Topic 3: Membranes

Question 1

Describe fatty acids

Answer 1

Long chain of carbon atoms with a carboxyl group at one end

Question 2

Average number of carbons in a fatty acid chain

Answer 2

12-20

Question 3

Describe triacylclylcerols

Answer 3

3 fatty acids bound to a glycerol anchor

Question 4

Describe a phospholipid

Answer 4

a glycerol head at the top, attached to two fatty acid tails

Question 5

What are triacylglycerols used for?

Answer 5

to store energy

Question 6

‘Amphipathic’ means…

Answer 6

having both hydrophilic (polar) and hydrophobic (non-polar) properties

Question 7

A micelle is…

Answer 7

a formation of phospholipids, like an oil drop in water. Glycerols face outwards.

Question 8

A liposome is…

Answer 8

a formation of phospholipids, used in medicine to deliver needed substances. Hollow ball of phospholipids, with hydrophilic properties facing outwards, but also inwards in a second layer

Question 9

Which type of proteins go all the way through the membrane?

Answer 9

Integral Proteins

Question 10

Peripheral proteins never touch….

Answer 10

the hydrophobic core

Question 11

Amphipathic proteins are…

Answer 11

integral proteins

Question 12

Four functions of membrane proteins

Answer 12

Transport, enzymatic activity, signal transduction, and attachment recognition

Question 13

Sterols can prevent freezing in the bilayer by…

Answer 13

embedding themselves between the phospholipids, preventing them from packing too tightly

Question 14

Sterols can prevent melting in the bilayer by…

Answer 14

embedding themselves between the phospholipids to fill in the gaps.

Question 15

Four ways to increase membrane fluidity

Answer 15

1) short chain fatty acids
2) unsaturated fatty acids
3) sterols
4) higher temperatures

Question 16

Four ways to decrease membrane fluidity

Answer 16

1) long chain fatty acids
2) saturated fatty acids
3) sterols
4) lower temperatures

Question 17

True or False: Sterols are amphipathic

Answer 17

True

Question 18

Order the following from best to worst for crossing the cell membrane:
Ions, small uncharged polar molecules, large uncharged polar molecules, non-polar molecules

Answer 18

1) non-polar molecules
2) small, uncharged polar molecules
3) large uncharged polar molecules
4) ions

Question 19

True or False: facilitated diffusion is active transport

Answer 19

False

Question 20

Aquaporins are…

Answer 20

narrow channel proteins that allow the passage of water across the membrane

Question 21

A Gated channel is…

Answer 21

a channel protein that can switch between open, closed, and intermediate states to transport most ions across the cell membrane

Question 22

Carrier proteins…

Answer 22

passively transport larger molecules across the cell membrane using diffusion and facilitated transport

Question 23

Why do cells need a selective barrier?

Answer 23

To maintain homeostasis in dynamic environments

Question 24

How does diffusion work in relation to the concentration gradient of a solute

Answer 24

works with the concentration gradient to reach equilibrium, does not require ATP

Question 25

Osmosis vs Diffusion

Answer 25

Osmosis is specifically the diffusion of water. If the solute can’t diffuse to reach equal concentrations, water will diffuse to do so

Question 26

Type of diffusion represented with a linear function

Answer 26

Simple diffusion (rate of reaction increases steadily with concentration)

Question 27

Type of diffusion represented with a logarithmic function

Answer 27

Facilitated diffusion (rate of reaction increases drastically at first, but levels out and reaches a plateau)

Question 28

A 5M liposome placed in a 10M solute, solution is….

Answer 28

hypertonic. water diffuses outwards

Question 29

4.2M liposome placed in a 4.2M solute, solution is….

Answer 29

isotonic. At equilibrium

Question 30

9.2M liposome placed in 4.2M solute, solution is….

Answer 30

hypotonic, water diffuses inwards

Question 31

Secondary Active Symport…

Answer 31

a solute is transported against it’s own concentration gradient with the help of a driving ion in the same direction

Question 32

Secondary Active Antiport

Answer 32

a solute is transported against its own concentration gradient with the help of a driving ion in the opposite direction

Question 33

Secondary Active Transport…

Answer 33

indirectly uses ATP, taking energy released by other reactions

Question 34

Primary Active Transport…

Answer 34

requires ATP

Question 35

Which of the following is NOT found in a triglyceride?
Saturated fatty acids, unsaturated fatty acids, charged organic group, or glycerol anchor.

Answer 35

Charged organic group

Question 36

A larg epolar molecule moves through a protein against its concentration gradient, and hydrolyzes ATP during the process. What is this?

Answer 36

Primary active transport

Question 37

What could a cell do to prevent its membrane from becoming too viscous?

Answer 37

Increase sterols, increase unsaturated phospholipids

Question 38

Which of the following can most easily diffuse across a lipid bilayer?
Methane, water, glucose, or H+

Answer 38

Methane
(non-polar small molecule)

Question 39

How does preserving olives in brine (20-30% salt solution) help prevent it from spoiling or being contaminated by microorganisms?

Answer 39

Bacteria can’t survive in a hypertonic solution because their cytoplasm loses wate

Question 40

Which of the following is NOT a component of a phospholipid?
A 3-carbon glycerol backbone
A phosphate group
A core of four fused carbon rings
Two fatty acid tails

Answer 40

A core of four fused carbon rings

Question 41

A cell wanting to move Magnesium ions across a lipid bilayer down its concentration gradient would use…

Answer 41

a protein channel

Question 42

Unsaturated fatty acids cause a membrane to be fluid at lower temperatures. Why?

Answer 42

The double bonds form a kink in the fatty acid tails, forcing adjacent lipids to be spaced further apart

Question 43

In the fluid mosaic model, what does ‘fluid’ refer to?

Answer 43

The movement and exchange of phospholipids and proteins within the two layers of phospholipids

Question 44

What is the difference between simple diffusion and facilitated transport?

Answer 44

Facilitated transport requires a transport protein, while simple diffusion does not

Question 45

What 2 terms can refer to the movement of water across a membrane from an area of lower solute concentration to an area of higher solute concentration?

Answer 45

Diffusion & Osmosis