Metabolism quiz,.linte!

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the net gain of ATP during glycolysis?

0 ATP

2 ATP (correct)

4 ATP

6 ATP

Which enzyme catalyzes the first regulatory step of glycolysis?

Fructose kinase

Hexokinase (correct)

Pyruvate kinase

Phosphofructokinase

What inhibits the enzyme phosphofructokinase in glycolysis?

High levels of ADP

Low levels of glucose-6-phosphate

High levels of AMP

High levels of ATP (correct)

In which cells is fructose converted to fructose-6-phosphate?

Muscle cells Signup and view all the answers

What is the role of 1,3-bisphosphoglycerate in glycolysis?

It provides phosphate groups for ATP production. Signup and view all the answers

What is a key feature of the regulatory steps in glycolysis?

They have large negative ΔG values and are essentially irreversible. Signup and view all the answers

Which compound provides the phosphate group in the formation of ATP during the second half of glycolysis?

Phosphoenolpyruvate Signup and view all the answers

Which statement about glycolysis and insulin regulation is true?

Insulin has no effect on fructose metabolism. Signup and view all the answers

What is formed when acetoacetate undergoes oxidation?

Acetone Signup and view all the answers

Which enzyme activates protein digestion in the stomach?

Pepsin Signup and view all the answers

Which of the following is NOT an end product of protein digestion?

Peptides Signup and view all the answers

What is the primary function of proteins in the body?

Provide amino acids for protein synthesis Signup and view all the answers

What happens during the process of transamination?

An amino group is transferred from an amino acid to an α-keto acid Signup and view all the answers

Which product is formed when acetoacetate goes through decarboxylation?

Acetone Signup and view all the answers

During digestion, trypsin is primarily responsible for hydrolyzing which type of molecule?

Peptides Signup and view all the answers

Which of the following compounds are products of fatty acid digestion?

Glycerol Signup and view all the answers

What is the primary purpose of catabolic reactions in metabolism?

To break down large molecules for energy. Signup and view all the answers

What characterizes a cyclic metabolic pathway?

It regenerates the first reactant after a series of reactions. Signup and view all the answers

Which stage of metabolism primarily involves breaking down large molecules to smaller ones?

Stage 1: Digestion and hydrolysis. Signup and view all the answers

Where does the oxidation of small molecules occur in the process of energy production?

In the citric acid cycle and electron transport chain. Signup and view all the answers

How is energy stored in the cells after metabolizing food?

As adenosine triphosphate (ATP). Signup and view all the answers

What role do NADH and FADH2 play in metabolism?

They carry electrons for ATP synthesis. Signup and view all the answers

What is the composition of the outer membrane of mitochondria?

50% lipid and 50% protein. Signup and view all the answers

What is the role of organelles within the cell?

To carry out specific cellular functions. Signup and view all the answers

What happens to fructose and galactose in the liver?

They are converted to glucose. Signup and view all the answers

What is the primary purpose of glycolysis?

To degrade glucose to pyruvate. Signup and view all the answers

Where does glycolysis take place within the cell?

In the cytoplasm. Signup and view all the answers

What is the nature of glycolysis in terms of oxygen requirement?

It is anaerobic and does not require oxygen. Signup and view all the answers

What characterizes the energy-investment phase of glycolysis?

Phosphate groups are added to glucose. Signup and view all the answers

How many ATP molecules are produced during the energy-production phase of glycolysis?

Four ATP molecules. Signup and view all the answers

What is the process of substrate-level phosphorylation?

It involves the direct transfer of a phosphate group to ADP. Signup and view all the answers

Which of the following molecules are produced from glucose in the glycolysis pathway?

Pyruvate molecules. Signup and view all the answers

What is the product formed when the carbamoyl group is transferred to ornithine?

Citrulline Signup and view all the answers

In which part of the cell does citrulline combine with aspartate during the urea cycle?

Cytosol Signup and view all the answers

What energy source is utilized during the condensation of citrulline and aspartate?

ATP Signup and view all the answers

Which intermediate is cleaved from argininosuccinate in the urea cycle?

Fumarate Signup and view all the answers

What is the final product of arginine hydrolysis in the urea cycle?

Urea Signup and view all the answers

What component is returned to the mitochondrion to pick up another carbamoyl group?

