questions

Question 1

Dietary recommendations for patients with early stage kidney disease include following a low protein, high carbohydrate diet. What is the metabolic reasoning for such a diet?

Answer 1

In early-stage kidney disease, a low-protein, high-carbohydrate diet is recommended to minimize nitrogen waste production, reduce the kidney’s workload, prevent the breakdown of muscle protein, manage acidosis, and possibly lower the risk of cardiovascular complications. This type of diet helps slow the progression of kidney damage and preserve kidney function for a longer period.

Question 2

Give FOUR experimental parameters which are varied in the search to grow protein crystals suitable for structural studies

Answer 2

Protein Concentration: Optimized to avoid precipitation and ensure sufficient material for crystal growth (typically 5–20 mg/mL).
Salt Concentration and Type: Adjusted to stabilize the protein and promote crystal formation, typically ranging from 0.1 M to 1.5 M.
pH: Varied to stabilize the protein’s structure, usually in the range of 4.5 to 8.5, depending on the protein.
Temperature: Controlled to balance crystal growth rate, with lower temperatures (4°C–20°C) often improving crystal quality by slowing growth.

Question 3

Patients with thiamine deficiency have higher levels of pyruvate in the blood. Briefly explain the role of thiamine in cell metabolism, and why blood pyruvate would be elevated in thiamine deficiency.

Answer 3

Thiamine (vitamin B1) is a cofactor for several enzymes involved in cellular metabolism, particularly in the conversion of pyruvate to acetyl-CoA via the pyruvate dehydrogenase complex. Thiamine is also involved in the pentose phosphate pathway and the transketolase enzyme.

In thiamine deficiency, the pyruvate dehydrogenase complex becomes impaired, preventing the conversion of pyruvate to acetyl-CoA. As a result, pyruvate accumulates in the blood because it cannot be efficiently metabolized through the citric acid cycle. This leads to elevated pyruvate levels in the blood, a hallmark of thiamine deficiency.

Question 4

Briefly explain the role of malonyl-CoA in the regulation of fatty acid synthesis and degradation.

Answer 4

Malonyl-CoA plays a key regulatory role in both fatty acid synthesis and degradation:

Fatty Acid Synthesis: Malonyl-CoA is the primary substrate for fatty acid synthase in the biosynthesis of fatty acids, providing the building blocks for elongation of the fatty acid chain.
Fatty Acid Degradation: Malonyl-CoA inhibits carnitine acyltransferase I (CAT-I), which is involved in transporting fatty acids into the mitochondria for β-oxidation. This prevents fatty acid degradation when synthesis is active.
Thus, malonyl-CoA regulates the balance between synthesis and degradation by promoting one while inhibiting the other.

Question 5

identify if t or f
All of the intermediates in the TCA cycle carry a phosphate group

Answer 5

FALSE. Not all intermediates in the TCA cycle carry a phosphate group. For example, citrate and isocitrate do not carry a phosphate group

Question 6

T or F
None of the reactions in the TCA cycle involve molecular oxygen.

Answer 6

TRUE. The TCA cycle itself does not directly involve molecular oxygen. However, oxygen is required in oxidative phosphorylation to regenerate NAD+ and FAD, which are needed for the cycle to continue.

Question 7

T or F
The coenzyme FADH/FADH2 is required in several of the enzyme-catalyzed steps in the glycolytic pathway.

Answer 7

FALSE. FADH/FADH2 is not used in glycolysis. Glycolysis mainly involves NAD+ as a coenzyme (e.g., in the oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate).

Question 8

T or F
Two reactions in the TCA cycle lead to the loss of a molecule of carbon dioxide.

Answer 8

TRUE. Two decarboxylation reactions in the TCA cycle release carbon dioxide:
The conversion of isocitrate to α-ketoglutarate (catalyzed by isocitrate dehydrogenase).
The conversion of α-ketoglutarate to succinyl-CoA (catalyzed by α-ketoglutarate dehydrogenase).

Question 9

T or F
The net gain of ATP from gluconeogenesis is 2 ATP.

Answer 9

FALSE. The net gain of ATP from gluconeogenesis is -4 ATP (it consumes 6 ATP and produces 2 ATP and 2 GTP).

Question 10

T or F
Only one reaction in the TCA cycle involves substrate-level phosphorylation.

