HumBio3A-Notes2 Flashcards
sequence of food to cells
food, catabolic pathways, biosynthesis, anabolic pathways, cells
what is the original source of all energy?
the sun
respiration
sugars + O2 = H2o + CO2
photosynthesis
Co2 +H20= O2 + Sugars
Catabolism - type of reaction
energetically favorable reaction
Anabolism - type of reaction
energetically unfavorable reaction
ATP
adenisine tri-phosphate
ATP is the ______ of the cell
energy currency of the cell
How much ATP is needed in a cell?
100,000 X more than what is in the cell
ATP hydrolysis provide______
chemical energy to power reactions that requre energy
3 uses of energy/ATP
transport work, mechanical work, biosynthetic work
transport work
pumping Na+ and K+ in nerves of the brain, pumping H+ into the stomach
What is ATP?
small molecule, ribose ring coupled to an adenine base, with tri-phosphate chain
Why does ATP contain so much energy?
it’s like a compressed spring. It takes A LOT of energy to form the bond, and that is released when it breaks apart
ATP successor
ADP + Pi + energy
Does ADP become ATP again?
yes, using energy from food via mitochondria
ATP analogy in class
Starbucks charge card
types of bonds that hold ATP together
covalent bonds
How does ATP hydolysis power reactions that require input of energy to proceed?
energy coupling
example of energy coupling
muscle contraction
Relaxed muscle p + nATP=
contracted muscle +nADP + nPi
△G
change in free energy of a reaction
△G =
G(final) - G(initial)
can delta G values for coupled reactions be added together?
yes
If the final form has less free energy, then _________
△G is negative and the reaction can proceed
Can a reaction that results in positive delta G occur?
yes, because of thermal bombardments
Equilibrium
number of Y molecules being converted to X each second is exactly equal to the number of X molecules being convertted to Y molecules each second, so that ther is no net change in the ratio of X to Y.
At equlibrium, delta G is ________
0
Are most reactions in our cells at equilibrium?
no! we’d be dead
ATP + H2O =
ADP + H3PO4
Why is ATP an effective energy carrier?
because equilibirume in the basic reaction is reached very slowly
does delta G predict the rate of a reaction?
no! it only predicst the types of reactions that may occur
How can reactions be coupled?`
when a favorable reaction in the sequence uses up the product of an unfavorable reaction, thus driving the unfav reaction (unsettling the equilibirum)
Another way of coupling reactions…?
Using the energy of ATP hydeolysis to drive formation of new chemical bonds
what does delta G predict?
which reactions can occur
Why can’t ATP be used to predict the rate of reactions?
the activation energy required
Why can ATP be an energy carrier?
it has a large activation barrier
How do cells get around the activation barrier?
Catalysis
What lowers the activation barrier?
an enzyme
Are enzymes broad or specific?
very specific
