Exam 4 Lesson 40

Question 1

What role do structural fibers play?

Answer 1

They provide tensile strength and prevent stretching.

Question 2

What role does hydrated matrix play?

Answer 2

Provides resistance to compression and also supports the structural fibers to restrict lateral movement.

Question 3

What is a hydrated matrix?

Answer 3

It is a gel. Sugar groups with a charge attract ions; they are osmotically active and attract water molecules; withstand compressive forces.

Question 4

Cell walls/ECMs of bateria are made of

Answer 4

peptidoglycan,

Question 5

cell walls/ECMs of fungi are made of

Answer 5

structural fibers: chitin, beta-glucan

hydrated matrix: glycoproteins, proteoglycans, etc.

Question 6

cell walls/ECMs of animals are made of?

Answer 6

structural fibers: chitin, collagen, elastin

hydrated matrix: GAGs, glycoproteins, proteoglycans, etc.

Question 7

what are collagen and elastin made of?

Answer 7

protein

Question 8

cell walls/ECMs of plants are made of?

Answer 8

structural fibers: cellulose, extensin

hydrated matrix: pectins, glycoproteins, etc.

Question 9

what is extensin made of?

Answer 9

protein

Question 10

what is bacterial peptidoglycan made from?

Answer 10

a repeating disaccharide of N-acetylglucosamine (NAC) and N-acetylmuramic acid (NAM)

Question 11

How is the NAM sugar modified in bacterial peptidoglycan?

Answer 11

it is modified to include a peptide side chain (That varies among bacteria) that provides cross-linking between the polymer chains

Question 12

why do gram-positive bacteria retain the crystal violet stain?

Answer 12

because of large amount of peptidoglycan in cell wall.

Question 13

What type of bacteria has an outer layer of only peptidoglycan?

Answer 13

gram-positive bacteria

Question 14

what steps of peptidoglycan synthesis are targeted by antibiotics?

Answer 14

transglycosidase and transpeptidase

Question 15

what does transglycosidase do?

Answer 15

elongates chain

Question 16

what does transpeptidase do?

Answer 16

cross-links through peptide

Question 17

beta-lactam antibiotics like penicillin inhibit

Answer 17

the transpeptidase

Question 18

why are gram-positive bacteria sensitive to penicillin?

Answer 18

because they use DD-transpeptidase to build the cell wall.

Question 19

what are archaeal cell walls made from?

Answer 19

N-glycosylated surface proteins

Question 20

Is Hyaluron a structural fiber?

Answer 20

No. It is a GAG, part of the hydrated matrix for animal cells.

Question 21

chitin synthase

Answer 21

synthesizes chitin, a carb structural fiber.

Question 22

Beta-glucan synthase

Answer 22

synthesizes carb structural fiber beta-glucan (fungi only)

Question 23

cellulose synthase

Answer 23

synthesizes carb structural fiber cellulose (plants, algae and other eukaryotes)

Question 24

Why can elastin fibers stretch without deformation? For what kind of tissue is this trait valuable?

Answer 24

They lack secondary structure and have a high degree of cross-links. Valuable for tissue that must stretch and then return to original shape.

Question 25

what are cellulose structural fibers in plant cell walls deposited by?

Answer 25

cellulose synthase

Question 26

What is the hydrated matrix a product of?

Answer 26

the secretory pathway

Question 27

what is hyaluron synthase?

Answer 27

helps make hydrated matrix in animal cells.

Question 28

In animal cells, what are GAGS synthesized by?

Answer 28

they are synthesized by hyaluronan synthase on the plasma membrane.

Question 29

What is hyaluron? How is it synthesized?

Answer 29

It is a very long chain GAG. It is synthesized on the plasma membrane by hyaluron synthase. It is not attached to a protein.

Question 30

Why are GAG molecules highly hydrated?

Answer 30

to resist compressive forces

Question 31

How do some GAGS play essential roles in signaling?

Answer 31

they bind signal molecules, inhibiting their diffusion or acting as “co-receptors”.