Metabolism

Question 1

An organism’s metabolism transforms matter and energy how?

Answer 1

via metabolic pathways

Question 2

Free energy change means what?

Answer 2

between reactants and products tells us which reactions occur spontaneously and which require input of energy

Question 3

How does ATP work

Answer 3

powers cellular work by coupling energy-producing and energy-requiring reactions

Question 4

exergonic meaning

Answer 4

spontaneous

Question 5

endergonic meaning

Answer 5

not spontaneous

Question 6

Exergonic reactions

Answer 6

not necessarily fast; enzymes speed up metabolic reactions by lowering energy barriers

Question 7

how is enzyme function affected

Answer 7

by local conditions (temp, pH) and other chemical regulators (activators, inhibitors)

Question 8

Metabolism meaning

Answer 8

sum of an organism’s chemical reactions

Question 9

Catabolic pathways

Answer 9

release energy by breaking down complex molecules to simpler molecules

Question 10

example of catabolic pathway

Answer 10

oxidation of glucose during cell respiration

Question 11

Anabolic pathways

Answer 11

use energy to build complicated molecules from simpler ones

Question 12

example of anabolic pathway

Answer 12

synthesis of sugars during photosynthesis, or polymers from monomers

Question 13

where is chemical energy stored

Answer 13

in the position of electrons

Question 14

electrons in the outer shell have…

Answer 14

more potential energy than electrons in inner shells

Question 15

how can electrons transfer in chemical reactions?

Answer 15

transferred between atoms and can move to a lower energy state

Question 16

what happens when electrons move to a lower energy state?

Answer 16

energy is released as electrons fall down this energy gradient from high to low energy state

Question 17

lots of potential energy

Answer 17

have an abundance of hill top electrons in a high energy state

Question 18

what happens with electron movement

Answer 18

potential energy (and/or entropy) may change during chemical reactions due to electron movement

Question 19

Reaction of 2 hydrogen and 1 oxygen

Answer 19

• electrons are held more tightly in the products than the reactants
• product has lower potential energy than the reactants
• reaction is spontaneous
• doesn’t require energy but releases energy

Question 20

making more complex structures

Answer 20

does not occur spontaneously and requires input of energy

Question 21

higher entropy and less ordered reactions

Answer 21

are spontaneous, energetically favourable, process

Question 22

exergonic reactions energy

Answer 22

release energy for cellular work (- amount of kJ/mol)

Question 23

endergonic reactions energy

Answer 23

absorb energy (+ amount of kJ/mol)

Question 24

Cell work that requires energy

Answer 24

• cilia and flagella movement
• active membrane transport
• synthesis of polymers/complex molecules

Question 25

ATP stands for?

Answer 25

adenosine triphosphate

Question 26

ATP consists of

Answer 26

Three phosphate groups, a ribose sugar, and adenine

Question 27

high potential energy in ATP is from

Answer 27

4 negative charges in P groups repel each other

Question 28

Hydrolysis means

Answer 28

breaking of bonds between phosphates by addition of water.

Question 29

what does hydrolysis release

Answer 29

inorganic phosphate and energy

Question 30

phosphorylation meaning

Answer 30

the addition of a phosphate group to a protein or other organic molecule

Question 31

what can phosphorylation do?

Answer 31

change the shape or confirmation of molecules to make things work within cells

Question 32

how does ATP power cellular work

Answer 32

by coupling exergonic reactions to endergonic reactions

Question 33

The ATP cycle meaning

Answer 33

catabolic processes continuously provide energy to regenerate ATP by phosphorylation

Question 34

what do reactions require? and how does it happen?

Answer 34

breaking of chemical bonds and formation of bonds. molecules must pass through less stable transition state

Question 35

transition state involves?

Answer 35

an initial increase in free energy

Question 36

why is energy required in reactions?

Answer 36

to contort reactant molecules so old bonds break and new bonds can form

Question 37

increase in free energy =

Answer 37

activation energy

Question 38

enzymes function

Answer 38

catalysts that lower the activation energy barrier and increase rate of reaction

Question 39

4 ways enzymes lower activation energy

Answer 39

1) bring reactants together in specific orientations in the active site 2) stabilize the transition state by interactions with AA side-chains 3) provides micro-environment more conducive to reaction 4) R-groups in active site can participate directly in reaction

Question 40

enzymes characteristic

Answer 40

not rigid or static, they are flexible and dynamic

Question 41

induced fit model

Answer 41

substrate binding changes the shape of the enzyme. Results in tighter substrate binding facilitating chemical reactions

Question 42

initiation of enzyme action

Answer 42

reactants bind to active site in specific orientation, forming enzyme-substrate complex

Question 43

transition-state facilitation enzyme action

Answer 43

enzyme-substrate interaction lowers activation energy required for reaction

Question 44

termination of enzyme action

Answer 44

products have lower affinity for the active site and are released. enzyme is unchanged after reaction

Question 45

enzymes don't work alone...

Answer 45

they require cofactors (metal ions) or small organic molecules, coenzymes

Question 46

most enzymes are regulated...

Answer 46

regulatory molecules can either activate or inactivate enzymes

Question 47

regulation by competitive inhibition

Answer 47

a molecule similar in size/shape to a substrate binds at the active site. Competition with the substrate for the active site reduces reaction rates

Question 48

Allosteric regulation

Answer 48

regulatory molecules bind away from the active site. Binding changes the shape of the enzyme and the active site

Question 49

activation of allosteric regulation

Answer 49

make the active site more accessible to substrates

Question 50

inhibition of allosteric regulation

Answer 50

less accessible to substrates

Question 51

rate of catalysis - low substrate concentration

Answer 51

reaction rates increase in linear fashion

Question 52

rate of catalysis - intermediate substrate concentration

Answer 52

the increase begins to slow

Question 53

rate of catalysis - high substrate concentration

Answer 53

reaction rates plateau at a maximum speed (saturation kinetics)

Question 54

when the enzymes become saturated

Answer 54

at some point active sites on the enzyme cannot accept substrates any faster no matter how large the substrate concentration is