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Biology 101, Chapter 5

Terms in this set (60)

Energy
The capacity to do work
Kinetic energy
energy of motion
potential energy
stored energy. (objects are not moving, but have the capacity to do so)
first law of thermodynamics
The total amount of energy before and after every conversion is always the same; energy cannot be created or destroyed
heat
during each conversion, energy is lost as what?
second law of thermodynamics
the tendency of entropy to increase (energy tends to spread out spontaneously)
entropy
a measure of how much the energy of a particular system has become dispersed
heat
what is random molecular motion that is produced as entropy increases?
through the sun
how does energy flow into the biological world?
chemical bonds
how is energy stored?
reactants
starting substances in a chemical reaction
products
ending substances in a chemical reaction
activation energy
the minimum energy required to start a reaction
endergonic reactions
1. reactants have less free energy than the products
2. converts molecules with lower free energy to molecules with higher free energy
endergonic reaction
What kind of reaction is this?
both
Which reactions need enzymes: endergonic or exergonic?
endergonic
Which reactions need energy: endergonic or exergonic?
exergonic rections
1. reactants have more free energy than the products
2. converts molecules with higher free energy to molecules with lower free energy
exergonic reaction
What kind of reaction is this?
catalysts
substances that influence bonds in a way that lowers the activation energy
enzymes
1. can be re-used
2. recognize reactants and products and can catalyze reactions in both directions
3. have active sites
4. cannot make endergonic reactions happen spontaneously
active sites
areas that allow binding to specific substances
Transition state
occurs when reactions overcome activation energy and run spontaneously
helping substrates get together,
orienting substrates in positions that favor reactions,
inducing a fit between enzymes and substrates,
shutting out water molecules that interfere with reactions
how do enzymes bring on the transition state?
high
enzymes are denatured at ___ temperatures
neutral, acidic (for digestive)
most enzymes in the human body function best at a ___ p.h., but some digestive enzymes work best at ___ p.h.
metabolic pathways
enzyme-mediated sequences of reactions
allosteric enzymes
have regulatory sites where an inhibitor or activator binds, altering the enzyme's configuration
feedback inhibition
the end product inhibits an enzyme in the pathway
redox reactions
electron transfers between molecules
reduced
a molecule that accepts electrons is ___
oxidized
the molecule that looses electrons is ___
cofactors
metal ions or organic molecules that bind to many enzymes and make them more reactive
coenzymes
organic molecules that carry chemical groups, atoms, or electrons from one reaction to another in metabolic pathways
ATP
an important co-enzyme that functions in energy transfer
phosphate bonds
where is energy stored?
periferal proteins
membrane protein that is on the surface
integral proteins
membrane protein that goes through the phospholipid bilayer
channels
integral proteins can form ___ that allow other molecules to travel through the membrane
integral proteins
Channel proteins are also what?
adhesion proteins
hold cells together
recognition proteins
distinguishes self from non-self
receptor proteins
attachment sites for hormones or toxins
transport proteins
help move substances across the plasma membrane
diffusion
a net directional movement of molecules
dynamic equilibrium
when there is no gradient, there is no net movement in any direction. molecules collide randomly.
semipermeable membranes
allow molecules of a certain size to pass
osmosis
the movement of water across membranes
tonicity
relative concentrations of 2 solutions
hypertonic
a fluid that has high solute concentration
hypotonic
a fluid that has a low solute concentration
isotonic
2 fluids with identical solute concentrations and are separated by a semipearmiable membrane
hypotonic to hypertionic
which direction does water move?
small, uncharged molecules
what kind of molecules can move across the cell membrane by diffusion/osmosis?
charged molecules, large molecules
what molecules can't move across the cell membrane without assistance (sometimes energy)?
Passive transport
gradients drive diffusion of a substance across a cell membrane through transport proteins
active transport
to move ions & large molecules across a membrane against a concentration gradient, special proteins are induced to change shape, but only with an energy boost from ATP
exocytosis
a vesicle moves to the cell's surface, and its membrane fuses with the plasma membrane. its contents are released to the surroundings.
endocytosis
particles outside of the cell are enclosed in small portions of the cell membrane. Vesicles are formed and move into the cytoplasm
phagocytosis
The cell engulfs microorganism, debris, or food particles.
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