Answer 10

TRUE. The only substrate-level phosphorylation in the TCA cycle occurs during the conversion of succinyl-CoA to succinate, which generates GTP (or ATP, depending on the tissue type).

Question 11

T or F
Acetyl coenzyme A (AcetylCoA) conveys two carbon atoms from the “link reaction” into the TCA cycle.

Answer 11

TRUE. Acetyl-CoA, produced in the link reaction from pyruvate, donates its two-carbon acetyl group to oxaloacetate, forming citrate to begin the TCA cycle.

Question 12

T or F
Each of the reactions in the TCA cycle produces a reduced hydrogen carrier.

Answer 12

TRUE. Each turn of the TCA cycle produces reduced coenzymes: 3 NADH, 1 FADH2, and 1 GTP (or ATP). These reduced carriers are essential for the electron transport chain.

Question 13

Summarise, in your own words, the main steps by which ubiquitin is attached to a target protein.4 mark

Answer 13

Ubiquitination is the process by which a small protein called ubiquitin is attached to a target protein, marking it for degradation by the proteasome. The main steps involved are:

Activation of Ubiquitin: Ubiquitin is first activated by an enzyme called E1 (ubiquitin-activating enzyme), which attaches ubiquitin to itself in an ATP-dependent manner, forming a high-energy thioester bond.
Conjugation: The activated ubiquitin is then transferred to a ubiquitin-conjugating enzyme (E2). This step involves the transfer of ubiquitin from the E1 enzyme to the E2 enzyme.
Ligation: The E3 ubiquitin ligase enzyme facilitates the transfer of the ubiquitin from the E2 enzyme to the target protein. E3 ensures specificity, selecting the appropriate target protein for ubiquitination.
Polyubiquitination: A chain of ubiquitin molecules is often added to the first ubiquitin via isopeptide bonds (specifically between lysine 48 of one ubiquitin and the C-terminal glycine of another). This polyubiquitin chain signals that the target protein should be degraded by the proteasome.

Question 14

Briefly describe the role of glycogen synthase and Amylo-(1,4 →1,6)-transglycosylase in glycogen synthesis.4marks

Answer 14

Glycogen synthase and Amylo-(1,4 → 1,6)-transglycosylase are both key enzymes in glycogen synthesis:

Glycogen Synthase: This enzyme is responsible for the elongation of the glycogen chain by adding glucose units from UDP-glucose to the non-reducing ends of the growing glycogen molecule. It forms α-1,4-glycosidic bonds, extending the glycogen chain during synthesis.
Amylo-(1,4 → 1,6)-transglycosylase (also known as branching enzyme): This enzyme introduces branch points into the glycogen molecule by transferring a segment of the linear chain (typically 6-7 glucose units) from the α-1,4-glycosidic bond to a hydroxyl group of a glucose residue, forming α-1,6-glycosidic bonds. This creates the characteristic branching structure of glycogen.
Together, these enzymes ensure the synthesis of a highly branched glycogen molecule, which is important for efficient storage and rapid mobilization of glucose.

Question 15

T or F
Glycogen is a storage polysaccharide that contains two different types of glycosidic linkage.

Answer 15

TRUE. Glycogen is a highly branched polysaccharide made up of glucose units. It contains α-1,4-glycosidic bonds in the linear chain and α-1,6-glycosidic bonds at the branch points.

Question 16

T or F
The first reaction in glycolysis is phosphorylation by hexokinase or glucokinase.

Answer 16

TRUE. The first step in glycolysis is the phosphorylation of glucose to form glucose-6-phosphate, catalyzed by hexokinase (in most tissues) or glucokinase (in the liver).

Question 17

T or F
The glycolytic pathway is tightly regulated at the step cataly by the enzyme aldolase.

Answer 17

FALSE. The glycolytic pathway is regulated at three key steps, but aldolase is not one of the regulatory enzymes. The main regulatory steps are catalyzed by hexokinase, phosphofructokinase-1 (PFK-1), and pyruvate kinase.

Question 18

T or F
All of the enzymes involved in the glycolytic pathway are kinases.

Answer 18

FALSE. While many enzymes in glycolysis are kinases (e.g., hexokinase, phosphofructokinase, pyruvate kinase), not all enzymes are kinases. For example, aldolase is an aldolase enzyme, and enolase is an isomerase.

