U1- Topic 2: Cellular Membranes

Question 1

Lipids

Answer 1

water insoluble (hydrophobic)
mostly composed of carbon and hydrogen atoms
- triacylglycerides
- steroids
- phospholipids

Question 2

Fatty Acids

Answer 2

Triacylglycerides & Phospholipids

long chain of C atoms with carboxyl group at end (hydrocarbons)

Question 3

Saturated Fatty Acid

Answer 3

Single bonds
Stearic acid
higher melting point

Question 4

Unsaturated Fatty Acids

Answer 4

Double bonds present, makes kinks/bends in carbon chains
Oleic acid
uncommon
lower melting point

Question 5

Animal Fats vs. Plant Oils/Fats

Answer 5

Animal fat: saturated, high melting point

Plant fat: unsaturated, lower melting point

Question 6

Compounds with ____ carbons store MORE energy

Answer 6

saturated

Question 7

Compounds with ____ carbons store LESS energy

Answer 7

unsaturated

Question 8

Triglycerides

Are they saturated or unsaturated?

Answer 8

3 fatty acids bound to glycerol “anchor”
energy storage molecules
- saturated

Question 9

Phospholipids

Answer 9

2 fatty acid “tails” bound to glycerol “anchor”

Amphipathic

Question 10

amphipathic

Answer 10

has both hydrophobic and hydrophilic properties

Question 11

Phospholipid Head

Answer 11

Polar, often charged, hydrophilic

faces outward

Question 12

Phospholipid Tail

Answer 12

Nonpolar, hydrocarbon chains, hydrophobic

faces inward

Question 13

Causes of higher membrane fluidity:

Answer 13

Short fatty acid tails
Unsaturated fatty acid tails
More sterols
higher temperature

Question 14

Sterols Regulate Membrane Fluidity by:

Answer 14

Preventing freezing = prevents phospholipid from packing too tightly
Preventing melting = filling in haps between phospholipid

Question 15

“Leaky” Membrane = ?

Answer 15

more permeable, more types of solutes can cross bilayer, solutes move through bilayer more quickly

Question 16

Aquaporins

Answer 16

Membrane protein channel that helps water cross membranes

Question 17

Hypotonic Condition

Answer 17

Inside is more concentrated than outside, cell swells

Question 18

Hypertonic Condition

Answer 18

Inside is less concentrated than outside, cell shrivels

Question 19

Isotonic Conditions

Answer 19

Happy (net movement is balanced)

Question 20

Simple Diffusion

Answer 20

Small hydrophobic & small polar solutes diffuse across phospholipid bilayers directly
*dont need proteins to assist

Question 21

Facilitated Diffusion

Answer 21

No ATP needed
Proteins, shaped like tunnels assist solute to cross the membrane
example: aquaporins
*create path for impermeable molecules to diffuse down a conc. gradient

Question 22

Primary Active Transport

Answer 22

Highly specific carrier proteins move solutes AGAINST their conc. gradient powered by ATP hydrolysis
*ATP used to create conc. gradient

Question 23

Secondary Active Transport

Answer 23

Pump protein “couples” movement of 2 solutes (DOES NOT USE ATP HYDROLYSIS)

• one solute moves UP its conc. gradient
• one solute moves DOWN its conc. gradient

Question 24

Symporter

Answer 24

Both solutes move in the SAME direction

Question 25

Antiporter

Answer 25

2 solutes move in OPPOSITE directions