Lipids

Question 1

Biological functions of lipids

Answer 1

• energy storage
• membrane structure
• signalling molecules
• enzyme cofactors
• antioxidants
• pigments

Question 2

Classifications of lipids:

Answer 2

1. Biologically active lipids
   a. prostaglandins
   - sterols
2. Complex lipids
   a. structural lipids
   - phospholipids
   - sphingolipids
   b. storage lipids
   - triglycerols
   - waxes

Question 3

Properties of fatty acids

Answer 3

• amphipathic molecules with 3-35 carbons and a carboxylic group
• have both systematic and common names
• fully ionized at pH-7.0
• almost all (natural) fatty acids have an even number of C
• most natural fatty acids are unbranched
• they can be saturated or unsaturated
• numbered starting with the carboxyl end
• physical properties are defined by chain length and degree of saturation
• all naturally occurring double bonds have cis configuration

Question 4

an 18:1 fatty acid has __ carbon(s) and __ double bond(s)

Answer 4

18/1

Question 5

double bonds create ___ which means saturated fatty acids are ___ packed than unsaturated, less saturated = ___ melting point

Answer 5

kinks/more/lower

Question 6

chemists naming system: starts from the ___ end = __:__(Δ^__)

Answer 6

carboxyl/# of carbons/#of double bonds/double bond placement

Question 7

physiologist naming: starts from ___ end =omega-___

Answer 7

methyl/first double bond placement

Question 8

essential lipids

Answer 8

those we don’t naturally produce in the body, linoleic (omega-6) and linolenic (omega-3)

Question 9

tons f.a. are formed by partial ___ of unsaturated f.a., they allow f.a. to ___ more regularly which ___ the melting point, making them more like ___ f.a. than ___ f.a.

Answer 9

hydrogenation/pack/saturated/unsaturated

Question 10

Why are saturated and trans f.a. worse for health?

Answer 10

they increase blood cholesterol levels by providing proper packing domains for cholesterol which increases membrane rigidity, this reduces fluidity, PRO function, and flexibility

Question 11

Triglycerides: a ___ + ___ f.a., a ___ triglyceride has ___ of the same f.a. attached and a ___ triglyceride has different f.a. attached. ___ linkages bind the f.a. to the glycerol, formed by a ___ reaction

Answer 11

glycerol/3/simple/3/complex/Ester/condensation

Question 12

Chemical hydrolysis of a triglyceride can be achieved using a ___ ___ or ___ ___

Answer 12

strong acid/strong base

Question 13

Waxes: formed by ___ reaction between ___ f.a. and ___ hydrocarbon chains. They act as metabolic ___ or a ___ ___. They have a ___ melting point and can be broken down by ___ ___.

Answer 13

condensation/long/alcohol/fuel/protective coating/high/strong acid

Question 14

Phospholipids: ___+___+ ___ f.a., the prefix for naming is ___- and the suffix is the name of the ___ ___ substituent attached to the ___. Their most common role is in ___. They are attached via ___ linkages.

Answer 14

glycerol/phosphate/2/phosphatidyl/head group/phosphate/membranes/phosphodiester

Question 15

The head group substituents attached to the phosphate in phospholipids are usually ___. They control the ___ of the phospholipids so different ___ usually have ___ head groups

Answer 15

alcohols/properties/organelles/different

Question 16

Sphingolipids: ___+___+___/___/___

the different types are: …

Answer 16

sphingosine/fatty acid/saccharide/phosphate/H

- ceramide, sphingomyelin, cerebroside, ganglioside

Question 17

Sphingosine is a …

Answer 17

long-chain amino alcohol

Question 18

The fatty acid in a sphingolipid is attached via an ___ linkage, not an ___ linkage

Answer 18

amide/ester

Question 19

What differentiates the different types of sphingolipids?

Answer 19

Ceramides: spingosine+f.a.+H
Sphingomyelin: sphingosine+f.a.+PO4-choline
Cerebrosides: sphingosine+f.a.+monosaccharide
-glucosylcerebroside: monosaccharide=glucose
-lactosylcerebroside: =di/tri/tetra saccharide
Ganglioside:sphingosine+f.a.+oligosaccharide

Question 20

Blood groups are partly determined by types of ___ located on sphingolipids, specifically on ___. The structure of the ___ is determined by ___ ___: those with inactive ___ ___ have the O antigen, those with ___ ___ that transfers N-acetylgalactosamine have the ___ antigen, those with ___ ___ that transfers ___–>phosphate have the B antigen. Those with the AB antigen have both ___ and ___ properties.

Answer 20

sugars/glycosphingolipids/sugar/glycosyl transferase/glycosyl transferase/glycosyl transferase/A/glycosyl transferase/galactose/A/B

Question 21

Phospholipases: lipid-specific ___ that cleaves ___ linkages
phospholipase A1: cleaves ___ linked f.a.
phospholipase A2: cleaves ___ linked f.a
phospholipase ___: cleaves C3 linked phosphoric acid
phospholipase D: cleaves phosphodiester linked ___ ___

Answer 21

enzyme/ester/C1/C2/C/head groups

Question 22

Biologically active lipids: no not contain ___ or ___. They occur in ___ amounts in cells and tissues. The recruit the activities of ___ and ___. The two major classes are ___ and ___.

Answer 22

f.a./glycerol/smaller/proteins/receptors/steroids/prostaglandins

Question 23

Prostaglandins:

Answer 23

generated through f.a. modification

Question 24

Steroids:

Answer 24

metabolically important for digestion and as hormones, generated from two carbon acids and through modifications of sterols

Question 25

Cholesterol:

Answer 25

steroid nucleus (4 carbon rings)+-OH+non-polar branches side chain
prevents close packing of the lower ends of f.a. chains (decreases melting point of membranes) but promotes tight upper packing of f.a. so it works as a membrane fluid buffer (without we would respond to changing temperatures by changing concentration of saturated and unsaturated f.a.)

Question 26

Lipid aggregates: three possible structures; lipid ___ (when heat to tail ratio is ___), lipid ___ (when head to tail ratio is ___), and ___ (with enclosed ___).

Answer 26

micelles/>1:1/bilayer/=1:1/liposomes/H2O

Question 27

Characteristics of the cell membrane:

1. it is ___ to large molecules and charged ions
2. it is ___ in appearance
3. it is ___-like, so lipids can diffuse ___ and ___
4. membrane lipids are ___ distributed
5. membranes of different cellular ___ and different lipid ___
6. The cell membrane contains many ___ proteins where the phospholipids act as a solvent, the three classes are ___, ___, and ___

Answer 27

1) impermeable
2) tri-laminar
3) fluid/laterally/spin
4) asymmetrically
5) organelles/composition
6) globular/integral/anchored/peripheral

Question 28

The enzymes that help with equilibrium in the membrane are ___ (moves PE and PS from outer to inner layer), ___ (moves phospholipids from inner to outer layer), and ___ (moves lipids in either direction towards equilibrium). These maintain ___. ___ like to be oriented outwards but if ___ is oriented outwards it is a signal for cell death so these enzymes are very important

Answer 28

flippase/floppase/scramblase/asymmetry/glycerolphospholipids/phosphatidylserine (PS)