Glycolysis and Enzyme Functions

False (B)

1,3-bisphosphoglycerate

<p>thioester</p> Signup and view all the answers

<p>Phosphorylation of fructose-6-phosphate = Formation of fructose-1,6-bisphosphate Cleavage of fructose-1,6-bisphosphate = Production of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate Oxidation of glyceraldehyde-3-phosphate = Conversion to 1,3-bisphosphoglycerate Transfer of phosphate from 1,3-bisphosphoglycerate = Formation of 3-phosphoglycerate</p> Signup and view all the answers

<p>Protects against malaria (C)</p> Signup and view all the answers

<p>Phosphorylase (B)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>2 ATP and 2 NADH</p> Signup and view all the answers

<p>lactase</p> Signup and view all the answers

<p>Mannose metabolism = Mannose Fructose metabolism = Fructose Galactose metabolism = Galactose Glycogen degradation = Glucose</p> Signup and view all the answers

<p>Cirrhosis (A)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate produces NADH.</p> Signup and view all the answers

<p>Pyruvate carboxylase (B)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>-74 kJ/mol</p> Signup and view all the answers

<p>dihydroxyacetone phosphate (DHAP)</p> Signup and view all the answers

<p>Pyruvate carboxylase = Converts pyruvate to oxaloacetate PEP carboxykinase = Converts oxaloacetate to phosphoenolpyruvate Fructose-1,6-bisphosphatase = Converts fructose-1,6-bisphosphate to fructose-6-phosphate Glucose-6-phosphatase = Converts glucose-6-phosphate to glucose</p> Signup and view all the answers

<p>Mitochondria (D)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>biotin</p> Signup and view all the answers

<p>6 (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Glycolysis = Breakdown of glucose for energy Gluconeogenesis = Formation of glucose from non-carbohydrate sources Calvin Cycle = Uses NADPH to reduce carbon dioxide Pentose Phosphate Pathway = Produces NADPH and ribose 5-phosphate</p> Signup and view all the answers

<p>They are metabolic pathways that convert glucose and pyruvate, but function in opposite directions.</p> Signup and view all the answers

<p>It transports CO2 between active sites. (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>fructose 1,6-bisphosphatase</p> Signup and view all the answers

<p>glucose 6-phosphatase</p> Signup and view all the answers

<p>Formation of oxaloacetate from pyruvate = Mitochondria Conversion of malate to oxaloacetate = Cytoplasm Hydrolysis of fructose 1,6-bisphosphate = Cytoplasm Generation of glucose from glucose 6-phosphate = Endoplasmic reticulum</p> Signup and view all the answers

<p>It transports glucose and Pi back into the cytoplasm. (C)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>It is a key intermediate that is metabolized in the reverse direction of glycolysis.</p> Signup and view all the answers

<p>Galactose (B)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>pyruvate</p> Signup and view all the answers

<p>liver</p> Signup and view all the answers

<p>Sucrase = Breaks down sucrose into glucose and fructose Lactase = Hydrolyzes lactose into glucose and galactose Maltase = Converts maltose into two glucose molecules α-Dextrinase = Cleaves α-1,6-bonds in dextrins</p> Signup and view all the answers

<p>Gluconeogenesis (C)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Energy production</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>pentose phosphate</p> Signup and view all the answers

<p>Liver = Major site of NADPH production Adipose tissue = Fatty acid synthesis Red Blood Cells = Maintaining reduced iron Mammary glands = Lactation-related biosynthesis</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Glycolysis, gluconeogenesis, synthesis of glycogen, pentose phosphate pathway</p> Signup and view all the answers

<p>Protection against malaria (A)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Pentose phosphate pathway</p> Signup and view all the answers

<p>greater than 1</p> Signup and view all the answers

<p>NADPH = Protects against oxidative damage Pentose phosphate pathway = Generates NADPH and ribose Reactive Oxygen Species (ROS) = Causes oxidative damage Respiratory Quotient (RQ) = Indicates fuel source efficiency</p> Signup and view all the answers

<p>It acts as a transport molecule for CO2. (B)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Glucose 6-phosphatase</p> Signup and view all the answers

<p>fructose 1,6-bisphosphatase</p> Signup and view all the answers

<p>Pyruvate Carboxylase = Enzyme that converts pyruvate to oxaloacetate Fructose 1,6-bisphosphatase = Catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate Glucose 6-phosphatase = Enzyme that converts glucose 6-phosphate to glucose Phosphoenolpyruvate Carboxykinase = Converts oxaloacetate to phosphoenolpyruvate</p> Signup and view all the answers

