Metabolism

Question 1

Metabolism

Answer 1

Chemical processes that occur within a living organism in order to maintain life

Series of chemical reactions in a living organism to sustain life

Question 2

Anabolism

Answer 2

The synthesis of complex molecules from simpler ones

Question 3

Catabolism

Answer 3

The breakdown of complex molecules into simpler ones

Question 4

Oxidoreductase

Answer 4

A class of enzyme that catalyzes oxidation reduction reactions

Question 5

Transferase

Answer 5

A class of enzyme that catalyzes the transfer of chemical groups between molecules

Question 6

Hydrolase

Answer 6

A class of enzyme that catalyzes bond cleavages by reaction with water

Question 7

Lyase

Answer 7

Lyases catalyse the removal of groups from their substrate by mechanisms other than hydrolysis, leaving double bond

Question 8

Isomerase

Answer 8

A class of enzyme that catalyzes conversion of a specified compound to an isomer

Question 9

Ligase

Answer 9

A class of enzyme that catalyzes the joining (ligation) of two molecules by forming a new chemical bond

Question 10

Enzyme

Answer 10

A substance produced by a living organism that acts as a catalyst to bring about a
specific biochemical reaction.

Question 11

Apoenzyme

Answer 11

An enzyme that requires a cofactor but does not have one bound

Question 12

Holoenzyme

Answer 12

And apoenzyme together with its cofactor(s)

Question 13

Allosteric site-

Answer 13

An allosteric site is a specific spot on an enzyme or protein where a molecule can bind. This binding can change the shape and activity of the enzyme

Question 14

Define the terms metabolism, catabolism and anabolism and explain how they relate to each other.

Answer 14

Metabolism: Chemical processes that occur within a living organism in order to maintain life; “collection of controlled biochemical reactions that take place within a microbe”;

Happens through enzyme catalyzed reactions that constitute metabolic pathways
Metabolism requires energy from light or from catabolism of nutrients
Generation of ATP: carbohydrate metabolism, cellular respiration, fermentation
Organisms release energy from nutrients (can be concentrated and stored in high energy phosphate bonds [ATP])
Phosphorylation: organic phosphate is added to substrate
Cells phosphorylate ADP to ATP in 3 ways
substrate-level phosphorylation,
oxidative phosphorylation,
Photophosphorylation
Synthesis of macromolecules: lipids, carbohydrates, amino acids, nucleic acids

Catabolism: degradative phase of metabolism in which organic nutrient molecules are converted into smaller and simpler end products
Cells catabolize nutrients to form precursor metabolites

Anabolism: or biosynthesis, where small simple precursors are built up into larger more complex molecules like lipids, polysaccharides, proteins, nucleic
Precursor metabolites, energy from ATP, and enzymes are used in anabolic reactions (form macromolecules)
Anabolic pathways use some energy of ATP by breaking a phosphate bond

Question 15

Discuss oxidation-reduction reactions. Explain how electrons are involved. List examples.

Answer 15

Underlying chemical reactions of Metabolism
Transfer of electrons from an electron donor to an electron acceptor
Reactions always occur simultaneously
Cells use electron carriers to carry electrons (often in H atoms)
3 Important electron carriers: NAD+, NADP+, and FAD->FADH2
OIL RIG
Oxidation is loss of electrons, reduction is gain of electrons

Question 16

Describe the function and role of enzymes in the cell. Describe common features and how they relate to function.

Answer 16

Enzymes are organic catalysts (increase likelihood of a reaction)
Lower energy of activation
6 categories of enzymes based on mode of action (LIL HOT):
Lyase: breaking of C-C, C-O, C-N, and other bonds by a means other than hydrolysis
Isomerase: reactions involving isomerizations
Ligase: joining of 2 molecules using ATP
Hydrolase: hydrolysis of molecules
Oxidoreductase: oxidation-reduction reactions
Transferase: reactions involving the transfer of chemical groups between molecules
Makeup of Enzymes
Many protein enzymes are complete in themselves
Apoenzymes are inactive if not bound to non-protein cofactors (inorganic ions or coenzymes)
Binding of apoenzyme and its cofactor(s) yields holoenzyme
Some are RNA molecules called ribozymes
Influences on the rate of enzymatic reactions: temperature, pH, enzyme and substrate concentrations, presence of inhibitors

Question 17

Discuss methods of enzyme inhibition.

Answer 17

Mess with temperature, pH, enzyme and substrate concentrations, or add inhibitors
Too high temperature - denatures proteins (breaks down levels of structure)
Non-ideal pH - enzymes work best at about 6-8 pH
Inhibitors: substances that block an enzyme’s active site (does not denature enzymes)
Competitive - block active site (competitive inhibitors competes for active site so that reaction can’t happen)
Can have reversible competitive inhibitors (block active site until substrate concentration is higher)

Allosteric
(non competitive) - changes shape of enzyme so that it can no longer bing to substrate

Question 18

Discuss commercial products produced by fermentation process

Answer 18

CO2 propionic acid (example: swiss cheese)
Lactic acid (example: cheddar cheese, yogurt, soy sauce)
Co2, ethanol (example: wine, beer)
Acetone, isopropanol (example: nail polish remover, rubbing alcohol)