proteins

Question 1

dynein

Answer 1

In cilia and flagella, a large motor protein extending from one microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in dynein shape that lead to bending of cilia and flagella.

Question 2

actin

Answer 2

globular protein that forms the twisted double chains of microfilaments

Question 3

myosin

Answer 3

• A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction. Thicker than actin.
• Like dynein, myosin acts as a motor protein by means of projections that “walk” along the actin filaments.
• Part of contractile apparatus of MUSCLE cells

Question 4

pectin

Answer 4

Sticky polysaccharide that makes up the middle lamella.

Question 5

fibronectin

Answer 5

• An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix.
• Fibronectin and other ECM proteins bind to cell-surface receptor proteins called integrins that are built into the plasma membrane.

Question 6

integrin

Answer 6

• Cell-surface receptor protein built into the plasma membrane; has 2 subunits.
• Span the membrane and bind on their cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton.
• Transmit signals btwn ECM and cytoskeleton; thus integrates changes occurring inside and outside the cell.

Question 7

lignin

Answer 7

• a complex organic polymer deposited in the cell walls of many plants, making them rigid and woody.
• Present in all vascular plants, but not in bryophytes.
• Relatively indigestible; accounts for more than a quarter of the dry mass of wood.

Question 8

suberin

Answer 8

• As cork cells mature, they deposit a waxy, hydrophobic material called SUBERIN in their walls and then die.
• B/c cork cells have SUBERIN and are usually compacted together, most of the periderm is impermeable to water and gases.