Ornithine Signup and view all the answers

What overall transformation does the urea cycle facilitate?

Aspartate to Fumarate Signup and view all the answers

In the urea cycle, which of the following represents the stoichiometry of the overall reaction?

1 NH4+ + CO2 + 3 ATP = 1 Urea + 2 ADP + AMP + 4 Pi + Fumarate Signup and view all the answers

What occurs during the hydrolysis of succinyl CoA?

It breaks the thioester bond to generate GTP. Signup and view all the answers

During the dehydrogenation of succinate, what is produced?

FADH2 and fumarate Signup and view all the answers

What is the purpose of hydration in the conversion of fumarate?

It converts fumarate to malate by adding water. Signup and view all the answers

What does malate convert to during its dehydrogenation?

Oxaloacetate with a C=O double bond Signup and view all the answers

What is the result of the oxidation of succinate during dehydrogenation?

It creates a double bond in fumarate. Signup and view all the answers

Which molecule is directly involved in the reduction of FAD to FADH2?

Succinate Signup and view all the answers

What initiates the conversion of succinyl CoA to GTP?

The breaking of the thioester bond Signup and view all the answers

Which of the following statements about the reactions is correct?

Malate is formed after hydration of fumarate. Signup and view all the answers

Study Notes

Metabolic Pathways and Energy Production

Metabolism encompasses all chemical reactions within cells, breaking down (catabolism) or building (anabolism) molecules.
A metabolic pathway is a sequence of linked reactions, each catalyzed by a specific enzyme.
Pathways can be linear, where a final product is generated, or cyclic, where the first reactant is regenerated.
Food (polysaccharides, lipids, proteins) is digested into smaller molecules (glucose, fatty acids, amino acids) releasing energy.
Cells store energy as ATP (adenosine triphosphate); this is then broken down to do work.
Catabolic reactions involve breaking down large, complex molecules into smaller ones, releasing energy.
Anabolic reactions use ATP energy to build larger molecules.
Metabolism's stages are organized into:
- Stage 1: Digestion and hydrolysis break down large molecules to small ones.
- Stage 2: Degradation breaks down molecules into two- and three-carbon compounds.
- Stage 3: Oxidation of small molecules in the citric acid cycle and electron transport provide ATP energy (electrons are carried by NADH and FADH2).

Metabolism and Cell Structure

Metabolic reactions occur within specific sites in cells, namely organelles.
Organelles are minute structures in cytoplasm that perform specific cellular functions.
Organelles are surrounded by cytosol, the fluid part of the cytoplasm.
The main organelles involved in metabolism are:
- Nucleus
- Rough endoplasmic reticulum
- Smooth endoplasmic reticulum
- Ribosomes
- Mitochondria
- Golgi complex
- Lysosomes
- Plasma membrane

Important Nucleotide-Containing Compounds in Metabolic Pathways

ATP (adenosine triphosphate) is the main energy currency in cells, formed by the oxidation of food.
ATP consists of adenine, ribose sugar, and three phosphate groups.
Hydrolysis of ATP to ADP releases energy (7.3 kcal/mol or 31 kJ/mol).
Hydrolysis of ADP to AMP also releases energy.

Coenzymes in Metabolic Pathways

Many metabolic reactions, involved in energy extraction, entail oxidation and reduction.
Oxidation involves the loss of Hydrogen atoms.
Reduction involves the gain of Hydrogen atoms.
Coenzymes are necessary to transport hydrogen and electrons.

Oxidation and Reduction

Oxidation is the loss of electrons or hydrogen or the gain of oxygen.
Reduction is the gain of electrons or hydrogen or the loss of oxygen.

Coenzyme NAD+

NAD+ is a coenzyme involved in redox reactions.
It accepts hydrogen and electrons when an oxidation reaction occurs in metabolic pathways.

Coenzyme FAD

FAD is a coenzyme involved in redox reactions.
It accepts hydrogen and electrons during redox reactions by forming a double bond in the substance.

Coenzyme A

Coenzyme A (CoA) activates acyl groups, especially in the transfer of acetyl groups.
It has a reactive thiol group (-SH) that forms a high-energy thioester with acyl groups.

High-Energy Phosphate Compounds

High-energy compounds contain one or more very reactive bonds, often called "strained bonds."
The energy balance in chemical reactions between breaking and reforming bonds determines whether there's a net gain or loss of energy.