Question 19

T or F
All the reactions of glycolysis take place within the mitochondrial matrix.

Answer 19

FALSE. The reactions of glycolysis occur in the cytoplasm, not the mitochondrial matrix. Only later steps, such as the citric acid cycle, occur in the mitochondrial matrix.

Question 20

T or F
Four molecules of acetyl CoA leave the pathway for every molecule of glucose that enters the pathway.

Answer 20

FALSE. For each molecule of glucose that undergoes glycolysis, two molecules of acetyl-CoA are generated (one from each pyruvate molecule produced).

Question 21

T or F
The structure of the nucleoside triphosphate ATP contains a carbohydrate moiety.

Answer 21

TRUE. ATP (adenosine triphosphate) contains a ribose sugar (carbohydrate moiety), which is part of the nucleoside structure (adenosine).

Question 22

T or F
All of the intermediates between glucose and pyruvate carry at least one phosphate group.

Answer 22

TRUE. All intermediates in glycolysis between glucose and pyruvate (such as glucose-6-phosphate, fructose-1,6-bisphosphate, etc.) carry at least one phosphate group, except for pyruvate at the final step.

Question 23

D-Glucose can form a 5-membered ring structure true or false

Answer 23

D-Glucose can form a 5-membered ring structure through a process called intramolecular cyclization, where the hydroxyl group on carbon 5 reacts with the aldehyde group on carbon 1. This forms a furanose ring, a five-membered structure. However, D-glucose primarily exists in a 6-membered pyranose ring form (with carbon 1 and carbon 5 bonding), but it can indeed also form a 5-membered furanose ring under certain conditions.

Question 24

Two reactions in the TCA cycle lead to the loss of a molecule of carbon dioxide false or true

Answer 24

TRUE.

Two reactions in the TCA (tricarboxylic acid) cycle result in the loss of a molecule of carbon dioxide (CO₂):

Isocitrate to α-Ketoglutarate: Catalyzed by isocitrate dehydrogenase, this reaction releases one molecule of CO₂.
α-Ketoglutarate to Succinyl-CoA: Catalyzed by α-ketoglutarate dehydrogenase, this reaction also releases one molecule of CO₂.
These decarboxylation reactions contribute to the overall loss of carbon atoms in the TCA cycle.

Question 25

Each of the reactions in the TCA cycle produces a reduced hydrogen carrier true or false

Answer 25

TRUE.

Each of the reactions in the TCA cycle produces a reduced hydrogen carrier, either in the form of NADH or FADH2:

NADH is produced during:
The conversion of isocitrate to α-ketoglutarate (catalyzed by isocitrate dehydrogenase).
The conversion of α-ketoglutarate to succinyl-CoA (catalyzed by α-ketoglutarate dehydrogenase).
The conversion of malate to oxaloacetate (catalyzed by malate dehydrogenase).
FADH2 is produced during:
The conversion of succinate to fumarate (catalyzed by succinate dehydrogenase).
These reduced carriers (NADH and FADH2) are used in the electron transport chain to generate ATP.

Question 26

Only one reaction in the TCA cycle involves substrate-level phosphorylation true or false

Answer 26

TRUE.

Only one reaction in the TCA cycle involves substrate-level phosphorylation:

The reaction that involves substrate-level phosphorylation is the conversion of succinyl-CoA to succinate. This reaction is catalyzed by succinyl-CoA synthetase (also known as succinate thiokinase), and it generates either ATP or GTP (depending on the cell type) directly through the transfer of a phosphate group.
All other reactions in the TCA cycle involve redox reactions, but not substrate-level phosphorylation.

Question 27

All of the intermediates in the TCA cycle carry a phosphate group.true false

Answer 27

FALSE.

Not all intermediates in the TCA cycle carry a phosphate group. For example:

Citrate, isocitrate, and α-ketoglutarate are intermediates in the TCA cycle that do not carry a phosphate group.
However, intermediates like succiny-CoA and GTP/ATP (formed in substrate-level phosphorylation) do involve phosphate groups.
Thus, only some intermediates in the TCA cycle are phosphorylated, not all.

Question 28

Which of the below is correct with regards to the Link Reaction?

