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Questions and Answers
What is the scientific naming of microorganisms called?
Which of the following is true about prokaryotic cells?
Eukaryotic cells have ribosomes that are 70S.
False
What is the function of the bacterial cell wall?
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Which of the following structures is NOT found in prokaryotic cells?
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Bacteria are unicellular microorganisms measured in ______.
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Match the following types of bacteria with their characteristics:
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Study Notes
Prokaryotes vs. Eukaryotes
- Prokaryotes reproduce asexually through binary fission, use their cytoplasmic membrane for respiration, lack a nucleolus and nuclear membrane, have a single circular chromosome located in the cytoplasm, and lack mitochondria. Examples include bacteria and rickettsia.
- Eukaryotes reproduce sexually or asexually, use mitochondria for respiration, have a nucleolus and nuclear membrane, have pairs of linear chromosomes located in the nucleus, and contain mitochondria. Examples include human cells, animal cells, fungi, and protozoa.
Bacterial Classification
- Binomial nomenclature uses genus and species to name bacteria. Example: Staphylococcus aureus
Bacterial Morphology
- Size: Bacteria are unicellular microorganisms measured in micrometers.
- Shape and arrangement are key identifying characteristics.
- Gram stain categorizes bacteria into Gram-positive and Gram-negative based on cell wall structure.
- Growth temperature, sporulation, motility, and capsule formation are other relevant factors for classification.
Bacterial Structure
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Essential components:
- Cell wall: Provides shape, support, and a barrier.
- Cytoplasmic membrane: Semi-permeable, regulates passage of substances.
- Cytoplasm: Contains ribosomes, plasmids, and metabolic granules.
- Nuclear material: Single circular chromosome.
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Surface structures:
- Capsules: Protect against phagocytosis.
- Flagella: Provide motility.
- Pili: Attachment structures.
- Endospores: Dormant, resistant structures.
Cell Wall
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Types:
- Gram-positive: Thick peptidoglycan layer, retains Gram stain.
- Gram-negative: Thin peptidoglycan layer, outer membrane with lipopolysaccharide (LPS), does not retain Gram stain.
- Acid-fast bacilli: Unique cell wall with waxy mycolic acids.
- Cell wall deficient: Lacking a complete cell wall.
Lipopolysaccharide (LPS)
- Lipid A: The lipid component of LPS, also known as endotoxin, can trigger fever, septic shock, and inflammation when released from dead Gram-negative bacteria.
Function of the Bacterial Cell Wall
- Maintains shape and integrity of the cell.
- Protects the cell against osmotic pressure.
- Determines Gram reaction.
- Essential for cell division.
- Provides attachment sites for bacteriophages.
- Contains antigenic determinants.
- Responsible for endotoxin activity in Gram-negative bacteria.
- Important target for antibiotics.
Bacteria with Deficient Cell Wall
- Naturally deficient: Mycoplasma
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Induced deficiency:
- L-forms: Caused by antibiotics, high salt concentration, or lysozyme.
- Protoplasts: Gram-positive organisms without a cell wall.
- Spheroplasts: Gram-negative organisms without a cell wall (partially degraded).
Staining Properties
- Gram-positive: Stain purple due to thick peptidoglycan layer.
- Gram-negative: Stain pink due to thin peptidoglycan layer.
Cytoplasmic Membrane
- Structure: Double-layered structure consisting of phospholipids and protein.
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Functions:
- Selective permeability barrier: Regulates passage of molecules into and out of the cell.
- Active transport: Moves ions and nutrients across the membrane.
- Energy production: Electron transport and oxidative phosphorylation.
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Description
Test your knowledge on the differences between prokaryotic and eukaryotic cells. This quiz covers their reproduction methods, cellular components, and classification. Additionally, explore bacterial classification and morphology with specific examples.
