Biochemistry Chapter on Metabolism
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Questions and Answers

What is the primary function of ATP in the body?

  • To provide immediate energy for cellular functions (correct)
  • To store excess sugar
  • To carry oxygen in the blood
  • To facilitate fat digestion

Which metabolic process is responsible for the production of lactate?

  • Krebs cycle
  • Anaerobic respiration (correct)
  • Gluconeogenesis
  • Lipolysis

What percentage of energy from catabolic reactions is typically transferred to ATP?

  • 20%
  • 80%
  • 60%
  • 40% (correct)

Which of the following is not a step in the metabolic process of carbohydrates?

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

What is the primary role of the urea cycle in protein metabolism?

<p>To remove excess nitrogen from amino acids (B)</p> Signup and view all the answers

Which metabolic process occurs during the absence of oxygen?

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

Which of the following correctly describes catabolic reactions?

<p>They break down organic molecules to release energy (C)</p> Signup and view all the answers

What happens when the body has a net negative energy balance?

<p>The body uses energy stores for fuel (C)</p> Signup and view all the answers

What triggers the release of insulin from pancreatic beta cells?

<p>Ingestion of food and rise in blood glucose concentrations (C)</p> Signup and view all the answers

During starvation, which of the following is prioritized for survival?

<p>Conservation of amino acids for proteins (A)</p> Signup and view all the answers

What hormone is released by the alpha cells of the pancreas in response to low blood glucose levels?

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

What process begins in the liver when blood glucose concentrations decrease?

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

Which mechanism of heat exchange involves the evaporation of water from the skin's surface?

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

What is the definition of a calorie in terms of water temperature change?

<p>The energy it takes to increase the temperature of 1g of water by 1 degree Celsius (A)</p> Signup and view all the answers

What role does the hypothalamus play in thermoregulation?

<p>It regulates body temperature within certain boundaries (D)</p> Signup and view all the answers

Which mechanism of heat exchange transfers heat without direct contact between two objects?

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

What is the primary fuel for ATP production in cells?

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

During starvation, what process does glucagon stimulate?

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

What hormone is primarily synthesized in response to stress and increases blood glucose levels?

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

Excess fat is predominantly stored in which type of cells?

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

What do anabolic reactions primarily involve?

<p>Combining smaller molecules into larger ones (A)</p> Signup and view all the answers

The deficiency of which enzyme leads to Phenylketonuria (PKU)?

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

Cushing syndrome is associated with what major hormonal imbalance?

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

What metabolic process breaks down triglycerides for energy?

<p>Beta-oxidation (D)</p> Signup and view all the answers

Which hormone is responsible for stimulating muscle growth and strength?

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

In Addison's disease, what is primarily insufficiently produced?

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

The primary treatment for Pyruvate dehydrogenase complex deficiency involves what?

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

Which nutrient is broken down into nucleotides during digestion?

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

What is a common manifestation of high levels of phenylalanine in the body?

<p>Neuro-toxicity (B)</p> Signup and view all the answers

Which substance is typically synthesized from monosaccharides in anabolic reactions?

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

What is the main purpose of anaerobic respiration?

<p>To generate energy quickly when oxygen is absent (C)</p> Signup and view all the answers

Which molecule is primarily responsible for carrying high-energy electrons to the electron transport chain?

<p>FADH2 (B)</p> Signup and view all the answers

In glycolysis, how many ATP molecules are produced from one molecule of glucose?

<p>2 (C)</p> Signup and view all the answers

What is the end product of glycolysis?

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

Which coenzyme functions alongside NAD+ in redox reactions?

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

During the Krebs cycle, what molecule does acetate combine with to form citric acid?

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

What is produced during fermentation when pyruvate is converted in the absence of oxygen?

<p>Lactic acid or ethanol (C)</p> Signup and view all the answers

How many total ATP molecules can be produced from one glucose molecule during aerobic respiration?

<p>36-38 (A)</p> Signup and view all the answers

Which step of cellular respiration does not require oxygen?

