Lipid Review

Question 1

Characteristics of lipids? (hydrophilicity, solubility, polarity, components)

Answer 1

Hydrophobic, insoluble in water, non-polar, long hydrocarbon chains (many C-C and C-H bonds)

Question 2

what are the two types of glycerolipids

Answer 2

Triacylglycerol and phospholipids
Both contain a glycerol backbone

Question 3

Structure of a glycerol backbone

Answer 3

Question 4

Types of fatty acids? Differences?

Answer 4

Saturated: no double/triple bonds
Unsaturated: has double/triple bonds

Question 5

types of non-glycerolipids?

Answer 5

Sphingolipids, waxes, and sterols (example of sterol is cholesterol)

Question 6

Types of lipid complexes?

Answer 6

Lipoproteins (extracellular)
lipid droplets (intracellular)

Question 6

Characteristics of unsaturated and saturated fatty acids? (MP, state at room temp)

Answer 6

unsaturated (double bonds): Low MP, liquid at room temp
Saturated (no double bonds): higher MP, solid at room temp

Question 6

What are the two things all fatty acids have?

Answer 6

All have a carboxyl carbon and a long carbon chain

Question 6

Fatty acid nomenclature

Answer 6

1st number: how many carbons
2nd number: how many double bonds
3rd number: position of double bond/s

Question 6

What are the following components of?
Phospholipids, triacylglycerol, cholesterol + fatty acids, proteins attached to certain fatty acids

Answer 6

Phospholipid: membrane structure, cell signaling
Triacylglycerol: Stored energy, source of ATP
Cholesterol + fatty acids: cholesterol ester
Proteins attached: membrane attachment

Question 7

Sources of Fatty acids

Answer 7

Diet and synthesis

Question 8

How are fatty acids synthesized

Answer 8

synthesized from acetyl CoA

Question 9

Products of FA oxidation

Answer 9

Acetyl CoA, FADH2, NADH

Question 10

How are phospholipids organized in a lipid bilayer

Answer 10

Polar head group point out,
non-polar tails point inwards

Question 11

why does fatty acid composition of phospholipids regulate membrane fluidity

Answer 11

They are rigid enough to be a barrier and flexible enough to allow transports of proteins, lipids, other molecules

Question 12

function of glycosylphosphatidylinositol (GPI) anchors? How many human proteins are GPI-anchored proteins?

Answer 12

Functions to tether proteins to outside of cell membrane, 150 human proteins are GPI-anchored

Question 13

T/F Different cellular membranes have the same phospholipid compositions

Answer 13

false

Question 14

how can lipid asymmetry regulate signals

Answer 14

Rearranging, certain types of phospholipids from inside to outside can activate enzymes that need that specific phospholipid to activate. exposure to PS to outer regions that are - charged can interact with proteins that are + charged

Question 15

how does lipid asymmetry allow for membrane curvature

Answer 15

Different phospholipids have different shapes usually dictated by head group, a mixture of different phospholipids allows for necessary curvature and flexibility of a membrane.

Question 16

What shape is phosphatidylcholine and phosphatidylethanolamine?

Answer 16

Phosphatidylcholine: cylindrical, flat sheets
Phosphatidylethanolamine: conical, curvature

Question 17

How are fatty acids connected to glycerol

Answer 17

by an ester bond

Question 18

Why do we store TG instead of fatty acids?

Answer 18

Fatty acids are toxic at high concentrations. (abnormal cell signaling, dissolve cellular membrane)
TG are chemically inert and we can store lots of TG for energy

Question 19

T/F TG have a mixed FA composition in different tissues

Answer 19

True

Question 20

Kennedy pathway of lipid synthesis

Question 21

What tissue is responsible for TG storage

Answer 21

Adipose tissue, TG also found in liver, small intestine, and mammary gland

Question 22

Describe the catabolism of stored fat in adipose tissue?

Answer 22

When blood glucose is low, lipases will break down TG, the fatty acids will then undergo B-oxidation to create CO2 and ATP in muscle

Question 23

Functions of cholesterol

Answer 23

Makes bile acids (important for absorption of nutrients) Important for membrane structure (30-50% of lipids in membrane are cholesterol) Precursor of steroids

Question 24

what is atherosclerosis? Causes?

Answer 24

Build-up of plaque in arteries that can lead to blood clots Caused by increased cholesterol

Question 25

Review sources of cholesterol slide

Question 26

Functions of chylomicrons, VLDL, LDL, and HDL

Answer 26

Chylomicrons and VLDL: transport TG (still carry some cholesterol) LDL and HDL: Transport Cholesterol (still carries a little TG)

Question 27

Rank chylomicrons, VLDL, LDL, and HDL in terms of size

Answer 27

Largest Chylomicrons VLDL LDL HDL (most dense, heavier) Smallest

Question 28

Which cholesterol is bad and which is good

Answer 28

LDL = bad Most of the body's cholesterol is bad, increases risk of heart disease and stroke HDL = good Carries cholesterol from tissues to the liver excreted from the body in bile lowers risk for heart disease and stroke

Question 29

What are the uses of phosphatidylcholine and phosphatidylethanolamine

Answer 29

Uncharged, PC: structural PE: structural/protein tether

Question 30

What is the use of phosphatidylinositol and phosphatidylserine

Answer 30

Net negative charge PI: signaling, protein tether PS: apoptosis, blood clotting

Question 31

Kennedy pathway of lipid synthesis

Answer 31

Starts with glycerol 3-Phosphate which is acted on by acyl transferase twice to attach two fatty acids one to C1 and one to C2, resulting in phosphatidic acid. Phosphate is then removed from phosphatidic acid by phosphatidic acid phosphatase to become 1,2 diacylglycerol. Where it is then acted upon by acyl transferase gain another fatty acid onto C3 to become triacyl glycerol

Question 32

Describe cholesterol synthesis (main enzyme)

Answer 32

Starts with 3 acetyl CoA which then undergoes multiple reactions until it comes to a reaction catalyzed by HMG- CoA reductase. HMG CoA reductase regulates cholesterol metabolism. After that reaction, it will eventually become cholesterol which in turns provides feedback onto HMG CoA reductase to reduce synthesis

Question 33

Four types of lipids

Answer 33

Fatty acids GLycerolipids Non-glycerolipids Lipid complexes