Pyruvate + Coenzyme A + NAD+ → acetyl CoA + CO2 + NADH

Pyruvate + Coenzyme A + NADH → acetyl CoA + CO2 + NAD+

Pyruvate + acetylCoA + NAD+ → CoenzymeA + CO2 + NADH

Pyruvate + acetylCoA + NADH → CoenzymeA + CO2 + NAD+

Answer 28

The correct equation for the Link Reaction (also called Pyruvate Decarboxylation) is:

Pyruvate + Coenzyme A + NAD+ → Acetyl-CoA + CO2 + NADH

This reaction occurs in the mitochondria, where pyruvate is decarboxylated (loses one CO₂ molecule) and combined with Coenzyme A to form acetyl-CoA. Additionally, NAD+ is reduced to NADH in the process.

Question 29

Glycogen is a storage polysaccharide that contains two different types of glycosidic linkage

True

False

Answer 29

TRUE.

Glycogen is a storage polysaccharide that contains two different types of glycosidic linkages:

α-1,4-glycosidic bonds: These link the glucose units in the linear chains of glycogen.
α-1,6-glycosidic bonds: These occur at the branch points, creating the branched structure of glycogen.
These two types of glycosidic linkages are critical for the highly branched structure of glycogen, which allows for efficient storage and rapid release of glucose when needed.

Question 30

The nucleoside triphosphate ATP contains a carbohydrate moiety.

True false

Answer 30

TRUE.

The nucleoside triphosphate ATP (adenosine triphosphate) contains a carbohydrate moiety, which is ribose. The structure of ATP consists of:

A nitrogenous base: Adenine.
A ribose sugar (the carbohydrate moiety), which is a 5-carbon sugar.
Three phosphate groups attached to the ribose.
The ribose sugar is part of the nucleotide structure that links to the adenine base, making ATP a nucleoside (adenosine) triphosphate.

Question 31

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
All of the reactions involved in the glycolytic pathway are reversible

Answer 31

FALSE.

Not all of the reactions in the glycolytic pathway are reversible. While some reactions are reversible, three key reactions in glycolysis are irreversible due to the large negative change in free energy associated with them. These irreversible steps are:

Hexokinase/Glucokinase: The phosphorylation of glucose to glucose-6-phosphate.
Phosphofructokinase-1 (PFK-1): The phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate.
Pyruvate kinase: The conversion of phosphoenolpyruvate (PEP) to pyruvate.
These steps are regulated and essentially drive the pathway forward, making them irreversible in the context of glycolysis.

Question 32

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
The glycolytic pathway is tightly regulated at the step catalysed by the enzyme aldolase

Answer 32

FALSE.

Not all of the reactions in the glycolytic pathway are reversible. While some reactions are reversible, three key reactions in glycolysis are irreversible due to the large negative change in free energy associated with them. These irreversible steps are:

Hexokinase/Glucokinase: The phosphorylation of glucose to glucose-6-phosphate.
Phosphofructokinase-1 (PFK-1): The phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate.
Pyruvate kinase: The conversion of phosphoenolpyruvate (PEP) to pyruvate.

Question 33

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
Three molecules of acetyl CoA leave the pathway for everymolecule of glucose that enters the pathway.

Answer 33

FALSE.

Not all of the reactions in the glycolytic pathway are reversible. While some reactions are reversible, three key reactions in glycolysis are irreversible due to the large negative change in free energy associated with them. These irreversible steps are:

Hexokinase/Glucokinase: The phosphorylation of glucose to glucose-6-phosphate.
Phosphofructokinase-1 (PFK-1): The phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate.
Pyruvate kinase: The conversion of phosphoenolpyruvate (PEP) to pyruvate.
These steps are regulated and essentially drive the pathway forward, making them irreversible in the context of glycolysis.

Question 34

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
The net yield of ATP (via substrate-level phosphorylation only)is two molecules of ATP per molecule of glucose that enters the pathway

Answer 34

TRUE.

The net yield of ATP via substrate-level phosphorylation in glycolysis is two molecules of ATP per molecule of glucose. Here’s why:

Glycolysis involves the conversion of one molecule of glucose (6 carbons) to two molecules of pyruvate (3 carbons each).
Two ATP molecules are consumed in the early steps of glycolysis (steps 1 and 3), while four ATP molecules are produced in later steps (steps 7 and 10) via substrate-level phosphorylation.
Therefore, the net ATP yield from glycolysis is 4 ATP produced - 2 ATP consumed = 2 ATP.
This is the net gain of ATP from glycolysis, with the ATP generated only through substrate-level phosphorylation.

