chapter 8: bioenergetics

Question 1

1st law of thermodynamics

Answer 1

energy is neither created or destroyed

Question 2

2nd law of thermodynamics

Answer 2

when energy is converted from one form to another, some of that energy becomes unavailable to do work

Question 3

why can products have less potential energy than reactants?

Answer 3

at least some energy is lost during the reaction; changes forms (heat)

Question 4

chemical form of energy

Answer 4

stored in bonds

Question 5

electrical form of energy

Answer 5

separation of charges

Question 6

heat form of energy

Answer 6

transfer due to temperature difference

Question 7

light form of energy

Answer 7

electromagnetic radiation stored as photons

Question 8

mechanical form of energy

Answer 8

energy of motion

Question 9

metabolism

Answer 9

the sum of all biochemical reactions in an organism

Question 10

spontaneous, exergonic reactions

Answer 10

when delta G is negative, energy released, energetically favorable

Question 11

nonspontaneous, endergonic reactions

Answer 11

delta G is positive, energy consumed, need energy input to occur

Question 12

redox reactions

Answer 12

• may transfer electrons alone or with protons
• reduction: gain of electron
• oxidation: loss of electron

Question 13

FAD and NAD

Answer 13

• oxidized and reduced constantly - very easy to oxidize and reduce
• need to couple the reduction reaction with another one
• endergonic, nonspontaneous

Question 14

coupling reactions

Answer 14

exergonic reaction drives an endergonic reaction

Question 15

ATP

Answer 15

energy currency of the cell

Question 16

where does ATP hold its energy

Answer 16

phosphate bonds

Question 17

when is energy released from ATP?

Answer 17

when it is hydrolyzed
- not a redox reaction
- catabolic bc it involves breaking down a molecule

Question 18

how much ATP does the body turn over every day?

Answer 18

equivalent to its own body weight; ATP continuously recycled in organisms

Question 19

what is ATP hydrolysis coupled to

Answer 19

endergonic reactions in cells

Question 20

enzymes

Answer 20

• contain binding sites for coupled reactions so they can occur together
• increase reaction rate exponentially
• max rate depending on concentration
• if all enzyme is bound to substrate - max reaction rate

Question 21

how do enzymes help biochemical reactions occur

Answer 21

they reduce energy investment into biochemical reactions by facilitating the reaction between molecules

Question 22

allosteric regulation: noncompetitive inhibition

Answer 22

• binding of regulatory subunit to enzyme, changes shape of enzymes so substrate cant bind at active site anymore

Question 23

competitive inhibition

Answer 23

molecule similar to substrate binds to active site and blocks substrate binding

Question 24

allosteric regulation: activation

Answer 24

binding of a regulatory subunit to enzyme, changes shape of enzymes and now substrates can bind to active site

Question 25

allosteric regulation: adding a phosphate *i could see this being on an exam*

Answer 25

changes 3-D shape of a protein to reveal an active site so a substrate can bind

Question 26

cofactors

Answer 26

nonprotein molecules or inorganic ions, often a metal ion, that some proteins require in order to function - includes coenzymes and ATP

Question 27

how did metabolic pathways probably evolve? | not sure if we will actually need to know this

Answer 27

backwards 1) enzyme 1 evolves and converts substrate 1 into a key product 2) substrate 1 is used up, new enzymatic activity evolves to produce substrate 1 from another substrate 3) the cycle repeats, additional steps added to series of reactions ultimately forming a full pathway

Question 28

glycogen

Answer 28

carbohydrate that represents a huge amount of energy; >30 ATP from one molecule