<p>Oxaloacetate (A)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>It is converted into glycogen.</p> Signup and view all the answers

<p>Lactic Acid (B)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>To regenerate the reduced form of glutathione (GSH)</p> Signup and view all the answers

<p>hemolytic anemia</p> Signup and view all the answers

<p>Glutathione (GSH) = Reduced form of glutathione. Oxidized glutathione (GSSG) = Form of glutathione after it has donated electrons. NADPH = A cofactor that provides reducing power. Heinz bodies = Aggregates formed in red blood cells lacking GSH.</p> Signup and view all the answers

<p>Formation of Heinz bodies (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Clumps of denatured hemoglobin in red blood cells.</p> Signup and view all the answers

<p>Ribose 5-phosphate (C)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Irreversible dehydrogenation</p> Signup and view all the answers

<p>phosphopentose epimerase</p> Signup and view all the answers

<p>Phosphopentose isomerase = Converts ketose to aldose Transketolase = Transfers two-carbon units 6-Phosphogluconate dehydrogenase = Oxidative decarboxylation Transaldolase = Transfers three-carbon units</p> Signup and view all the answers

<p>Glucose-6-phosphate dehydrogenase reaction (B)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Phosphopentose isomerase, phosphopentose epimerase, transketolase, transaldolase, and an additional reaction.</p> Signup and view all the answers

<p>Poorly metabolized galactitol (A)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>glucose</p> Signup and view all the answers

<p>galactitol</p> Signup and view all the answers

<p>Glycogenolysis = Breakdown of glycogen for energy Gluconeogenesis = Production of glucose from non-carbohydrate precursors Glycolysis = Conversion of glucose into pyruvate Pentose Phosphate Pathway = Generation of NADPH from glucose</p> Signup and view all the answers

<p>Pentose Phosphate Pathway (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>oxidative damage</p> Signup and view all the answers

<p>carbohydrate</p> Signup and view all the answers

<p>NADPH production = Protects against oxidative stress Pentose phosphate pathway = Compensates for RQ &gt; 1 Hummingbirds = Aerobic animals with high activity Glucose 6-phosphate dehydrogenase deficiency = Protects against malaria</p> Signup and view all the answers

<p>Glucose-6-Phosphate Dehydrogenase (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Transketolase</p> Signup and view all the answers

<p>D-Ribulose-5-P (B)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Thiamine pyrophosphate (TPP) and Schiff base</p> Signup and view all the answers

<p>6 (C)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>NADPH</p> Signup and view all the answers

<p>unusual</p> Signup and view all the answers

<p>Glycolysis = Produces pyruvate Gluconeogenesis = Produces glucose Pentose phosphate pathway = Generates NADPH Calvin cycle = Converts CO2 to hexoses</p> Signup and view all the answers

<p>Adipose tissue and red blood cells (C)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Skeletal muscle</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Carboxylation of pyruvate</p> Signup and view all the answers

<p>dihydroxyacetone phosphate</p> Signup and view all the answers

<p>Pyruvate carboxylase = Converts pyruvate to oxaloacetate PEP carboxykinase = Converts oxaloacetate to phosphoenolpyruvate Fructose-1,6-bisphosphatase = Converts fructose-1,6-bisphosphate to fructose-6-phosphate Glucose-6-phosphatase = Converts glucose-6-phosphate to glucose</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Cofactor for pyruvate carboxylase</p> Signup and view all the answers

<p>To generate NADPH and ribose-5-phosphate (A)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Cancer cells metabolize glucose mainly to lactate, even in the presence of oxygen.</p> Signup and view all the answers

<p>anaerobic</p> Signup and view all the answers

<p>NADPH = Biosynthesis Ribose-5-phosphate = Nucleotide synthesis Transketolase = 2-carbon transfer Transaldolase = 3-carbon transfer</p> Signup and view all the answers

<p>Lactate dehydrogenase (B), Lactate dehydrogenase (D)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Pentose phosphate pathway</p> Signup and view all the answers

<p>liver</p> Signup and view all the answers

<p>TPP (thiamine pyrophosphate) (D)</p> Signup and view all the answers

The phosphorylation of fructose-6-phosphate to yield fructose-1,6-bisphosphate, catalyzed by the allosteric enzyme phosphofructokinase (PFK).

Phosphofructokinase (PFK) is an allosteric enzyme that catalyzes the phosphorylation of fructose-6-phosphate to yield fructose-1,6-bisphosphate.

