Microbiology Chapter 4 Quiz

Questions and Answers

How much peptidoglycan is found in a Gram-positive cell wall?

60-90%

How much peptidoglycan is found in a Gram-negative cell wall?

10-20%

How do some antibiotics and disinfectants kill bacteria?

Some will target the cell capsule and prevent formation of cell wall.

What is the bacterial shape of coccus?

Spherical Signup and view all the answers

What is the bacterial shape of bacillus?

Rodlike Signup and view all the answers

What is the bacterial shape of vibrio?

Comma shaped Signup and view all the answers

What is the bacterial shape of spirillum?

Rigid Signup and view all the answers

What is the bacterial shape of spirochete?

Corkscrew Signup and view all the answers

What is pleomorphism?

Some bacteria varying widely in form even within a single culture. Signup and view all the answers

What is the arrangement of cells in diplo?

Cells in pairs Signup and view all the answers

What is the arrangement of cells in strepto?

Cells in chains Signup and view all the answers

What is the arrangement of cells in tetrads?

4 cells arranged in a cube Signup and view all the answers

What is the arrangement of cells in sarcinae?

8 cells arranged in a cube Signup and view all the answers

What is the arrangement of cells in staphylo?

Grape-like clusters Signup and view all the answers

Structurally, what do bacterial cells consist of?

A cell membrane, usually surrounded by a cell wall, internal cytoplasm with ribosomes, nuclear region, external structures: capsules, flagella, and pili. Signup and view all the answers

What are two important functions of the bacterial cell wall?

Maintains the characteristic shape of the cell and prevents the cell from bursting when fluids flow into the cell. Signup and view all the answers

What is the single most important component of the bacterial cell wall?

Peptidoglycan Signup and view all the answers

What is endotoxin?

Important part of the outer membrane and is released when cell walls of dead bacteria are broken down. Signup and view all the answers

What does endotoxin consist of?

Polysaccharides and lipid A Signup and view all the answers

What is the periplasmic space?

A gap between the cell membrane and the cell wall in bacteria. Signup and view all the answers

Why is the periplasmic space important?

A very active area of cell metabolism. Signup and view all the answers

Study Notes

Bacterial Cell Wall Composition

Gram-positive cell walls contain 60-90% peptidoglycan.
Gram-negative cell walls consist of 10-20% peptidoglycan.

Antibiotic Mechanisms

Certain antibiotics and disinfectants target the cell capsule, hindering cell wall formation and contributing to bacterial cell death.

Bacterial Shapes

Coccus: spherical shape.
Bacillus: rod-like shape.
Vibrio: comma-shaped.
Spirillum: rigid structure.
Spirochete: corkscrew form.

Pleomorphism

Refers to the variability in bacterial shape, with some bacteria showing diverse forms even within a single culture.

Cellular Arrangements

Diplococci: bacteria arranged in pairs.
Streptococci: bacteria organized in chains.
Tetrads: four cells structured in a cube.
Sarcinae: eight cells arranged in a cube.
Staphylococci: bacteria clustered in grape-like formations.

Structural Components of Bacterial Cells

Bacterial cells consist of a cell membrane, a cell wall, internal cytoplasm containing ribosomes, a nuclear region, and external structures like capsules, flagella, and pili.

Functions of the Bacterial Cell Wall

Maintains the specific shape of the bacterium.
Prevents rupture of the cell when subjected to osmotic pressure from fluids.

Key Cell Wall Component

Peptidoglycan is the single most crucial element of the bacterial cell wall.

Endotoxin Details

Endotoxin is integral to the outer membrane of Gram-negative bacteria and is released upon the breakdown of dead bacteria's cell walls.
It comprises polysaccharides and lipid A.

Periplasmic Space

The periplasmic space is the area between the cell membrane and the cell wall.
This space is pivotal for bacterial metabolism, indicating a high level of cellular activity.

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Description

Test your knowledge on Gram-positive and Gram-negative cell walls with this quiz. Learn about peptidoglycan content and the mechanisms of antibiotics. Assess your understanding of bacterial shapes and their characteristics.