Fat and Protein Metabolism

Question 1

the most energy-dense dietary source

Answer 1

fatty acids

Question 2

how are fats digested?

Answer 2

1. dietary fats are insoluble, so bile is released to emulsify fat particles into dispersed, soluble micelles
2. intestinal lipases degrade the fats so they can be absorbed and converted into TAG (triacylglycerols)
3. which are then incorporated into chylomicrons

Question 3

lipoproteins are useful for…examples…

Answer 3

packaging and transporting lipids after they’ve been reconstituted into triacylglycerides in the core of a protein molecule
HDL, LDL, chylomicrons (this holds the triacyglycerides)

Question 4

apolipoproteins are useful for…

Answer 4

signaling. determine the functional properties of lipoproteins, which express apolipoproteins

Question 5

apolipoproteins are…

Answer 5

lipoproteins unbound to lipids. vary in their ratios of proteins to lipids.

Question 6

what makes lipoproteins dense?

Answer 6

the higher ratio of proteins to lipids. this density is what makes lipoproteins function differently

Question 7

how do the majority of fatty acids enter the outer membrane of the mitochondria?

Answer 7

the majority are too large to freely diffuse into the membrane. energy has to be coupled to bring the fatty acids, by way of carnitine shuttle. carnitine-bound fatty acids enter the outer membrane through an enzyme called transferase

Question 8

Krebs Cycle produces how much ATP?

Answer 8

remember: per 1 acetyl-CoA, 10 ATP is produced

Question 9

oxidation of fatty acids produces how many NADH and FADH2?

Answer 9

1 molecule of NADH and 1 molecule of FADH2

Question 10

a 20 carbon fatty acid yields how many acetyl-CoA’s after how many oxidations?

Answer 10

10 acetyl-CoA’s and 9 passes

Question 11

ATP per NADH, FADH2

Answer 11

2.5 for NADH, 1.5 for FADH2

Question 12

what are the major products of amino acid catabolism?

Answer 12

ketone bodies and glucose

1. there are two main pathways for amino acid metabolism
2. defined by the end products degraded
3. one is degraded to acetyl-CoA or acetoacetyl-CoA, the other to pyruvate (ketogenic and glucogenic)

Question 13

how many amino acids are essential for life?

Answer 13

21 amino acids are used by humans, and 9 are considered essential (meaning we can’t make them ourselves)

Question 14

Oxaloacetate (OAA)

Answer 14

an important intermediate in the CAC and gluconeogenesis, formed by pyruvate or malate

Question 15

ketogenic amino acids

Answer 15

metabolized to form acetyl-CoA

Question 16

glucogenic amino acids

Answer 16

enter the citric acid cycle at different points, with the goal of producing glucose; catabolized to form pyruvate or OAA

Question 17

fatty acid metabolism

Answer 17

metabolized to form acetyl-CoA, which enters the CAC

Question 18

three fuels of the human body

Answer 18

1. glycogen - way of storing carbohydrates (long chain polymer of glucose molecules attached to each other) stored in liver and muscles (4 kcal/g)
2. protein - long chains of amino acids (muscles) (4 kcal/g)
3. fats - stored in adipose tissue (9 kcal/g)

Question 19

triacylglyceride (three main properties)

Answer 19

same as a fat

1. inert (non-polar) - not very reactive
2. energy-rich - contains many hydrogens
3. plays no functional role in the body except energy storage
4. hydrophobic - think about glycogen has a lot of water weight, so we’d weigh much more if glycogen was our storage source

Question 20

lumen

Answer 20

the same that food travels in the small intestine

Question 21

lipase

Answer 21

an enzyme released by the pancreas and cells lining the small intestines

Question 22

bile

Answer 22

secreted by the liver, stored in the gallbladder, useful as a detergent to break up fatty globules through emulsification

Question 23

what does lipase do?

Answer 23

cleaves triacylglycerides (with the addition of water) at the ester linkages; produces a free glycerol backbone and three fatty acids (which are carboxylic acids)

Question 24

carboxylic acid

Answer 24

draw it out

Question 25

how do chylomicrons travel in the body?

Answer 25

they are too large to fit in capillaries, so they enter the lacteal (lymph system), which drains into veins at the left and right thoracic ducts, which go into the arteries and capillary beds

chlymicron is a lipoprotein

Question 26

liver converts glucose into fatty acids

Answer 26

the acetyl-CoA is a precursor to fatty acid synthesis, which occurs in the cytosol. citrate is shuttled out of the mitochondria, and broken down into OAA and acetyl-coA. the acetyl-coA then uses the energy gained from converting OAA into pyruvate (NADPH)

Question 27

lipoprotein lipase

Answer 27

breaks down the chylomicron and breaks it apart into fatty acids and glycerol backbone, the fatty acids can be taken up by adipose cells. the chylomicron becomes remnants which are taken up by the liver

Question 28

what are fatty acids synthesized from?

Answer 28

8 acetyl-coA, to form 16-carbon fatty acid called palmitic acid, plus we need ATP and NADPH

Question 29

VLDL

Answer 29

very low density lipoprotein, which is produced in the liver and allows for fats to travel in the blood stream

Question 30

lots of additional information (hard to follow) in fatty acid synthesis

Answer 30

…

Question 31

what is acyl-coA?

Answer 31

get attacked by carnitine to form a carnitine fatty acid

Question 32

gluconeogenesis

Answer 32

breakdown of fatty acids cannot produce glucose, but the breakdown of proteins can