CH 3 Test Review

Question 1

Organelles (Parts) of Prokaryotic Cells & Their Functions

Answer 1

Cell Membrane: Controls the movement of substances in/out of the cell.

Cytoplasm: Contains enzymes and is the site of metabolic reactions.
Ribosomes: Sites for protein
synthesis.

Nucleoid: Region where the bacterial DNA is located (not membrane-bound).

Plasmids: Small, circular DNA molecules that often carry genes for antibiotic resistance.

Flagella: Tail-like structure for movement.
Pili: Hair-like projections involved in attachment and genetic exchange (conjugation).

Question 2

Characteristics of Bacterial Cells

Answer 2

Unicellular: Single-celled organisms.
Lack of Membrane-bound Organelles: No nucleus or mitochondria.

Peptidoglycan Cell Wall: A rigid cell wall made of peptidoglycan.

Shapes: Cocci (spherical), Bacilli (rod-shaped), Spirilla (spiral-shaped).

Question 3

Plasmids

Answer 3

Extra-chromosomal DNA is found in many bacteria.

Functions:
Antibiotic resistance.
Virulence factors (ability to cause disease).
Additional metabolic functions.

Question 4

Structures Allowing Bacteria to Cause Disease

Answer 4

Toxins:
Exotoxins: Secreted toxins (e.g., tetanus toxin).

Endotoxins: Found in the outer membrane of Gram-negative bacteria.

Adhesion Structures:
Pili: For attachment to host tissues.

Capsules: Protect against phagocytosis.

Invasion Factors: Enzymes to help bacteria invade and spread in the host.

Question 5

Gram Staining

Answer 5

Purpose: To differentiate bacteria into Gram-positive and Gram-negative.
Steps:

Crystal Violet: Stains all cells purple.

Iodine: Fixes the stain inside the cell.

Alcohol: Decolorizes Gram-negative cells.

Safranin: Stains decolorized cells pink.

Gram-positive: Purple; thick peptidoglycan layer.

Question 6

Common Gram + vs. Gram – Organisms

Answer 6

-Both are prokaryotes, meaning they don’t have a nucleus.
-Both have a cell wall that helps protect the cell.
-Both have a plasma membrane that controls what enters and exits the cell.
-Both contain DNA in a single, circular chromosome.
-Both have ribosomes for protein production.

Question 7

Differences Between Gram + and Gram – Organisms

Answer 7

Cell Wall Composition:
Gram-positive: Thick peptidoglycan.
Gram-negative: Thin peptidoglycan with an outer lipid membrane.

Staining:
Gram-positive: Purple.
Gram-negative: Pink.

Antibiotic Sensitivity:
Gram-negative: More resistant to antibiotics due to outer membrane.

Question 8

Types of Staining (and Structures You Can View)

Answer 8

Gram Staining: Differentiates between

Gram-positive and Gram-negative.
Acid-Fast Staining: Used for bacteria with waxy cell walls, e.g., Mycobacterium.

Endospore Staining: Stains bacterial spores, e.g., Bacillus.

Capsule Staining: Highlights bacterial capsules.

Flagella Staining: Observes flagella for bacterial motility.

Question 9

Shapes & Arrangements of Bacteria Cells

Answer 9

Shapes:
Cocci: Spherical.
Bacilli: Rod-shaped.
Spirilla: Spiral-shaped.

Arrangements:
Cocci: Chains (Streptococcus), clusters (Staphylococcus).
Bacilli: Single, pairs, chains (Bacillus).
Spirilla: Helical shapes.

Question 10

Unique Types of Cell Walls Amongst Bacteria (ex. Mycobacterium)

Answer 10

Mycobacterium: Waxy, lipid-rich cell wall (resistant to staining).

Archaea: Lack peptidoglycan, have pseudomurein or S-layer proteins.

Mycoplasma: No cell wall; naturally resistant to beta-lactam antibiotics.

Question 11

Phenotypic Traits of Bacteria (Outward Appearance)

Answer 11

Colony Morphology: Shape, size, color, and texture of bacterial colonies.

Microscopic Shape: Observed under a microscope (cocci, bacilli, etc.).

Biochemical Properties: Fermentation, enzyme production.

Antigenic Properties: Surface markers recognized by the immune system.

Question 12

Chemotaxis

Answer 12

Definition: The movement of bacteria in response to chemicals in their environment.
Positive Chemotaxis: Movement towards attractants (e.g., nutrients).

Negative Chemotaxis: Movement away from harmful substances.