Metabolism Overview Quiz

Metabolism Overview

• Metabolism is the sum of all chemical reactions within a cell or organism.
• These reactions provide energy for vital processes and create new organic material.
• Bioenergetics studies energy flow in living systems.

Learning Outcomes

• Describe anabolic and catabolic pathways in metabolism.
• Explain different types of energy and chemical reactions that use/release energy.
• Explain how the first two laws of thermodynamics relate to living organisms.
• Describe the role of ATP in cellular energy use and metabolic processes.
• Describe the functions and regulation of enzymes in cell metabolism.

Learning Objectives

• Define a metabolic pathway and categorize it as catabolic or anabolic.
• Discuss feedback inhibition in metabolic pathways.
• Identify endergonic and exergonic reactions and describe changes in Gibbs free energy (ΔG).
• Explain how the first two laws of thermodynamics relate to living organisms
• Define activation energy and explain why even exergonic reactions require it.
• Explain the role of ATP as cellular energy currency.
• Describe how energy is released through hydrolysis of ATP.
• Explain how enzymes function as molecular catalysts.
• Discuss enzyme regulation by various factors.

Energy and Metabolism

• Earth's life forms get energy from the sun.
• Bioenergetics studies how energy flows in living systems

Metabolic Classification

• All organisms fall into phototrophs or chemotrophs based on energy source.
• Autotrophs use inorganic carbon sources and heterotrophs use organic carbon sources.
• Examples include cyanobacteria, vascular plants, heliobacteria, sulfur-oxidizing bacteria, and animals.

Metabolism Definition

• The sum of chemical reactions within each cell of a living organism providing energy for processes and creating new organic material

Metabolic Pathways

• Anabolic reactions synthesize large molecules from smaller ones, requiring energy.
• Catabolic reactions break down large molecules into smaller ones, releasing energy.

ATP's Role

• ATP is a small, water-soluble molecule, the cell's primary energy currency.
• Removing a phosphate group releases energy, a reversible reaction.

Functions of ATP

• Gluconeogenesis: making glucose from non-carbohydrate sources.
• Active transport (e.g., sodium-potassium pump).
• Cellular signaling: activates molecules to signal.
• Nucleic acid (DNA/RNA) synthesis.
• Protein synthesis: energy-dependent process on ribosomes.
• Movement and Muscle contraction (actin-myosin interaction).
• Phagocytosis (cell engulfing pathogens).
• Neurotransmitter (e.g., smooth muscle activation).

Types of Energy

• Energy is the ability to do work.
• Energy can be kinetic (motion) or potential (stored)
• Chemical energy is stored in bonds of molecules.

Free Energy

• Gibbs Free Energy (G) is the amount of energy available to do work.
• ΔG (change in G) after a reaction:
• Negative ΔG indicates spontaneous exergonic reactions.
• Zero ΔG indicates equilibrium reactions (no net change).
• Positive ΔG indicates non-spontaneous endergonic reactions

Enzymes

• Enzymes are protein catalysts
• Speed up reactions by lowering activation energy.
• Bind reactants, promoting bond-breaking and forming.
• Highly specific for one reaction only.

Enzyme-Substrate Specificity

• Enzymes have active sites where substrates bind.
• Induced fit: enzyme changes to fit the substrate
• Products leave the active site, releasing the enzyme for use with another substrate.

How Enzymes Lower Activation Energy

• Enzymes lower the "activation energy" (energy needed to start a reaction).
• This allows reactions to occur faster at normal physiological temperatures, without the need for extreme temperatures that damage cells.

Enzyme Regulation

• Cells control enzyme activity.
• Enzyme regulation helps cells meet needs (e.g., digestive enzymes more active after meals).
• Temperature and pH can affect enzyme activity.
• Coenzymes/cofactors affect enzyme activity.
• Inhibitors and Activators regulate enzyme activity (increasing/decreasing rate of reaction).

Control of Metabolic Sequences

• Products from one reaction become a substrate for the next.

End Product Inhibition

• End-product inhibits an earlier enzyme in the pathway.

Everyday Connection (Drug Discovery)

• Drugs often target enzymes in specific pathways as inhibitors.

Examples of Enzymes

• Lactase (breaks down lactose)
• Catalase (breaks down hydrogen peroxide)
• Glycogen synthase (forms glycosidic bonds between glucose molecules)
• ATPase (breaks down ATP)

Enzyme Cofactors

• Cofactors are inorganic (e.g., Fe+, Mg+, Zn+) or organic (e.g., coenzymes) molecules that help enzymes work.
• Some vitamins act as coenzymes.

Factors affecting Enzyme Activity

• Temperature (optimum temperature needed)
• pH (optimal pH)
• Enzyme concentration (increased activity to a point)
• Substrate concentration (increased substrate activity to a point)

Test your knowledge on the essential concepts of metabolism, including anabolic and catabolic pathways. This quiz covers key components such as ATP, enzyme functions, and the laws of thermodynamics as they relate to living organisms. Prepare to deepen your understanding of bioenergetics and metabolic processes.