Unit 1, Lecture 3
Describe the composition of a Gram-positive cell walls.
A broad dense cell wall Numerous layers of peptidoglycan Teichoic acids and lipoteichoic acids. Studded with protein
Define antigen
A substance that reacts with antibody molecules and antigen receptors on lymphocytes. When recognized by the body as nonself it stimulates an adaptive immune response
Read the description of Mycobacterium tuberculosis and match the bacterium with the description of the organism and the infection it causes.
ACID-FAST CELL WALL:Acid-fast bacteria such as the mycobacteria have a cell wall with a relatively impermeable outer membrane containing a waxy lipid called mycolic acid. This mycolic acid outer membrane impedes the entry of many harmful disinfectants and antibiotics but also slows the entry of nutrients needed for bacterial growth.
What are the possible beneficial functions to the bacterium of adhesin?
Adhesins allow bacteria to adhere to host cell surfaces, colonize, and resist flushing
Indicate the possible beneficial functions to the bacterium of the adhesins in Gram-negative
Adhesins allow bacteria to adhere to host cell surfaces, colonize, and resist flushing.
Indicating the roles of autolysins in peptidoglycan synthesis
Autolysins break the bonds between monomers as well as the cross links between the polysaccharide chains.
Name at least 4 risk factors for UTIs.
Being female Being sexually active Having a suppressed immune system Certain birth control
a peptidoglycan monomer
Composed of NAM, NAG, and a pentapeptide. This best describes:
Describe the composition of a Gram-negative cell wall
Consists of 2-3 layers of peptidoglycan Composed of phospholipids, lipoproteins, and lipopolysaccharides. Outer membrane
autolysins
Enzymes that break the glycosidic bonds and peptide cross bridges so that new monomers can be inserted during peptidoglycan synthesis are called:
transpeptidases
Enzymes that reform the peptide cross bridges between the layers and rows of peptidoglycan during bacterial cell wall synthesis are called:
Name the most common bacterium to cause UTIs.
Escherichia coli
Indicate the possible beneficial functions to the bacterium of the porins in Gram-negative
Funcation in the body defense and pathogenesis by monitoring the entry or exclusion of molecules
When Gram-negative bacteria enter the blood and cause septicemia, most of the harm to the body is due to a massive inflammatory response. What might explain this
GRAM-NEGATIVE CELL WALL:The outer membrane of the gram-negative cell wall contains lipopolysaccharide or LPS. This LPS can bind to receptors on body defense cells and stimulate inflammation. While acute inflammation is critical to body defense, excessive inflammation can be very destructive to the body.
Indicate the possible beneficial functions to the bacterium of the invansins in Gram-negative
Invasins allow certain bacteria to enter host cells.
What are the possible beneficial functions to the bacterium of invasin ?
Invasins allow certain bacteria to enter host cells.
State the 3 parts of a peptidoglycan monomer
NAG, NAM, and a pentapeptide
Name at least 3 common symptoms of UTIs
Pain or burning when urinating Pain in lower belly Cloudy urine with pink or red color
Briefly describe how antibiotics such as penicillins, cephalosporins, and vancomycin affect bacteria and relate this to their cell wall synthesis.
Penicillins bind to transpeptidase enzymes Prevents the enzymes from resealing the peptidoglycan The cell wall becomes weak The bacterium bursts as a result of osmotic pressure.
Describe the composition of an acid-fast cell wall.
Peptidoglycan Glycolipids such as mycolic acid which makes up 60%. Porins
State the function of peptidoglycan in bacteria
Peptidoglycan prevents osmotic lysis.
What are the possible beneficial functions to the bacterium of peptidoglycan in gram positive?
Peptidoglycan prevents osmotic lysis.
State what color Gram-negative bacteria stain after Gram staining.
Pink
Indicate the beneficial function to the bacteriums of porins.
Porins are required to transport small molecules through the outer membrane of the acid-fast cell wall. There are far fewer porins in the acid-fast cell wall compared to the gram-negative cell wall and the pores are much longer. This is thought to contribute significantly to the lower permeability of acid-fast bacteria.
The function of peptidoglycan in bacteria is to:
Prevent bacterial lysis in a hypotonic environment
Indicate the possible beneficial functions to the bacterium of the outer membrane in Gram-negative
Prevents some toxic materials such as lysozyme and penicillin G from entering many gram-negative bacteria.
State what color Gram-positive bacteria stain after Gram staining.
Purple
State what color acid-fast bacteria stain after acid-fast staining.
Red
State what color acid-fast bacteria stain.
Red
What are the possible beneficial functions to the bacterium of teichoic acids in gram positive?
Teichoic acids add strength to the gram-positive cell wall.
Briefly describe how LPS and other PAMPs of the Gram-negative cell wall can promote inflammation.
The LPS binds to a LPS-binding protein circulating in the blood and this complex, in turn, binds to a receptor molecule found on the surface of body defense cells called macrophages. This triggers the macrophages to release various defense regulatory chemicals called cytokines, The cytokines then bind to cytokine receptors on target cells and initiate inflammation, as well as activating both the complement pathways and the coagulation pathway.
Indicate the possible beneficial functions to the bacterium of the lipossaccharides in Gram-negative
The Lipopolysaccharides or LPS function as an endotoxin.
Why the the color of acid-fast stain is that color that it produces?
The acid fast cell wall contains only small amounts of peptidoglycan but large amounts of glycolipids such as mycolic acid. A waxy lipid called mycolic acid makes up approximately 60% of the wall and makes the cell wall relatively impermeable.
Indicating the roles of bactoprenols in peptidoglycan synthesis
The bactoprenols transport the peptidoglycan monomers across the cytoplasmic membrane and helps insert them into the growing peptidoglycan chains.
Define epitope
The part of an antigen that react with receptors on B-lymphocytes and T-lymphocytes, as well as with free antibody molecules. 5 to 15 amino acids of a protein antigen or 3 to 4 sugar residues of a polysaccharide antigen.
Briefly describe how PAMPs of the Gram-positive cell wall can promote inflammation.
The peptidoglycan monomers and teichoic acids bind to a receptor molecules found on the surface of body defense cells called macrophages. This triggers the macrophages to release various defense regulatory chemicals called cytokines, including IL-1, IL-6, IL-8, TNF-alpha, and PAF. The cytokines then bind to cytokine receptors on target cells and initiate inflammation, as well as activating both the complement pathways and the coagulation pathway.
Bacteria normally live in a hypotonic environment. Since water flows into a cell in an environment that is hypotonic, why don't the bacteria burst from osmotic pressure?
The rigid layer of peptidoglycan in the bacterial cell wall creates a turgor pressure and prevents the cell from bursting.
Indicate the beneficial function to the bacteriums of mycolic acid.
To make the acid-fast cell wall rather impermeable Impedes the entry of chemicals This causes the bacteria to grow slowly To be more resistant to chemical agents and lysosomal components
Indicating the roles of transglycosylase in peptidoglycan synthesis
Transglycosylase enzymes then insert and link new peptidoglycan monomers into the breaks in the peptidoglycan.
Indicating the roles of transpeptidases in peptidoglycan synthesis
Transpeptidase enzymes reform the peptide cross-links between the rows and layers of peptidoglycan.
Cystitis
inflammation of the bladder
Pyelonephritis
inflammation of the kidneys when a Urinary tract infection travels to the kidney
Urethritis
inflammation of the urethra
Define periplasm.
the region between inner and outer membranes of Gram negative bacteria.