Cleavage of fructose-1,6-bisphosphate yields glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.

Dihydroxyacetone phosphate is isomerized to give glyceraldehyde-3-phosphate.

Oxidation of glyceraldehyde-3-phosphate to give 1,3-bisphosphoglycerate generates energy in the form of a phosphate group.

Glycolysis is a metabolic pathway that breaks down glucose into pyruvate, producing ATP and NADH. It occurs in the cytoplasm of cells and involves 10 enzymatic reactions.

Glycolysis produces a net gain of 2 ATP molecules per glucose molecule. This ATP is generated through substrate-level phosphorylation, a direct transfer of a phosphate group from a substrate to ADP.

Glucose is oxidized during glycolysis, losing electrons. This is seen in the formation of NADH. The electrons are transferred to NAD+, reducing it to NADH.

Reaction 6 is the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. This is an irreversible step catalyzed by phosphofructokinase-1 (PFK-1) and is the rate-limiting step of glycolysis.

Reaction 9 is the conversion of phosphoenolpyruvate (PEP) to pyruvate, catalyzed by pyruvate kinase. This step generates ATP through substrate-level phosphorylation.

Mannose, a sugar similar to glucose, enters glycolysis after being converted to fructose-6-phosphate.

Fructose is metabolized differently depending on glucose levels. In the liver, it's converted to either fructose-6-phosphate or glyceraldehyde-3-phosphate, joining glycolysis at different points.

Galactose, another sugar found in milk products, is converted to glucose-1-phosphate, entering glycolysis at the same point as glucose.

Gluconeogenesis is the process of synthesizing glucose from pyruvate, while glycolysis is the process of breaking down glucose into pyruvate.

Gluconeogenesis requires more energy (NTPs) than glycolysis. It needs 6 NTPs to form glucose from pyruvate, compared to 2 NTPs hydrolyzed in glycolysis.

Glycolysis and gluconeogenesis are reciprocally regulated, meaning when one pathway is active, the other is inactive. This ensures efficient metabolic control.

Glucose can be used for various cellular processes: glycogen synthesis, pentose phosphate pathway, and glycolysis.

The PPP is a metabolic pathway that produces NADPH and ribose-5-phosphate. It's important in biosynthesis.

PPP produces NADPH for fatty acid and steroid synthesis, and ribose-5-phosphate for RNA, DNA, and coenzyme synthesis.

PPP and the Calvin cycle are mirror images: PPP oxidizes glucose to produce NADPH, while the Calvin cycle utilizes NADPH to reduce carbon dioxide.

PPP occurs in various tissues like liver, mammary glands, adrenal glands, adipose tissue, and red blood cells.

The process of synthesizing glucose from non-carbohydrate sources like pyruvate, lactate, or glycerol.

An intermediate in both glycolysis and gluconeogenesis. It is a key point where glycerol enters either pathway.

Gluconeogenesis primarily occurs in the cytoplasm of cells, except for two specific enzymes:

• Pyruvate carboxylase: located in the mitochondria.
• Glucose-6-phosphatase: bound to the endoplasmic reticulum membrane.

While sharing 7 steps with glycolysis, gluconeogenesis replaces three key enzymes:

• Pyruvate kinase is replaced by pyruvate carboxylase and PEP carboxykinase.
• Phosphofructokinase is replaced by fructose-1,6-bisphosphatase.
• Hexokinase is replaced by glucose-6-phosphatase.

Glycolysis has a negative ΔG, meaning it releases energy. If gluconeogenesis were simply a reverse, it would have a positive ΔG, requiring energy input. This is not the case; gluconeogenesis uses different enzymes and has its own regulatory mechanisms.

An enzyme in gluconeogenesis that converts pyruvate to oxaloacetate. It requires biotin as a cofactor and uses a three-step mechanism.

A vitamin that acts as a cofactor for pyruvate carboxylase. It helps the enzyme bind and transfer carbon dioxide.

Pyruvate carboxylase uses a three-step mechanism:

1. Biotin carboxylase domain creates carboxyphosphate.
2. Carboxyl carrier protein carries the activated CO2.
3. Pyruvate carboxylase domain adds the CO2 to pyruvate.

A genetic condition where individuals lack the enzyme Glucose-6-phosphate dehydrogenase, which is crucial for the pentose phosphate pathway. This deficiency makes red blood cells vulnerable to oxidative damage.

Glucose-6-phosphate dehydrogenase deficiency provides a surprising protection against malaria. The deficiency disrupts the pentose phosphate pathway, hindering parasite growth by depriving them of NADPH, an essential molecule for their survival.

