Functional anatomy of Prokaryotic and Eukaryotic cells Flashcards
What are the main functions of the cell wall?
Prevents cell lysis, helps maintain cell shape, point of anchorage for flagella
What is the primary component of the bacterial cell wall?
Peptidoglycan
What are the two main types of bacterial cell walls?
Gram-positive and Gram-negative
Describe the structure of Gram-positive cell walls.
Thick peptidoglycan layer
Teichoic acid links the sheet layers of peptidoglycan together.
Lipoteichoic acid links peptidoglycan to the plasma membrane.
Describe the structure of Gram-negative cell walls.
Outer membrane
-lipopolysaccharide (endotoxin)
- Periplasm
- Porins: channel protein that allows transport throught the membrane.
Thin layer of peptidoglycan
Is the Gram stain a simple stain or a differential stain?
Differential stain
What reagent is used first in the Gram staining process?
Crystal violet
What is the role of iodine in the Gram stain mechanism?
A mordant
Forms crystals with crystal violet (CV-I complexes) that are too large to diffuse across the gram-positive cell wall.
What effect does alcohol have during the Gram staining process on Gram-positive bacteria?
Dehydrates peptidoglycan, making it more impermeable
What effect does alcohol have during the Gram staining process on Gram-negative bacteria?
Dissolves outer membrane and creates holes in the thin peptidoglycan layer
What is an example of atypical cell walls?
Acid-fast bacteria (Mycobacterium and Nocardia)
What is osmotic lysis?
The bursting of a cell due to excessive water intake
In a hypotonic solution
What is plasmolysis?
The shrinking of a cell due to loss of water
In a hypertonic solution
What are the three types of osmotic solutions?
- Isotonic solution
- Hypotonic solution
- Hypertonic solution
What is the medical significance of peptidoglycan?
Unique to bacteria, it is a target of some antibiotics and recognized by the innate immune system
What are teichoic acids?
Components of Gram-positive cell walls that link peptidoglycan layers together
What is the primary function of fimbriae in prokaryotic cells?
Allow attachment to surfaces and other cells
What is the difference between prokaryotic and eukaryotic cells regarding chromosomes?
Prokaryotes have one circular chromosome, not in a membrane; eukaryotes have paired chromosomes in a nuclear membrane
What are the common bacterial morphologies?
- Coccus (spherical)
- Bacillus (rod-shaped)
- Coccobacillus (short, fat bacillus)
- Spiral (curved)
What are the common bacterial arrangements?
- Diplo- (pairs)
- Strepto- (chains)
- Staphylo- (clusters)
- No arrangement (random)
What is the role of capsules in prokaryotic cells?
Aid in attachment and impair phagocytosis
What is the main function of flagella in prokaryotic cells?
Enable motility
What is the significance of the periplasm in Gram-negative bacteria?
Contains peptidoglycan, degradative enzymes, and toxins
What are the main functions of mitochondria and chloroplasts in eukaryotic cells?
Energy conversion reactions; mitochondria for cellular respiration and chloroplasts for photosynthesis
What is selective permeability in the plasma membrane?
Allows passage of select molecules while restricting others
What are the types of passive transport across membranes?
Simple diffusion
Facilitated diffusion
Osmosis
What does the endosymbiotic theory explain?
The evolution of eukaryotic cells’ organelles from prokaryotes.
What is the structure of prokaryotic ribosomes compared to eukaryotic ribosomes?
Different in structure, prokaryotic ribosomes are 70S
A small subunit: 20s
A large subunit: 50s
Complete unit: 70s.
What are plasmids?
Small, circular, extrachromosomal DNA in prokaryotic cells
What is sporulation?
Endospore formation
Triggered by nutrient deficiency of key nutrients.
What is germination?
Return vegetative (active) state. Triggered by physical or chemical damage to the endospore’s coat.
Can also be triggered by nutrient availability.
What is the role of lysozyme in relation to peptidoglycan?
Attacks disaccharide bonds in peptidoglycan. Causing damage to the cell wall.
Bacteria with weakened cell walls are susceptible to osmotic lysis.
What is the effect of penicillin on bacterial cell walls?
Inhibits peptide cross-bridge formation in peptidoglycan
What is active transport in prokaryotic cells?
Movement of solutes against their concentration gradient requiring energy
Define simple diffusion
Movement of a solute from an area of high concentration to an area of low concentration.
Facilitated diffusion
Solute relies on a transporter protein in order to move down its gradient.
Define Osmosis
Diffusion of water down its gradient.