Digestion of Carbohydrates (Glycolysis)

Stage 1 of carbohydrate digestion: Polysaccharides are broken down into monosaccharides.
Stage 2: Degradation of monosaccharides (glucose)into smaller molecules.
Glycolysis involves a series of reactions that degrades glucose (6 carbon atoms) to pyruvate (3 carbon atoms).
Glycolysis is an anaerobic process that does not require oxygen.

Pathways for Pyruvate

Depending on oxygen availability, pyruvate has different fates:
- Aerobic conditions: Pyruvate is decarboxylated to Acetyl CoA, a crucial molecule for the citric acid cycle.
- Anaerobic conditions (humans, animals, and some microorganisms): Pyruvate is reduced to lactate, an important molecule to regenerate NAD+ and sustain glycolysis.
- Anaerobic conditions (some microorganisms): Pyruvate is converted to ethanol through decarboxylation and reduction.

The Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle, is a crucial aerobic pathway for energy production in mitochondria.
It involves the oxidation of acetyl CoA into CO2, generating energy-carrying molecules (NADH and FADH2) and ATP.
This stage of metabolism occurs under aerobic conditions and proceeds in a cycle.

Electron Transport Chain

The electron transport chain involves a series of protein complexes embedded in the inner mitochondrial membrane.
Electrons from NADH and FADH2 are passed along the chain to oxygen, generating ATP.
The flow of protons through ATP synthase, a protein complex also in the membrane, drives ATP synthesis.

Oxidative Phosphorylation and ATP

Oxidative phosphorylation involves ATP synthase utilizing the proton gradient across the inner mitochondrial membrane to produce ATP.

Fatty Acid Oxidation

Fatty acids are activated in the cytosol by combining them with coenzyme A (CoA) to form fatty acyl-CoA.
Fatty acyl-CoA is transported into mitochondria.
Fatty acyl-CoA undergoes a cycle known as beta-oxidation to produce acetyl-CoA, NADH, and FADH2, while shortening the fatty acid molecule.
The acetyl-CoA molecules enter the citric acid cycle for further energy production.

Ketogenesis and Ketone Bodies

Ketogenesis is a process that produces ketone bodies (acetoacetate, 𝛽-hydroxybutyrate, and acetone) from acetyl CoA when carbohydrates aren't available as an energy source.
Ketone bodies are utilized as alternative energy sources by the brain and other tissues.
Ketosis, an elevated level of ketone bodies, can result from conditions like uncontrolled diabetes and starvation.

Protein Metabolism

Protein digestion involves breaking down proteins to individual amino acids.
In the stomach, HCl activates pepsin to break peptide bonds.
Trypsin and chymotrypsin, in the small intestine, further break down polypeptides to individual amino acids.
The amino acids are absorbed into the bloodstream to be used by cells.

Transamination

Transamination is the process of transferring an amino group from one amino acid to a keto acid, producing a new amino acid and a new keto acid.
Glutamate is the primary amino acid in transamination reactions.
Transamination reactions are commonly catalyzed by enzymes called transaminases or aminotransferases.

Oxidative Deamination

Oxidative deamination is a process where the amino group is removed from glutamate, generating ammonium ion (NH4+).
This process provides a-ketoglutarate, necessary for transamination reactions and other metabolic processes.

Urea Cycle

The urea cycle converts harmful ammonium ions (NH4+) into urea in the liver.
Urea is an excretable waste product that's non-toxic and transported to kidneys for excretion.
The urea cycle consists of several reactions that convert ammonium with CO2 and aspartate to urea.

Fate of Carbon Atoms from Amino Acids

Carbon skeletons of different amino acid families (e.g., C-3 family, C-4 family, C-5 family) enter different intermediates via pyruvate, oxaloacetate, or a-ketoglutarate. These intermediates are then used in the citric acid cycle for further energy production.

Glucogenic and Ketogenic Amino Acids

Glucogenic amino acids can be converted to glucose or intermediates used for glucose synthesis.
Ketogenic amino acids cannot be converted to glucose, instead they provide carbon skeletons for ketone body synthesis and fatty acid production.

Additional Information (General Overview)

Anabolic pathways build molecules, requiring ATP.
Catabolic pathways break down molecules, releasing ATP.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Ambot!