Ch 3: Cell Biology- Plasma Membrane/ Transport Mechanisms

Question 1

Name 3 functions of the plasma membrane

Answer 1

• Separates the intracellular fluid (IF) from the extracellular
• Also known as the cell membrane
• Also encloses and supports cell contents
• Attaches cells to extracellular environment or to other cells
• Aids in communication
• Determines what moves into and out of cells

Question 2

Define the words fluid and mosaic of fluid mosaic model of the plasma membrane

Answer 2

• Fluid = dynamic and constantly changing
• Mosaic = made of many tiny parts all working together
Composed of:
• Lipids
• Mostly phospholipids but also cholesterol and glycolipids
• Proteins
• Carbohydrates (part of glycocalyx)

Question 3

What are the two components of membrane lipids?

Answer 3

1. Phospholipids
2. Cholesterol

Question 4

________ interspersed among phospholipids. The amount determines the fluid nature of the membrane

Answer 4

Cholesterol

Question 5

__________: bilayer. Polar heads facing water in exterior of the cell (hydrophilic); nonpolar tails faci interior of the membrane (hydrophobic).

Answer 5

Phospholipids

Question 6

Fluid nature provides/ allows these 3 things

Answer 6

• Distribution of molecules within the membrane.
•
Phospholipids automatically reassembled if membrane is damaged.
•
Membranes can fuse with each other.

Question 7

What are the two components of membrane proteins?

Answer 7

•Intergral membrane proteins
•Peripheral membrane proteins

Question 8

Which type of membrane protein can form channels through the membrane?

Answer 8

Integral

Question 9

________membrane proteins are attached to ________ proteins at either the inner surfaces of the lipid bilayer.

Answer 9

Peripheral; integral

Question 10

Name the 3D shape or chemical characteristics that affect membrane protein functions

Answer 10

Markers, attachment sites, channels, receptors, enzymes, or carriers.

Question 11

Glycoproteins or glycolipids are examples of

Answer 11

Marker molecules

Question 12

What is the function of marker molecules?

Answer 12

Allow cells to identity one another or other molecules.
• Immunity.
• Recognition of oocyte by sperm cell.
• Intercellular communication.
• Glycocalyx - “sugar covering”

Question 13

_______attach cells to other cells while _______ attach to extra cellular molecule

Answer 13

Cadherin; Integrins (integral proteins)

Question 14

What are the 3 types of cell junctions and their general property

Answer 14

•Tight junctions - impermeable junctions
•Desmosomes - anchoring junctions (think like zippers)
•Gap junctions - cell connections with hollow cylinders
—-materials pass through cylinders from one cell to next

Question 15

_________ binds cells together

Answer 15

Cell junctions

Question 16

What cell junction anchors and works like a zipper?

Answer 16

Desmosomes

Question 17

Cell junction with hollow cylinders

Answer 17

Gap junction

Question 18

What protein includes channel proteins, carrier proteins and ATP-powered pumps?

Answer 18

Transport proteins

Question 19

Hydrophilic region faces inward; charge determines molecules that can pass through is a characteristic of what?

Answer 19

Transport proteins

Question 20

________ proteins- integral membrane proteins that form tiny channels through membrane

Answer 20

Channel

Question 21

Leak Ion channels are always open and are responsible for the ________ of the plasma membrane ions at rest

Answer 21

Permeability

Question 22

_______(type of channel protein) can be open or closed by certain stimuli

Answer 22

Gated ion channel

Question 23

Small molecules binding to proteins or glycoproteins is a characteristic of what type of channel protein?

Answer 23

Ligand-gated ion channel

Question 24

What must happen for a voltage-gated ion channel to open?

Answer 24

Charge change across the plasma membrane

Question 25

T/F: Carrier proteins are also known as transport proteins.

Answer 25

False: transporters

Question 26

Intergral proteins moving ions, sugars or amino acids from one side of the membrane to the other is an example of ________ proteins

Answer 26

Carrier proteins

Question 27

Uniporters, symporters and antiporters are _______ of carrier proteins

Answer 27

Different Forms

Question 28

T/F: Uniporters move two ions/ molecules in the opposite directions at the same time

Answer 28

False: antiporters

Question 29

If antiporters move two ions/ molecules in the opposite directions at the same time, which carrier protein would do the opposite?

