ch 6 Flashcards
organisms that capture energy from sunlight are called
phototrophs (plants are most common example)
plants use the energy of sunlight to convert carbon dioxide and water into __ and __
sugar and oxygen
organisms that obtain energy by breaking down organic compounds acquired from ingesting other organisms into carbon dioxide and water
chemotrophs (animals)
organisms that are able to convert carbon dioxide into glucose are called
autotrophs (or “self feeders”)
organisms that obtain their carbon by eating other organisms or molecules derived from other organisms are called
heterotrophs (or “other feeders”)
plants are phototrophs and autotrophs, making them
photoautotrophs
animals are both chemotrophs and heterotrophs, making them
chemoheterotrophs
microorganisms that gain energy from sunlight but obtain their carbon from preformed organic molecules are called
photoheterotrophs
microorganisms that extract energy from inorganic sources but build their own organic molecules are called
chemoautotrophs
The building and breaking down of carbon sources to harness or release energy
metabolism
catabolism:
the set of chemical reactions that break down molecules into smaller units and produce ATP
anabolism:
the building of molecules from smaller units, requiring an input of energy (ATP)
the energy of a system is:
the system’s capacity to do work
kinetic energy:
the energy of motion
ex: a ball bouncing down a set of stairs posses kinetic energy
potential energy:
stored energy
ex: the potential energy of a ball at the top of a flight of stairs is higher than it’s potential energy at the bottom of the stairs
chemical energy is a form of __ energy
potential
ATP is composed of:
adenosine- base adenine & 5 carbon sugar ribose attached to triphosphate (3 phosphate groups)
the chemical energy of ATP is held in the ____
bonds connecting the phosphate groups
the chemical bonds connecting the phosphate groups in ATP store ___ energy that is released when the bonds are broken. In turn, the released energy can power the __ of a cell.
potential; work
the first law of thermodynamics:
(law of conservation of energy) the universe contains a constant amount of energy. energy is neither created nor destroyed, it just changes from one form to another
when energy changes form, the total amount of energy remains __. But in going from one form of energy to another, the energy available to do work __.
constant; decreases
second law of thermodynamics:
the transformation of energy is associated with an increase of disorder in the universe
the degree of disorder in the universe is called
entropy (S)
__ __ is a form of kinetic energy corresponding to the random motion of molecules, and results in a given temperature.
thermal energy
in chemical reactions, most of the entropy increase occurs through the transformation of various forms of energy into ___, which we experience as heat
thermal energy
in living organisms, catabolic reactions result in an __ of entropy as a single ordered biomolecule is broken down into several smaller ones with more freedom to move around
increase
anabolic reactions seem to __ entropy bc they use individual building blocks to synthesize more ordered biomolecules such as proteins or nucleic acids
decrease
the amount of energy available to do work is called
Gibbs Free Energy (G)
reactions with a negative deltaG that release energy and proceed spontaneously are called
exergonic
reactions with a positive deltaG that require an input of energy and are not spontaneous are called
endergonic
a chemical reaction in which a water molecule is split into a proton (H+) and a hydroxyl group (OH-)
ATP + H2O –> ADP + P
the reaction of ATP with water is an __ reaction that releases energy
exergonic
__ is an energy acceptor and __ is an energy provider.
ADP; ATP
proteins that act as catalysts in most chemical reactions are
enzymes
the energy input necessary to reach the transition state is called the
activation energy
enzymes reduce activation energy by:
stabilizing the transition state and decreasing its free energy
enzymes are folded into 3D shapes that bring particular amino acids into proximity to form an __
active site
(this explains why enzymes are so big, so they can move as they need to in order to bring together the amino acids to form the active site)
the __ of an enzyme is the portion of the enzyme that binds substrate and converts it into product
active site
irreversible inhibitors:
usually form covalent bonds with enzymes and irreversibly inactivate them
reversible inhibitors:
form weak bonds with enzymes and easily dissociate from them
competitive inhibitors:
bind to the active site of the enzyme and prevent the binding of a substrate (compete with substrate by being structurally similar)
> can be overcome by increasing the concentration of the substrate
non competitive inhibitors:
usually have a structure very different from the substrate and bind to the enzyme at a place different from the active site, so enzyme can still bind to substrate but it slows down the enzymes ability to catalyze by changing the shape of the enzyme and reducing its activity
negative feedback:
the final product inhibits the first step of the reaction
allosteric enzyme:
an enzyme that is activated or inhibited when binding to another molecule changes its shape.
Chemical energy:
possible due to the position of electrons around the nucleus of an atom. The farther away the electron is from the nucleus, the larger the amount of potential energy present
the total energy available
enthalpy (H)
Catabolic reactions have a __ ΔG and release energy, often in the form of ATP.
negative
Anabolic reactions have a __ ΔG and require an energy input, often in the form of ATP
positive
