ch 6: lipids and membranes

Question 1

lipid

Answer 1

organic substance that does not dissolve in water, but dissolves well in nonpolar organic solvents

Question 2

what are the kinds of lipids

Answer 2

fatty acids, fats, oils, waxes, steroids and phospholipids

Question 3

what are the monomers of lipids?

Answer 3

fatty acids

Question 4

what are characteristics of lipids?

Answer 4

hydrophobic and nonpolar

Question 5

why are lipids insoluble?

Answer 5

high proportion of nonpolar C-C and C-H bonds relative to polar functional groups

Question 6

saturated lipids

Answer 6

hydrocarbon chains that consist of only single bonds between carbons

Question 7

unsaturated lipids

Answer 7

one or more double bonds exist in the hydrocarbon chains

Question 8

what happens if lipids are in a straight chain?

Answer 8

they pack tightly together and form a solid through van der Waals

Question 9

what happens if lipids are bent?

Answer 9

they have fewer interactions and form a liquid

Question 10

3 types of lipids

Answer 10

steroids, fats, and phospholipids

Question 11

fats (aka triglycerides)

Answer 11

3 fatty acids joined by ester linkages to a glycerol molecule

Question 12

are fats polar or nonpolar?

Answer 12

NONPOLAR

Question 13

how do fats form?

Answer 13

through condensation reaction between hydroxyl group of gylcerol and carboxyl group of a free fatty acid

Question 14

phospholipids

Answer 14

consists of glycerol that is linked to a phosphate group and two hydrocarbon chains of either isprenoids or fatty acids

Question 15

phospholipids are ________

Answer 15

amphipathic: contains hydrophilic and hydrophobic regions

Question 16

what are the regions of a phospholipid?

Answer 16

phosphate hydrophilic head and fatty acid hydrophobic tail

Question 17

function of fats

Answer 17

energy storage

Question 18

function of phospholipids

Answer 18

cell membrane

Question 19

what are the phosphate heads stabilized by?

Answer 19

stabilized by hydrogen bonds with water and each other

Question 19

what are the fatty acid tails stabilized by?

Answer 19

van der Waal interactions with each other

Question 20

unsaturated hydrocarbon tails are _____

Answer 20

more fluid because they are not tightly packed together
- liquid

Question 21

saturated hydrocarbon tails are ____

Answer 21

less fluid because they are tightly packed
- solid

Question 22

how does cholestrol stabilize membrane?

Answer 22

keeps lipid bilayer more stable and less fluid at high temps and more fluid at low temps

Question 23

micelles

Answer 23

spherical aggregates that have hydrophobic tails and hydrophilic heads formed by FATTY ACIDS (single hydrocarbon chains)

Question 24

lipid bilayers

Answer 24

created when a lipid molecule aligns in paired sheets and form in water - has hydrophilic heads on top and bottom and hydrophobic tails in center

Question 25

selective permeability

Answer 25

some substances cross a membrane more easily than other substances do

Question 26

what crosses the bilayer quicker?

Answer 26

small, nonpolar molecules such as gases

Question 27

what crosses the bilayer a little slower?

Answer 27

small polar and uncharged polar molecules

Question 28

what cannot cross the bilayer?

Answer 28

large, uncharged polar molecules and ions

Question 29

short and unsaturated hydrocarbon tails have ______ permeability

Answer 29

higher

Question 30

long and saturated hydrocarbon tails have ______ permeability

Answer 30

lower

Question 31

what happens as temps drop in a bilayer?

Answer 31

molecules move slower and become less fluid and solidfy

Question 32

diffusion

Answer 32

substances on one side move to other side of bilayer, with no energy

Question 33

what does diffusion require?

Answer 33

concentration gradient: high concentration to low - molecules move down the CG

Question 34

osmosis

Answer 34

water molecules move from low solute/high water to high solute/low water

Question 35

hypertonic solution

Answer 35

solution outside vesicle has a high solute concentration, so water moves out of vesicle to establish equilibrium - causes vesicle to shrink

Question 36

hypotonic solution

Answer 36

solution outside has lower concentration of solutes, so water moves inside vesicle - vesicle swells and can burst

Question 37

isotonic solution

Answer 37

solute concentrations are equal so there is no change to vesicle

Question 38

what type of structures are plasma membranes?

Answer 38

fluid mosaic: components move laterally and can be changed based on needs of cell and are made up of more than one type of biomolecule

Question 39

what biomolecule is important part of plasma membranes?

Answer 39

integral and peripherial proteins

Question 40

integral proteins

Answer 40

inside the cell membrane, spanning the phospholipid bilayer

Question 41

peripheral proteins

Answer 41

loosely attached to surface of cell membrane, outside phospholipid bilayer

Question 42

4 critical functions of plasma membranes

Answer 42

1. allow some things to enter and others to leave 2. recognizes signals and responds 3. barrier: keeps inside in and outside out 4. attaches to other things

Question 43

what type of proteins change permeability of plasma membranes?

Answer 43

integral membranes

Question 44

facilitated diffusion

Answer 44

movement of molecules from high to low concentration through a protein tunnel (passive transport)

Question 45

channel proteins

Answer 45

only allows specific molecules through - many of specific molecule enters when it changes shape to open - either open or closed - works like a bridge

Question 46

carrier proteins

Answer 46

only allow specific molecules through and usually 1-3 for each change in shape - changes shape to open - picks up solute and drops it off to other

Question 46

aquaporin

Answer 46

channel protein for water - allows up to 100 milion - direction depends on concentration gradient

Question 47

passive transport

Answer 47

high to low concentration - no energy needed - type of facilitated diffusion

Question 48

what does active transport require?

Answer 48

1. input of energy 2. carrier protein to move it across membrane (protein pump)

Question 49

active transport moves molecules ________

Answer 49

against their concentration gradient