BIO 1140 - Cell Metabolism Flashcards
What is Energy?
capacity to cause change, especially to do work (to move matter against an opposing force).
- Different forms of energy are interconvertible
What is Kinetic Energy?
energy associated with the relative motion of objects
What is Chemical Energy?
energy available in molecules for release in a chemical reaction (= potential energy)
What is Thermal Energy?
kinetic energy due to the random motion of atoms and molecules (= heat)
What is Potential Energy?
energy that matter possesses as a result of its location or spatial arrangement
What is the First Law of Thermodynamics?
thetotal amountof energyin theuniversemustalways bethesame
What is the Ultimate Source of Energy?
Light Energy
- Universal source is the sun
- Used in photosynthesis
- the radiant energy of sunlight sustains all life, with few exceptions
What type of Energy do All Animals live on?
All animals live on energy stored in the chemical bonds of organic molecules (from food)
- Animals eat plants or eat other animals that eat plants.
- Plants obtain their energy directly from sunlight.
How does Solar energy enter the living world?
Solar energy enters the living world through photosynthesis in plants
What is Photosynthesis?
Photosynthesis is a process that converts the electromagnetic energy in sunlight into chemical-bond energy in organic molecules.
What is Cellular Respiration?
Cellular Respiration is a process that extracts energy from organic molecules (food) by gradual oxidation.
What is Oxidation?
The addition of oxidizing agent
- Takes away electrons
- Most common agent is oxygen
What is Reduction?
The converse reaction, called reduction, involves the addition of electrons to an atom.
What is the Second Law of Thermodynamics?
Living cells create and maintain order in a universe that is tending always toward greater disorder.
What is Entropy?
Measure of system’s disorder
- Requires constant energy for cell function + organization
- creates more favourable environments for cell systems
- Order is necessary for survival
When is Disorder increased?
The increased order inside the cell is accompanied by increased disorder in the cells’ surroundings
- Disorder increases when useful energy that could be harnessed to do work (free energy) is dissipated as heat
What is Gibb’s Free Energy?
amount of energy available in a molecule to do work in a system when the temperature and pressure are uniform
- measured in in kcal/mole.
- can also be expressed in joules (1 cal = 4.184 joules
Where is Gibb’s Free Energy Stored?
stored in the bonds between individual atoms of a molecule
What does Gibb’s Free Energy cause?
causes vibration, rotation and movement of the molecule through space
What are the Two ways Chemical Reactions in a cell can Cause Disorder?
- The reaction can decrease the amount of order in the cell
- Changes of bond energy of the reacting molecules can cause heat to be released, which disorders the environment around the cell
What does the Free-Energy Change determine?
The free-energy change for a reaction determines whether it can occur
What does the Change in Free Energy measure?
measures theamount ofdisordercreated in the universewhen areactioninvolving these moleculestakesplace
- the change inorder inside the cell and the change in order of the surroundings
What is the Free Energy of a Spontaneous Reaction?
A chemical reaction that occurs spontaneously must have a negative ΔG
- The disorder of the universe can only increase.
- ΔG is negative if the disorder of the universe (reaction plus surroundings) increases
- Exergonic Reaction
- Favourable
What happens to Reactions at Equilibrium?
the rates of the forward and reverse reactions are equal
- Reactions will eventually reach a chemical equilibrium
- ΔG = 0, so the reaction will not proceed forward or backward
What is Standard Free Energy used to predict?
Standard free energy change (ΔG°) is used to predict the outcome of a reaction
- The ΔG° is independent of concentration
- it depends only on the intrinsic characters of the reacting molecules
What does Standard Free Energy represent?
the gain or loss of free energy as one mole of reactant is converted to one mole of product under “standard conditions”
- all molecules present at a concentration of 1 M and pH 7.0
What are Coupled Reactions?
A reaction that is unfavorable (has a positiveΔG°) can be driven by a second, highly favorable reaction.
What are Exergonic and Endergonic Reactions?
A reaction with negative change in free energy (ΔG<0) is considered exergonic
A reaction with positive change in free energy(ΔG>0)is considered endergonic
What is an Exergonic Reaction?
Spontaneous reactions are exergonic: they release energy (∆G <0)
- energetically favorable reactions
- reaction product has a lower free energy level (more stable)
- Can release the free energy (potential energy) contained in bonds
What are Endergonic Reactions?
Non-spontaneous reactions are endergonic: they require energy (∆G >0)
- energeticallyunfavorablereactions
- The reaction product has a higher free energy level than the substrate
- Can store energy in molecules
What are Activated Carriers?
Activated carriers can store energy either as a readily transferable chemical group or as readily transferable (“high energy”) electrons
- ATP, NADH and NADPH are the most important activated carriers.
What is Catabolism and Anabolism?
Catabolism: The breakdown of complex molecules into a more simple form (building blocks)
Anabolism: The synthesis of complex molecules from simple forms (building blocks)
What is ATP?
ATP is the most widely used activated carrier
- adenosine triphosphate
- 1 adenosine (nitrogenous base) + 1 ribose (sugar) + 3 phosphate groups
How is ATP synthesized?
ATP is synthesized in an energetically unfavorable phosphorylation reaction
- a phosphate group is added to ADP (adenosine 5ʹ-diphosphate)
What are Enzymes?
Activation of enzyme is required to start chemical reactions
- cells control enzymes
- inhibitors
What are the two types of Inhibition?
- Competitive Inhibition
- Allosteric inhibition
What is Competitive Inhibition?
Competes with substrate to active site
- blocks substrates from binding
What is Allosteric Inhibition?
Attach to enzyme to change its conformation
- non-competitive
- Deactivates enzyme
How do Enzymes help reactions?
Enzymescatalyze reactions and speed up their rate, but they cannot change theΔG°of a reaction.
- A spontaneous reaction is not necessarily an instantaneous reaction
What is Activation Energy?
Even energetically favorable reactions require activation energy to get them started
- energy required to start a reaction
- Prevents unnecessary / unwanted reactions from occurring
- Enzymes act as catalysts and lower the activation energy
Where does the varying Activation Energy come from?
The varying energies come from collisions with surrounding molecules, which make the substrate molecules jiggle, vibrate, and spin.
- produces heat
- increase in temp
- increase in kinetic energy
What is a Metabolic Pathway?
A series of enzyme-catalyzed reactions forms a metabolic pathway
- Each enzyme catalyzes a chemical reaction involving a particular molecule.
- Chemical reactions involve making, breaking and rearranging covalent bonds.
What is Metabolism?
Metabolism is the sum total of all the chemical reactions inside the cell
- Metabolic pathways are linked to one another, forming a complex web of interconnected reactions.
