Chapter 5 Flashcards
what is the first law of thermodynamics?
energy cannot be created nor destroyed
what is the second law of thermodynamics?
entropy increases spontaneously and energy transfer is never completely efficient
what is entropy?
the measure of disorder of a system
why do cells need energy?
to do work
what is the ultimate source of energy for living organisms?
the sun
energy from the sun flows in what direction through the food chain?
sun > producers > consumers
in what form does energy escape with each energy transfer?
heat (dispersed heat is not a useful form of energy)
what does a metabolic reaction involve?
reactants, intermediates, products
what are the molecules involved with metabolism?
enzymes, energy carriers, cofactors, transport proteins
which reactions require energy/ATP?
endergonic
which reactions release energy/ATP?
exergonic
when is energy released?
when ATP gives up a phosphate group
when ATP gives up a phosphate group, it becomes ____
ADP (which has less potential energy than ATP)
what is phosphorylation?
the transfer of energy when a phosphate group is transferred to another molecule
a cell requires ____ to accumulate ATP by regenerating ADP
energy
without ____, biochemical reactions would proceed very slowly
enzymes
how do enzymes speed up reactions?
they lower the activation energy of reactions
what are the features of enzymes?
- speed up reactions, DO NOT CAUSE reactions
- are not used up in reactions
- work for both forward and backward reactions
- easily recognize and bind to certain substances
where do certain substrates bind to proceed with reactions?
active sites of enzymes (substrate-specific)
what does enzyme activity depend on?
temperature, pH, salt, allosteric regulators, coenzymes, cofactors
when do enzymes become denatures?
in extreme pH and heat
what is an allosteric site?
a region of the enzyme other than the active site; alters the enzyme shape
cofactors, or enzyme helpers, include ____ and ____
coenzymes, metal ions
coenzymes include…
NAP+, NADPH+, NADPH, FAD
what do coenzymes transport?
electrons and protons
what is feedback inhibition?
where the end product in a series of enzymatic reactions inhibits the first enzyme in the series
almost all ____ are coenzymes, or precursors of them
vitamins
unlike enzymes, coenzymes can become ____ during use
altered
what are the two types of metabolic pathways?
anabolic and catabolic
which type of metabolic pathway builds up molecules (biosynthetic)?
anabolic
what type of metabolic pathway breaks down molecules (degradive)?
catabolic
redox reactions involving addition of electrons are ____ reactions
reduced
redox reactions involving removal of electrons are ____ reactions
oxidized
reduced and oxidized redox reactions are how the electron transport chain works in ____ and ____
cellular/aerobic respiration, photosynthesis
cells must have a ____ to control what goes in and out of the cell
membrane layer
____ are responsible for membrane activity
proteins
describe the basic structure of all cell membranes
lipid bilayer with many embedded proteins
in the lipid bilayer, the outer portion of phospholipids is ____
hydrophobic
in the lipid bilayer, the inner portion of phospholipids is ____
hydrophilic
the membrane is a mosaic of…
phospholipids, glycolipids, sterols, proteins
what are the different types of membrane proteins?
active transport, passive transport, receptive, recognition
when does transport require energy?
sometimes if the substance is moving against a concentration gradient
____ is when ions or molecules move away from a concentration gradient
diffusion
the cell membrane is not selective against the movement of…
oxygen, carbon dioxide, nonpolar small molecules, water
the cell membrane is selective against the movement of…
large, organic molecules (such as glucose and ions such as H, Cl, Na, K, Ca)
what do diffusion rates depend on?
temperature, size of concentration gradient, size of molecules
diffusion is higher in ____ temperature, ____ concentration gradient, and ____ molecule size
increased, steeper, small
moving passively from areas of high concentration to low concentration
osmosis
a solution that has higher concentration of solutes than surrounding concentration
hypertonic
a solution that has a lower concentration of solutes than surrounding concentration
hypotonic
a solution that has the same amount of solutes than the surrounding concentration
isotonic
pressure exerted by fluid on the walls of a cell
hydrostatic pressure
cell contents exit the cell by ____
exocytosis
cell contents enter the cell by ____
endocytosis
name the three types of endocytosis
receptor-mediated, phagocytosis, bulk-phase
type of endocytosis where a product binds to receptors on the plasma membrane, where a vesicle is formed
receptor-mediated
type of endocytosis where microorganisms or cellular debris are engulfed
phagocytosis
type of endocytosis where a vesicle forms around a small volume of extracellular fluid regardless of substance
bulk-phase
