Biology 241 Topic 4

Question 1

What is facilitated diffusion?

Answer 1

The use of tunnel shaped proteins in the membrane to allow diffusion down the concentratiion gradient

Question 2

What are 4 characteristics of facilitated diffusion

Answer 2

-Each channel is substrate specific
-Does not need ATP (energy)
-[gradient] determines rate
-can be reversed

Question 3

What uses facilitated diffusion?

Answer 3

large polar molecules or ions

Question 4

Whats the difference between channel proteins and carrier portein in facilitated transport/diffusion?

Answer 4

Channel: |o| or }o{ (straight path)

Carrier: \o/ -> |o| -> /o\ (Waits for solute to bind to then changes shape

Question 5

What is the difference between simple and facilitated diffusion graphed?

Answer 5

Facilitated approaches a maximum while simple is a psoitive linear incline

Question 6

What type of environment do cells live in… and what does mean in terms of the cell?

Answer 6

Dilute, the cell needs the to keep the molecules on the inside rather than diffuse towards the environment

Question 7

How do cells establish a concentration gradient? What does this require?

Answer 7

The solutes must move away from equlibrium, thus requiring an energy source

Question 8

What is Primary Active Transport?

Answer 8

When a highly specific protein pump uses ATP to transports a solute against its [gradient] (low to high) and across the membrane.

Question 9

What is Secondary Active Transport?

Answer 9

A highly specific protein that transports solutes up the [gradient] (low to high). Generates power by having a different solute move down its own [gradient]

Question 10

What is the difference between symporters and antiporters in secondary activde transport?

Answer 10

Symporters: Both solutes move in the same direction
Antiporters: Solutes move in opposite directions

Question 11

What are the forms of Passive transport? (aside osmosis)

Answer 11

Simple diffusion and Facilitated Diffusion

Question 12

What solutes use simple diffusion?

Answer 12

Small hydrophobic (non-polar) and small polar (hydrophilic) solutes

Question 13

What is simple diffusion?

Answer 13

Direct diffusion across the phospholipid bilayer down the concentration gradient (high to low)

Question 14

What does a large concentration gradient cause in terms of simple diffusion?

Answer 14

A faster rate of diffusion

Question 15

Why do phospholipids form bilayers in water?

Answer 15

Hydrophobic tails move inwards away from water while the Hydrophilic head move outwards toward the water
E.g.
OOOOOOOOO
|||||||||||||
OOOOOOOOO

Question 16

What are lipids?

Answer 16

Hydrophobic molecules comprised mostly of carbon and hydrogen molecules

Question 17

What are the three Biological lipids?

Answer 17

-Triglycerides(Triacylglycerolds)
-Phospholipids
-Sterols

Question 18

What is the function of triglycerides

Answer 18

Energy Storage

Question 19

Which 2 Biological Lipids are bulding blocks for the cell membrane

Answer 19

Phospholipids and Sterols

Question 20

Fatty acids are the building blocks of which biological lipids

Answer 20

Triglycerides and phospholipids

Question 21

What are Fatty Acids comprised of?

Answer 21

Hydrocarbons with a Carboxyl group

Question 22

Which one does not have any C=C bonds and which has one or more C=C (C=C stands for carbon carbon double bond):
-Saturated Fatty Acid
-Unsaturated Fatty Acid

Answer 22

-Saturated FattyAcid has no C=C
-Unsaturated Fatty Acid has one or more C=C

Question 23

What increases the fluidity of a membrane?

Answer 23

-increase tempurature
-more unsaturated fatty acids
-short chains in the fatty acid tails
-cholesterol

Question 24

Why is the Lipid Bilayer considered fluid?

Answer 24

Each phospholipid is independant and not attached to one another (able to move freely along the plane of the membrane)

Question 25

What is a Fluid Mosaic Model?

Answer 25

Visually demonstrates the structure of the membrane; includes the phospholipid bilayer and protein channels
Fluid reffering to its independant movemennt of phospholipids across the membrane and mosaic reffering to its mulitple parts.

Question 26

What is the difference between a natural unsaturated fatty acid and an unnatural one?

Answer 26

Natural: Cis double bond (hydrogens are side by side)

Unnatural: Trans double bond (hydrogens are on opposite sides)

Question 27

What does a Tryglyceride structure look like

Answer 27

3 fatty acid tails bound by a glycerol anchor through ester linkage

Question 28

What are phospholipids comprised of

Answer 28

Head: Organic molecule, phosphate, glycerol
+
2 fatty acid tails

Question 29

Phospholipids are amphipathic, what does this mean?

Answer 29

Has a hydrophobic end and a hydrophilic end

Question 30

What do sterols(cholesterol)do in regards to membrane fluidity?

Answer 30

Regulates fluidity, prevents viscosity by preventing them from being too tightly packed and prevents too much fluidity by filling in gaps

Question 31

What is the relationship between membrane fluidity and permeability?

Answer 31

Fluid membrane: More solutes can pass (and quicker)
Viscous membrane: Fewer solutes may pass (and slower)

Question 32

Ordering from 1-4, what can diffuse (passively) through a membrane and what cannot

Answer 32

1 (diffuse quickly): Non polar molecules (O2, CO2, N2)
2 (diffuse slowly): Small, uncharged polar molecules (H2O, indole, glycerol)
3 (cannot diffuse) : Large, uncharged polar molecules (Glucose, scrose)
4 (cannot diffuse): Ions (Cl-, K+, Na+)

Question 33

How does water cross membranes

Answer 33

Through water pores called Aquaporins (only allow H2O)

Question 34

What is diffusion?

Answer 34

The tendency dissolved molecules to become evenly distributed [High] to [low]

Question 35

What 2 things do equilibrium result in

Answer 35

-The [gradient] is eliminated
-Lower energy state

Question 36

What is a condition of diffusion

Answer 36

Only works if solute can pass through the bilayer freely

Question 37

What is osmosis?

Answer 37

If the solute cannot move, water will move from low [solute] to high [solute]

Question 38

What are the 3 states of tonicity in regards to osmosis

Answer 38

Hypertonic- [solute] is higher in solution, cell shrivels
Hypotonic- [solute ] is lower in solution. cell swells and possibly bursts
Isotonic- balanced, cell does not change shape