Chapter 6: Lipids, Membranes, and the First Cells

Question 1

Hydrocarbons

Answer 1

Hydrophobic non-polar molecules that are composed of entirely hydrogens and carbons in different combinations

Question 2

Fatty Acid

Answer 2

Non-polar hydrocarbon tail with a head composed of carboxylic acid

“Fatty” part is the hydrocarbon chain

Question 3

Saturated Fat

Answer 3

Fatty acid completely saturated with hydrogens, with only single bonds between hydrogens and carbons

Question 4

Unsaturated Fat

Answer 4

Hydrocarbon chains with one or more double bonds, which form a “kink” in the chain

Question 5

Ester Linkage

Answer 5

Linkage between glycerol and fatty acid molecules

Question 6

Amphipathic

Answer 6

A substance with both hydrophilic (polar) and hydrophobic (non-polar) regions

Question 7

Lipid Bilayer

Answer 7

Created when lipid molecules align in paired sheets (think 2 ply paper, with the tails of each lipid pointing to eachother)

Question 8

Micelles

Answer 8

Singularly layered phospholipids that organize into spherical aggregates

Question 9

Selective Permeability

Answer 9

A quality of the cellular membrane where certain substances can pass through the membrane more easily than others

Question 10

Diffusion

Answer 10

When molecules tend to move from high concentrations to lower concentrations

Question 11

Concentration Gradient

Answer 11

Difference in concentration from one area compared to another

Question 12

Equilibrium

Answer 12

Where both sides of a concentration gradient have reached equal concentration levels

Question 13

Passive transport

Answer 13

Doesn’t require energy input to happen. Spontaneous process when happening.

Question 14

Passive Transport Proteins

Answer 14

Points in the cell membrane where particles can move through the membrane if the concentration gradient favors it.

Question 15

Osmosis

Answer 15

Only occurs when solutions are separated by a membrane that is permeable only by water and not other solvents.

Question 16

Hypertonic

Answer 16

Question 17

Hypotonic

Answer 17

Question 18

Isotonic

Answer 18

At equilibrium

Question 19

Fluid Mosaic Model

Answer 19

Question 20

Transmembrane Proteins

Answer 20

Span the entirety of a membrane, serve as a “tunnel” protein through the membrane. AKA Integrins from Exam 2.

Transmembrane proteins depicted in red.

Question 21

Peripheral Membrane Proteins

Answer 21

Proteins attached to the plasma membrane that do not go completely through the membrane. AKA peripheral proteins from Exam 2.

Question 22

Electrochemical Gradient

Answer 22

Electrochemical difference across a cell membrane. Most animal cells have a 50 millivolt difference across the cell membrane.

Question 23

Facilitated Diffusion

Answer 23

Passive diffusion facilitated by assisting proteins which allow substances to cross the plasma membrane that otherwise would not be able to. Requires no energy.

Question 24

Active Transport

Answer 24

Transport through the cell membrane that requires energy input to happen. Usually moves against the concentration and electrochemical gradients

Question 25

Secondary Active Transport

Answer 25

Pump proteins pump ions to another area to create an electrochemical gradient, which will force the diffusion of another substance through the plasma membrane. Secondary transporter doesn't require ATP to operate.

Question 26

Saturated lipid structure

Answer 26

Single bonds, so stack on top of eachother in a straight line, normally in solid state

Question 27

Unsaturated lipid structure

Answer 27

Have kinks, double bonds change the angle of the hydrocarbon chain so they don't stack in a single straight line, normally in liquid state

Question 28

Polyunsaturated lipid structure

Answer 28

Same as unsaturated lipids but more extreme as they have more than 1 double bonds, usually in liquid state

Question 29

Wax lipid structure

Answer 29

Very long hydrocarbon chains, wax doesn't have a carboxylic head, therefore wax molecules are very strong and can conform to well organized shapes. Usually in solid state

Question 30

How does hydrogenation affect the structure and physical state of unsaturated oils

Answer 30

Adding hydrogens to the carbon atoms which have double bonds with hydrogen removes the double bonds, so it converts the oil to a saturated fat.

Question 31

Give some examples of steroids

Answer 31

Horomones estrogen and testosterone

Question 32

Define 4 parts of a phospholipid

Answer 32

Fatty acids + glycerol + phosphate + an R group

Question 33

What makes cholesterol and phospholipids amphipathic

Answer 33

Both molecules have one portion that is polar and one that is non-polar. Cholesterol has a polar alcohol group at one end while it has a nonpolar isoprenoid tail at the other end that makes it amphipathic. Phospholipids have a polar head with a nonpolar tail that makes them amphipathic.

Question 34

Permeability increases when temperature \_\_\_\_\_\_\_

Answer 34

Increases. Temperature is a measure of the kinetic energy of molecules, therefore the higher the temperature the easier it is for a substance to permeate through a membrane

Question 35

Adding cholesterol to a membrane ____ permeability

Answer 35

Reduces. Adding cholesterol increases the density of the hydrophobic sections of the membrane and therefore reduces permeability.

Question 36

Channel proteins facilitate diffusion in ___ direction (s)

Answer 36

One, and when the concentration gradient is favorable by the channel protein