Highly active animals like hummingbirds face a constant challenge of ROS (reactive oxygen species) damage. Their high metabolic activity intensifies this issue, necessitating a robust defense mechanism.

Hummingbirds have a unique RQ greater than 1 when fueled by carbohydrates. This indicates that the pentose phosphate pathway is actively generating extra CO2 as a byproduct of NADPH production.

Hummingbirds utilize the pentose phosphate pathway to fuel their muscles with ATP and simultaneously protect themselves from ROS damage by generating NADPH. This mechanism is also relevant for athletes during vigorous exercise.

Pyruvate carboxylase is a tetrameric enzyme, meaning it is composed of four subunits. One subunit of this enzyme is the BCCP (biotin carboxyl carrier protein), responsible for carrying CO2 during the carboxylation process.

Biotin, a covalently attached vitamin to the BCCP subunit of pyruvate carboxylase, plays a key role in CO2 transport during the carboxylation reaction.

Oxaloacetate, a crucial intermediate in gluconeogenesis, is produced by pyruvate carboxylase in the mitochondria.

Once formed in the mitochondria, oxaloacetate is reduced to malate. Malate is then transported to the cytoplasm via specific shuttles.

In the cytoplasm, malate is reoxidized back to oxaloacetate, generating cytoplasmic NADH in the process.

Phosphoenolpyruvate (PEP), a high-energy molecule necessary for gluconeogenesis, is synthesized from oxaloacetate by the action of phosphoenolpyruvate carboxykinase.

Fructose 1,6-bisphosphatase is a crucial enzyme involved in the gluconeogenesis pathway, catalyzing the hydrolysis of fructose 1,6-bisphosphate to fructose 6-phosphate.

Glucose 6-phosphatase, a critical enzyme in the final step of gluconeogenesis, is primarily found in the liver. It catalyzes the formation of glucose from glucose 6-phosphate.

Glucose 6-phosphatase is an integral membrane protein residing on the inner surface of the endoplasmic reticulum. It facilitates the removal of phosphate from glucose 6-phosphate, generating free glucose.

In tissues other than the liver, glucose 6-phosphate is primarily converted to glycogen for storage, rather than being dephosphorylated to free glucose.

Three transport proteins (T1, T2, and T3) are involved in the process of glucose 6-phosphate dephosphorylation. T1 transports glucose 6-phosphate across the membrane, while T2 and T3 transport phosphate and glucose, respectively, back into the cytoplasm.

The conversion of pyruvate to phosphoenolpyruvate (PEP) involves two distinct steps: pyruvate carboxylation to oxaloacetate (occurs in the mitochondria) and oxaloacetate conversion to PEP (occurs in the cytoplasm).

A metabolic pathway that breaks down glucose into pyruvate, generating ATP and NADH in the process.

Glycolysis uses polysaccharides from food broken down into monosaccharides (e.g., glucose, fructose), or glycogen from the liver degraded into glucose.

Salivary α-amylase breaks down α-1,4-bonds in polysaccharides, but is inhibited by stomach acid (HCl).

They can enter glycolysis by converting to glycolytic intermediates. Monosaccharides include glucose, fructose, galactose, and mannose.

Almost all organisms use glucose as a fuel. In mammals, it's the only fuel the brain uses under non-starvation conditions and the only fuel red blood cells use.

Pyruvate carboxylase, PEP carboxykinase, and fructose-1,6-bisphosphatase.

An important intermediate in gluconeogenesis, produced by pyruvate carboxylase in the mitochondria. It can be converted into phosphoenolpyruvate (PEP) in the cytoplasm.

Malate is a form of oxaloacetate that is transported from the mitochondria to the cytoplasm. It's converted back to oxaloacetate, generating NADH, which is used to make PEP.

An enzyme that converts oxaloacetate to PEP, a key step in gluconeogenesis. This step occurs in the cytoplasm and requires GTP as an energy source.

An enzyme that catalyzes the hydrolysis of fructose 1,6-bisphosphate to fructose 6-phosphate, a step in gluconeogenesis. It is a key regulatory enzyme.

An enzyme that removes a phosphate group from glucose 6-phosphate, generating free glucose. It is primarily found in the liver and is a key enzyme in gluconeogenesis.

These transport proteins work together to move glucose 6-phosphate into the endoplasmic reticulum, where it is dephosphorylated. They also transport phosphate and glucose back into the cytoplasm

The process of converting pyruvate to glucose requires a significant amount of energy, needing 6 NTPs (nucleoside triphosphates) per glucose molecule.