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

What occurs to pyruvate in the Krebs cycle?

<p>It generates NADH and FADH2 (B)</p> Signup and view all the answers

What is the role of coenzymes in oxidation-reduction reactions?

<p>To accept hydrogen atoms (D)</p> Signup and view all the answers

What is the primary waste product generated from aerobic respiration?

<p>Carbon dioxide and water (C)</p> Signup and view all the answers

Which process involves the splitting of glucose into pyruvate?

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

What enzyme do coenzymes work best with in redox reactions?

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

What is the primary function of the electron transport chain in cellular respiration?

<p>To generate ATP by creating a proton gradient (D)</p> Signup and view all the answers

Which molecule is produced when glucose undergoes gluconeogenesis?

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

What hormone triggers the release of pancreatic lipase during lipid metabolism?

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

In the breakdown of fatty acids, what is the process that generates energy called?

<p>Beta-oxidation (D)</p> Signup and view all the answers

What are ketone bodies primarily used for by the body?

<p>As an alternative energy source (B)</p> Signup and view all the answers

What is the main purpose of the urea cycle?

<p>To prevent toxic levels of ammonia in the body (B)</p> Signup and view all the answers

Which product is NOT a result of lipogenesis?

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

What end product results from the breakdown of fatty acids through the Krebs cycle?

<p>NADH and FADH2 (A)</p> Signup and view all the answers

When does the absorptive state occur?

<p>After a meal (A)</p> Signup and view all the answers

What chemical structure do ketones contain?

<p>R-C(=O)-R (C)</p> Signup and view all the answers

Which enzyme is primarily responsible for breaking down triglycerides in the intestine?

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

What process occurs when the energy from amino acids is utilized?

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

What happens to protons (H+) during the electron transport chain process?

<p>They create a concentration gradient across the membrane. (C)</p> Signup and view all the answers

Which process would occur predominantly if glucose levels are low in the body?

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

Flashcards

Cellular Respiration

The process by which cells break down glucose to produce energy (ATP) in the presence of oxygen. It involves glycolysis, the Krebs cycle, and the electron transport chain.

Glycolysis

The first stage of cellular respiration, occurring in the cytoplasm, where glucose is broken down into pyruvate, producing a small amount of ATP and NADH.

Krebs Cycle

The second stage of cellular respiration, occurring in the mitochondria, where pyruvate is further broken down, generating more ATP, NADH, and FADH2.

Electron Transport Chain

The final stage of cellular respiration, occurring in the mitochondria, where electrons from NADH and FADH2 are passed along a chain of molecules, releasing energy used to generate ATP.

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Anaerobic Respiration

The process cells use to produce energy (ATP) in the absence of oxygen. It involves glycolysis followed by fermentation, producing lactate or ethanol.

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Lipolysis

The breakdown of lipids (fats) into fatty acids and glycerol.

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Ketogenesis

The process of creating ketone bodies from fatty acids in the liver, especially when glucose is low.

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Catabolic Reactions

Chemical reactions that break down larger molecules into smaller ones, releasing energy.

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Sugar Catabolism

The process of breaking down polysaccharides into their simplest units, monosaccharides, for energy production.

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Glucose's Role in ATP Production

Glucose is the primary fuel source for creating ATP, the energy currency of cells.

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Excess Glucose Storage

Excess glucose is stored as glycogen in the liver and muscles, or converted into fat in adipose cells.

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Lipid Catabolism (Beta-Oxidation)

The process of breaking down triglycerides (fats) into fatty acids for energy production.

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Fat Storage Locations

Half of excess fat is stored in subcutaneous tissue, the rest in other tissues and organs.

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Protein Catabolism

The breakdown of proteins into their building blocks, amino acids.

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Amino Acid Usage

Amino acids are either used to build new proteins or broken down further for energy production.

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Starvation and Protein Breakdown

During starvation, the body breaks down proteins for energy, leading to body deterioration.

