Chapter 6

Question 1

what separates the cell from the outside, creates intracellular compartments (organelles), and is selectively permeable

Answer 1

biological membrane or cell membrane

Question 2

what does a fluid mosaic model do

Answer 2

it describes the general structure of biological membranes

Question 3

what are the characteristics of a phospholipid head

Answer 3

• a phosphate group and glycerol
• negatively charged
• polar
• hydrophilic
• face outward toward the
  aqueous environment

Question 3

what are the characteristics of a phospholipid tail

Answer 3

• two fatty acid chains
• uncharged
• nonpolar
• hydrophobic
• face inward toward each other

Question 4

how far to transmembrane proteins extend?

Answer 4

extend all the way through the phospholipid bilayer, with one or more transmembrane domains.

Question 4

what is an anchored membrane protein

Answer 4

covalently attached to fatty acids or other lipids

Question 4

what is a peripheral membrane protein

Answer 4

lack hydrophobic regions and do not penetrate the bilayer; located on one side of the membrane

Question 5

what are the three types of membrane proteins

Answer 5

integral, peripheral, and anchored

Question 5

what is a integra membrane protein

Answer 5

least partly embedded in the bilayer; the hydrophilic domain sticks
out into the inside or outside of the cell; the hydrophobic domain interacts with the fatty acids in the interior. Some extend across the lipid bilayer; others are partially
embedded.

Question 5

can the different domains have different functions

Answer 5

yes

Question 6

what do the membrane have on the outer surface that perform many different functions for the cell

Answer 6

Carbohydrates

Question 7

What are glycolipids

Answer 7

(carbohydrate + lipid)
* less diverse group
* facilitate cell recognition (self vs. non-self)

Question 8

what are glycoproteins

Answer 8

(carbohydrate + protein)
* more diverse group
* serve as receptors for chemical signals

Question 9

what do cells arrange themselves into

Answer 9

tissues

Question 10

what are tissues

Answer 10

specialized groups with similar functions

Question 11

what are the two process that cells arrange themselves

Answer 11

cell recognition and cell adhesion

Question 12

what is cell recognition

Answer 12

one cell type specifically recognizes and binds to another cell type

Question 13

what is cell adhesion

Answer 13

connections between two cells is strengthened

Question 14

what are cell junctions

Answer 14

they are specialized structures associated with the plasma
membrane of epithelial cells; adhesion & intercellular communication

Question 15

what are the 3 types of junctions

Answer 15

Tight, desmosomes, and gap junctions

Question 16

what are tight junctions

Answer 16

• prevent substances from
  moving through the spaces
  between cells;
• help ensure directional
  movement of materials

Question 17

what are desmosomes

Answer 17

• hold neighboring cells firmly
  together (rivets)
• provide mechanical stability for
  tissues under physical stress
  (skin)

Question 18

what are gap junctions

Answer 18

• channels that run between
  membrane pores in adjacent
  cells, allowing substances to
  pass between them
• communication

Question 19

what else do cell membranes adhere to

Answer 19

extracellular matrix

Question 20

what transmembrane protein binds to the actin filaments

Answer 20

integrin

Question 21

is the binding covalent and unreversible

Answer 21

no

Question 22

how do cells move within a tissue

Answer 22

by the binding and reattaching of integrin to the extracellular matrix

Question 23

what 2 things is this cell movement important for

Answer 23

developing embryos and the spread of cancer cells

Question 24

do membranes have selective permeability

Answer 24

yes

Question 25

what does selective permeability mean

Answer 25

some substances can pass through but others can't

Question 26

what is passive transport

Answer 26

no energy input for the transport (diffusion), energy comes from concentration gradient

Question 27

what is concentration gradient

Answer 27

the difference in concentration between one side of the membrane and the other

Question 28

what is active transport

Answer 28

moves substances against a concentration and/or electrical gradient; requires energy * The energy source is often adenosine triphosphate (ATP).

Question 29

what does the primary active transport require

Answer 29

requires direct hydrolysis to ATP

Question 30

where does the energy for secondary active transport come from

Answer 30

an ion concentration gradient that is established by primary active transport

Question 31

since macromolecules are too big to cross the membrane, how do they get in

Answer 31

they can be taken in or secreted by membrane vesices

Question 32

what is endocytosis

Answer 32

brings molecules and cells into a eukaryotic cell; the cell membrane folds inward around the material, forming a vesicle

Question 33

what are the 3 types of endocytosis

Answer 33

phagocytosis, pinocytosis, and receptor mediated endocytosis

Question 34

what is phagocytosis

Answer 34

molecules or entire cells are engulfed

Question 35

do some white bloods cells do this

Answer 35

yes

Question 36

what forms during this that attaches to lysosomes for digestion

Answer 36

a food vacuole or phagosome

Question 37

what is pinocytosis

Answer 37

a vesicle forms to bring small dissolved substances or fluids into a cell

Question 38

what is receptor mediated endocytosis

Answer 38

macromolecules to be moved bind to receptor proteins

Question 39

what are receptor proteins

Answer 39

integral membrane proteins located at specific sites on the cell membrane

Question 40

what is exocytosis

Answer 40

materials packaged in vesicles are secreted from a cell when it fuses with the cell membrane

Question 41

can a pore form without a membrane fusion

Answer 41

yes