Energy and Metabolism Overview
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Questions and Answers

What is the difference between catabolism and anabolism?

  • Catabolism breaks molecules down to produce energy, while anabolism builds up body tissues. (correct)
  • Catabolism and anabolism are the same processes with different names.
  • Catabolism stores energy, while anabolism releases it.
  • Catabolism builds molecules, while anabolism breaks them down.

Which type of work involves moving molecules across membranes?

  • Transport Work (correct)
  • Chemical Work
  • Thermal Work
  • Mechanical Work

What happens to the oxidation state of a molecule during oxidation?

  • It remains unchanged.
  • It increases as the molecule loses electrons. (correct)
  • It decreases as the molecule gains electrons.
  • It fluctuates depending on the medium.

What role do activated carrier molecules play in cellular energy transformations?

<p>They store and transfer energy captured from metabolic processes. (B)</p> Signup and view all the answers

How does lowering activation energy affect reaction rates?

<p>It generally increases the reaction rates. (B)</p> Signup and view all the answers

What is the transition state in enzyme-catalyzed reactions?

<p>The high-energy state between reactants and products. (D)</p> Signup and view all the answers

What defines the active site of an enzyme?

<p>The region where the substrate binds and the reaction occurs. (C)</p> Signup and view all the answers

What effect do enzymes have on the activation energy of a reaction?

<p>They stabilize the transition state, effectively lowering the activation energy. (B)</p> Signup and view all the answers

What does Vmax represent in enzyme kinetics?

<p>The maximum rate of reaction when the enzyme is fully saturated with substrate (C)</p> Signup and view all the answers

Which statement best describes Km?

<p>It is the substrate concentration at which the reaction rate is half of Vmax (B)</p> Signup and view all the answers

What distinguishes competitive inhibition from non-competitive inhibition?

<p>Competitive inhibitors resemble the substrate and block the active site (D)</p> Signup and view all the answers

What is a key characteristic of irreversible enzyme inhibition?

<p>The inhibitor binds covalently and permanently inactivates the enzyme (A)</p> Signup and view all the answers

How do cofactors differ from coenzymes?

<p>Coenzymes are organic molecules that transfer chemical groups (C)</p> Signup and view all the answers

Which effect does increasing temperature have on enzyme activity within a certain limit?

<p>It speeds up enzymatic reactions until denaturation occurs (C)</p> Signup and view all the answers

What happens when enzymes are exposed to extreme pH levels?

<p>Enzymes may change shape, reducing their activity (C)</p> Signup and view all the answers

What is the primary result of the digestion stage in cellular metabolism?

<p>Nutrients are broken down into their simplest forms for absorption (B)</p> Signup and view all the answers

What role do second messengers play in signal transduction?

<p>They carry signals inside the cell. (A)</p> Signup and view all the answers

Which type of signaling involves a cell sending signals through the bloodstream to distant cells?

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

Which component acts as the 'worker' in the signal transduction process?

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

What is the primary function of G-Protein Coupled Receptors (GPCRs) in signal transduction?

<p>To initiate a cascade of reactions using G proteins. (D)</p> Signup and view all the answers

Which of the following best describes autocrine signaling?

<p>Cells signal themselves. (A)</p> Signup and view all the answers

What distinguishes receptor tyrosine kinases (RTKs) from other receptor types?

<p>They add phosphate groups to proteins. (C)</p> Signup and view all the answers

During the adrenaline signaling process in muscle cells, what is the primary result of the signaling cascade?

<p>Muscle cells break down glycogen into glucose. (B)</p> Signup and view all the answers

In which type of receptor do ligands typically enter the cell and affect gene expression directly?

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

What is the first step in the activation of Receptor Tyrosine Kinases (RTKs) during signal transduction?

<p>A signal binds to the RTK and pairs it with another RTK. (C)</p> Signup and view all the answers

Which of the following molecules is considered a second messenger in cell signaling?

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

How do membrane receptor-mediated and nuclear receptor-mediated signal transduction mechanisms primarily differ?

<p>Membrane receptors relay signals from the surface, while nuclear receptors pass signals through the membrane. (D)</p> Signup and view all the answers

What role do protons play in chemiosmotic coupling within mitochondria?

