Ch 8 Microbial Metabolism

Question 1

Metabolism of microbes

Answer 1

-All chemical reactions and physical workings of the cell
-Occurs through arise of enzyme-catalyzed reactions

Question 2

Anabolism

Answer 2

-Synthesis - built up
-Biosynthesis: synthesis of cell molecules and structures
-Requires energy input
*Lipids, polysaccharides, proteins and nucleic acid

Question 3

Catabolism

Answer 3

-Break the bonds of larger molecules
-Release energy

Question 4

Catalysts (enzyme)

Answer 4

-Speed up the rate of a chemical reaction without becoming part of the products or being consumed in the reaction

Question 5

Enzymes overcome the activation energy allowing the reaction to proceed by:

Answer 5

-Increasing thermal energy (heating) to increase the velocity of molecules
-Increasing the concentration of reactants to increase the rate of molecular collisions
-Adding a catalyst

Question 6

Characteristics of Enzyme

Answer 6

-Most composed of protein; may require cofactors
-Act as organic catalysts to speed up the rate of cellular reactions
-Lower the activation energy required for a chemical reaction to proceed
-Have an active site for target molecules (substrates)
-Associate closely with substrates but do not become integrated into the reaction products
-Are not used up or permanently changed by the reaction
-Can be recycled, thus function in extremely low concentrations
-Can be regulated by feedback and genetic mechanism

Question 7

Substrates

Answer 7

-reactant molecules upon which enzymes act
-Bind to the active/catalytic site “ock and key” fit.

Question 8

How do enzymes work?

Answer 8

-Bind to substrates and participate directly in changes to the substrate
-Does not become part of the products
-Is not used up by the reaction
-Can function over and over again

Question 9

Simple enzymes

Answer 9

consist of protein alone

Question 10

Conjugated enzyme/holoenzyme

Answer 10

-Contains protein and some other non-protein molecule
-A combination of the protein called apoenzyme and one or more cofactors

Question 11

Apoenzyme

Answer 11

-Protein portion of the enzyme
-the actual site where the substrate binds
-three dimensional crevice or groove formed by the way amino acid chains are folded
*Each enzyme has a different primary structure, variations in folding and unique active site

Question 12

Cofactor

Answer 12

-Non protein portion (metal ions/ in-oraganic)
-Binds to the enzyme
-increase the rate of the reactions with covalent interactions
-

Question 13

Coenzyme

Answer 13

-Organic cofactors
-Organic non-protein molecules that carry chemical groups between enzymes
-“carriers”
-loosely bound
-made of vitamins, biotin, coenzyme A

Question 14

Apoenzyme levels of structure

Answer 14

-Primary: polypeptide chain
-Secondary: chain begins to fold
-Tertiary: folds turn into 3D shape which creates active sites

-Quaternary: Complex enzymes consists of several polypeptide chains bound by weak forces.

Question 15

Constitutive enzymes

Answer 15

-Present in constant amounts inside the cell

Question 16

Regulated enzymes

Answer 16

-Concentration of regulated enzymes in cell increase or decrease in response to substrates
-Production is turned on (induced) or turned off (repressed)

Question 17

Enzyme repression

Answer 17

-Stops further synthesis of an enzyme somewhere along it’s pathway
-if product of enzymatic reaction reaches excess, the genetic apparatus for replacing enzymes is suppressed

Question 18

Enzyme induction

Answer 18

-Enzymes are induced when suitable substrates are present

Question 19

Competitive inhibition

Answer 19

-A molecule that resembles the substrate occupies the active site, preventing the substrate from binding
-Enzyme cannot act on the inhibitor and is effectively shut down

Question 20

Non-competive inhibition

Answer 20

-Some enzymes have two binding sites—the active site and the regulatory site
-Regulated by the binding of molecules other than the substrate to the regulatory site
-Often, the regulatory molecule is the product of the enzymatic reaction
-Provides negative feedback that slows enzyme activity once a certain concentration of product is reached