Chapter 5

Question 1

Cell membrane function

Answer 1

Controls interactions with other cells
Controls passage of materials inside and outside of the cell (homeostasis) (Selectively permeable

Question 2

Integral protein

Answer 2

Goes through the phospholipid bilayer.
Span the lipid bilayer (transmembrane proteins) Non polar regions of protein within interior of bilayer and polar regions protrude from both sides of bilayer. (Secondary Structure)

Question 3

Peripheral protein

Answer 3

Only 1 side of phospholipid bilayer (Usually intracellular)
Anchoring molecules attach membrane protein to surface (tertiary structure)

Question 4

Fluid Mosaic Model

Answer 4

Phospholipids in a bilayer with additional lipid, protein, and carbohydrate molecules
Properties that resemble a fluid because lipids and proteins can move relative to each other within membrane (Not rigid)

Question 5

Membrane structure 4 compnents

Answer 5

1 Phospholipid Bilayer (flexible matrix, barrier to permeability)
2 Transmembrane proteins (Integral membrane proteins [go through phospholipid bilayer]
3 Interior protein network (peripheral or intracellular membrane proteins)
4 Cell surface markers (Glycoproteins and glycolipids)

Question 6

Phospholipids are amphipathic (two natures) molecules

Answer 6

Hydrophobic
Hydrophilic
(Also contains cholesterol)

Question 7

Saturated and unsaturated fatty acids

Answer 7

Saturated fatty acids make membrane less fluid than unsaturated fatty acids

Question 8

Membrane proteins various functions

Answer 8

Transporters
Enzymes
Cell-surface receptors
Cell-surface identity markers
Cell to cell adhesion proteins
Attachments to the cytoskeleton

Question 9

Transmembrane domain

Answer 9

Spans the lipid bilayer. Hydrophobic amino acids arranged in alpha helices. Single or multiple transmembrane domains ( multiple helices)

Question 10

Pores

Answer 10

Beta pleated sheet proteins
Extensive nonpolar regions can create a pore through the membrane
Cylinder of beta sheets in the protein secondary structure (Beta barrel) [Interior polar and allows water and small polar molecules to pass through membrane]

Question 11

Passive transport

Answer 11

DOES NOT require energy, goes with the concentration gradient.
1 Diffusion (simple)
2 Facilitated diffusion
3 Osmosis

Question 12

Diffusion (Passive transport)

Answer 12

Movement of molecules from high concentration to low concentration. Will continue until concentration is at equilibrium.

Question 13

Selectively permeable membrane

Answer 13

Hydrophobic interior repels polar molecules, but not nonpolar molecules. Nonpolar move until equilibrium. Small polar molecules have limited permeability (O2, CO2). Very limited permeability to larger polar molecules and ions.

Question 14

Facilitated diffusion

Answer 14

Polar molecules and larger molecules with help of a protein to move across membrane.
1 Channel proteins - can be open or closed
2 Carrier proteins - need to physically bind to specific molecules and pull across membrane

Question 15

Ion channels and 3 conditions to determine direction

Answer 15

Allow passage or ions. Gated, open or close due to stimuli
1 Relative concentration on either side or membrane
2 Voltage differences across membrane (charge of cell compared to surroundings)
3 Gated channels: Open or closed

Question 16

3 Electrochemical questions

Answer 16

1 Where is ions more abundant and where does it want to go chemically (Conc. Gradient)
2 What is the charge of the cell and the ion? Which way does it electrically want to go
3 Is vm (membrane potential) = to Ek (equilibrium)?

Question 17

Facilitated diffusion limitations

Answer 17

Saturated because only one molecule can enter at a time
Requires concentration difference

Question 18

Osmosis

Answer 18

Channel to move H2O. Net diffusion of water across a membrane toward a higher solute concentration. (Moves from pure to less pure)
Water is solvent. Dissolved substances are solutes

Question 19

Hypertonic Solution

Answer 19

Has a higher solute concentration

Question 20

Hypotonic Solution

Answer 20

Has a lower solute concentration

Question 21

Isotonic solution

Answer 21

Same osmotic concentration

Question 22

Aquaporins

Answer 22

facilitates osmosis (Channels to move H2O [pores])

Question 23

Osmosis in animal cells

Answer 23

Must maintain balance between extracellular and intracellular solute concentrations to maintain their size and shape

Question 24

Crenation

Answer 24

Shrinking in a hypertonic solution

Question 25

Lysis

Answer 25

bursting in a hypotonic solution

Question 26

Osmosis in plant cells

Answer 26

Cell wall prevents major changes in cell size (Prevents lyce) Turgor pressure - force due to internal pressure of water pushes plasma membrane against cell wall (Maintain size and shape) Plasmolysis - plant wilt because water leaves plant cells Central vacuole pushes on cell wall to maintain shape

Question 27

Active transport. 2 types

Answer 27

Requires energy (ATP), against concentration gradient. (From low to high) Direct - primary active transport Indirect - secondary transport (Coupled transport)

Question 28

Carrier proteins used in active transport include

Answer 28

Uniporters - move one molecule at a time Symporters - move two molecules in the same direction Antiporters - Move two molecules in opposite directions

Question 29

Sodium-Potassium Pump (Na+ - K+)

Answer 29

Direct ATP for active transport, binds phosphate group to protein to open. Antiporters move 3 Na+ out of cell and 2 K+ into cell. Against concentration gradient

Question 30

Plasmolysis

Answer 30

Plant wilt because water leaves plant cells

Question 31

Secondary/Coupled transport

Answer 31

Indirectly uses ATP, uses symporter or antiporter. One molecule goes with conc. grad. and that energy moves a different molecule against its con. grad.

Question 32

Bulk Transport types

Answer 32

Endocytosis (into cell) and Exocytosis (EX- EXit the cell)

Question 33

Endocytosis types

Answer 33

Phagocytosis Pinocytosis Receptor-mediated endocytosis

Question 34

Phagocytosis

Answer 34

Cell takes in particulate matter (Cellular eating)

Question 35

Pinocytosis

Answer 35

Cell takes in only fluid (Cellular drinking) (Mostly water)

Question 36

Receptor-mediated endocytosis

Answer 36

Specific molecules are taken in after they bind to a protein receptor, formation of clathrin-coated pits and vesicles

Question 37

Clathrin-coated pits and rings

Answer 37

After receptor mediated endocytosis pits form to trap molecules and then form vesicles with clathrin-coated rings around them

Question 38

Channel Proteins

Answer 38

Hydrophilic channel when open. Ex ion channel

Question 39

Carrier Proteins

Answer 39

Bind specifically to molecules they assist. Pull across membrane