<p>They create a chemical gradient that drives ATP synthesis. (A)</p> Signup and view all the answers

What is the primary function of the β subunits in the FoF1 ATP synthase complex?

<p>To bind ADP and synthesize ATP through conformational changes. (B)</p> Signup and view all the answers

What is the primary purpose of glycolysis from a cellular perspective?

<p>To produce ATP and NADH for quick cellular energy (B)</p> Signup and view all the answers

During which stage of glycolysis is glucose converted into two identical 3-carbon molecules?

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

What are the overall inputs required for glycolysis?

<p>1 Glucose, 2 NAD+, 2 ADP, and 2 Pi (C)</p> Signup and view all the answers

Why is it essential for cells to regenerate NAD+ after glycolysis?

<p>NAD+ acts as an electron carrier necessary for glycolysis to continue. (A)</p> Signup and view all the answers

How do cells regenerate NAD+ in the absence of oxygen?

<p>By converting pyruvate into lactic acid or ethanol. (D)</p> Signup and view all the answers

What is the role of acetyl CoA in cellular metabolism?

<p>To carry energy-rich molecules into the citric acid cycle. (B)</p> Signup and view all the answers

What are the main products of the citric acid cycle?

<p>Energy carriers like NADH and FADH2, and CO2 as waste (A)</p> Signup and view all the answers

What is the energy transformation that occurs during oxidative phosphorylation?

<p>Addition of inorganic phosphate to ATP using energy from nutrient oxidation. (B)</p> Signup and view all the answers

Flashcards

Metabolism

All chemical and physical activities in the body that use or convert energy.

Catabolism

Breaks down molecules to release energy.

Anabolism

Builds molecules, using energy.

Activation Energy

Minimum energy needed to start a chemical reaction.

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Enzyme

Protein that speeds up chemical reactions by lowering activation energy.

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Active Site

Region on an enzyme where the substrate binds, reaction happens.

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Substrate

Molecule acted upon by an enzyme.

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Biological Oxidation/Reduction

Molecules lose/gain electrons, changing oxidation state

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Michaelis-Menten equation

Describes the relationship between substrate concentration and reaction rate, plateauing at maximum velocity (Vmax).

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Vmax

Maximum reaction rate with enzyme saturated by substrate.

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Km

Substrate concentration at half Vmax.

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Reversible inhibition

Inhibitor binds non-covalently; enzyme activity returns.

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Irreversible inhibition

Inhibitor binds permanently by covalent bonds.

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Competitive inhibition

Inhibitor resembles substrate; blocks active site but overcomeable.

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Non-competitive inhibition

Inhibitor binds elsewhere, changing shape and reducing activity.

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Food Molecule breakdown stages

Proteins, polysaccharides, and fats broken down into amino acids, sugars and fatty acids, either outside cells or in lysosomes.

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Glycolysis Purpose

Breaks down glucose to make ATP and NADH, providing quick energy for cells.

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Glycolysis Inputs

Glucose, 2 NAD+, 2 ADP, and 2 Pi

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Glycolysis Outputs

2 Pyruvate, 2 NADH, and 2 ATP (net gain)

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NAD+ Regeneration (Fermentation)

Cells convert pyruvate into lactic acid or ethanol/CO2 to recycle NAD+ when oxygen is absent.

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NAD+ Regeneration (Aerobic Respiration)

Pyruvate enters mitochondria, cycles to produce more ATP and regenerate NAD+.

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Acetyl CoA Role

Delivers energy fragments from sugars, fats, and proteins to the citric acid cycle for energy extraction.

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Citric Acid Cycle

Series of reactions taking Acetyl CoA to produce energy carriers (NADH, FADH2) and CO2.

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Oxidative Phosphorylation

Uses energy from oxidation to add inorganic phosphate to ADP and make ATP.

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Receptor Tyrosine Kinases (RTKs)

Membrane receptors that activate downstream signaling pathways when a signal molecule binds to them.

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Second Messenger

Small molecules that relay signals inside a cell, amplifying and spreading the initial signal received at the cell surface.

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Electron Transport Chain (ETC)

Series of protein complexes that transfer electrons, creating a proton gradient for ATP synthesis.

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Proton Motive Force

Electrochemical gradient generated by pumping protons across a membrane, driving ATP synthesis.

