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BIBC 102 > Lecture 9- Lipid Catabolism > Flashcards

Lecture 9- Lipid Catabolism Flashcards

1
Q

Draw out a basic Triglycerides

A

Glycerol with three fatty acid tails

- we store fats as triglycerides

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2
Q

Draw out Diglycerides

A

Glycerol with two fatty acid tails

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3
Q

Draw out Monoglycerides

A

Glycerol with one fatty acid tail

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4
Q

Monounsaturated fatty acids

A
  • Fatty acids that contain one double bond so are “kinked,” assuming they are cis-unsaturated, which is what all natural unsaturated fatty acids are
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5
Q

Polyunsaturated fatty acids

A
  • Fatty acids that have multiple double bonds
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6
Q

Chylomicrons

A
  • A lipid monolayer that forms a mycel and contains triglycerides and cholesteryl esters inside
  • There are proteins in the lipid monolayer to help direct the chylomicron to go where it needs to go, and there is also cholesterol in the membrane
  • Used to ship lipids around the body
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7
Q

Lipoprotein

A
  • A protein that is composed of a hydrophobic part that is embedded in the chylomicron’s lipid monolayer, and a hydrophilic part that is exposed to the outer world
  • Are used for the cells to recognize the chylomicron
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8
Q

Apoliproteins

A

-Proteins that bind to lipids to form lipoproteins

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9
Q

Carnitine. Also draw it out

A
  • Carries fatty acids across the inner membrane
  • We make acyl-CoA in the cytosol, convert it to carnitine to get it across the inner mitochondrial membrane, then once inside the matrix we convert it back to acyl-CoA
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10
Q

acyl-CoA. Also draw it out

A
  • Carries/transports fatty acids; the “acyl” part contains the fatty acid
  • The carbonyl carbon of the fatty acid is connected to the thiol group of CoA
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11
Q

Beta-oxidation

A

Step 1: The fatty acid attached to CoA is oxidized by FAD to give a double bond between the alpha and beta carbons
Step 2: The molecule is then hydrated and water (OH) is added onto the beta carbon and a hydrogen is added onto the alpha carbon
Step 3: The beta carbon is then oxidized again, this time by NAD to form a carbonyl
Step 4: CoA comes in and uses its thiol group to attack the newly formed carbonyl, causes the molecule to split apart into acetyl-CoA (the acetyl group coming from the original carbonyl on the original fatty acid), and acyl-CoA, only two carbons shorter now
- This beta-oxidation pathway then repeats over and over again, until we run out of carbons
- This makes this pathway an iterative pathway

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12
Q

Peroxisome

A
  • Also catabolize fatty acids
  • Have their own fatty acid oxidation pathway different from that of mitochondria
  • The FAD doesn’t go to the e- transport chain, but instead gets dumped directly onto O2 to give hydrogen peroxide, which is constantly being made in peroxisomes
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13
Q

Ketone body

A
  • Produced from acetyl-CoA when we have a build-up of acetyl-CoA
  • Is another pathway for acetyl-CoA to take, other than entering the Krebs cycle
  • Produced only in the liver, however
  • When we have a high demands of blood glucose, we get a high level of acetyl-CoA in the liver. The liver converts these to ketone bodies to send them out, and then other tissues metabolize the ketone bodies back to acetyl-CoA, and use acetyl-CoA in the Krebs cycle in their cells
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14
Q

HMG-CoA

A

H

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15
Q

Ketosis

A

F

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16
Q

Lipase

A

V

17
Q

lactone

A

-Internal (cyclic) ester

18
Q

Draw out a phospholipid

A
  • A glycerol with two fatty acid tails and a phosphate and more stuff attached to its other oxygen
19
Q

fatty acids

A
  • Long, hydrocarbon tails that start out with a COO-, making them amphiphilic
  • Can be free, just floating around, or can be part of other molecules, like phospholipids and triglycerides
  • When connected to a glycerol, like in a phospholipid, or glyceride, the bond it makes with it is an ester bond
  • Are fantastic energy storages
20
Q

Bond between a fatty acid and glycerol

A
  • An ester bond
21
Q

How does a fatty acid molecule, ingested as a triglyceride, get transformed into an acetyl group in beta-oxidation?

A

-First, the fatty acid gets phosphorylated by attacks the alpha phosphate of ATP, dephosphorylating ATP. This is catalyzed by fatty acyl-CoA synthetase. Then CoA comes in and attacks the carbonyl group of the fatty acid, and since its newly attached adenosine is a good leaving group, it leaves, giving us acyl-CoA. This is catalyzed also by fatty acyl-CoA synthetase.
- This acyl-CoA is produced in the cytosol, and needs to get into the matrix of the mitochondria
-Now the beta-oxidation pathway takes place
Step 1: The fatty acid attached to CoA is oxidized by FAD to give a double bond between the alpha and beta carbons
Step 2: The molecule is then hydrated and water (OH) is added onto the beta carbon and a hydrogen is added onto the alpha carbon
Step 3: The beta carbon is then oxidized again, this time by NAD to form a carbonyl
Step 4: CoA comes in and uses its thiol group to attack the newly formed carbonyl, causes the molecule to split apart into acetyl-CoA (the acetyl group coming from the original carbonyl on the original fatty acid), and acyl-CoA, only two carbons shorter now
- This beta-oxidation pathway then repeats over and over again, until we run out of carbons
- This makes this pathway an iterative pathway

22
Q

How does the cell deal with a cis-double bond during beta-oxidation?

A

-When we reach a cis-double bond in an unsaturated fat, there is a special enzyme that isomerizes that double bond into a trans-double bond. A trans double bond is what is made in the first step of beta-oxidation, so we can continue on with the process from there.

23
Q

What is a propionyl-CoA, and how does the cell deal with it?

A
  • Propionyl-CoA is the result when we have an uneven number of carbons in our fatty acid, so the last product you get is an acetyl-CoA with an extra CH2 (propionyl-CoA)
  • We undergo a series of reactions to deal with this
  • Step 1: In a biotin-based reaction, bicarbonate is used to carboxylate the alpha carbon on propionyl-CoA, producing D-methyl-malonyl-CoA
    Step 2: an epimerase isomerizes D-Methyl-malonyl-CoA into L-methyl-malonyl-CoA
    Step 3: A mutate with a B12 cofactor uses radical based chemistry to change the L-methyl-malonyl-CoA into succinyl-CoA, which can directly enter the Krebs cycle.
24
Q

Draw out fatty acid oxidation

A

d

25
Q

Draw Carnitine

A

j

26
Q

Write out the ENTIRE process of a 16 carbon fatty acid getting broken down

A

f

BIBC 102 (10 decks)

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