lecture 6 lipids

Question 1

lipids

Answer 1

Lipids are defined as molecules that are not soluble in water, but are soluble in organic solvents. They are hydrophobic (e.g. fats, oils, waxes) or amphipathic (e.g., fatty acids, phospholipids, glycolipids, steroids)

Question 2

5 classes of lipids

Answer 2

Free fatty acids: A common fuel. Triacylglycerols: Fats and Oils, storage form of fatty acids. Phospholipids: Membrane lipids. Glycolipids: Membrane lipids composed in part of carbohydrates. Steroids: hydrocarbons with four rings (e.g., estrogens, androgens, cortisone, cholesterol, bile acid)

Question 3

fatty acids are a main source of ___

Answer 3

fuel

Question 4

Most fatty acid chains are ___ carbons in living system

Answer 4

16 or 18 carbons, always in even numbers

Question 5

chains with double bonds are (saturated/unsaturated) with hydrogens

Answer 5

unsaturated

Question 6

chains with no double bonds are (saturated/unsaturated) and (cis/trans)

Answer 6

unsaturated, trans

Question 7

trans/saturated: oil or fat at room temp?

Answer 7

fat

Question 8

Micelle structure

Answer 8

polar heads out, ONE TAIL in - thermodynamically stable form

Question 9

smallest fatty acid

Answer 9

acetic acid

Question 10

fatty acids

Answer 10

Fatty acids are chains of hydrogen-bearing carbon atoms that have a carboxylic acid at one end and a methyl group at the other end.

Question 11

draw a glycerol

Answer 11

Question 12

draw a fatty acid

Answer 12

Question 13

Fatty acid carbon atoms are usually numbered beginning with the ___ terminal carbon atom.

Answer 13

carboxy

Question 14

triacylglycerol

Answer 14

aka a triglyceride- a glycerol backbone + fatty acid- THIS IS A FAT

Question 15

are fats and oils polar/nonpolar molecules?

Answer 15

mostly nonpolar

Question 16

how does chain length influence a fatty acid’s properties?

Answer 16

Short chain length and the presence of cis double bonds enhances the fluidity of fatty acids. (less opportunities to form van der waals forces with its own chain)

Question 17

Cis ____fatty acids are essential components of our diets because humans have little ability to synthesize double bonds distal

Answer 17

polyunsaturated

Question 18

_____ are energy rich. Because they are hydrophobic and reduced, a gram of anhydrous fat stores more than six times the energy of a gram of hydrated glycogen.

Answer 18

Triacylglycerols

Question 19

where are triacylglycerols normally stored?

Answer 19

adipose (fat) tissue

Question 20

The three common types of membrane lipids are:

Answer 20

1. Phospholipids
2. Glycolipids
3. Cholesterol

Question 21

phosphoglycerides

Answer 21

type of phospholipid that is bound to a glycerol backbone. theres a phosphate group within the fatty acid chain.has a phosphate group attached to the O of the glycerol. Also attacheed to a small organic molecule

this is the umbrella group containing phosphatidylcholine, etc

Question 22

Phospholipids are composed of four components:

Answer 22

fatty acids (usually 2), a platform/backhone, a phosphate, and an alcohol (small molecule on end). Two common platforms are glycerol and sphingosine

Question 23

Phospholipids with a glycerol platform are called

Answer 23

phosphoglycerides

Question 24

whats the major class of membrane lipids

Answer 24

phospholipids

Question 25

sphingolipids

Answer 25

phospholipids with a sphingosine backbone instead of glycerol

Question 26

what's different about Archea phospholipids

Answer 26

Archea phospholipids have ether linkages instead of ester linkage of acyl chains. The ether linkages and branching structure of membrane lipids of extremophiles prevent hydrolysis and oxidation of membranes in harsh environments.

Question 27

t/f: membrane lipids can include carbohydrates

Answer 27

true

Question 28

what are glycolipids and what do they do

Answer 28

Glycolipids are carbohydrate-containing lipids. The carbohydrate components of glycolipids are on the extracellular surface of the cell membrane, where they play a role in cell-cell recognition.

Question 29

give an example (the simplest form) of a glycolipid

Answer 29

Cerebrosides are the simplest glycolipids with one sugar attached to sphingosine.

Question 30

what are gangliosides

Answer 30

a type of glycolipid, isolated from the brain- complex sugar chains. in taysachs, lack enzyme to degrade these.

Question 31

what are membrane anchors

Answer 31

Membrane anchors are hydrophobic groups that are covalently attached to proteins (in blue) and tether the proteins to the membrane

Question 32

structure of steroids

Answer 32

3 hexagons + 1 pentagon

Question 33

is cholesterol polar or nonpolar?

Answer 33

OH group makes it a little polar. Whole thing is amphipathic.

Question 34

name the functions of cholesterol

Answer 34

1) need it to make hormones , 2) make bile, and 3) be a major component in cell membranes , adding to fluidity (tails cant pack as well with cholesterol stuck in there) and stability

Question 35

Subunit structure of glycolipids

Answer 35

more protein than sugar. lipids with a carbohydrate attached by a glycosidic bond.

Question 36

acyl group

Answer 36

fatty acid

Question 37

how do you modify steroids to make different things

Answer 37

Different functional groups (e.g., -OH, -CH3, =O) hang off the rings, creating different molecules (e.g., cholesterol, cortisone, estrogen, progesterone, testosterone, bile acid)