Question 35

All of the reactions in the TCA cycle have negative ∆G values. true or false

Answer 35

FALSE.

Not all of the reactions in the TCA cycle have negative ∆G values. While many reactions in the TCA cycle are exergonic (releasing energy), some reactions, particularly those involving ATP or NADH/FADH2 production, have near-zero or slightly positive ∆G values under standard conditions.

In the TCA cycle, the reactions that typically have negative ∆G are those that involve decarboxylation (like the conversion of isocitrate to α-ketoglutarate or α-ketoglutarate to succinyl-CoA), as these reactions release CO2 and provide energy. However, other reactions, such as the conversion of succinyl-CoA to succinate, are near equilibrium and can have a ∆G close to zero or slightly positive under certain conditions.

Thus, not all TCA cycle reactions are exergonic with negative ∆G values.

Question 36

Acetyl coenzyme A (AcetylCoA) conveys two carbon atoms from the “link reaction” into the TCA cycle true false

Answer 36

TRUE.

Acetyl-CoA conveys two carbon atoms from the link reaction (also known as pyruvate decarboxylation) into the TCA cycle. In the link reaction, each molecule of pyruvate (a 3-carbon molecule) is converted into acetyl-CoA (a 2-carbon molecule) by the enzyme pyruvate dehydrogenase. This 2-carbon acetyl group is then transferred to oxaloacetate in the TCA cycle, forming citrate (a 6-carbon molecule), starting the cycle.

Question 37

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
All of the intermediates between glucose and pyruvate carryat least one phosphate group.

Answer 37

TRUE.

All intermediates between glucose and pyruvate in the glycolytic pathway carry at least one phosphate group. Here’s the breakdown:

Glucose is phosphorylated to glucose-6-phosphate (one phosphate).
Glucose-6-phosphate is converted to fructose-6-phosphate (still one phosphate).
Fructose-6-phosphate is then phosphorylated to fructose-1,6-bisphosphate (two phosphates).
This molecule is split into two 3-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P) (both carry phosphate groups).
Glyceraldehyde-3-phosphate is then oxidized to 1,3-bisphosphoglycerate (with a phosphate group).
1,3-Bisphosphoglycerate is converted to 3-phosphoglycerate (phosphate group retained).
Further steps proceed with phosphate groups until the final product, pyruvate, is generated.
Thus, all intermediates in the glycolytic pathway between glucose and pyruvate indeed carry at least one phosphate group.

Question 38

With regards to Gibbs free energy which of the following is correct?

∆G = Δ[H] - [T] . Δ[S]

∆H = Δ[G] - [T] . Δ[S]

∆G = Δ[H] - [S] . Δ[T]

∆G = Δ[S] - [T] . Δ[H]

Answer 38

∆G = ∆H - T∆S

Question 39

t or f
Carbohydrates must contain Carbon, and Phosphorus atomsHydrogen

Answer 39

False.

Carbohydrates must contain carbon (C), hydrogen (H), and oxygen (O) atoms. They do not necessarily contain phosphorus.

Carbohydrates are organic compounds that typically follow the general formula (CH₂O)n, where n is the number of carbon atoms. They are primarily composed of carbon, hydrogen, and oxygen, and are a key source of energy for living organisms.

Phosphorus atoms are not a standard component of carbohydrates, though some carbohydrates can be phosphorylated (e.g., glucose-6-phosphate), but this is an additional modification rather than a required element of the carbohydrate structure.

Question 40

NAD+ is the only hydrogen carrier used in the TCA cycle of reactions
true or false

Answer 40

False.

NAD+ is one of the hydrogen carriers used in the TCA cycle, but it is not the only one. The TCA cycle also involves FAD (flavin adenine dinucleotide), which acts as a hydrogen carrier in one of the key reactions.

