Exam 4 Lesson 40 Flashcards
What role do structural fibers play?
They provide tensile strength and prevent stretching.
What role does hydrated matrix play?
Provides resistance to compression and also supports the structural fibers to restrict lateral movement.
What is a hydrated matrix?
It is a gel. Sugar groups with a charge attract ions; they are osmotically active and attract water molecules; withstand compressive forces.
Cell walls/ECMs of bateria are made of
peptidoglycan,
cell walls/ECMs of fungi are made of
structural fibers: chitin, beta-glucan
hydrated matrix: glycoproteins, proteoglycans, etc.
cell walls/ECMs of animals are made of?
structural fibers: chitin, collagen, elastin
hydrated matrix: GAGs, glycoproteins, proteoglycans, etc.
what are collagen and elastin made of?
protein
cell walls/ECMs of plants are made of?
structural fibers: cellulose, extensin
hydrated matrix: pectins, glycoproteins, etc.
what is extensin made of?
protein
what is bacterial peptidoglycan made from?
a repeating disaccharide of N-acetylglucosamine (NAC) and N-acetylmuramic acid (NAM)
How is the NAM sugar modified in bacterial peptidoglycan?
it is modified to include a peptide side chain (That varies among bacteria) that provides cross-linking between the polymer chains
why do gram-positive bacteria retain the crystal violet stain?
because of large amount of peptidoglycan in cell wall.
What type of bacteria has an outer layer of only peptidoglycan?
gram-positive bacteria
what steps of peptidoglycan synthesis are targeted by antibiotics?
transglycosidase and transpeptidase
what does transglycosidase do?
elongates chain
what does transpeptidase do?
cross-links through peptide
beta-lactam antibiotics like penicillin inhibit
the transpeptidase
why are gram-positive bacteria sensitive to penicillin?
because they use DD-transpeptidase to build the cell wall.
what are archaeal cell walls made from?
N-glycosylated surface proteins
Is Hyaluron a structural fiber?
No. It is a GAG, part of the hydrated matrix for animal cells.
chitin synthase
synthesizes chitin, a carb structural fiber.
Beta-glucan synthase
synthesizes carb structural fiber beta-glucan (fungi only)
cellulose synthase
synthesizes carb structural fiber cellulose (plants, algae and other eukaryotes)
Why can elastin fibers stretch without deformation? For what kind of tissue is this trait valuable?
They lack secondary structure and have a high degree of cross-links. Valuable for tissue that must stretch and then return to original shape.
what are cellulose structural fibers in plant cell walls deposited by?
cellulose synthase
What is the hydrated matrix a product of?
the secretory pathway
what is hyaluron synthase?
helps make hydrated matrix in animal cells.
In animal cells, what are GAGS synthesized by?
they are synthesized by hyaluronan synthase on the plasma membrane.
What is hyaluron? How is it synthesized?
It is a very long chain GAG. It is synthesized on the plasma membrane by hyaluron synthase. It is not attached to a protein.
Why are GAG molecules highly hydrated?
to resist compressive forces
How do some GAGS play essential roles in signaling?
they bind signal molecules, inhibiting their diffusion or acting as “co-receptors”.
