Cell Bio Exam 2: pt. 1 - Bioenergetics
Studied by 0 people
Learn
Practice Test
Spaced Repetition
Match
Flashcards1/78
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
|---|
No study sessions yet.
79 Terms
bioenergetics
the flow of energy in the cell
what is energy
the capacity to cause specific chemical or physical changes
what 6 categories of change require energy
synthetic, mechanical, concentration, electrical, generation of heat, and generation of light
what is synthetic work
changes in chemical bonds
what is an example of synthetic work
the process of photosynthesis
what does biosynthesis do
aids in growth and maintenance of cells and cellular structures
what is mechanical work
changes in the location or orientation of a cell or subcellular structure
what is often required for movement
cilia or flagella
what is an example of mechanical work in the body
muscle contraction
what is concentration work
moving molecules across a membrane against a concentration gradient
what does concentration work do
accumulates substances within a cell or removes toxic by-products
what are examples of concentration work in a cell?
the concentration of specific molecules and enzymes in organelles and import of sugar/amino acids into cells
what is electrical work
moving ions across a membrane against an electrochemical gradient
what happens during electrical work
ions are transported across a membrane
what is the result of ions being transported across a membrane
a difference in concentration and electrical potential
what is an example of electrical work in cells
the membrane potential of mitochondrion
what is heat work
an increase in temperature that is useful to warm0blooded animals
what is a homeotherm
animals that regulate their body temperature independent of the environment
What is bioluminescence?
the product of light by living organisms (fireflies)
how is bioluminescence generated?
by the reaction of ATP with luminescent compounds
what is a type of fluorescent protein useful to biologists?
green fluorescent protein
how do organisms obtain energy
phototrophs: sunlight
chemotrophs: oxidation of chemical compounds
how do phototrophs get energy from sunlight?
they use solar energy to produce all the carbon compounds they need from CO2
how do chemotrophs get energy from oxidation of chemical compounds?
they oxidize chemical bonds in organic molecules (carbohydrates)
what is the equation for phototroph's synthesis of light?
CO2 + H2O -> sugars +O2
what is the equation for chemotroph's synthesis of sugars?
sugars + O2 -> CO2 +H2O
What 4 atoms cycle continuously between phototrophs and chemotrophs?
carbon, nitrogen, oxygen, and phosphorous
what is oxidation
the removal of electrons from a substance, usually hydrogen atoms and addition of oxygen atoms
do oxidation reactions release energy
yes
what is reduction
the addition of electrons to a substance through addition of hydrogen atoms (and loss of oxygen atoms)
do reduction reactions require energy
yes
what is energy flow in the universe governed by
3 laws of thermodynamics
what is thermodynamics
area of science that deals with energy transactions that accompany all physical and chemical processes
what is the "system" in thermodynamics
the energy under consideration in any particular case
what is the "surroundings" in thermodynamics
everything outside the system
what is a closed system
it is sealed from the environment and can neither take nor release energy
what is an open system
it can have energy added to it or removed from it
are organisms open or closed systems
open
what does the exchange of energy between a system and its surroundings occur as?
heat or work
why is heat not a useful energy source for cells?
because many biological systems are isothermal (at a fixed temperature)
what is work?
the use of energy to drive a process other than heat flow
what is the unit for quantifying energy changes during chemical reactions?
calorie/kcal
what unit of energy do physicists prefer?
joules (J)
How many calories is one Joule?
0.239 calories
what is the first law of thermodynamics?
law of conservation of energy: energy cannot be made or destroyed
what is the total energy stored within a system called?
internal energy
what is delta E?
the difference in internal energy of a system before a process (E1) and after it (E2)
How is delta E written in a chemical reaction?
delta E = E products - E reactants
what do biological processes focus on calculating in a system?
enthalpy
what is enthalpy (H)?
the heat content of a system
does delta E usually equal delta H?
yes because there is little change in pressure and volume in biological reactions
how is enthalpy change calculated for a reaction?
delta H = delta H of products - delta H of reactants
What does it mean if delta H is negative?
it is an exothermic reaction; energy is released
what is an example of an exothermic reaction?
burning gasoline in a car
what does it mean if delta H is positive?
the reaction is endothermic, energy is absorbed
what is an example of an endothermic reaction?
melting of an ice cube
what is the second law of thermodynamics?
reactions have directionality; they can proceed spontaneously only in one direction
what is thermodynamic spontaneity?
a measure of whether or not a reaction or process can occur
what does it mean for a reaction to be thermodynamically spontaneous?
it is a favorable reaction
what is entropy (S)
measure of randomness of disorder
when does entropy increase in a system?
when the system becomes disordered
when does entropy decrease in a system
when the system becomes more ordered
what is free energy (G)
the measure of spontaneity for a given system; gibbs free energy
what is every spontaneous reaction characterized by
a decrease in free energy of the system
how do you calculate delta G?
delta G = G products - G reactants
what does it mean if delta G < 0
the reaction is thermodynamically spontaneous
how do you calculate delta G in a system?
delta H - T*delta S
when does delta G increase
when delta H increases
when does delta G decrease
when delta S increases
what is an exergonic reaction
an energy-yielding reaction that occurs spontaneously
is the oxidation of glucose exergonic or endergonic
exergonic
What is the delta G calculated for the oxidation of glucose?
-686 kcal/mole
what is an endergonic reaction
energy is required and it does not occur spontaneously
is the reduction of carbon dioxide endergonic or exergonic?
endergonic
what is the delta G calculated for the reduction of carbon dioxide?
+686 kcal/mole
what is the rate of a reaction at equilibrium?
the forward and backward rates are the same
what would happen if a cell reached equilibrium?
it would be dead
what makes life possible?
cells maintaining a steady state and never reaching equilibrium
what makes it possible for cells to remain in a steady state?
the cell being an open system that receives energy from the environment