Lecture 24: Intro to Metabolsim

Question 1

living organisms require a continual input of free energy for 3 major purposes:

Answer 1

1. mechanical work
2. active transport of molecules and ions in/out of cells
3. making biomolecules and their building blocks

Question 2

what is metabolism?

Answer 2

highly integrated network of chemical pathways that enables a cells to get and use energy from the environment

Question 3

phototrophs

Answer 3

get energy by capturing sunlight in its chemical form

Question 4

chemotrophs

Answer 4

get energy by oxidation of carbon fuels

Question 5

fuels are degraded and large molecules are made step by step in a series of linked reactions called ___

Answer 5

metabolic pathways

Question 6

an energy currency common to all life-forms is ___ and links what 2 pathways?

Answer 6

ATP; energy-releasing and energy-requiring

Question 7

____ powers the formation of ATP

Answer 7

oxidation of carbon fuels

Question 8

t/f a limited number of types of reactions and intermediates are common to many pathways

Answer 8

true

Question 9

metabolic pathways are highly regulated to allow __ and coordinate ___

Answer 9

efficient use of fuels; biosynthetic processes

Question 10

what are the 2 major divisions of metabolism?

Answer 10

catabolism and anabolism

Question 11

catabolism

Answer 11

process that breaks down fuels into cellular energy

Question 12

anabolism

Answer 12

processes that use energy to make biomolecules

Question 13

what are the 3 stages of a metabolic pathway?

Answer 13

1. interconversion of polymers with monomeric intermediates
2. interconversion of monomers with still simpler organic metabolic intermediates
3. the ultimate degradation to or synthesis from inorganic compounds

Question 14

metabolic pathways are __ -dependent

Answer 14

inter

Question 15

metabolic pathways are regulated and controlled in 3 ways

Answer 15

1. control enzyme amounts
2. regulation of catalytic activities of many enzymes
3. compartmentalization

Question 16

how are the enzyme amounts controlled?

Answer 16

regulation of the rate of their synthesis and degradation

Question 17

how is the regulation of catalytic activities achieved?

Answer 17

by allosteric interactions and by covalent modification

Question 18

what is compartmentalization?

Answer 18

movement of many substrates into cells and sub cellular compartments

Question 19

a pathway must satisfy 2 criteria:

Answer 19

1. individual reactions are specific

2. the entire set of reactions must be thermodynamically favoured

Question 20

how are individual reactions made specific?

Answer 20

specificity of enzymes

Question 21

a thermodynamically unfavourable reaction can be driven by __

Answer 21

being coupled with a thermodynamically favourable reaction

Question 22

delta G (free energy) depends on __ and ___ of the reactants

Answer 22

nature and concentration

Question 23

t/f overall free energy change = sum of free energy changes for each step

Answer 23

true

Question 24

ATP is energy rich because its triphosphate contains 2 __

Answer 24

phosphoanhydride linkages

Question 25

an otherwise unfavourable reaction can be made possible by coupling to __

Answer 25

ATP hydrolysis

Question 26

t/f ATP shifts equilibrium. of coupled reactions

Answer 26

true

Question 27

amount of ATP in the body __ and amount used daily__

Answer 27

250g; 60-80 kg

Question 28

ATP and ADP differ due to 4 factors that make ATP an efficient energy currency

Answer 28

1. electrostatic repulsion (ATP has 4- charge resulting in repulsion, reduced by creating ADP)
2. resonance stabilization of othrophosphate
3. increase entropy of the products
4. stabilization due to hydration of ADP and Pi (makes reverse rxn less likely)

Question 29

t/f there is no special reason why ATP is used and not other NTPs, they all have ~ the same delta G, cells have just evolved to use ATP

Answer 29

true

Question 30

t/F ATP is typically in higher concentrations in the cell than other NTPs

Answer 30

true

Question 31

carbon fuels are mainly __

Answer 31

glucose and fats

Question 32

t/f there is considerable energy released by the conversion of glucose to CO2

Answer 32

true

Question 33

in the catabolism of glucose under aerobic conditions, 3 pathways occur

Answer 33

1. glycolysis
2. pyruvate oxidation
3. critic acid cycle

Question 34

glycolysis converts ___ to ___

Answer 34

1 glucose to 2 pyruvate

Question 35

pyruvate oxidation converts ___ to __ and __

Answer 35

2 pyruvate to 2 acetyl CoA and 2 CO2

Question 36

the citric acid cycle converts ___ to __

Answer 36

2 acetyl CoA to 4 CO2

Question 37

carbon oxidation is paired with __

Answer 37

reduction

Question 38

in aerobic oxidation of carbon fuels into CO2, electrons are removed from __ and passed to __

Answer 38

carbon to O2

Question 39

t/f the more reduced a carbon is to begin with, the more free energy it will release when oxidized

Answer 39

true

Question 40

why are fats a more efficient fuel source than carbohydrates?

Answer 40

because the carbons are more reduced to begin with and will release more energy when oxidized

Question 41

what is an activated carrier?

Answer 41

a small molecule carrying activated functional groups that can be donated to another molecule

Question 42

what are 3 examples of activated carriers in metabolism?

Answer 42

ATP, NADH and acetyl CoA

Question 43

the reactions that activated carriers participate in are always enzyme catalyzed

Answer 43

true

Question 44

many activated carriers function as ___ and are derived from vitamins

Answer 44

co-enzymes