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ATP Synthase

Enzyme complex that uses the proton gradient to synthesize ATP from ADP and inorganic phosphate.

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Oxidative Phosphorylation

Process where energy carriers (NADH, FADH2) power ATP production, the cell's energy currency.

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Cell Signaling

Relay race-like process where cells communicate using signals, receptors, and response mechanisms.

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Signal Transduction Components

Includes signals, receptors, effectors, second messengers, and cellular response during cell signaling.

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Ligand

Molecule that attaches to a receptor to initiate a signal. Hormones, neurotransmitters are examples.

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G-Protein Coupled Receptor (GPCR)

Cell surface receptor that activates intracellular signaling pathways using G proteins.

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Receptor Tyrosine Kinase (RTK)

Receptor activating multiple signaling pathways by adding phosphate groups inside the cell.

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Second Messengers

Molecules carrying the signal to inside of a cell, initiating a response.

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Autocrine Signaling

Cell signaling where a cell signals itself.

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Study Notes

Energy and Metabolism

  • Metabolism encompasses all chemical and physical activities using or converting energy
  • Catabolism breaks down molecules to produce energy
  • Anabolism builds up body tissues and energy stores

Energy and Cell Work

  • Energy is the capacity to do work
  • Chemical work: molecule synthesis
  • Mechanical work: movement
  • Transport work: molecule movement across membranes

Oxidation and Reduction

  • Oxidation: molecule loses electrons (or gains oxygen), increasing its oxidation state
  • Reduction: molecule gains electrons (or loses oxygen), decreasing its oxidation state

Activated Carrier Molecules

  • Store and transfer energy in cells
  • Capture energy from processes like food breakdown, powering activities like muscle contraction and molecule synthesis

Enzymes and Activation Energy

  • Enzymes lower activation energy, speeding up chemical reactions
  • Activation energy: minimum energy needed to start a reaction
  • Lowering activation energy accelerates reactions

Enzyme Activity and Substrate Specificity

  • Active site: enzyme region where substrate binds, reacting
  • Substrate: specific molecule upon which an enzyme acts
  • Enzyme's active site shape and properties are specific, like a “lock and key,” ensuring only corresponding substrates bind

Enzyme Inhibition

  • Competitive inhibition: inhibitor resembles substrate, binding to the active site, blocking substrate binding. It can be overcome by increasing substrate concentration.
  • Non-competitive inhibition: inhibitor binds to a site other than the active site, changing the enzyme's shape and reducing its activity. It cannot be overcome by increasing substrate concentration

Cofactors and Coenzymes

  • Cofactors: inorganic molecules helping stabilize or assisting enzyme reaction (ex. metal ions)
  • Coenzymes: organic molecules (ex. vitamins) transferring chemical groups between molecules

Temperature and pH Effects

  • Enzyme activity increases with temperature but decreases significantly beyond optimal temperature
  • Enzyme activity is best at optimal pH; too acidic or basic changes enzyme structure and reduces activity

Food Energy Stages

  • Digestion: proteins, polysaccharides, and fats break down into smaller molecules (amino acids, sugars, and fatty acids)
  • Glycolysis: partially breaks down glucose, producing ATP and NADH
  • Oxidative Phosphorylation: uses energy from molecules' oxidation to form ATP using inorganic phosphate

Glycolysis

  • Purpose: break down glucose for quick energy and production of molecules needed for further energy production
  • Inputs: glucose, 2 NAD+, 2 ADP + 2Pi
  • Outputs: 2 pyruvate, 2 NADH, 2 ATP (net gain)

Acetyl CoA

  • Delivers energy-rich molecules to the citric acid cycle from broken-down sugars, fats, and proteins

Citric Acid Cycle and Oxidative Phosphorylation

  • Citric Acid Cycle: produces energy carriers (NADH and FADH2) and CO2
  • Oxidative Phosphorylation: energy carriers (NADH and FADH2) power ATP production using an electron transport chain and electrochemical gradient

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Unit 3 Exam Study Guide PDF

Description

This quiz covers key concepts in energy and metabolism, including the roles of catabolism and anabolism, the different types of cellular work, and the significance of oxidation and reduction reactions. It also discusses activated carrier molecules and the function of enzymes in lowering activation energy. Test your understanding of these fundamental biological processes!

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