Fatty Acid Synthesis Process

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Questions and Answers

Where does fatty acid synthesis occur?

Matrix

Cytosol (correct)

Mitochondria

Nucleus

What enzyme converts acetyl-CoA to malonyl-CoA?

Citrate synthase

Fatty acid synthase

Acetyl-CoA-carboxylase (correct)

Malonyl-CoA transferase

How is acetyl-CoA moved from mitochondria to the cytosol for fatty acid synthesis?

As citrate (correct)

As oxaloacetate

As malonyl-CoA

As acetyl-CoA

What is the first product in the condensation step of fatty acid synthesis?

Acetyl group Signup and view all the answers

What molecule is not involved in the fatty acid synthesis process?

FADH2 Signup and view all the answers

Which product is generated from the dehydrogenation step in fatty acid breakdown?

FADH2 Signup and view all the answers

What is the ultimate fate of the carbon skeleton from amino acid degradation?

Conversion to glucose or ATP Signup and view all the answers

To enter the urea cycle, the amino group must be converted into which compound?

Carbamoyl phosphate Signup and view all the answers

What happens to the amino group after it is removed from the amino acid?

It is transferred to Alphaketo and forms glutamate Signup and view all the answers

What is the breakdown product of alanine in muscles?

Pyruvate Signup and view all the answers

What role does pyruvate play in the glucose-alanine cycle?

It is converted into alanine in muscles and then back into pyruvate in the liver Signup and view all the answers

What is produced when alanine reacts with alpha-ketoglutarate?

Glutamate and pyruvate Signup and view all the answers

Which enzyme is responsible for converting pyruvate and NH₂⁺ to alanine in muscles?

Amino-transferase Signup and view all the answers

Where is alanine converted back to pyruvate in the glucose-alanine cycle?

In the liver Signup and view all the answers

Where are the protein complexes of the electron transport chain located?

Inner membrane of mitochondria Signup and view all the answers

What role does ATP synthase play in oxidative phosphorylation?

It allows protons to pass out, converting ADP + Pi to ATP. Signup and view all the answers

Which molecule is reduced to H2O in the electron transport chain?

O2 Signup and view all the answers

Which co-factors are involved in the electron transport chain?

Amino acids and metal ions Signup and view all the answers

What is the source of electrons for the electron transport chain?

NADH and FADH2 Signup and view all the answers

What is the immediate consequence of proteins funneling H+ ions into the mitochondrial membrane space?

A proton gradient is established. Signup and view all the answers

What second step follows the transfer of energy from electrons during oxidative phosphorylation?

Generational of high proton concentration Signup and view all the answers

What type of reaction is primarily involved in the electron transport chain's transfer of electrons?

Redox reactions Signup and view all the answers

What is the first step of the urea cycle?

Generating carban monophosphate Signup and view all the answers

Which enzyme class is responsible for the transfer of electrons via oxidation or reduction?

Oxidoreductases Signup and view all the answers

Where does the asparate used in the urea cycle come from?

Oxoacetate Signup and view all the answers

Which process generates alphaketo skeletons that can enter the TCA cycle directly?

Glucogenesis Signup and view all the answers

What is generated in the last step of glycolysis pay-off phase?

Pyruvate Signup and view all the answers

Which of the following is not an example of an enzyme class listed in the table?

Synthases Signup and view all the answers

Which process forms intermediates like fumarate in the urea cycle?

Signup and view all the answers

What is added to the double bond at the beta carbon in the hydration step of β-oxidation?

H2O Signup and view all the answers

How many Acetyl-CoA molecules are generated from the breakdown of a C16 fat (palmitate)?

8 Signup and view all the answers

Which molecule is generated during the first dehydrogenation step in β-oxidation?

FADH2 Signup and view all the answers

What is the final product of the acyl transfer step in β-oxidation?

Acetyl-CoA Signup and view all the answers

Which of the following steps in β-oxidation involves the conversion of a double bond into a hydroxyl group?

Hydration Signup and view all the answers

Approximately how much ATP is generated from metabolizing palmitate?

106 ATP Signup and view all the answers

During β-oxidation, which enzyme is used in the acyl transfer step?

Acetyltransferase (thiolase) Signup and view all the answers

How many β-oxidation cycles are required to fully break down a C16 fat (palmitate)?

7 Signup and view all the answers

What is the process of making glucose from pyruvate called?

Gluconeogenesis Signup and view all the answers

Which enzyme is used during Step 5 of the TCA cycle?

Ligase Signup and view all the answers

What is generated in Step 4 of the TCA cycle?

CoA Signup and view all the answers

What is the primary function of TCA in cellular respiration?

Oxidizing carbons Signup and view all the answers

Which step in the TCA cycle involves an isomerisation reaction?

Step 2 Signup and view all the answers

What is the outcome of Step 3 of the TCA cycle?

Removal of the second carbon dioxide molecule Signup and view all the answers

What kind of reaction is involved in Step 7 of the TCA cycle?

Redox and ligase reactions Signup and view all the answers

Which molecule is regenerated in the last step of the TCA cycle?

Oxaloacetate Signup and view all the answers

How many ATP are produced net in glycolysis?

2 Signup and view all the answers

What is the role of NADH and FADH2 in metabolism?

To carry electrons to the electron transport chain Signup and view all the answers

What molecule is generated when fatty acids are first converted for β-oxidation?

Acyl-CoA Signup and view all the answers

What is the carrier molecule that transports fatty Acyl-CoA into the mitochondria?

Carnitine Signup and view all the answers

Which step of β-oxidation involves the creation of a reactive double bond between the alpha and beta carbon?

