Biochem Exam 2

The 'lock and key hypothesis' attempts to explain the mechanism of

enzyme specificity

Which of the following activates glycolysis

fuctose-2,6-bisphosphate

Enzymes are a special type of

protein

The molecule to which an enzyme joins is called its

substrate

What is the function of the glycolytic pathway

to break glucose down to pyruvate and other intermediates that can be used in the body

Glycolysis ends in the production of

two molecules of pyruvic acid

What is the difference between ~P and -P

~P is a high energy bond that can make ATP -P can't make ATP yet

Explain the importance of the primary structure of collagen

-Gly-X-Y structure, X usually Pro and Y usually Hyp. -Hydroxylated amino acids Hyp and Hyl are found exclusively in collagen

What cofactors are required by Kinase enzymes

-Mg2+ -ATP

There are six classes of enzymes in the classification scheme. Which of these classes are represented by glycolytic enzymes

-Oxido reductase -Transferase -Hydrolysis -Ligase -Isomerase -Lyase

What are three classes of reversible inhibitors (toxins) of enzyme activity

-competitive inhibitors -noncompetitive inhibitors -uncompetitive inhibitors

Identify three differences that an enzyme has as compared to an inorganic catalyst like Pt

-enzymes have an extremely high specificity towards their substrate and usually only catalyze one reaction -enzymes undergo conformational changes -enzyme activity is easily controlled

What are five mechanisms of enzyme reuglation employed by biological symptoms

-induction -allosteric regulation -partial proteolysis -covalent modification -control proteins

What molecules can serve as substrates from which glucose can be made

-lactic acid, pyruvate -Asp, Ala -Glycerol -Propinyl CoA

During the process of glycolysis, how many substrate level phosphorylation events occur for each molecule of glucose metabolized, and at what point in the glycolytic process do these occur?

1. glucoase to glucose-6-phosphate 3. fructose-6-phosphate to fructoase-1,6-bisphosphate 6. 1,3-bisphosphoglycerate to 3-phosphoglycerate 9. phosphoenolpyruvate to pyruvate

What is the glycolytic substrate for the enzyme enolase

2-PGA (2-phosphoglycerate)

Glycolysis requires an initial 'investment' of

2ATP

What is a pyranose

Carbohydrates with 5C and 1O

Where would i go about finding a molecule of G-6-Pase in the human body

Endoplasmic reticulum of liver and kidney

The fluoride ion has beneficial effects on bone and tooth development but in the glycolytic process it can be detrimental. Why?

F is a toxin to enolase (2-PGA to PEP) if enolase doesn't work, glycolysis wills top at 2PGA and it wont go further

What is responsible for the contraction in muscle fibers

Myosin heads grab and release the actin filament, pulling towards the M line. THis has to do with mysoin binding to ATP, and ATP hydrolysis and release. Ca2+ controlls troponin, which causes tropomyosin to either block or unblock the actin binding site

Which of these molecules are produced by glycolysis

NADH

What cofactors are required by the dehydrogenase enzyme of glycolysis and gluconeogenesis?

NADH and Pi

Metabolism of glucose via the glycolytic pathway results in the fomraiton of a net of two ATP molecules. If we had a died that supplied fructose instead of glucose how much ATP would we get?

Net would still be 2 ATP

What cofactors are required by carboxylase enzymes?

PC requiers Mg2+, ATP, and biotin

Which enzyme is the priary site of regulation in the glycolytic pathway and specifically how is this regulation achieved?

PFK is the primary site of regulation, achieved by allosteric regulation. ATP: inhibition AMP: activation Citrate: inhibition F-2,6-BP: activation H+ ions: inhibition G-6-P: inhibition

How is the activity of the enzyme Phosphoglycerate Mutase controlled

The reaction that PGM catalyzes is bidirectional, so this enzyme is controlled by equilibrium

How could you identify which class one of these inhibitors falls into

You can look at the [s]/V grapths -competative has two different starting points and cross on the Y axis -noncompetitive has the same starting point but two ending points -uncompetitive are two parallel lines

If NADH were not reoxidized to NAD, what affect would this have on glycolysis?

You would run out of NAD, and GAP wouldn't be converted to 1,3-BGP anymore after a certain point

What is the definition of a cofactor

a cofactor is an activator metal or coenzyme that needs to be present for a enzyme to work

Explain how chromatography can be used to separate two different proteins from a single solution

can be separated based on their molecular weight or size -will react with the liquid and will move a certain distance based on its affinity and size

Under some circumstances (futile cycle) fructose-1,6-bisphosphate may be hydrolyzed to form fructose-6-phosphate and phosphoric acid nearly as rapidly as it is formed. When this is happening, the major effect noticed would be

increased temperature in the tissue and organism.

At 25 C, the optimum reaction rate of a certain enzyme occurs at a pH of 7. A greater reaction rate could probably be attained by

increasing the temperature to 35C and keeping the pH 7

The source of blood glucose during the early stages of starvation is primarily

liver glycogen

Of the five mechanisms, which occurs most rapidly and which occurs most slowly

most rapid: allosteric slowest: induction

Coenzymes are best defined as

organic molecules which help in enzyme-catalyzed reactions by bonding with electrons

List three factors which influence the rate of enzyme activity and specificity explain their influence on this activity

pH: depends on the enzyme but away from optimum denatures temperature: higher temp increases rate until it causes the enzyme to denature substrate concentration: higher the [s], the greater the enzyme activation

We consume some fructose in our diet. The fructose can provide energy by

phosphorylation by fructokinase or hexokinase to form fructose-1-phosphate or fructose-6-phosphate and further oxidation through glycolysis