Fatty acid metabolism

Question 1

what are the sources of lipids and fatty acids

Answer 1

diet
adipose storage
synthesis in tissue

Question 2

what are the fates of lipids and fatty acids

Answer 2

energy substrates
precursors (acrachodinate acid)
structural elements(phospholipids)
signaling molecules(

Question 3

what are bile salts and what do they do

Answer 3

emulsify dietary fats(lipids) in the small intestine and form mixed micelles

Question 4

what do lipases do

Answer 4

degrade triaclyglycerols in to fatty acid

Question 5

what do fatty acids get put back together in?

Answer 5

chylomicrons

Question 6

what is a chylomicron?

Answer 6

it is an apolipoprotein that travels through the lymphatic system and blood stream to tissues that need them
carry triglycerides and fatty acids
made in enterocyte ER

Question 7

what are apolipoproteins

Answer 7

lipid binding proteins
combine with lipids to form lipoproteins
diverse functions

Question 8

what are the two ways that fatty acids are transported?

Answer 8

carried by serum albumin(free fatty acids)

and in lipoproteins (chylomicron)

Question 9

what are the four types of lipoproteins

Answer 9

chylomicrons
very low density lipoprotein (VLDL)
low density lipoprotein (LDL)
high density lipoprotein (HDL)

Question 10

where are the VLDLs produces?

Answer 10

liver

Question 11

VLDL takes the fatty acid and cholesterol to the blood stream to target tissues. What are they called once they deliver the fatty acids or cholesterol?

Answer 11

LDL and go back to liver

also can deliver cholesterol to Macs

Question 12

What is the exogenous pathway?

Answer 12

fats from our diet are packaged into chylomicrons and is sent to the liver for processing into VLDL

Question 13

what is the endogenous pathway?

Answer 13

fats from the liver are put into VLDL and sent to target tissues (muscle, adipose, adrenal gland, gonads)

Question 14

what do high density lipoproteins do?

Answer 14

take the excess cholesterol from the macs and the body back to the liver

Question 15

what is the receptor on the LDL particle necessary for endocytosis?

Answer 15

apoB-100

Question 16

When an LDL is internalized and broken down what can it be made into?

Answer 16

AAs, FAs and cholesterol

Question 17

What is the triacylglycerol cycle?

Answer 17

under conditions of starvation or intense exercise fatty acids from adipose tissue and released into blood.
75% of released FAs are cycled back liver where they are make into triglycerides and transported via lipoproteins t target tissues

Question 18

fatty acid mobilization process

Answer 18

glucagon released from pancreas stimulates Gprotein receptor to activate adenylyl cylcase

• this activates PKA(protein kinase A)
• this phosphorylates perilipin
• this causes it to dissociate and release CGI
• CGI activates Adipose tryglyceride lipase (ATGL)
• ATGL breaks down lipids into monoacylglycerol and diacylglycerol
• PKA also phosphorylates hormone sensitive lipase
• HSP breaks down the diacylglycerol into monoacylglycerols
• Monoglyceride lipase removes the glycerol so the fatty acids can be released

Question 19

how are triglycerides broken down?

Answer 19

via lipases
broken down into glycerol and fatty acids
fatty acids form fatty acyl CoAs
glycerol is made into glyceraldehyde 3-phosphate

Question 20

how do the fatty acyl CoA get into the matrix of mitochondria?

Answer 20

via carnitine through an antiporter

**the CoA does NOT get transferred with the fatty acyl

Question 21

what are the three stages of fatty acid oxidation?

Answer 21

1. beta oxidation
2. citric acid cycle
3. Oxidative phosphorylation
   * *remember this happens in the matrix of mitochondria

Question 22

how much ATP is produced by 1 16 carbon (palmiate) fatty acid?

Answer 22

108

Question 23

per 1 oxidation step in beta oxidation what are the products?

Answer 23

1 Acetyl CoA (goes to CAC)
1 NADH ( goes to ETC)
1 FADH2 (goes to ETC)

Question 24

what enzyme feeds directly into the ETC?

Answer 24

acyl-CoA dehydrogenase, produces FADH2

Question 25

what are the two fates of acetyl CoA made in the liver?

Answer 25

- goes into CAC for production of glucose through gluconeogenesis - can go form ketone bodies

Question 26

what are the three ketone bodies to know? why are they important?

Answer 26

- Acetoacetate, Acetone(cannot be converted back into acetylCoA), beta-hydroxybutyrate - allow for recycling of CoA and also serve as energy for fuel for heart, muscle, kidney, and brain

Question 27

how do dietary proteins and carbs get turned into fatty acids and eventually triacylglycerols?

Answer 27

- the acetyl CoA is carboxylated into malonyl CoA - acetyl CoA and malonyl CoA combine to start a acyl chain - fatty acid synthase adds malonyl CoA carbons to create palmitate - modified in ER (sterols, phospholipids)

Question 28

the citrate shuttle

Answer 28

transports acetyl CoA that is produced in the matrix into the cytoplasmic space where lipid synthesis occurs

Question 29

what does malic enzyme do and what does it produce?

Answer 29

takes malate to pyruvate | produces NADPH

Question 30

What enzyme carboxylates acetyl CoA into Malonyl-CoA

Answer 30

Acetyl-CoA carboxylase (ACC) | biotin is required(vit. B7)

Question 31

What are the two types of fatty acid synthase?

Answer 31

- type I vertebrates and fungi (only makes plamitate) 16 carbon saturated fatty acids - type II in bacteria and plants

Question 32

Acyl carrier protein

Answer 32

fatty acid synthase(FAS) prosthetic group holds malonyl group to FAS needs pantothenic acid (vit. B5)

Question 33

lipid synthesis steps

Answer 33

``` malonyl added to acetyl via condensation step NADPH reduces dehydration reduction again by NADPH **adds two carbons at a time ```

Question 34

what essential fatty acid is produced by fatty acid synthase II

Answer 34

alpha linolenate

Question 35

what is the longest carbon chain that we can create as humans?

Answer 35

18 carbons

Question 36

how does Acetyl-CoA Carboxylase activity regulate fatty acid synthesis and breakdown

Answer 36

insulin activates ACC(phosphate dephosphoryates) glucagon deactivates ACC(phosporylated by PKA) **high levels of malonyl CoA deactivate fatty acid beta oxidation at the carnitine acyl transferase I enzyme

Question 37

fatty acid addition make phospholipids and triglycerides | what is the process?

Answer 37

- glucose and glycerol and 2 acyl chains form phosphatidic acid - head groups and FAs are added to phosphatidic acid to make phospholipids - phosphatase can remove phosphate group and allow addition of another fatty acid to make a triglyceride - this occurs at the ER of the cell

Question 38

what does excess acetate lead to?

Answer 38

the formation of cholesterol, which is the basis for many sterols

Question 39

T/F cholesterol is involved in lipoprotein and hormone formation?

Answer 39

True, it is a necessary component of lipoprotein walls and for hormones

Question 40

what are foam cells?

Answer 40

macrophages that have taken up too many cholesterol molecules and build up in the arteries and form atherosclerosis. *hence HDL is very important in removing the cholesterol from the macrophages