C485 Quiz 7

1) What enzyme activities are required to metabolize an odd carbon unsaturated fatty acid and an even carbon unsaturated fatty acid.
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1) What enzyme activities are required to metabolize an odd carbon unsaturated fatty acid and an even carbon unsaturated fatty acid.
1) Odd carbon chains require an isomerase
2) Even carbon chains require dehydrogenase then an isomerase
2) Calculate the energy yield from a C-10 saturated fatty acid. A C-12 fatty acid with an odd carbon double bond. A C-12 fatty acid with an even carbon double bond.
C10) 4 FA + 5 AcCoA -2 ATP = 64
C12O) 5 FA + 6 AcCoA - 2 ATP - QH2 = 76.5
C12E) 5 FA + 6 AcCoA - 2 ATP - NADH = 75.5
3) List the differences between FA synthesis and degradation.
1) Cytoplasm vs Mitochondria
2) locked intermediates vs Free CoA thioesters
3) One protein vs multiple enzymes
4) Uses NADPH vs Uses NADP+
5) Carbons from malonyl CoA vs carbons make AcCoA
4) What is an ACP? Describe its role in fatty acid synthesis.
an acyl carrier protein that contains a pantathene prosthetic group. Arm can reach all active sites and acts as foundation for growing FA
5) Describe the basic organization of a fatty acid synthase.
Homodimer enzyme that natively contains the functions needed for FA synthesis
6) What is the first committed step in fatty acid synthesis? Draw the mechanism.
formation of malonyl CoA from an acetyl CoA and AcCoA Carboxylase
Image: 6) What is the first committed step in fatty acid synthesis? Draw the mechanism.
7) Describe the requirements in building blocks, ATP and NADPH for the synthesis of palmitate.
7 HCO3, 8 AcCoA, 7 ATP, 14 NADPH
8) Outline the first round of fatty acid synthesis starting from AcCoA and malonyl CoA.
Bicarbonate is combined with AcCoA through the biotin AcCoA Carboxylase
9) Is there a direct mechanism for generation of AcCoA in the cytoplasm? If not, why might this be a problem? How do cells deal with this?
There is no direct mechanism which is a problem because AcCoA must be used for FA synthesis in the cytoplasm. Citrate is brought from the mitochondria and lysed in the cytoplasm to form AcCoA and OAA
10) Name and outline (show the reactions) the process used to solve the problem in question 10.
Image: 10) Name and outline (show the reactions) the process used to solve the problem in question 10.
11) In what other ways does the generation of AcCoA in the cytoplasm address a problem of fatty acid biosynthesis.the process forms 8 NADPH which accounts for some of the 14 needed for palmitate synthesis12) Draw the structures of ketone bodies. Where are they synthesized and where are they predominantly used.they are made in the liver and predominantly used in cardiac muscle but can be used by the brain under starvation conditions13) Calculate the energy yield from beta-hydroxy butyrate. (You will have to do a little thinking here.)oxidation of beta-hydroxy butyrate creates an NADH and a succinyl CoA which is broken down into 2 AcCoA however 1 GTP cannot be formed from succinyl CoA which brings total to 22.5-1= 21.514) Outline (structures) the process by which ketone bodies are made.15) What are peroxisomes and what do they do? How is this process different from normal beta oxidation of fatty acids?Peroxisomes degrade long fatty acids by using FADH2 to convert O2 into HOOH during the initial dehydrogenase reaction16) Under what conditions would you expect ketone body formation? Why? Explain the statement - "fats burn in the flame of carbohydrates".ketone bodies are formed from the AcCoA produced from FA degradation. Under starvation conditions, oxaloacetate is being used in gluconeogenesis and cannot be used to bring AcCoA into CAC17) How does the brain adapt to starvation?the brain can operate on up to 75% ketone bodies18) How does the energy charge of a cell affect the regulation of FA synthesis. Describe how this takes place and the role of any hormones in this process.Low energy turns off FA synthesis. AMP will bind AMPK which turns off AcCoA carboxylase19) List the small molecules that activate FA synthesis and briefly say how they do this.1) Citrate - activates carboxylase through polymerization 2) malonyl CoA - turns off Cat1 so synthesis and degradation arent happening simultaneously20) List the small molecules that inhibit FA synthesis and briefly say how they do this.1) epinephrine - activates AMPK which inactivates AcCoA carboxylase 2) Palmitoyl CoA - depolymerization21) How does malonyl CoA affect FA metabolism? Explain the logic of this.Malonyl CoA acts as the high energy molecule the drives the reaction towards completion. ATP used in the carboxylation of AcCoA to malonyl CoA is stored then released during decarboxylation1) What is the first step in amino acid breakdown?conversion of an AA to an alpha-keto-acid