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Nucleic Acid Catabolism

Nucleic acids (DNA, RNA) are broken down into nucleotides, which are absorbed and used for nucleic acid metabolism.

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Anabolic Reactions: Combining Molecules

Anabolic reactions join monosaccharides into polysaccharides, fatty acids into triglycerides, amino acids into proteins, and nucleotides into nucleic acids.

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Catabolic Hormones

Hormones that stimulate the breakdown of molecules and energy production.

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Anabolic Hormones

Hormones that stimulate the synthesis of molecules, building new structures.

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Metabolic Diseases

Diseases caused by malfunctioning proteins or enzymes involved in metabolic pathways.

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Cushing Syndrome

A condition caused by excessive cortisol production, leading to weight gain, depression, and other symptoms.

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Phenylalanine Restriction

A dietary approach for managing phenylketonuria (PKU) by limiting foods containing phenylalanine, such as artificial sweeteners, high-protein foods, and some grains.

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Oxidation-Reduction Reactions (Redox)

Chemical reactions involving the transfer of electrons, where one molecule loses electrons (oxidation) and another gains electrons (reduction).

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What are Coenzymes?

Non-protein molecules that work with enzymes to facilitate chemical reactions. They often carry specific molecules or atoms, like hydrogen.

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NAD+ and FAD+

Common coenzymes involved in redox reactions. NAD+ accepts two electrons and one proton (H+), while FAD+ accepts two electrons and two protons (H+).

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ATP: Energy Currency

Adenosine triphosphate, a high-energy molecule used as the primary energy source for cellular processes.

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NADH & FADH2

High-energy molecules produced during glucose breakdown that carry electrons from the breakdown of glucose to the electron transport chain.

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Pyruvate

A 3-carbon molecule produced during glycolysis, the first stage of glucose breakdown. It serves as a starting material for the Krebs cycle.

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Acetyl CoA

A 2-carbon molecule formed from pyruvate and enters the Krebs cycle, starting the process of energy production.

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Carbohydrate Digestion: Quick Summary

Polysaccharides are broken down into monosaccharides, absorbed in the small intestines, transported to the liver, and either used for energy or stored as glycogen.

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Cellular Respiration Overview

The process of energy production in cells by breaking down glucose in a series of steps: glycolysis, Krebs cycle, and electron transport chain.

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Glycolysis: Breakdown of Glucose

Glucose is broken down into pyruvate in the cytoplasm, producing ATP and NADH.

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Anaerobic Respiration: When Oxygen is Limited

Cells produce energy in the absence of oxygen by converting pyruvate into lactic acid or ethanol, generating a small amount of ATP.

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Aerobic Respiration: Energy with Oxygen

Cells produce energy using oxygen by breaking down glucose through glycolysis, the Krebs cycle, and electron transport chain, generating a significant amount of ATP.

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Krebs Cycle: Central Metabolic Pathway

Pyruvate is further broken down in the mitochondria, producing ATP, NADH, and FADH2.

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Electron Transport Chain: Final Step

High-energy electrons carried by NADH and FADH2 move along a chain of proteins, generating a proton gradient that drives ATP production.

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What is the post-absorptive state?

The state after digestion, absorption, and storage of food, where the body relies on stored energy reserves.

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What does glucagon do?

A hormone released by the pancreas in response to low blood glucose, stimulating glycogen breakdown and glucose production in the liver.

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What is gluconeogenesis?

The process of creating new glucose from non-carbohydrate sources, like amino acids, in the liver.

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What is starvation mode?

The body's response to prolonged food deprivation, prioritizing glucose for the brain and conserving amino acids for essential proteins.

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How does the hypothalamus regulate temperature?

By adjusting blood flow to the skin (sweating or shivering) to maintain a steady internal temperature.

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What is conduction?

The transfer of heat through direct contact between objects of different temperatures.

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What is evaporation?

The transfer of heat by the conversion of liquid water into water vapor.

