Chapter 15

Question 1

Function of extracellular matrix?

Answer 1

provides structural support to cells and tissues and regulates cell bahviour

Question 2

cell wall function?

Answer 2

determines cell shape and prevents cells from swelling and bursting

Question 3

bacterial cell wall shapes ?

Answer 3

rod shaped, spherical, spiral shaped

Question 4

two classes of bacteria?

Answer 4

gram positive and gram negative bacteria

Question 5

difference b/w gram positive and negative bacteria?

Answer 5

gram-ve=thin cell wall

gram+ve=thick cell wall

Question 6

main component of bacterial cell wall?

Answer 6

peptidoglycan

Question 7

FtZ

Answer 7

cell division

Question 8

MreB

Answer 8

cell elongation

Question 9

main component of cell walls of eukaryotes?

Answer 9

polysaccharides

Question 10

fungal cell walls and exoskeletons of anthropoids?

Answer 10

chitin

Question 11

what is the cell wall of algae and higher plants made of ?

Answer 11

cellulose

Question 12

what are the linkages between chitin and cellulose ?

Answer 12

beta 1—>4 linkages

Question 13

highly branched polysaccharides H bonded to the surface of cellulose microfibrils, provide stability and mechanical strength ??

Answer 13

hemicellulose

Question 14

branched polysaccharides with negatively charged galacturonic acids?

Answer 14

pectins(cross link cellulose microfibrils)

Question 15

primary cell walls?

Answer 15

thin, flexible , contain equal amounts of cellulose, hemicellulose and pectins

Question 16

secondary cell walls?

Answer 16

1-present b/w plasma membrane and primary cell wall after cell growth
2-lack pectin and are50-80% cellulose

Question 17

are complex polymer of phenolic residues that gives strength and density to wood?

Answer 17

lignin

Question 18

do cells maintain osmotic balance between the cytosol and extracellular fluids?

Answer 18

no

Question 19

what builds up in the cell and eventually equalizes the osmotic pressure and prevents further influx of water and leads to rigidity of plant tissues ?

Answer 19

hydrostatic pressure/turgor pressure

Question 20

which plant hormones activate proteins called expansins which weaken the Reginas of the cell wall allowing expansion?

Answer 20

auxins

Question 21

where does all the water accumulate so the cell can’t expand without increasing the volume of the cytosol?

Answer 21

large central vacuole

Question 22

what enzyme synthesizes cellulose from UDP glucose ?

Answer 22

cellulose synthase

Question 23

what are laid down parallel to cortical microtubules under the plasma membrane?

Answer 23

microfibrils

Question 24

what guides the movement of cellulose synthase and defines the orientation of the newly synthesized microfibrils?

Answer 24

microtubules

Question 25

what defines the direction of cell wall growth and cell expansion and ultimately the shape of the entire plant ?

Answer 25

cortical microtubules

Question 26

thin layers on which epithelial cells rest and surround muscle cells, dispose cells and peripheral cells ?

Answer 26

basal laminae

Question 27

where is extracellular matrix most abundant ?

Answer 27

connective tissue

Question 28

tendons?

Answer 28

high proportion of fibrous proteins

Question 29

cartilage?

Answer 29

high level of polysacchrides

Question 30

bone matrix?

Answer 30

calcium phosphate crystals

Question 31

the major structural protein?

Answer 31

collagen

Question 32

what is collagen made up of ?

Answer 32

triple helices(three polypeptide chains)

Question 33

smallest amino acid?

Answer 33

glycine

Question 34

what does the triple helix domains amino acid sequence consist of?

Answer 34

Guy-X-Y

Question 35

what is formed in the ER by modification of proline in collagen polypeptide chains?

Answer 35

hydroxyproline

Question 36

type 1 collagen forms _______ in which the triple helical molecules form regular staggered arrays.

Answer 36

collagen fibrils

Question 37

procollagens?

Answer 37

assembly of fibrils occurs outside the cell from soluble precursor

Question 38

what cross links b/w side chains of lysine and hydrooxylysine residues help strengthen the fibrils?

Answer 38

covalent cross links

Question 39

Fibril associated collagens bind to collagen fibrils and link them to one another and to other matrix components. T/F

Answer 39

True

Question 40

what type of collagen is basal laminae ?

Answer 40

type IV

Question 41

what is present in organs that stretch and return to shape such as lungs ?

Answer 41

elastic fibres that are made of elastin

Question 42

extracellular matrix gels are formed from polysaccharides called _______.

Answer 42

GAGs(glycosaminoglycans)-they are repeating units of disaccharides

Question 43

what is the only GAG that is a single long polysaccharide chain?

Answer 43

hyaluronan

Question 44

GAGs link to proteins to form?

Answer 44

proteoglycans

Question 45

what is the major proteoglycan of cartilage that has about 100 chains of chondroitin sulphate attached to a core protein?

Answer 45

aggrecan

Question 46

____ link matrix components to one another and to cell surfaces.

Answer 46

matrix adhesion proteins

Question 47

what is the main adhesion protein of connective tissues?

Answer 47

fibronectin

Question 48

basal laminae belong to which family?

Answer 48

laminin family

Question 49

laminas are tightly associated with _____ and adhesion protein that also binds to type IV collagen.

Answer 49

nidogen

Question 50

transmembrane proteins that attach cells to the extracellular matrix??

Answer 50

integrins

Question 51

_____ were first identified by immunofluorescence and immunoelctron microscopy of transmembrane glycoproteins at points of cell adhesion to the matrix.

Answer 51

integrins

Question 52

bundles of actin filaments are anchored to beta subunits of integrins via other proteins??

Answer 52

focal adhesions

Question 53

they anchor epithelia cells to basal laminae?

Answer 53

hemidesmosomes

Question 54

name cell adhesion molecules ?

Answer 54

selecting, integrins, immunoglobulin superfamily, cadherins

Question 55

what do selectins do?

Answer 55

mediate transient interactions b/w leukocytes and endothelial cells

Question 56

____ leave the circulation at sites of tissue inflammation by interacting with endothelial cells of capillaries.

Answer 56

leukocytes

Question 57

example of heterophilic interaction?

Answer 57

binding of ICAMS to integrins

Question 58

heterophilic interaction?

Answer 58

an adhesion molecule on one cell recognizes a different molecule on another cell

Question 59

homophilic interactions ?

Answer 59

adhesion molecule on one cell binds to the same molecule on another cell

Question 60

what links actin filaments of adjacent cells ?

Answer 60

adherens junctions

Question 61

what links intermediate filament cytoskeletons of adjacent cells ?

Answer 61

desmosomes

Question 62

____ in epithelial cell sheets from a seal that prevents free passage of molecules and ions b/w cells.

Answer 62

tight junctions

Question 63

what acts as a glue to hold adjacent cells together?

Answer 63

middle lamella

Question 64

adjacent plant cells communicate through cytoplasmic connections called?

Answer 64

plasmodesmata