2a plasma membrane

Question 1

epithelia

Answer 1

sheets of tissue that cover all body surfaces

Question 2

amphipathic

Answer 2

molecule with both polar and nonpolar regions

Question 3

ex of amphipathic

Answer 3

phosphatidylcholines are common in animal cell membranes)

Question 4

when the melting point is low, is it going to be more or less fluidity?

Answer 4

more

Question 5

Would you expect a thermo-conforming animal to have

Answer 5

more unsaturated bonds (as a phosphatdyethanolamines) which is more than phophatidylcholines

Question 6

integral

Answer 6

permanently embedded in the membrane

Question 7

peripheral

Answer 7

connected to the membrane, but removable

Question 8

aqueous pores

Answer 8

channels through which aqueous solutions
can pass from one side of the membrane to the other.

type of channel protein

Question 9

Channel proteins

Answer 9

Control

diffusion of aqueous solutes
osmosis of water

Question 10

Transporter (carrier) proteins

Answer 10

Move specific molecules across a membrane by reversibly (non-covalently) bonding with them to facilitate transport

-can be active or facilitative

Question 11

Membrane-bound Enzymes

Answer 11

Protein catalysts of various types embedded in membranes

Question 12

Receptor proteins

Answer 12

– exact def of carrier proteins but can cause signal transduction

– signal transduction: 1. primary messenger, which may be a chemical signal, electrical pulse, or even physical stimulation. Then, the receptor protein embedded in the cellular membrane must accept the signal. Upon receiving the signal, this protein goes through a conformational change. This changes its shape and thus, how it interacts with the molecules around it.

2. Some proteins activate other molecules, called second messengers, which carry the message to the nucleus or other organelles. Other proteins use the energy from ATP to activate enzymes, which carry out metabolic reactions.

–responsible for mediating responses to chemical signals arriving at the cell membrane.

Question 13

Structural proteins

Answer 13

• anchor intracellular elements to the cell membrane
• form cell junctions
• form the protein infrastructure of the membrane

Question 14

epithelium

Answer 14

• –lines a cavity in an organ or body
• –forms boundaries between body regions
• –forms boundaries between an animal and its external environment

Question 15

apical (mucosal) surface

Answer 15

facing the side of an open membrane

Question 16

basal (serosal) region

Answer 16

towards the tissue to which the epithelium is attached

Question 17

basement membrane or basal lamina

Answer 17

• — thin, permeable, non-living, non-cellular fibrous matrix
• — allow gas exchange

Question 18

name 3 of the simple and stratified epithelia

Answer 18

1. squamous epithelium (cell width > height)
2. cuboidal epithelium (cell width = height)
3. columnar epithelium (cell width < height)

Question 19

simple vs stratified

Answer 19

stratified has more than one layer

Question 20

pseudo stratified

Answer 20

really one layer but looks like more than one layer because nuclei are on opp sides

Question 21

What is the functional significance of microvilli? (How do they increase transport efficiency?)

Answer 21

increase surface area for transport across membranes

Question 22

brush border

Answer 22

microvilli often resemble the bristles of a brush when viewed under the microscope, a row of microvilli

Question 23

tight junctions

Answer 23

Found only in vertebrates.
Block the interstice between two adjacent cells
Prevent interstitial movement of solutes from apical to basal regions. ( sealed together)
Substances must enter via cell membrane channels.
serve as barriers and prevent leaks

Question 24

Septate junction

Answer 24

used as tight junctions for invetebrates

Question 25

isoenzymes

Answer 25

as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. These enzymes usually display different kinetic parameters (e.g. different KM values), or different regulatory properties.

Question 26

covalent modulation

Answer 26

activation or inactivation of enzymes, either by phosphorylation/dephosphorylation or by proteolytic cleavage. A major means of regulation of enzyme action by hormones.