Energy and Enzymes

Question 1

redox

Answer 1

• electrons are energized–> so also transferring energy

Question 2

Electron carrier

Answer 2

• Intermediate step- holds onto/carries electrons to move somewhere else

Question 3

NAD + electron carrier ((Nicotinamide adenine dinucleotide)

Answer 3

• Enzyme cofactor that acts to carry electron
• 2 nucleotides: NMP(+) with AMP
• electrons go on + charge N–> to make neutral, also take H+
• -> creates NADH

Question 4

endergonic

Answer 4

• when delta G is positive
• product takes more energy to make than reactants has
• Unfavorable reactions never go w/o supply of energy from another source. Product higher energy than reactant

Question 5

exergonic

Answer 5

• when deltaG is negative

- Favorable, spontaneous, some energy given off reactant higher energy state than the product

Question 6

ATP hydrolysis

Answer 6

• Take ATP, hydrolyzed to ADP, put Phosphate onto OH to create an intermediate product with a high energy phosphate that can fall off
• Products of ATP hydrolysis
• CONDENSATION STEP: connection of “A” back onto the “B”stand
  Glu + NH3 > Gln would have a positive Delta G
• Glu + NH3 + ATP&raquo_space;> ADP + Pi + Gln has an overall negative DeltaG
• Sum up the Delta G’s and calculate that it is overall a spontaneous reaction

Question 7

catabolic reactions

Answer 7

• reactions of breakdown are mostly spontaneous reactions

Question 8

anabolic reactions

Answer 8

• Reactions of synthesis
• steroids, anabolic steroids
• Mostly unfavorable so require energy

Question 9

Effect of enzyme on the activation energy

Answer 9

• destabilizes chemical bonds to lower activation energy

- More likely to convert to products by lowering the activation energy. Therefore more rapid progression

Question 10

Action of enzyme

Answer 10

• Polypeptide folded up in 3d shape and has active site
• catalysis happens at active site on the enzyme - the place where the substrate binds (substance acted upon by enzyme)
• induced fit- enzyme tightens up on substrate to destabilize bonds

Question 11

enzyme-substrate complex

Answer 11

• substrate binds to enzyme and form enzyme-substrate complex
• enzyme places stress on bond bond (substrate)–> breaks bonds and products are released

Question 12

enzyme pathway

Answer 12

• enzymes have evolved to form chains where the product is the substrate of the adjacent enzyme
• Substrate > enzyme 1 > enzyme 2 > …. > enzyme x > product
• in membrane or cytoplasm

Question 13

feedback inhibition

Answer 13

• when final product give feedback and inhibits enzyme at the start of the process
• final product able to interact with the beginning of the pathway and turn it down activity

Question 14

Competitive inhibition

Answer 14

• some other substance fits in this active site and interferes–> substrate cannot bind to enzyme
• Vmax is the same, Km is higher, affinity for substrate is lowered

Question 15

Noncompetitive inhibition (allosteric inhibition)

Answer 15

• Allosteric site, different shape that binds to different active site–> this changes the shape of enzyme so that the original substrate can no longer bind to the enzyme’s active site
• Vmax is lowered, Km is the same

Question 16

PH optimum

Answer 16

• Enzymes work best at particular pHs- 7 is normal
• ex. Trypsin- lives in lower digestive tract, can see change in folding shape, 6.8 is optimal
• ex. Pepsin works in the stomach (protein digestion) but has an acid pH and works best at low levels

Question 17

temperature optimum

Answer 17

• Optimum temp for human enzyme is 40 degrees C, our bodies are 38 degrees C

Question 18

Michaelis-Menten Plot

Answer 18

• Vmax = (Km)/2Km
• Competitive inhibition- Vmax same, but Km will be larger because the competitor slows down ability of substrate to bind to active site
• noncompetitive- Lower Vmax, Km same because competitor binds to different spot on enzyme

Question 19

competitive inhibition

Answer 19

inhibitors competing with substrate for binding to active site; competitors slow down ability of substrate to bind with active site. Get to point where there are so many substrate molecules that they out-compete competitive inhibitor.

Question 20

noncompetitive inhibition

Answer 20

competitor binds to different spot on enzyme (not active site), which inactivates enzyme by changing its shape – knocks out some proportion of enzyme that is not bound by competitor

Question 21

sucrase enzyme cycle

Answer 21

• enzyme takes sucrose and breaks into glucose and fructose
• enzyme substrate complex- where linkage is destabilized and activation E lowered
• binding site places strain on bond–> products released