business

Question 1

FA as a fuel?

Answer 1

Stored as triacylglycerol

TAG oxidised to meet energy needs

Question 2

fatty acids we need to know

Answer 2

Palmitate is 16 Carbons long

Stearate is 18 Carbons long

Question 3

Plant oil

Answer 3

55-83% oliec acid

liquid at room temp

Question 4

Animal fats

Answer 4

Saturated fatty acids

solid at room temp

Question 5

What does hydrogenation do to fats

Answer 5

adds H over the double bond i.e unsaturated to saturated

increases melting point

make spreads and shit

Level of hydrogenation controlled by H2, temp and time

Question 6

What does hydrogenation do to fat stereochemistry

Answer 6

converts cis to trans which is more stable

Trans isomers are implicated in disease. bad cholesterol

Question 7

Types of membrane lipids

Answer 7

Phospholipids
Glycolipids
Cholesterol

Question 8

Phospholipid structure

Answer 8

.

Question 9

Sphingosine

Answer 9

instead of glycerol sometimes

Question 10

Phospholipids derived from glycerol

Answer 10

Phosphoglycerides

Question 11

Phospholipid without alcohol

Answer 11

Phosphatidate

Question 12

Glycolipids

Answer 12

• Includes a fatty acid unit and a sugar unit (glucose or galactose)
• Orient asymmetrically with the sugar pointing extracellularly
• Have a sphingosine backbone

Question 13

Cholestrol

Answer 13

• 25% of neuronal lipid is cholesterol
• Has a hydroxyl group at one end.
• Long carbon tail
• Many aromatic rings

Question 14

Soluble Proteins

Answer 14

Common examples are N-myristoyl and S-palmitoyl anchoring motifs

Question 15

β-oxidation

Answer 15

• Fatty Acid ->Acetyl CoA->Citric Acid Cycle->Energy

1) Oxidation: activated FA oxidized to introduce a double bond by a dehydrogenase
b. Redox cofactor is FAD FADH2

2) Double bond hydrated-introduces a hydroxyl group
a. Catalysed by hydratase family enzyme

3) OH group oxidised Ketone
a. Redox therefore catalysed by dehydrogenase
b. Redox cofactor= NAD+ NADH

4) Fatty Acid Cleavage acetyl CoA and FA that is 2C shorter
a. Catalysed by thiolase enzyme
b. Cofactor= CoA

Question 16

Absorption, Transport and Storage or fatty acids

Answer 16

Most ingested FA are triacylglycerol (TAG)
Lipases neck it to fatty acids
absorbed by intestinal cells
packages TAG into chylomicrons
chylomicrons travel in lymph and blood to adipose and muscle cells
broken down to FFA by active hormone-sensitive lipase if needed or just stored as TAG

Question 17

Triacylglycerol as energy stores

Answer 17

Highly concentrated stores of metabolic energy because they are reduced

TAG are nonpolar so are stored in an anhydrous form

Question 18

Fatty Acid Activation and Transport

Answer 18

FA must be activated first before it can enter mitochondria via formation of thioester linkage to coenzyme A

Reaction takes place on outer mitochondrial membrane
Translocase enzyme does the actual translocation

Question 19

Ketone Bodies

Answer 19

are formed from Acetyl CoA when fat breakdown predominates

Question 20

Fatty acid precursors

Answer 20

recursors for nearly all FA synthesis is acetyl CoA

Question 21

Sources of Acetyl CoA

Answer 21

glycolysis (pyruvate)
fatty acid degradation
and fatty acids

Question 22

Fatty Acid Synthesis

Answer 22

takes place in the cytosol

Question 23

Formation of malonyl CoA

Answer 23

Carboxylation of acetyl to malonyl
• First irreversible reaction is the committed step in fatty acid synthesis

• Reaction is catalysed by cytoplasmic enzyme acetyl CoA Carboxylase 1 (and 2)

Question 24

acetyl CoA Carboxylase 1

Answer 24

Plays essential roles in regulating fatty acid synthesis and degradation for fatty acid metabolism

Question 25

palmitate formation

Answer 25

Thioesterase hydrolyses C16-acyl ACPà palmitate and ACP Acts like a ruler to determine FA chain length 8 Acetyl CoA + 7 ATP + 14 NADPH + 6H --------> Palmitate + 14 NADP+ + 8 CoA + 6 H2O + 7 ADP + 7 Pi

Question 26

Citrate as a carrier

Answer 26

• Citrate carries acetyl groups from mitochondria to the cytoplasm for fatty acid synthesis • Mitochondria, however, are not readily permeable to acetyl CoA • Barrier to acetyl CoA is bypassed by citrate, which carries acetyl groups across the inner mitochondrial membrane

Question 27

Sources of NADPH for Fatty Acid Synthesis

Answer 27

Return of oxaloacetate formed in transfer of acetyl groups to the cytoplasm Additional 6 molecules of NADPH required come from pentose phosphate pathway

Question 28

Elongation and unsaturation of fatty acids are | accomplished by accessory enzyme systems

Answer 28

elongation reactions and addition of double bonds catalysed by enzymes mainly on cytosolic face of endoplasmic reticulum

Question 29

When is fatty acid synthesis maximum

Answer 29

maximal when carbohydrate and energy levels are plentiful and when fatty acids are scarce

Question 30

Allosteric regulation

Answer 30

stimulation of ACC by citrate inhibition of ACC by palmitoyl CoA

Question 31

Hormonal regulation

Answer 31

Glucagon and Epinephrine inhibit fatty acid synthesis by ACC phosphorylation by AMP-activated protein kinase Insulin stimulates fatty acid synthesis removal of phosphate

Question 32

LDL

Answer 32

Primary source of cholesterol from cells outside liver and intestine is plasma (not de novo synthesis)àPrimary source is LDL

Question 33

Cholesterol Synthesis

Answer 33

Derived from acetyl CoA in a three-stage synthetic process 1) Synthesis of isopentenyl pyrophosphate (an inactivated isoprene that is the key building block of cholesterol) 2) Condensation of six molecules of isopentenyl pyrophosphate to form squalene 3) Cyclization of squalene and tetracyclic product is subsequently converted into cholesterol 1) occurs in cytoplasm, 2) and 3) occur in ER

Question 34

Stage One: Mevalonate Synthesis

Answer 34

Starts with formation of HMG-CoA from acetyl CoA COMMITED step

Question 35

HMG-CoA reductase drugs

Answer 35

target of statin drugs to treat heart disease Lovostatin

Question 36

Receptor-mediate Endocytosis

Answer 36

1) B100 (apolipoprotein)- Found on surface of LDL particles and mediates binding to LDL receptor 2) Receptor: LDL particle complex is internalized by endocytosis 3) Endosome is acidified (proton pump) which causes the receptor to release LDL cargo a. Some receptor returns to the cell surface b. Some receptor is degraded 4) Endosome fuses with lysosome (full of enzymes) a. Protein component hydrolysed to free amino acids b. Cholesterol esterols hydrolysed (lipase) to release free cholesterol i. Membrane biosynthesis ii. Re-esterified (-chol-oleate: stored inside cell)

Question 37

Absence of LDL receptor

Answer 37

leads to hypercholesterolemia and atherosclerosis

Question 38

Familial hypercholesterolemia

Answer 38

Cholesterol is deposited in various tissue because the high concentration of LDL cholesterol in the plasma

Question 39

Important cholesterol derivatives

Answer 39

Bile salts | steroids