance of Peptidoglycan

Unique to bacterial cell walls, making it an effective target for antibiotics.

Classification of Bacteria

Based on macroscopic/microscopic appearance, growth/metabolic properties, antigenicity, and genetic properties.

Macroscopic Appearance

Analyzed through growth characteristics on selective media, which includes colony morphology like size, shape, and sugar fermentation.

Basic Bacterial Shapes

Cocci: round spheres.
Bacilli: rod-shaped.
Spirillum: spiral-shaped.

Bacterial Arrangements

Cocci and Bacilli arrangements: pairs, chains, or clusters.
Example of Spirochete includes Borrelia and Treponema.

Gram Staining Technique

Differentiates bacteria into Gram-positive (purple) and Gram-negative (pink) based on cell wall structure.

Organisms Not Classified by Gram Stain

Mycobacterium (due to waxy coat).
Mycoplasma (lacks peptidoglycan).
Chlamydia (spore-like).
Treponema (very thin).

Steps of Gram Staining

Use Crystal Violet (Gram+ turns purple, Gram- absorbs temporarily).
Iodine is applied to enhance staining.
Decolorizer (Alcohol/Acetone) removes purple from Gram- bacteria.
Apply Safranin Red, which stains Gram- pink/red while Gram+ remains purple.

Visual Characteristics

E.coli: short rods that lightly stain.
S.aureus: darkly staining clusters of cocci.

Clinical Significance of Gram Staining

Essential for determining appropriate antibiotic treatment based on bacterial characteristics (e.g., Staphylococcus vs. Streptococcus).

Growth/Metabolic Properties

Examined through oxygen requirements (aerobic vs. anaerobic), substrate utilization (fermenters vs. non-fermenters), and enzyme production.

Antigenicity

Defined by the presence of unique surface antigens on bacterial cells.

Serotyping

Method to distinguish bacterial strains using antibodies that detect specific antigens.

Genetic Properties

Identified through conserved and variable DNA sequences that aid in classifying bacteria into genus and species.

Prokaryotic Mutations

Any mutation in a prokaryotic mother cell is always expressed in daughter cells, as they are clones.

Prokaryotic Genetic Material

Chromosome found in the cytoplasm; no membrane-bound organelles and transcription coupled with translation.

Cytoplasmic Membrane Functions

Similar to eukaryotes but lacks sterols; involved in electron transport, ATP production, uptake, secretion, and cell division.

Cell Wall Characteristics

Outermost component in all bacteria except Mycoplasma, critical for structural integrity and preventing osmotic lysis.

PAMPs

Pathogen-Associated Molecular Patterns trigger innate immune responses due to repetitive structures on bacteria.

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Description

This quiz covers the classification and structural differences between prokaryotes and eukaryotes. It includes true/false questions and details about eukaryotic traits, providing a comprehensive overview of microbial biology. Perfect for biology students looking to enhance their understanding of microorganisms.