Lesson 7: Overview of Lipid Metabolism

What is the term used for the simplest of all lipids?

fatty acids

Do fatty acids have an even or odd number of carbons?

even

Describe the 2 classifications of fatty acids:

Saturated: no carbon to carbon double bonds

Unsaturated: one or more double bonds

one double bond=

2 or more double bonds=

monounsaturated; polyunsaturated

Are omega-3 and omega-6 polyunsaturated or monounsaturated fatty acids?

polyunsaturated 

Fatty acids are not soluble, therefore they need to be binded to the blood protien _________ to travel.

albumin

_______________ fatty acids are not attached to ester bonds.

non-esterified or free fatty acids

describe the difference in structures of saturated and unsatruated fatty acids.

saturated= linear, no double bonds, tightly packed

unsaturated= cis/trans(mostly cis), double bonds

Describe the form of liquids when comparing unsaturated and saturated fat.

Give examples of both

saturated fat= hard at room temp

ex. coconut oil

unsaturated fat= liquid at room temp

ex. vegetable oil

List the omegas that are essential(need from diet) and the ones that our body creates.

give examples

essential omegas: omega-3 and omega-6

• fatty fish

body creates= omega-9

• avacado; walnuts

In fatty acid nomenclature what do the omega and delta systems denote?

omega system= denotes chain length and amount of double bonds from the methyl end

delta system= denotes chain length and amount of bouble bonds from carboxylic end

When looking at fatty acid chains, if the first double bond is at postion 6, what does that make the fatty acid?

an omega-6 fatty acid

What essential fatty acid do you need to consume to make Eicosapentaenoic acid(EPA) and Docosahexanoic acid(DHA)?

a-Linolenate(a-linolenic acid)

What essential fatty acid do you need to consume to make y-Linolenate and Arachidonate?

Linoleate

a-linolenic acid/a-linolenate=omega-___

Linoleic acid= omega-___

• omega-3

• omega-6

a-linolenic acid and linoleic acid are essential fatty acids becuase they lack the enzymes to insert double bonds beyond carbon-___.

carbon-9

What food sources are omega-3 fatty acids found in?

cold water fish(salmon, tuna, halibut); nuts; seeds

What differences in affect do omega-3 and omega-6 fatty acids have on the body?

omega-3=anti inflamatory

omega-6=pro-inflamatory

What are some examples of preventative risk factors if intaking omega-3 fatty acids?

arthitis, cancer, and heart disease

What is the normal ratio of w-6 and w-3 within a healthy diet compared to the average american diet?

normal=2:1-5:1

american diet=10:1-30:1

What type of fats has the FDA now banned?

trans-fats

describe the formation of trans fatty acids:

Hint: (cis/trans; double bonds etc.)

one or more trans double bonds

Although trans fats are associated with negative outcomes, what is the one form or trans fat that is good for our diet?

Conjugated linoleic acid(CLA)

naturally found in dairy products(cows make trans fats)

Most FAs in nature are found as _____________.

glycerolipids

Triacylgylcerides are solids are room temperature if they have more ____________ fatty acids.

saturated

Triacylgylcerides are more liquid at room temperature if they have more ___________ fatty acids.

unsaturated

Sterols are charachterized by a ___-ring structure.

4

What is the only sterol made by humans?

cholesterol

Cholesterol can be found with a FA attached, which is called a cholesterol ________.

ester

R group of a phospholipid is commonly ______ or inositol.

choline

Name the 3 types of glycerolipids/acylglycerols:

Monoglyceride, diglyceride, and triglyceride

all glycerol backbones for triglycerides and adipose tissue are made de novo from ___________.

glucose

Within the formation of triglycerides, each fatty acid is added sequentially to a __________ backbone.

glycerol 

what does the melting point of triacylglycerides depend on?

melting point

Do oils have lower or higher melting points? Making them what type of fatty acid?

oils have a lower melting point which make them an unsaturated fats.

