PBIO EXAM 3 Flashcards
Energy
the capacity to do work
Thermodynamics
the science of energy transformations
Potential Energy
energy stored in an object?
First Law of Thermodynamics
energy can be changed from one form to another but cannot be created or destroyed
2nd Law of Thermodynamics
In all energy exchanges and conversions, if no energy leaves or enters the system under study, the potential energy of final state will always be less than the potential energy of the initial state.
Entropy
a measure of the randomness or disorder of a system
Open System
Life. energy in from the surroundings, energy out to the surroundings. Open system: order maintained.
Close System
No energy in from the surroundings. Closed system: order becomes disorder
Exergonic
energy out
Endergonic
energy in
Oxidation
the loss of a electron
Reduction
is the gain of an electron
Energy of activation
the energy that must be possessed by molecules in order to react is known as the
Enzyme
a substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction
Catalyst
is substance that lowers the activation energy required for a reaction by forming a temporary association with the molecules that are reacting
Substrate
the molecule on which an enzyme acts is known as its substrate
Active Site
This portion of the enzyme is known as the active site
Cofactor
One or more non-protien components require by enzymes in order to function many are metal ions; others are coenzymes
Coenzyme
an organic molecule, or nonprotein organic cofactor, that plays an accessory role in enzyme-catakyzed processes, often by acting as a donor or acceptor of electrons; NAD+ and FAD are common coenzymes.
Coupled Reactions
reactions in which energy-requiring chemical reactions are linked to energy-releasing reactions
Metabolic Pathway
Each enzyme catalyzes one small step in an ordered series of reactions that together form a metabolic pathway. (Chains of enzymatic cascade reactions)
Optimized Enzyme Working Environment
pH, temperature, and light
Induced Fit
A change in conformation occurs when the substrate is bound.
Lock and Key model
proposes that the enzyme’s active site and the shape of the substrate molecule are complementary to one another.
Photosynthesis
conversion of light energy to chemical energy; the production of carbohydrates from carbon dioxide and water in the presence of chlorophyll by using light energy
Photon
Elementary particle of light
The Hill Reaction
the portion of the light reations in which electrons from water are transferred to an electron acceptor, reducing the acceptor
Light-dependent reactions
Reactions happen in the thylakoid membrane of the chloroplasts and occur in the presence of sunlight
Two Steps of photosynthesis
Light dependent reactions on thylakoid membrane (hill reactions, Z shceme, energy transduction reactions) Carbon Fixation reactions
2. Light independent reactions in stroma (the dark reactions, carbon fixation reactions) Energy transduction reactions
The Z scheme
Photosynthetic electron transport. Describes the pathway of electron transfer from H2O to NADP+ that occurs during noncyclic electron flow, as well as the energy relationships
The Z scheme of photophosphorylation follows the following sequence: PS IIA→e−acceptorB→ETSB→PSIC→e−acceptorD→NADP+
Energy transduction reactions
Reactions that in which energy change forms. Light reactions are a good example
Carbon Fixed Reactions
In photosynthetic cells, the light independent ezymatic reactions concerned with the synthesis of glucose from CO2 ATP and NADPH. also called light independent reactions and dark reactions.
light-independent reactions
Takes place within the stroma. It contains exzymes that work with ATP and NADPH to “fix” carbon from carbon dioxide into molecules that can be used to build glucose.
dark reactions
is also called carbon-fixing reactions.
Stroma
Stroma is the fluid filling up the inner space of the chloroplasts which encircle the grana and the thylakoids. In addition to providing support to the pigment thylakoids, the stroma are now known to contain chloroplast DNA, starch and ribosomes along with enzymes needed for Calvin cycle.
thylakoids
each of a number of flattened sacs inside a chloroplast, bounded by pigmented membranes on which the light reactions of photosynthesis take place, and arranged in stacks or grana. They help absorb sunlight in order for photosynthesis to occur
The main photosynthetic pigments
Chlorophylls, carotenoids, and phycobilins
Chlorophylls
A (Blue, reflects green) B (Green reflects yellow?)
Carotenoids
carotenes and xanthophylls
mainly as anti-oxidants.