Dehydrogenation Signup and view all the answers

Which molecule is an isomer of dihydroxyacetone phosphate?

Fructose 1 phosphate Signup and view all the answers

What is the final product of Acyl-CoA breakdown in the citric acid cycle?

Water Signup and view all the answers

Which process generates a significant amount of ATP by oxidizing glucose through stages including glycolysis and the TCA cycle?

Aerobic respiration Signup and view all the answers

What is the role of glutamate in the urea cycle?

Acts as a shuttle for amino groups Signup and view all the answers

What is the first step of the urea cycle?

Generation of carbamoyl phosphate Signup and view all the answers

Which amino acids can enter the TCA cycle directly?

Glucogenic amino acids Signup and view all the answers

Which molecule is produced during the pay-off phase of glycolysis?

Pyruvate Signup and view all the answers

What class of enzymes is responsible for the rearrangement of a single substrate?

Isomerases Signup and view all the answers

From where does the second amino group in the urea cycle come?

Asparate Signup and view all the answers

Which step in the urea cycle involves the molecule ornithine?

First step Signup and view all the answers

Which molecule is generated as one of the intermediates in the urea cycle?

Fumarate Signup and view all the answers

Which enzyme class is involved in the transfer of chemical groups?

Transferases Signup and view all the answers

Which molecule can be funneled from the TCA cycle into the urea cycle?

Aspartate Signup and view all the answers

Study Notes

Fatty Acid Synthesis

Fatty acid synthesis is NOT the reverse of fatty acid breakdown, with different enzymes involved
Synthesis occurs in the cytosol, whereas breakdown occurs in the mitochondrial matrix
Acetyl-CoA is converted to a 3-carbon malonyl CoA molecule by acetyl CoA-carboxylase
The enzyme converts malonyl CoA to a longer chain by adding more Acetyl groups in consecutive reactions

Fatty Acid Synthesis Summary

Condensation: Acetyl CoA (2C) + malonyl CoA (3C) → Acetyl group (2C), CO2, NADPH + H+
Reduction: NADP+, H2O
Dehydration: NADPH + H+
Reduction: NADP+, Saturated acyl group (lengthened by 2C)

Fatty Acid Breakdown

Dehydrogenation: Palmitoyl-CoA → FADH2
Hydration: H2O
Dehydrogenation: NADH + H+
Acyl transfer: Acyl-CoA + acetyl CoA (2C)

Fatty Acid Synthesis: Getting Acetyl CoA

Acetyl CoA is in the mitochondria, but fatty acid synthesis occurs in the cytosol
Fatty acid breakdown generates energy from:
- Acetyl CoA (from fatty acids)
- NADH, FADH2 (from fatty acids)
- Glyceraldehyde-3-P (from glycerol)
Fatty acid synthesis is not the reverse of breakdown
There are many examples of integration of pathways

Breakdown of Amino Acids

We don't store protein as energy; instead, we recycle them as amino acids
Breakdown of amino acids:
- Carbon skeleton can be used as intermediates in the TCA cycle to generate energy
- Can be converted into glucose

Amino Acid Degradation and Nitrogen Excretion

A.a.catabolism summary: waste removal, catabolism, recycling
Carbon skeletons are converted into alphaketo acids, which can enter the citric cycle or be used to make glucose
Amino groups are transferred to alphaketo glutamate, which enters the urea cycle

Breakdown to NH₄⁺

For 19 amino acids, the amino group is transferred to alphaketo glutamate, generating glutamate
The last one is the breakdown of alanine, which generates pyruvate

Breakdown to NH₄⁺: Glucose-Alanine Cycle

Rapidly contracting muscle generates excess pyruvate and NH2+
Converted to alanine by amino-transferase (reverse reaction)
Alanine is transported to the liver and converted to pyruvate by amino-transferase (forward reaction)
Pyruvate is converted to glucose by gluconeogenesis, which is then transported back to the muscle for glycolysis to generate energy

Fats: β-Oxidation

4 steps:
1. Dehydrogenation: FADH2
2. Hydration: H2O
3. Dehydrogenation: NADH
4. Acyl transfer: Acetyl-CoA

β-Oxidation Summary

Breakdown of C16 fat (palmitate) requires 7 β-oxidations, generating:
- 8 Acetyl-CoA
- 7 NADH
- 7 FADH2
Metabolism of palmitate generates approximately 106 ATP

Urea Cycle

First step: generating carbamoyl phosphate
Amino group is transferred to alphaketo glutamate, generating glutamate
Glutamate is used to shuttle the amino group around
The urea cycle uses aspartate, which is generated from oxaloacetate in the TCA cycle

Krebs Cycle (TCA Cycle)

Glucogenic amino acids → alphaketo skeletons that generate energy
Ketogenic amino acids → don't have to go as far as some other mechanism generates this process

Glycolysis

Preparatory: Glucose → Glyceraldehyde 3-phosphate
Pay-off: Glyceraldehyde 3-phosphate → Pyruvate

Enzymes/Delta G

Oxidoreductases: transfer electrons via oxidation or reduction
Transferases: transfer chemical groups from one molecule to another
Hydrolases: cleavage of a substrate using water (hydrolysis)
Lyases: addition of groups to double bonds or formation of double bonds following removal of groups
Isomerases: rearrangement of a single substrate, generating isoforms
Ligases: joining of two substrates, often by eliminating water

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Description

Learn about the process of fatty acid synthesis, where it occurs in the cell, and the enzymes involved. Understand the difference between fatty acid synthesis and breakdown, and how acetylCoA is converted to malonyl CoA.