Answer 29

Symporters

Question 30

T/F: in ATP-powered pumps, rate of transport depends on the concentration of substrate and on concentration of ATP

Answer 30

True

Question 31

•Proteins or glycoproteins in membranes with an exposed receptor site on the cell's outer surface. •Can attach to specific chemical signal molecules and act as an intercellular communication system. Are characteristics of _______ proteins

Answer 31

Receptor

Question 32

________: some act to catalyze reactions at outer/ inner surface of plasma membrane

Answer 32

Enzymes

Question 33

An example of enzymes would be

Answer 33

Surface cells of small intestine produce enzymes that digest dipeptides.

Question 34

The plasma membrane only allows certain substances to pass through it meaning it is

Answer 34

Selectively permeable

Question 35

Diffusion, osmosis and facilitated diffusion are examples of what?

Answer 35

Passive membrane transport

Question 36

Endocytosis and exocytosis are components of which type of transport

Answer 36

Vesicular transport

Question 37

What are the three types of transport through the plasma membrane?

Answer 37

Passive membrane transport. • Diffusion. • Osmosis. • Facilitated diffusion. Active membrane transport. • Active transport. • Secondary active transport. Vesicular transport. • Endocytosis. • Exocytosis.

Question 38

Viscosity refers to

Answer 38

[in diffusion] The measure of a fluids resistance to flow

Question 39

The concentration difference between two points is known as

Answer 39

Concentration gradient [diffusion]

Question 40

Define Diffusion

Answer 40

Movement of solutes from an area of higher concentration to lower concentration in solution.

Question 41

T/F: water can move directly through plasma membrane (in between phospholipids) or through aquaporins

Answer 41

True

Question 42

Water diffused toward higher solute concentration (high solute, less water) across a membrane defines the process of

Answer 42

Osmosis

Question 43

T/F: osmosis= diffusion of water and is a form of passive transport

Answer 43

True

Question 44

In osmosis, distinguish between the terms isotonic, hypertonic and hypotonic

Answer 44

• Isotonic: cell neither shrinks nor swe • Hypertonic: cell shrinks (creation). • Hypotonic: cell swells (lysis).

Question 45

Lysis is the process of

Answer 45

Cell swelling

Question 46

Crenation is synonymous with hypertonic meaning the cell_____

Answer 46

Shrinks

Question 47

Osmosis: when solute concentration goes ____, water concentration goes_____

Answer 47

Up; down

Question 48

Protein carriers and channel proteins are required for which transport process to happen?

Answer 48

Facilitated diffusion

Question 49

• no ATP required. • Move large, water soluble molecules or electrically charred molecules across the plasma membrane. • Amino acids and glucose in, manufactured proteins out Are characteristics of what process?

Answer 49

Facilitated diffusion

Question 50

What 4 factors affect the rate of diffusion?

Answer 50

•1. size of concentration gradient •2. temperature of solution •3. size of diffusing molecules •4. viscosity of the solvent

Question 51

Sodium-potassium (Na +/ K +) pump that creates electrical potentials across membranes is an example of what?

Answer 51

Active transport

Question 52

T/F: Active transport does not require ATP

Answer 52

False

Question 53

Substances can be moved against their concentration gradients (that is, from low to high), allowing the substance to accumulate on one side of the plasma membrane is an example of

Answer 53

Active transport

Question 54

Define secondary active transport

Answer 54

Use of potential energy in concentration gradient of one substance (established by primary active transport) to help move another substance

Question 55

Movement of substances by formation or release of a vesicle. Requires ATP. Describes what type of transport

Answer 55

Vesicular transport

Question 56

_______(Cell eating): solid particle is ingested and large vesicle formed

Answer 56

Phagocytosis

Question 57

________(cell drinking): dissolves molecules ingested and small vesicles formed

Answer 57

Pinocytosis

Question 58

T/F: vesicular transport is receptor mediated meaning specific transport of materials to bind cells surface

Answer 58

True

Question 59

In DNA, what are the complementary base pairs and how many hydrogen bonds link them?

Answer 59

• C - G (3 hydrogen bonds link them) • T - A (2 hydrogen bonds link them)

Question 60

_______= phosphate, sugar, nitrogen- containing base (A,G,C,T)

Answer 60

Nucleotide

Question 61

What do complementary base pairs (A,G,C,T) stand for?

Answer 61

nitrogen bases- (Adenine, Guanine, Thymine, and Cytosine)

Question 62

To synthesize proteins, we must do two steps, in order:

Answer 62

• 1.) Transcription -DNA information coded in mRNA occurs in nucleus • 2.) Translation - mRNA decoded to assemble polypeptides Occurs in cytoplasm using ribosomes