What is the R group commonly made of within phospholipids?

choline and inositol

Within phospholipids there are dervatives of phosphatides. Name the 2 types of classifactions of phosphatides and sturctures:

glycerophosphatides: glycerol core structure

Sphingophosphatides: amino alcohol core structure

derivatives of phosphatidic acid, such as phosphatidyl _________ and phosphatidyl _________ are constituents of membranes.

choline and inositol

If we want to transport cholesterol and tryglycerides, were gonna have to transport them in __________.

lipoproteins

__________ are transporters of lipids throughout the body.

lipoproteins 

what are lipoproteins made out of?

phospholipid shell with some cholesterol and proteins(apolipoproteins) inserted throughout.

what are the 4 main categories of lipoproteins?

chylomicrons, HDLs, VLDLs, and LDLs

Where are chylomicrons made?

what is their job?

the small intestine (gut); carry triglycerides to adipose tissue

Where are VLDLs formed and what is their job?

found in liver; carry triacylglycerides to store in adipose tissue

Where are LDLs found and what is their job?

found in liver; carry cholesterol to tissues

where are HDLs found and what is their job?

found in liver; carry cholesterol away from tissues 

What type of the lipoprotein is the most dominant in a fed state?

chylomicrons

What is the dominant and 2nd most dominant lipoprotein in a fasted state?

VLDLs; then LDLs

When fatty acids are released from adipose tissues they are transported in the blood bound to ____________.

albumin 

Describe the function of the liver in terms of synthesis and stroage:

for export in VLDLs or storage for local energy production

Describe the function of adipose tissue in terms of synthesis and storage:

provides local energy and a source of energy production for other cells that have oxidative capacity.

What is fatty acid activation?

Term

adding a CoA to a fatty acid to make fatty acyl CoAs

What synthetase adds a CoA during FA activation? When this synthase occurs how many ATP are expensed?

Acyl CoA synthetase; 2 ATP

Best describe beta oxidation and where it occurs:

process by which fatty acids are oxidized to produce acetyl CoA; occurs in mitochondrial matrix

Since CoA molecules are not permeable to the inner mitochondiral membrane, CoA and FA is swapped for a _______ molecule via the enzyme ____________________.

carnitine; CPT1-carnitine palmitoyl transferase I

Where is carnitine made, and what is it made of?

made in liver; made of methionine and lysine

What is it called when 2 phosphates are stuck together?(PPi)

2 phosphates=pyrophospate

we regulate fatty acid metabolism by regulating ________.

CPT 1

Once carnitine is in the matrix, ________________________ swaps the carnitine for the CoA

CPT II-carnitine palmitoyl transferase I

What is the forward process to breakdown a fat? This process shortens a fatty acid by 2 carbons at a time.

beta oxidation

What does beta oxidation produce each turn of the cycle?

1 acetyl coA, 1 NADH, and 1 FADH2

everytime you cut off 2 carbons for beta oxidation you gain how many ATP?

4 ATP

within beta oxidation, every cycle producing an acetyl-CoA goes into what cycle?

beta oxidation

what are the products of the TCA cycle?

3 NADH, 1 FADH2, and 1 GTP

How much overall ATP does the TCA cycle produce?

10 ATP

every acetyl CoA equals how many carbons?

2 carbons

16 carbons equals how many acetyl CoAs?

(ATP production of palmitate)

8 carbons, because every acetyl CoA=2 carbons

under what type of oxidation do the cycles always have one less cycle compared others?

(ATP production of palmitate)

beta oxidation 

under an even # of saturated fatty acids how much ATP do acetyl CoAs create?

(ATP production of palmitate)

10 ATP

Under an even # of saturated fatty acids, how much ATP is created under beta oxidation?

(ATP production of palmitate)

4 ATP

Would you make less ATP if you have a double or single bond?

double

For every double bond in an unsaturated FA, you need to subtract ____ ATP from the total yeild(due to loss of a FADH2 produced)