2.1 Energy & Metabolism

All Lesson notes on Energy and Metabolism

What is Metabolism?

refers to all the chemical reactions that occur in a cell, usually to transform matter and energy

What are metabolic pathways?

Reactions which usually occur in step-by-step sequence

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eg. Product of one is the reactant in the next

What are anabolic reactions?

Each reaction is catalyzed by an enzyme that builds large molecules

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Small → Big (Build)

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ex. photosynthesis

What are catabolic reactions?

when large molecules are broken into smaller products

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Big → Small (Destroy)

Catastrophic

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Ex. Cellular respiration

What is Energy?

the capacity to do work

What is Kinetic energy?

the energy of motion

What is potential energy?

stored energy

What does the cell require?

the transformation of potential energy into kinetic energy

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ex. cilia moving, active transport and protein pumping

What is bond energy?

The energy required to break (or form) chemical bonds

What is an endothermic reaction?

when a chemical bond is broken between two atoms, energy is used

What is exothermic reaction?

when a chemical bond forms between two atoms, energy is released

What is crucial for respiration and photosynthesis?

endothermic and exothermic reactions are crucial in the production of energy and the absorption of energy

General Info on Bond Energy:

energy is always released when a bond forms, free (unbonded) atoms can be considered to have more chemical energy than any compound.

What is Thermodynamics?

the study of energy changes in a system

What is the First Law of Thermodynamics?

energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another

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ex. plants can absorb light but they can’t create it.

What is the Second Law of Thermodynamics?

during any process, the universe tends towards disorder

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ex. unless you consistently use energy to clean, your room will eventually get dirty

What is an Endergonic Reaction?

The products of the reaction contain more energy than the reactants, and energy must be supplied for the reaction to proceed.

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Endothermic reaction - up the hill diagram

What is an Exergonic Reaction?

The products contain less energy than the reactants, and excess energy is released.

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Exothermic reactions - down the hill diagram

(exit)

What do spontaneous reactions require?

an initial input of energy, such as a spark to begin them

What is activation energy?

destabilizes the existing chemical bonds

What are enzymes used for?

required to lower the activation energy of a reaction and reduce the amount of time it can take for a reaction to occur.

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* biological catalyst

what is ATP?

* energy released by catabolic reactions is captured in the molecule, and is used to power reactions in a coupled reaction.
* bonds between the negative phosphate groups in this molecule contain a large amount of energy
* when their bonds are hydrolyzed and broken, they release that stored energy to do work in the cell.

What is a Coupled Reaction?

* The use of ATP can be thought of as a cycle
* cells use exergonic reactions to provide the energy needed to synthesize ATP from ADP and Pi
* They then use the hydrolysis of ATP to provide the energy for endergonic reactions

What are Oxidation-Reduction Reactions

* “Redox” reactions
* Electrons move between atoms
* Loss of electrons is oxidation
* Gain of electrons is reduction

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LEO the lion says GER

What are Electron Carriers?

* redox reactions are coupled reactions
* electrons are said to carry reducing power since the reduced form of a molecule (which accepts electrons carrying energy) is always a higher energy level then the oxidized form

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compounds that pick up electrons from energy-rich compounds and donates them to low-energy compound

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What are the two most important electron carriers?

NAD+ (nicotinamide adenine dinuclotide) & the **reduced form** **NADH**

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FAD (flavin adenine dinuclotide) & the **reduced form FADH2**

What is a cofactor?

is a non-protein chemical compound or metallic ion that is required for an enzyme’s role as a catalyst.