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What is the difference between calorie and nutritional calorie?

A calorie is the energy required to raise 1g of water by 1°C, while a nutritional calorie (kcal) is the energy required to raise 1kg of water by 1°C.

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Electron Transport Chain (ETC)

The final stage of cellular respiration where electrons from NADH and FADH2 are passed along a chain of molecules, releasing energy to pump protons and generate ATP.

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Proton Gradient

The difference in proton concentration across the mitochondrial membrane, created by the ETC, driving ATP production.

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ATP Synthase

An enzyme that uses the proton gradient to generate ATP from ADP and a phosphate group.

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Lipid Digestion

The breakdown of fats in the intestines, beginning with pancreatic lipases breaking down triglycerides into monoglycerides.

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Chylomicrons

Fat carriers that transport triglycerides, cholesterol, and other lipids through the lymphatic and circulatory system.

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Gluconeogenesis

The process of creating new glucose molecules from non-carbohydrate sources like lactate, glycerol, or amino acids, mainly in the liver.

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Breakdown of Fatty Acids

The process by which stored fats are broken down to produce energy, involving beta-oxidation and the Krebs cycle.

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Beta-oxidation

The process within mitochondria where fatty acids are broken down into two-carbon acetyl CoA units.

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Ketones

Organic compounds containing a carboxyl group with two carbon substituents, used as an alternative fuel source when glucose is low.

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Ketone Oxidation

The process by which ketone bodies are used as a fuel source to generate energy.

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Energy from Amino Acids

Amino acids can be broken down into precursors for glycolysis or the Krebs cycle, generating energy.

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Metabolic Rate

The amount of energy consumed minus the amount of energy expended by the body.

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Study Notes

Carbohydrate Metabolism

  • Cellular Respiration (with oxygen): Glucose is broken down to produce ATP (energy). This process involves glycolysis, the Krebs cycle, and the electron transport chain.
  • Glycolysis: Glucose is oxidized (broken down) into 2 pyruvate molecules, producing ATP and NADH. Occurs in the cytoplasm without oxygen.
  • Krebs Cycle (Citric Acid Cycle): Pyruvate is further broken down, producing NADH, FADH2, ATP, and releasing carbon dioxide. Takes place in the mitochondrial matrix.
  • Electron Transport Chain (Oxidative Phosphorylation): NADH and FADH2 release energy to pump protons, creating a gradient that drives ATP synthesis. Oxygen is the final electron acceptor, forming water.
  • Anaerobic Respiration (without oxygen): Fermentation, converting pyruvate into lactic acid or alcohol, regenerates NAD+ for glycolysis. Produces less ATP than aerobic respiration.
  • Gluconeogenesis: Synthesis of glucose from non-carbohydrate sources (e.g., pyruvate, lactate) when glucose levels are low.

Lipid Metabolism

  • Lipolysis: Breakdown of triglycerides (stored fats) into glycerol and fatty acids.
  • Ketogenesis: Production of ketone bodies from fatty acids when glucose is insufficient.
  • Ketone Body Oxidation: Ketones are used as an alternative fuel source.
  • Lipogenesis: Synthesis of lipids (fats) from acetyl CoA when glucose is abundant.

Protein Metabolism

  • Protein Digestion/Proteolysis: Proteins are broken down into amino acids.
  • Energy from Amino Acids: Amino acids can be used to produce ATP or become precursors for other metabolic processes.
  • Urea Cycle: Converts ammonia (a byproduct of protein breakdown) into urea, which is less toxic and excreted in urine.

General Metabolic Principles

  • Metabolism: All chemical reactions in the body.
  • Catabolic Reactions: Break down large molecules into smaller ones, releasing energy (e.g., protein to amino acids).
  • Anabolic Reactions: Build larger molecules from smaller ones, requiring energy (e.g., amino acids to protein).
  • Energy Balance: Excess energy is stored as mass; insufficient energy uses stored reserves.
  • ATP (Adenosine Triphosphate): Energy currency of the cell, powers bodily functions directly.
  • Redox Reactions: Electron transfer reactions critical for energy production, catalyzed by specific enzymes and coenzymes NAD+ and FAD+.

