Lecture 11

Question 1

fibroblast

Answer 1

sit in spaces of connective tissue. bundle of collagen. organized

Question 2

extracellular matrix

Answer 2

• Gel-like “ground substance”
• Primarily made up of polysaccharides
-Glycosaminoglycans (GAGS)
-proteoglycans
• Fibrous proteins
-Collagen, elastin, fibronectin, laminin
-Structure and adhesive functions

Question 3

proteoglycan

Answer 3

protein that has sugars

Question 4

lamin

Answer 4

intermediate filaments on inner part of nucleus, where chromosomes gets bound to

Question 5

laminin

Answer 5

extracellular matrix protein

Question 6

GAGS

Answer 6

• Repeating disaccharide units
• One is an amino sugar
• Charged - sulfate and carboxyl groups
• Most anionic molecules of animal cells(negative)

Question 7

what follows charge?

Answer 7

water

Question 8

since GAGS are the most anionic molecules

Answer 8

• Attract positive ions (Na+)
• Attracts H2O
• Hydration creates swelling pressure - called turgor
• Protects joints - cartilage matrix protects from compressive forces

Question 9

GAGS examples

Answer 9

• Hyaluron - not sulfated
-secreted directly from cell surface
-doesn’t have to be bound to a protein
• Dermatin or chondroitin sulfate
• Heparin sulfate
• Keratin sulfate

Question 10

what is the function of GAGS?

Answer 10

regulate activity of secreted proteins

• Immobilize secreted molecules close to where they are secreted
• Provide a reservoir of protein for later use
• Protects proteins from proteolytic degradation

Question 11

Inflammatory response

Answer 11

chemokines are immobilized by proteoglycans on endothelial cells and allows for homing of lymphocyte

Question 12

fibrous proteins of ECM

Answer 12

-Collagen
-Elastin
-Fibronectin
they’re covalently bound to one another.

Question 13

Collagen

Answer 13

• Limits stretching and prevents tearing
• Skin and bone
• Secreted by fibroblasts
• 3 alpha helices: GXY; modified aa (hydroxyproline and hydroxylysine)
• intramolecular linkages

Question 14

GXY

Answer 14

(glycine [smallest], x and y are modified amino acids).

Question 15

hydroxyproline and hydroxylysine are

Answer 15

imino acids

Question 16

intermolecular cross link

Answer 16

between. linkages bw collagen fibers

Question 17

intramolecular cross link

Answer 17

within. 2 strands have this, so theyre strong

Question 18

covalently crosslinked helices

Answer 18

• Often fibrils perpendicular to each other
• Strong - resist tensile forces
• Deficiency in making these aa - Vit C (Scurvy-disease)

Question 19

not enough vit C

Answer 19

dont make collagen correctly

Question 20

Elastin

Answer 20

• Highly hydrophobic
• Secreted and also organized in fibers and sheets (covalently-crosslinked, similar to collagen)
• Structure makes them elastic
• Also has hydroxyproline and hydroxylysine

Question 21

Stretching important in numerous tissues

Answer 21

heart, lungs, bladder, kidney etc…

Question 22

fibrillin

Answer 22

Elastin molecules covered with another molecule

-Defects in fibrillin result in Marfan’s syndrome

Question 23

Fibronectin

Answer 23

• Helps cells attach to matrix
• Complex protein - binds to multiple substrates
• RGD sequence
• 2 separate polypeptide chains

Question 24

2 of fibronectin molecule make up

Answer 24

fibronectin protein. bound to C termini

Question 25

RGD sequence

Answer 25

-binds to integrins Not only used by fibronectin -Blood clotting - fibrinogen -RGD sequences in other proteins targetted by snake venom (inhibits blood clotting)

Question 26

what are integrins?

Answer 26

``` class of proteins, alpha and beta involved. plays a role in cell cell interactions and extracellular matrix -bind to fibronectin and gags ```

Question 27

so snake venom

Answer 27

inhibits binding to RGD sequence

Question 28

if normal mammalian cells were treated with nocodazole, where would you expect to see lysosomes by immunofluorescence?

Answer 28

nocodazole disrupts microtubles based on RILF exp. without nocodazole, lysosomes were clustered together in perinuclear region. now, they are dispersed away from single perinuclear location.

Question 29

actin can have both

Answer 29

T and D caps

Question 30

micortubules minus end plus end

Answer 30

- T caps | - T or D caps