Bioenergetics and Enzymes

Question 1

Metabolism

Answer 1

chemical reactions which organisms acquire and use energy and transform materials

Question 2

catabolic pathways

Answer 2

release energy by breaking down complex molecules into simple molecules

Question 3

anabolic pathways

Answer 3

absorb energy by using simple molecules to build complex molecules

Question 4

energy that can do work in the cell (free energy)

Answer 4

chemical- synthesizing polymers from monomers
transport- pumping substances across the membranes
mechanical- beating of cilia and muscle contraction

Question 5

energy that cannot do work (thermal)

Answer 5

never 100% effienct

Question 6

Free energy

Answer 6

can perform work when thermal and pressure are uniform through the system

Question 7

spontaneous reaction

Answer 7

releases free energy (G will be negative) and exergonic (energy outwards), free energy lost, downhill

Question 8

non-spontaneous reaction

Answer 8

absorbs free energy (G will be positive) and endergonic (energy inward), will not proceed unless coupled with an outside process that supplies energy

Question 9

Exergonic

Answer 9

releases energy, and produces more reactant potential energy then the products

Question 10

Endergonic

Answer 10

absorbs energy, and have products with more potential energy then reactants

Question 11

Cellular Metabolism

Answer 11

sum of endergonic and exergonic reactions in the cell

Question 12

Energy coupling

Answer 12

using energy released from exergonic reactions to drive endergonic reactions

Question 13

Kinetic energy

Answer 13

contains a moving mass or particles

energy transferred through a work place its involved

Question 14

chemical energy

Answer 14

flow of charged particles

Question 15

mechanical energy

Answer 15

energy in mechanical devices

Question 16

light energy

Answer 16

harnessed in photosynthesis

Question 17

Potential energy

Answer 17

stored engery

Question 18

chemical energy

Answer 18

stored in molecular bonds

Bond energy: chemical bonds take the same amount to break as to release energy

Question 19

Living Cells

Answer 19

stored energy on atomic bonds of food

release stored energy slowly through respiration

Question 20

ATP

Answer 20

energy carrier in cells - energizes molecules by phosphorylating them

Question 21

Hydrolysis of ATP is an?

Answer 21

Exergonic process

• ADP and Pi are more stable (less free energy) than ATP because charge repulsion
• stabilization of inorganic phosphate group
• loss of H+ by terminal phosphate group on ADP
• enhanced hydration of the products of the reaction compared to the reactants
• ATP has high activation energy therefore enzyme is needed for hydrolysis to occur at a rapid rate

Question 22

ATP synthesis is an ?

Answer 22

Endergonic process

• requires energy
• hydrolysis yields

Question 23

What happens when endergonic process and ATP hydrolysis are coupled?

Answer 23

reaction would be exergonic and spontaneous
Because
-hydrolysis doesn’t provide heat, phosphorylation does
- ATP hydrolysis only heats surrounding
-ATP hydrolysis provides own energy without phosphorylation and is bound tightly at the myosin head, then hydrolyzed, and the head changes position while ADP and Pi are released

Question 24

Enzymes are proteins that catalyze biochemical reactions

Answer 24

• lower activation energy of reactions makes reactions go faster
• doesn’t change G of reaction

Question 25

Enzymes are specific

Answer 25

one or few substrate (enzyme works on)

Question 26

Enzymes have active sites

Answer 26

(small part of enzyme to bind to substrate) | Induce fit: substrate binding causes a change in the shape of the active site

Question 27

Enzyme can lower activation energy by

Answer 27

- holding reactants in position to promote reaction - provide suitable micro-environment - employing amino acid side chains in the active site for covalent bond reorganization - Enzyme regenerates during reaction (further catalytic cycles) but not indefinitely (enzymes have half life)

Question 28

Affecting enzymes : Substrate concentration

Answer 28

- too little substrate= active sites arent occupied enough | - too much substrate= not enough active sites avaliable

Question 29

Affecting enzymes : Temperature

Answer 29

- high= high rate of enzyme reaction -too high= enzyme denatures (broken down) Enzyme has an optimal temperature

Question 30

Affecting enzymes : pH

Answer 30

- optimal pH 6-8 | - extreme pH = enzyme denatures (breaks down)

Question 31

Cofactors

Answer 31

small, non-proteinaceous molecules required by most enzymes for their catalytic activity - may bind tightly or loosely to active site or enzyme - some organic eg. coenzyme - some inorganic eg. metals

Question 32

Inhibitors and Activators; Competitive inhibitors

Answer 32

resembles enzymes normal substrate and competes with substrates for active site

Question 33

Inhibitors and Activators; Non-Competitive inhibitors

Answer 33

does not enter active site but binds elsewhere

Question 34

Feedback inhibition

Answer 34

product pathway inhibits the first enzyme of a pathway

Question 35

Negative Feedback

Answer 35

(metabolic path or hormone-secreting gland) is inhibited by the product of the reaction, gland or path as the concentration builds up the product molecules inhibit the process that produced them