lecture 2: energy and metabolism

Question 1

what is metabolism?

Answer 1

sum of all the chemical reactions within an organism

Question 2

what catalyzes reactions in our body?

Answer 2

enzymes

Question 3

what is a catabolic reaction?

Answer 3

-breaks down complex molecules into simpler compounds
-releases energy

Question 4

what type of reaction is cellular respiration?

Answer 4

catabolic

Question 5

what is an anabolic reaction?

Answer 5

-builds complex molecules from simpler ones
-requires energy

Question 6

what type of reaction is photosynthesis?

Answer 6

anabolic

Question 7

what are metabolic pathways?

Answer 7

they are series of reactions where the product of one reaction is the reactant of the next one. these pathways exist in our body. an enzyme catalyzes each reaction.

Question 8

what is the first law of thermodynamics?

Answer 8

energy is neither created or destroyed, it is transformed.

Question 9

what is the second law of thermodynamics?

Answer 9

every energy transformation makes the universe more disordered (increases entropy).

Question 10

what is the cause of the second law of thermodynamics?

Answer 10

during every reaction, some usable energy is lost as heat.

Question 11

true or false, all energy transformations are 100% efficient.

Answer 11

false! always some energy lost as heat

Question 12

what is Gibb’s free energy? what is the formula?

Answer 12

portion of a system’s energy that is available for work. G=H-TS

Question 13

what shows you if a chemical reaction is spontaneous or not?

Answer 13

-if delta G is negative: spontaneous, energy is released
-if delta G if positive: not spontaneous, energy us consumed

Question 14

what is the formula for the change in free energy (2)

Answer 14

-delta G= G final state-G starting state
-delta G= delta H- T(Delta S)

Question 15

what is the difference between endergonic and exergonic?

Answer 15

-endergonic: requires an input of energy
-exergonic: net release of energy

Question 16

give an example of a spontaneous (exergonic) reaction

Answer 16

cellular respiration

Question 17

give an example of a non-spontaneous (endergonic) reaction

Answer 17

photosynthesis

Question 18

what is a trick to know if a reaction is spontaneous/non-spontaneous, depending on a free energy graph?

Answer 18

if the energy level of the products is greater than the reactants, its non-spontaneous

Question 19

when can a system not do ANY work?

Answer 19

when its at equilibrium, because Delta G=0

Question 20

if a human cell is at equilibrium, can it survive?

Answer 20

no. since no work can be done inside the cell, the cell would die

Question 21

how are non-spontaneous reactions powered?

Answer 21

through energy coupling

Question 22

true or false? going against the concentration gradient requires energy

Answer 22

true!

Question 23

what is energy coupling?

Answer 23

when a spontaneous reaction is physically coupled with a non-spontaneous process so that energy released from the spontaneous reaction is used to power the non-spontaneous one

Question 24

how is the production of ATP an example of energy coupling?

Answer 24

1) glucose is broken down (spontaneous)
2) protons are (H+) are pumped from one side of the mitochondria to the other, against the concentration gradient (non-spontaneous)
3) the protons return to equilibrium, respecting the concentration gradient (spontaneous)
4) when the proteins return to equilibrium, they pass by a channel that is attached to a turbine. when they pass this turbine, they spin it, which attaches pi to ADP, and thus make ATP (non-spontaneous)

Question 25

is the work in our body endergonic or exergonic?

Answer 25

endergonic. thats why we need food and water to power cellular work.

Question 26

what are the 3 types of work done in our body that are endergonic?

Answer 26

-chemical (synthesis), like protein synthesis
-mechanical (beating cilia, chromosome movement, actin-myosin muscle contraction)
-intracellular transport (active transport)

Question 27

is the hydrolysis (breakdown) of ATP exergonic or endergonic?

Answer 27

it is highly exergonic. the energy released is how we power cellular work

Question 28

what is inorganic phosphate (pi)?

Answer 28

H3PO4

Question 29

where does the main source of energy come from when ATP IS hydrolisized? what does the part broken off become?

Answer 29

the last phosphate group. the broken off phosphate group becomes an inorganic phosphate

Question 30

How is the ATP cycle renewable?

Answer 30

Question 31

how much ATP can be formed from one glucose molecule?

Answer 31

in theory 94, in reality, 32 (energy lost as heat)

Question 32

how can ATP activate a reactant? give an example.

Answer 32

it can couple its hydrolysis to an endergonic chemical reaction. it can transfer one of its PHOSPHATE groups to the reactant. an example of this is the conversion of glutamic acid glutamine. We can link the hydrolysis of ATP to an endergonic reaction

Question 33

true or false? a reaction coupled to ATP hydrolysis is spontaneous.

Answer 33

true!

Question 34

what type of work can we couple ATP to in order to power them?

Answer 34

chemical (Synthesis) and transport work (active transport)

Question 35

how does ATP couple in order to power transport work?

Answer 35

the addition of a phosphate group (negative charge) to a carrier protein disrupts bonds on the protein, which makes it change forms. this change of shape allows it to move a molecule across a membrane. when P comes off, its now Pi, and the carrier protein changes shapes again.