Bio1332 Biochemistry - Lecture Nineteen - Fatty Acid Metabolism
To introduce fatty acids, triacylglycerol and phospholipids. Outline the mechanism and cellular localisation of energy production by fatty acid β-oxidation. Understand the purpose of the glyoxylate cycle in plants and microorganisms and appreciate the consequences for animals which lack this pathway. Describe the biosynthesis of fatty acids.
Questions and Answers
- 1.
Describe 3 functions of fatty acids.Check your answer with the feedback section after you've submitted it.Your answer will not contribute to your final mark for this quiz.
- 2.
Fatty acids normally have an odd number of carbon atoms.True or False?
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
FALSE.
Fatty acids normally have an even number of carbon atoms.Rate this question:
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- 3.
Please fill answer below:Fatty acids are often conjugated with ________ to form lipids.
Correct Answer
Glycerol
GlycerolsExplanation
Fatty acids are often conjugated with glycerol to form lipids. Glycerol is a three-carbon alcohol that serves as the backbone for triglycerides, which are the most common type of lipid found in our bodies. When three fatty acids are esterified to a glycerol molecule, a triglyceride is formed. This process is essential for the storage and transport of energy in the form of fats. Glycerols, on the other hand, is not a correct term and does not accurately describe the conjugation of fatty acids with glycerol.Rate this question:
- 4.
Please fill answer below:Triacylglycerol (TAG) consists of 3 fatty acids (acyl chains) linked by _____ bonds to glycerol.
Correct Answer
EsterExplanation
Triacylglycerol (TAG) is a type of lipid molecule that consists of three fatty acids linked to a glycerol molecule. The bond between the fatty acids and glycerol is called an ester bond. Ester bonds are formed through a condensation reaction between the carboxyl group of the fatty acid and the hydroxyl group of the glycerol. This linkage allows for the storage of large amounts of energy in the form of TAGs, making them an important energy reserve in organisms.Rate this question:
- 5.
Name the enzyme that catalyses TAG breakdown in adipose tissue.
Correct Answer
Triacylglycerol lipaseExplanation
Triacylglycerol lipase is the enzyme responsible for catalyzing the breakdown of triacylglycerols (TAGs) in adipose tissue. This enzyme breaks down TAGs into glycerol and fatty acids, which can then be used as a source of energy. Adipose tissue, also known as fat tissue, stores excess energy in the form of TAGs, and the action of triacylglycerol lipase helps release this stored energy when needed by the body.Rate this question:
- 6.
Which of the following is true?Fatty acid activation costs the equivalent of...
- A.
2 ATPs
- B.
1 ATP
- C.
3 ATPs
- D.
4 ATPs
Correct Answer
A. 2 ATPsExplanation
Fatty acid activation requires the attachment of a molecule called Coenzyme A (CoA) to the fatty acid, which requires the hydrolysis of ATP to AMP and pyrophosphate. This process occurs twice, resulting in the expenditure of 2 ATP molecules. Therefore, the correct answer is 2 ATPs.Rate this question:
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- 7.
In which organelle are fatty acids oxidised?
Correct Answer
Mitochondria
The mitochondriaExplanation
Fatty acids are oxidized in the mitochondria. This organelle is responsible for generating energy through the process of cellular respiration. Fatty acids are broken down into acetyl-CoA molecules, which enter the citric acid cycle in the mitochondria to produce ATP. The mitochondria have specialized enzymes and transporters that facilitate the oxidation of fatty acids and the production of energy.Rate this question:
- 8.
7 rounds of β-oxidation yields...
- A.
106 ATP
- B.
16 ATP
- C.
100 ATP
- D.
10 ATP
Correct Answer
A. 106 ATPExplanation
During β-oxidation, fatty acids are broken down into acetyl-CoA molecules. Each round of β-oxidation produces one molecule of acetyl-CoA, which enters the citric acid cycle and generates 3 molecules of NADH and 1 molecule of FADH2. These electron carriers go on to produce ATP through oxidative phosphorylation. In total, 7 rounds of β-oxidation would produce 7 acetyl-CoA molecules, resulting in the production of 21 NADH and 7 FADH2. Considering the ATP yield from oxidative phosphorylation, which is 2.5 ATP per NADH and 1.5 ATP per FADH2, the total ATP produced would be 106 ATP.Rate this question:
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- 9.
Animals cannot convert acetyl coenzyme A into sugars, but plants and fungi can.True or False?
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Plants and fungi have the ability to convert acetyl coenzyme A into sugars through a process known as photosynthesis. This metabolic pathway allows them to utilize sunlight, carbon dioxide, and water to produce glucose, which can then be used as an energy source for growth and other cellular functions. On the other hand, animals lack the necessary enzymes and mechanisms to perform photosynthesis, and therefore cannot convert acetyl coenzyme A into sugars. Hence, the statement that animals cannot convert acetyl coenzyme A into sugars is true.Rate this question:
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- 10.
Please fill answer below: Although mammals are incapable of producing glucose from acetyl CoA, mammals can make glucose from _________.
Correct Answer
propionyl coA
propionyl coenzyme AExplanation
Mammals are unable to produce glucose directly from acetyl CoA, but they can synthesize glucose from propionyl CoA or propionyl coenzyme A. This is achieved through a metabolic pathway called gluconeogenesis, which allows the conversion of non-carbohydrate sources, such as certain amino acids and organic acids, into glucose. Therefore, propionyl CoA or propionyl coenzyme A can serve as precursors for glucose production in mammals.Rate this question:
- 11.
Where does fatty acid synthesis occur?
- A.
The cytoplasm
- B.
The mitochondria
- C.
The ribosome
- D.
The nucleus
Correct Answer
A. The cytoplasmExplanation
Fatty acid synthesis occurs in the cytoplasm. This process involves the conversion of acetyl-CoA into fatty acids, which are essential for the synthesis of lipids. The enzymes required for fatty acid synthesis are located in the cytoplasm, specifically in a complex called the fatty acid synthase complex. This complex catalyzes the step-by-step synthesis of fatty acids, using acetyl-CoA as the building block. Therefore, the cytoplasm is the correct location for fatty acid synthesis to occur.Rate this question:
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- 12.
The first step in fatty acid synthesis is synthesis of __________________, catalysed by _________________.
Correct Answer
malonyl coA, Acetyl coA carboxylase
malonyl coenzyme A, Acetyl coenzyme A carboxylaseExplanation
The first step in fatty acid synthesis is the synthesis of malonyl coA, which is catalyzed by the enzyme Acetyl coA carboxylase. The alternative answer, malonyl coenzyme A, Acetyl coenzyme A carboxylase, is incorrect as the correct term is malonyl coA, not malonyl coenzyme A. Acetyl coA carboxylase is the enzyme responsible for catalyzing the synthesis of malonyl coA.Rate this question:
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