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Questions and Answers
What is the primary function of the Golgi apparatus in bacterial cells?
What is the primary function of the Golgi apparatus in bacterial cells?
- Protein glycosylation (correct)
- Gene replication
- Energy production
- Cell wall synthesis
Which of the following components is characteristic of Gram-negative bacteria?
Which of the following components is characteristic of Gram-negative bacteria?
- Outer membrane containing lipopolysaccharides (correct)
- Teichoic acids in the cell wall
- Thick peptidoglycan layer
- Single membrane structure
What role do pili play in bacterial cells?
What role do pili play in bacterial cells?
- Movement through flagella
- Attachment to surfaces and other cells (correct)
- Nutrient absorption
- Cellular respiration
Which statement is true regarding the bacterial cell wall structure?
Which statement is true regarding the bacterial cell wall structure?
How do bacterial cells move towards attractants?
How do bacterial cells move towards attractants?
What is a key characteristic of the lipopolysaccharide (LPS) found in Gram negative bacteria?
What is a key characteristic of the lipopolysaccharide (LPS) found in Gram negative bacteria?
Which component is responsible for antigenic variation in Gram negative bacteria?
Which component is responsible for antigenic variation in Gram negative bacteria?
How do Gram positive bacteria differ from Gram negative bacteria in terms of their cell wall structure?
How do Gram positive bacteria differ from Gram negative bacteria in terms of their cell wall structure?
What role does the plasma membrane have in prokaryotic cells?
What role does the plasma membrane have in prokaryotic cells?
What can occur as a result of very small amounts of lipopolysaccharide (LPS) in the bloodstream?
What can occur as a result of very small amounts of lipopolysaccharide (LPS) in the bloodstream?
Why do Gram positive bacteria not require porin proteins?
Why do Gram positive bacteria not require porin proteins?
Which statement about S. aureus is true regarding its cell wall?
Which statement about S. aureus is true regarding its cell wall?
How does a mesosome function in a prokaryotic cell?
How does a mesosome function in a prokaryotic cell?
What is the primary function of the endoplasmic reticulum in eukaryotic cells?
What is the primary function of the endoplasmic reticulum in eukaryotic cells?
Which components are primarily involved in glycosylation of proteins?
Which components are primarily involved in glycosylation of proteins?
What characterizes Gram-negative bacteria compared to Gram-positive bacteria?
What characterizes Gram-negative bacteria compared to Gram-positive bacteria?
What is the role of porin proteins in the Gram-negative cell wall?
What is the role of porin proteins in the Gram-negative cell wall?
Which of the following best describes the structure of the Golgi complex?
Which of the following best describes the structure of the Golgi complex?
What is a key function of lipoprotein in Gram-negative bacteria?
What is a key function of lipoprotein in Gram-negative bacteria?
What distinguishes the peptidoglycan layer in Gram-positive bacteria?
What distinguishes the peptidoglycan layer in Gram-positive bacteria?
In which cellular component does the initial glycosylation of proteins occur?
In which cellular component does the initial glycosylation of proteins occur?
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Study Notes
Lipopolysaccharide (LPS) in Gram-Negative Bacteria
- Each LPS molecule contains five lipid chains.
- Core polysaccharide is consistent within species and across genera.
- O antigenic side chain exhibits high variability, contributing to antigenic variation.
- Known as endotoxin; can be more toxic than other bacterial toxins.
- Minimal LPS amounts in blood may cause lethal anaphylactic shock.
Gram-Positive Cell Wall Structure
- Peptidoglycan layer is significantly thicker than that of Gram-negative counterparts.
- Contains other polymers, such as Teichoic acid.
- Lacks an outer membrane; solutes diffuse through the thick peptidoglycan.
- Proteins covalently linked to peptidoglycan extend into the environment, aiding in immune evasion.
- Common pathogenic example: Staphylococcus aureus.
Prokaryotic Structures and Functions
- Plasma Membrane:
- Selectively permeable barrier and mechanical cell boundary.
- Facilitates nutrient and waste transport, and hosts metabolic processes (e.g., respiration, photosynthesis).
- Plays a role in detecting environmental cues for chemotaxis.
- Mesosome:
- Potentially involved in cross-wall formation and chromosome distribution during cell division.
Protein Secretion in Eukaryotic Cells
- Protein glycosylation initiates in the endoplasmic reticulum (ER) and continues in the Golgi complex.
- Secretory proteins, such as IgG, undergo extensive processing before reaching the external environment.
Bacterial Cell Classification
- Primary classification of bacteria via Gram stain identifies two groups: Gram-positive and Gram-negative.
- Named after Christian Gram in 1884, correlating staining with cell envelope structure.
Gram-Negative Cell Wall Structure
- Multilayered wall with thin peptidoglycan and an outer membrane featuring LPS.
- Contains two membranes; outer membrane is rich in lipopolysaccharides.
- Peptidoglycan, also known as murein, provides osmotic strength and structural integrity.
- Lipoprotein links the peptidoglycan layer to the outer membrane.
- Porins are abundant protein pores allowing nutrient passage through the outer membrane.
- The space between inner and outer membranes is called the periplasmic space.
Bacterial Motility
- Bacteria display a run and tumble mode of locomotion.
- Flagella facilitate movement towards attractants while tumbling provides directional change.
Pili Structure and Function
- Pili are hair-like structures on bacterial surfaces, with various types serving different functions.
- E. coli has Type I pili for attachment to mammalian cells and larger F pili for mating processes.
Key Points to Remember
- Understand the mechanisms of protein targeting and secretion pathways.
- Familiarize with the chemical composition and differences in Gram-negative and Gram-positive cell walls.
- Learn how bacterial locomotion occurs through the run and tumble method.
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