Here’s how the hydrogen carriers are involved in the TCA cycle:

NAD+ is reduced to NADH in multiple steps, including:
The conversion of isocitrate to α-ketoglutarate.
The conversion of α-ketoglutarate to succinyl-CoA.
The conversion of malate to oxaloacetate.
FAD is reduced to FADH2 in the conversion of succinate to fumarate (catalyzed by succinate dehydrogenase).
Both NADH and FADH2 carry electrons to the electron transport chain for ATP production. Therefore, NAD+ is not the only hydrogen carrier in the TCA cycle.

Question 41

None of the reactions in the TCA cycle involve molecular oxygen.t or F

Answer 41

True.

None of the reactions in the TCA cycle (also known as the Krebs cycle or Citric Acid cycle) directly involve molecular oxygen (O₂). The TCA cycle itself is a series of enzyme-catalyzed reactions that occur in the mitochondrial matrix, and oxygen is not used in any of the reactions in the cycle.

However, oxygen is required for the electron transport chain, which occurs in the mitochondria after the TCA cycle. Oxygen acts as the final electron acceptor in the chain, allowing the entire aerobic respiration process to produce ATP efficiently. But oxygen is not directly involved in the steps of the TCA cycle itself.

Question 42

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
All the reactions take place within the mitochondrial matrix

Answer 42

False.

The glycolytic pathway occurs in the cytoplasm, not in the mitochondrial matrix. The entire process of glycolysis, which converts glucose into pyruvate, takes place in the cytosol of the cell.

However, after glycolysis, the pyruvate produced is transported into the mitochondrial matrix, where it undergoes the link reaction (pyruvate decarboxylation) to form acetyl-CoA, which enters the TCA cycle.

Question 43

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
The first reaction is phosphorylation by hexokinase or glucokinase.

Answer 43

True.

The first reaction in the glycolytic pathway is the phosphorylation of glucose, which is catalyzed by either hexokinase (in most tissues) or glucokinase (in the liver and pancreas). This reaction adds a phosphate group to glucose, converting it into glucose-6-phosphate, which traps the glucose inside the cell and begins the process of glycolysis.

Question 44

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
The reactions can continue under anaerobic conditions if thepathway terminates at lactate rather than at pyruvate.

Answer 44

True.

Under anaerobic conditions, glycolysis can continue by converting pyruvate to lactate (lactic acid fermentation), rather than fully oxidizing pyruvate in the mitochondria. This process is crucial because it allows for the regeneration of NAD+, which is required for the continuation of glycolysis.

In the absence of oxygen, the enzyme lactate dehydrogenase (LDH) converts pyruvate to lactate, thus enabling the glycolytic pathway to continue, producing ATP anaerobically. This process is typical in muscle cells during intense exercise when oxygen supply is limited.

Question 45

Glucose occurs naturally as the L isomer T or F

Answer 45

False.

Glucose naturally occurs as the D-isomer, not the L-isomer. The D- and L- nomenclature refers to the orientation of hydroxyl groups on the chiral carbon furthest from the carbonyl group (in the case of glucose, it’s the last carbon in the chain).

While both D- and L-isomers exist as enantiomers (mirror images), D-glucose is the one commonly found in nature, especially in biological systems, and is the form that is metabolized by living organisms. The L-isomer of glucose is rarely found in nature and does not participate in metabolic processes in the same way as D-glucose.

Question 46

Dihydroxyacetone is an example of a ketose sugar
true or false

Answer 46

True.

Dihydroxyacetone is indeed an example of a ketose sugar. Ketose sugars are carbohydrates that contain a ketone group (C=O) in their structure. In the case of dihydroxyacetone, the ketone group is located at the second carbon atom, making it a simple three-carbon ketose.

It is a monosaccharide and is one of the simplest forms of ketose sugars.

Question 47

Indicate whether the statement is true or false for theformation of pyruvate from glucose via the glycolytic pathway:
The glycolytic pathway is an anaerobic process and does notinvolve molecular oxygen.

Answer 47

True.

The glycolytic pathway is an anaerobic process and does not require molecular oxygen. Glycolysis occurs in the cytoplasm and involves the breakdown of glucose into pyruvate while generating small amounts of ATP and NADH.

Oxygen is not required for glycolysis, making it an anaerobic process. However, the pyruvate produced in glycolysis can later be processed in either aerobic conditions (where it enters the mitochondria for further oxidation) or anaerobic conditions (where it is converted to lactate or ethanol, depending on the organism).