Hormonal Regulation of Metabolism

  • Catabolic Hormones: Stimulate molecule breakdown and energy production (e.g., cortisol, glucagon, adrenaline).
  • Anabolic Hormones: Stimulate molecule synthesis (e.g., growth hormone, insulin-like growth factor, insulin, testosterone, estrogen).

Metabolic Diseases

  • Examples: Cushing syndrome (excess cortisol), Addison's disease (insufficient cortisol), Pyruvate dehydrogenase complex deficiency, Phenylketonuria (PKU).
  • Common Cause: Malfunctioning proteins/enzymes or imbalance in hormonal regulation.

Digestion and Absorption (Carbohydrates)

  • Carbohydrate digestion: Begins in the mouth with enzymes like salivary amylase, ends in small intestine with monosaccharides absorbed.
  • Monosaccharide transport: Absorbed into bloodstream, carried to liver.
  • Glucose storage/utilization: Liver either releases glucose or stores it as glycogen; cells use glucose to produce ATP via cellular respiration.

Cellular Respiration Steps

  • Aerobic Respiration Steps: Glycolysis, Krebs Cycle, Electron Transport Chain.
  • Glycolysis steps: Glucose is broken down to pyruvate, 2 ATP, and NADH are produced.
  • Krebs Cycle steps: Pyruvate is broken down, NADH, FADH2, and ATP are produced.
  • Electron Transport Chain steps: NADH and FADH2 release energy to form a proton gradient, ATP is produced.

Lipid Digestion

  • Lipid digestion: Begins in the intestines.
  • Bile salts: Emulsify fats for enzyme action.
  • Pancreatic lipases: Break down triglycerides.
  • Chylomicrons: Transport lipids in lymphatic and circulatory system.

Gluconeogenesis

  • Gluconeogenesis: Synthesis of glucose from non-carbohydrate sources (lactate, glycerol, amino acids).

Fatty Acid Breakdown

  • Breakdown of fatty acids: Released as needed into the bloodstream used to generate energy via beta-oxidation.
  • Beta-oxidation: Fatty acids are broken down into acetyl CoA.
  • Acetyl CoA entry into the Krebs Cycle: Used in Krebs, then through electron transport.

Ketogenesis and Ketones

  • Ketogenesis: Excess acetyl CoA forming ketone bodies.
  • Ketones: Alternative fuel source utilized when glucose is unavailable, generated in the liver.

Protein Digestion further

  • Protein digestion and absorption: Proteins are broken down by enzymes in the stomach and small intestine resulting in circulating amino acids.
  • Amino acid utilization: Used by the body to generate energy, and as precursors in building tissues.
  • Urea cycle: Critical process for converting ammonia to urea, which is then excreted.

Metabolic Rate and States

  • Metabolic Rate: Energy consumed minus energy expended.
  • Basal Metabolic Rate (BMR): Energy expenditure at rest.
  • Absorptive State: After a meal, nutrients are absorbed.
  • Post-absorptive State: After absorption, stored nutrients used to create energy.

Starvation

  • Starvation Body's response to prolonged lack of food to prioritize brain function and conserve proteins.

Thermoregulation

  • Hypothalamus control of thermoregulation: Controls core body temperature.
  • Mechanisms of heat exchange: Conduction, evaporation, radiation, convection.

Calorie and Nutritional Calories

  • Calorie: Energy to raise the temperature of 1 gram of water by 1 degree Celsius.
  • Nutritional Calorie (kcal): Energy to raise the temperature of 1 kilogram of water by 1 degree Celsius.

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Test your knowledge on the fundamental concepts of biochemistry and metabolism. This quiz covers ATP functions, metabolic processes, and the urea cycle. Challenge yourself with questions on energy transfer and catabolic reactions.

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