This pathway produces NADPH, a crucial reducing agent essential for fatty acid and steroid synthesis, and ribose-5-phosphate, a building block for RNA, DNA, and coenzymes.

These pathways are mirror images: the PPP oxidizes glucose to produce NADPH, while the Calvin cycle utilizes NADPH to reduce carbon dioxide during photosynthesis.

Red blood cells rely on the pentose phosphate pathway to generate NADPH, which protects them from oxidative damage and keeps iron in its reduced form, essential for oxygen transport.

Three key enzymes are crucial for gluconeogenesis: pyruvate carboxylase, PEP carboxykinase, and fructose-1,6-bisphosphatase. These enzymes bypass the irreversible steps of glycolysis.

This enzyme is located in the mitochondria and converts pyruvate to oxaloacetate, an essential intermediate in gluconeogenesis.

The first stage of the pentose phosphate pathway, where NADPH is produced by oxidizing glucose-6-phosphate. This phase is irreversible and tightly regulated.

The second stage of the pentose phosphate pathway, where the carbon backbone of sugars is rearranged to produce ribose-5-phosphate. This phase is reversible.

The enzyme that catalyzes the first committed step in the pentose phosphate pathway, oxidizing glucose-6-phosphate to 6-phosphogluconolactone. This reaction is irreversible and highly regulated.

Key enzymes in the non-oxidative phase of the pentose phosphate pathway. They catalyze the transfer of two-carbon and three-carbon units, respectively, rearranging sugar molecules.

Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is an essential reducing agent in various biosynthetic processes and serves as a defense against oxidative stress by combating reactive oxygen species.

Ribose-5-phosphate is a key component of nucleotides, essential for nucleic acid synthesis (DNA and RNA).

The pentose phosphate pathway is regulated by the cellular need for NADPH and ribose-5-phosphate. High NADPH levels inhibit the pathway, while a high demand for reducing power or nucleotides activates it.

A condition where lactic acid accumulates in muscles during intense activity due to limited oxygen supply.

The liver can convert lactate, produced by muscles during exercise, back into pyruvate using lactate dehydrogenase.

A tripeptide that helps control the levels of harmful peroxides (ROS) generated during metabolism.

Individuals deficient in glucose 6-phosphate dehydrogenase can experience hemolysis (destruction of red blood cells) from consuming fava beans or inhaling their pollen.

Clumps of denatured hemoglobin formed in red blood cells due to the absence of glutathione, making them prone to rupture.

The scientific name for the fava bean plant, which contains a purine glycoside that can cause oxidative damage in red blood cells.

The metabolic pathway which converts non-carbohydrate sources (like pyruvate, lactate, or glycerol) into glucose.

Biotin is a cofactor for pyruvate carboxylase, which catalyzes the conversion of pyruvate to oxaloacetate, a crucial step in gluconeogenesis.

Gluconeogenesis is an energy-intensive process, requiring 6 ATP molecules to convert pyruvate to glucose.

The PPP has an oxidative phase, where NADPH is generated, and a non-oxidative phase, where ribose-5-phosphate is produced by rearranging sugar molecules.

Clouding of the lens in the eye, often caused by the accumulation of galactitol, a poorly metabolized sugar.

A sugar alcohol formed from galactose, poorly metabolized and accumulating in the lens, leading to cataracts.

It allows the body to produce glucose when carbohydrate sources are limited, ensuring fuel for vital organs like the brain and red blood cells.

A key reaction in the non-oxidative phase of the pentose phosphate pathway, where a two-carbon unit is transferred from a donor molecule to an acceptor molecule. This reaction uses TPP as a coenzyme.

Another reaction in the non-oxidative phase of the pentose phosphate pathway, where a three-carbon unit is transferred. The transfer first involves an active-site lysine, then moves to the acceptor molecule.

The phenomenon observed in rapidly proliferating cancer cells that metabolize glucose mainly to lactate, even in the presence of oxygen.

NADPH plays crucial roles in biosynthesis, serving as a reducing agent for fatty acid and steroid synthesis, and is critical in defending against oxidative stress.

Red blood cells lack mitochondria and rely on glycolysis to generate ATP. Due to the lack of oxygen, they produce lactate as a byproduct.

Many organisms produce ethanol or lactate as a byproduct when oxygen is not present, a process used in brewing beer and wine, muscle soreness, etc.

Highly active animals like hummingbirds constantly face damage from ROS (reactive oxygen species). Their high metabolic activity intensifies this issue, necessitating a robust defense mechanism.