Sec 7- Energy Flashcards
Unit III- Energy Matters
What is energy?
The capacity to do work.
Energy comes in different forms:
* Light
* Electricity
* Heat
* Kinetic (movement)
* Potential (location)
What is the first law of thermodynamics?
Conservation of energy:
* Energy cannot be created or destroyed
* It can be converted from one form to another and thus transferred between objects or systems
What is the second law of thermodynamics?
- Energy tends to disperse spontaneously
- A bit disperses at each energy transfer, usually in the form of heat
- Entropy (randomness) always increases (without the input of energy)
Why does a cell need energy?
- Move things
- Metabolism (breaking and making molecules)
- Transport things across borders (cell membranes)
How does the cell store energy?
A cell stores energy in chemical bonds between atoms of molecules (chemical energy)
What is chemical energy?
Chemical energy is a form of potential energy, and it is stored in the bonds between atoms in molecules.
- Certain organisms capture the energy from the sun and convert that into the chemical energy of food, gasoline, and other fuels.
What is ATP?
- ATP is the energy currency of the cell; “carriers” energy
- ATP is a “middle man”
- Is made in mitochondria
- Is made through a process called cellular respiration
- In cellular respiration the chemical energy from food is transferred to the chemical energy of ATP
What is the structure of ATP?
Consists of adenosine plus a tail of three phosphate groups (adenosine triphosphate)
- Energy is stored in the bond to the third phosphate; when that bond is broken energy is released and the resulting molecule is called adenosine diphosphate (ADP)
What is the ATP Cycle?
- ATP is constantly made from, and broen down into, ADP and phsophate
- The addition of a phosphate is called phosphorylation (ADP is phosphorylated into ATP)
The removal fo a phsophate is called dephosphorylation (ATP is deohosphorylated into ADP)
What is energy transfer in chemical reactions?
Cells store and retrieve energy by making and breaking chemcial bonds in chemical reactions
- Some reactions require a net input of energy- others end with a net release of energy
- Chemical reations have reactants and products:
- Reactant- Molecule that enters a reaction
- Product- A molecule remaining at the end of a reaction
What are metabolic pathways?
- Series of enzyme-mediated reactions by which cells build, remodel, or break down an organic molecule
- Metabolic pathways can be linear or cyclical
Anabolic: Small molecules are assembled into large ones. Energy is required. (endothermic)
Catabolic: Large molecules are broken down into small ones. Energy is released. (exothermic)
What does the world not go up in flames?
Molecules of life release energy when combines with oxygen- but not spontaneously- energy is required to start even exergonic reactions.
- Activation energy- Minimum amount of energy required to start a reaction.
What is activation energy?
This is the energy needed for a reaction to occur.
What are enzymes?
Enzymes lower the activation energy, meaning that less energy is needed for a reaction to begin.
- Enzymes make chemical reactions proceedmuch faster than they would on their own.
- Enzymes are catalysts
- Enzymes lower the activation energy for chemical reactions to occur
- Protein (or RNA) that speeds a reaction without being changed by it (used over and over)
- Enzymes bind substrates (reactants)
- Many enzymes are named for their substrates but with an “ase” ending
- Sucrase
- Lactase
- Cellulase
What is induced fit?
The active site fits to the substrae, and the enzyme changes shape slightly. This interaction is called induced fit.
- Each enzyme is very selective; catalyzes specific reaction
- Each enzyme recongnizes a specific substrate
- An enzyme is not changed and can be used repeatedly
