Biology Ch. 4

• The tendency towwards randomness
• the more disordered the system, the higher the entropy

the ability ot do work, to move matter

• Stored energy available to do work
• A baseball player about to throw a ball

• energy being used to do work
• Any mkoving object possesses this
• The soaring baseball

the amount of energy required to raise the temp. of 1 gram of water from 14.5 degrees C to 15.5 degrees C

• The most common unit for measuring the nergy content of food and the heat output of organisms
• The energy required to raise the temp. of a kilogram of water by 1 degree C
• 1 kilocalorie=1000 calories

• The syudt of energy transformations
• The laws regulate the energy conversions vital for life, as well as those that occur in the nonliving world
• They apply to all energy transformations

• The law of energy conversion
• Energy cannot be created or destroyed but only converted into other forms
• The total amount of energy is constant

• all energy transformations are inefficient because every reaction loses some energy to the surroundings as heat.
• You will always lose some energy as heat with every chemical reaction
• Also says that organisms can increase in complexity as long as something else decreases in complexity by a greater amount

• The biochemical reactions of a cell
• Includes all of the chemical reactions in cells, including those that build new molecules and those that break down existing ones

• When the product of one reaction becomes the starting point, or substrate, of another
• Enzymes enable metabolic reactions to procedd fast enough to sustain life

• 1 type of metabolic reaction
• Requires an input of energy to proceed
• the products contain more energy that the reactants
• Tend to build complex molecules from simpler components
• Example- a disaccharide having more energy than its individual monosaccharides-->the reactants must have absorbed energy from its surroundings

• 1 type of metabolic reaction
• Releases energy
• The products contain less energy than the reactants
• Example-cellular respiration-the breakdown of glucose to carbon dioxide and water

• the reaction goes in both directions at the same rate
• Does not always mean that amounts are equal
• The rate of formation is equal

• Energy transformation- transfer energized electrons from one molecule to another
• Oxidation and reductions occur simultaneously b/c if one molecule is reduced (gains electrons), then another must be oxidized (loses electrons)

• the LOSS of electrons from a molecule, atom, or ion.
• Adding oxygen because that is strongly electronegative, which attracts electrons away from their original atom
• release energy as they degrade complex molecules into simpler products

• the GAIN of electrons
• require a net input of energy

• When groups of cytochromes align in membranes with other proteins, they form these
• each protein accepts an electron from the molecule before it and passing an electron to the next
• Small amounts of energy are released at each step of an electron transport chain, and the cell uses this energy in other reactions

• AKA adenosine triphosphate
• Temporarily stores much of the released energy of life
• A go-between molecule that holds the energy released in exergonic reactions, and then applies it to the endergonic ones
• Structurally similiar to a nucleotide
• All cells depend on ATP to power metabolism and many other cellular activities

simultaneous reactions in which one provides the energy that drives the other

• How a cell uses ATP as an energy source
• The transfer of its phosphate group to another molecule
• Can energize the target molecule, making it more likely to bond w/ other molecules-->ATP fuels endergonic reactions
• Can also change in the shape of the target molecule
• Uses these changes to move substances throughout the cell

• A protein that catalyzes (speeds) a chemical reaction without being consumed
• Usually either dismantle or build other molecules
• copy DNA, build proteinsdigest food, and recycle a cell's worn out parts
• Work faster as the temp increases, but only to a limit
• Drugs and poisons can inhibit function

• The amount of energy required to start a reaction
• Initial energy kick
• By reducing the energy activation, some enzymes increase reaction rates a billion times

• the region to which the reactants (substrates) bind
• The active site does not fit like a key in lock, but contorts slightly

• Nonprotein helpers
• Substances that must be present (with also water and substrates) for an enzyme to catalyze a chemical reaction
• Usually oxidized or reduced during the reaction
• Not consumed-->return to their original state when the reaction is complete
• Coenzymes=organic cofactors

• An excess of a reaction's product inhibits the enzyme that controls its formation
• When the product level falls, the pathway resumes its activity
• A thermostat shuts AC off when it's too cold

• When product molecules bind to the enzyme at a site other than the active site, but in a way that alters the shape of the enzyme so that it can no longer bind substrate
• Does not compete to occupy the active site

• The product of the reaction binds to the enzyme's active site, preventing it from binding substrate
• The product competes with the substrate to occupy the active site

• When a product activates the pathway leading to its own production
• Example- blood clotting

• A solute is more concentrated in one region than in a neighboring region
• Tea bag- water is darker around the tea bag

• When a substance moves across a membrane without the direct expenditure of cellular energy
• Involves diffusion

• the spontaneous movement of a substance from a region where it is more concentrated to a region where it is less concentrated.
• Does not require energy input

• a form of passive transport in which a solute moves dowm its concentratiobn gradient w/o the use of a carrier molecule
• Ex- lipids, O2, CO2,

the simplle diffusion of water across a biological membrane

• The plasma's solute concentration is the same as the inside of the red clood cell
• Water doesn't flow in or out of the cell
• Has normal doughnut-shaped form

• concentration of solutes is lower than inside the cell
• Water will enter a red blood cell immersed in pure water
• The cell may burst

• higher concentration of solutes than the cell's cytoplasm
• Cell shrivels and may die for lack of water

• The resulting force of water against the cell wall
• Wilted flower demonstrate lost turgor pressure

• A form of passive transport in which a membrane protein assists the movement of a polar solute along its concentration gradient
• Does not require energy expenditure
• Ex- glucose moves into red blood cells through this process

• A cell uses a transport protein to move a solute against its concentration gradient- from where it is less concentrated to where it is more
• energy to drive this process comes from ATP

Uses ATP as an energy souce to expel 3 sodium ions for every 2 potassium ions it admits

Allows a cell to engulf fluids and large molecules and bring them into the cell

The cell captures and engulfs large particles, such as debris or even another cell

• Opposite of endocytosis
• Uses vesicles to transport fluids and large particles out of cells