Biochemistry chapter 2

Question 1

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Answer 1

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Question 2

Since they are incredible biological catalysts.

• Lower the activation energy
• Increase the rate of the reaction
• Do not alter the equilibrium constant
• Are not changed or consumed in the reaction( which means that they will appear in both recants and products.)
• Are Ph- and temperature sensitive, with optimal activity at specific pH ranges and temperatures
• Do not affect the overall G of the reaction
• Are specific for a particular reaction or class of reactions

Answer 2

What are the functions of enzymes?

Question 3

The molecules upon which an enzyme acts are called substrates; with that being said a given enzyme will only catalyze or class of reactions with these substrates

Answer 3

What is enzyme specificity?

Question 4

Catalyze the movement of a functional group from one molecule to another. For example aminotransferase can convert aspartateand alpha-ketoglutarate–as a pair– to glutamate and oxaloacetate by moving the amino acid from aspartate to alpha- ketoglutarate . Kinases catalyze the transfer of a phosphate group, generally from ATP to another molecule

Answer 4

What is the enzyme transferases? What are kinases?Give an example

Question 5

Catalyzes the breaking of a compound into two molecules using the addition of water. For example peptidases, nucleases, and Lipase which break down proteins, nucleic acids, and lipids. These included with hydrolases.

Answer 5

What is the enzyme hydrolases ? Give examples of hydrolases

Question 6

Catalyze the cleavage of a single molecule into two products. They reverse their specific reaction, the synthesis of two molecules into a single molecule may also be catalyzed by a lyase. Or known as synthases

Answer 6

What is the enzyme Lyases?

Question 7

Catalyze the rearrangement of bonds within a molecule. Some isomerasescan be also be classified as oxidoreductases, transferases, or lyases just because its still a rearrangement at the end of the day depending on the mechanism.

Answer 7

What is the enzyme Isomerases?

Question 8

Catalyzes addition or synthesis reaction, generally between large molecules and often require ATP. Synthesis with smaller molecules are generally accomplished by lyases. Mnemonic: LI’L HOT
LigaseIsomeraseLyase
HydrolasesOxidoreductase
Transferase

Answer 8

What is the enzyme of Ligases? Also list the mnemonic for all the 6 enzymes

Question 9

The molecules upon which enzyme acts is a substrate. Then we have a physical interaction between these two is referred to as the enzyme-substrate complex

Answer 9

What is a substrate? What is enzyme-substrate complex?

Question 10

They are non protein molecules that both activators of enzymes. Cofactors tend to be inorganic minerals, while coenzymes tend to be small organic compounds (vitamins). Alsothe derivative of vitamins such as NAD+, and FAD. With In both water soluble vitamins include B complex vitamins and acerbic acid(vitamin C). They must be replenished regularly because they are easily secreted. The fat soluble vitamins A,D,E,K. In both casesthese regulators induce a conformational change in the enzyme that promotes its activity.

Answer 10

What do cofactors and coenzymes do? How do they differ? Name the organic compounds

Question 11

Enzymes without their cofactors are apoenzymes.
Without enzymes they are called holoenzyme.
Tightly bound cofactors or coenzyme that are necessary for enzyme function are known as prosthetic groups

Answer 11

What are apoenzymes? Holoenzymes?And prosthetic groups?

Question 12

When the rate of reaction can’t go any faster, especially at this rate when it is at maximum velocity denoted by Vmax . The only way to increase it is by increasing the enzyme concentration. In the cell, this can be accomplished by inducing the expression of the gene encoding the enzyme.

Answer 12

What is saturation? What is Vmax and how can we increase it?

Question 13

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Answer 13

<p>What is the ES complex?</p>

Question 14

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Answer 14

<p>What is the velocity of the enzyme to substrate concentration using the Michaelis- Mennen Equation ?</p>

Question 15

• Increasing [S] has different effects, depending on how much substrate is present to begin with. When the substance concentration is low, an increase in [S] causes a proportional increase in enzyme activity. At high [S}, however when the enzyme is saturated increasing [S] has no effect on activity because Vmax has already been attained
• Increasing [E] will always increase Vmax regardless of the starting concentration of enzyme

Answer 15

What are the effects of increasing [S] on enzyme kinetics? What about increasing [E] ?

Question 16

• Temperature; As temperature increases, enzyme activitygenerally increases(doubling approximately every 10 C)
• PH —Enzymes are maximally active within a small pH range; outside of this range activity drops quickly with changes in pH as the ionization of the active site changes and the protein is dentures
• Salinity changes can disrupt bonds within an enzyme, causing disruptions of tertiary and quaternary structure, which leads to loss of enzyme function.

Answer 16

What are the effects of temperature, PH, and salinity on the function of enzymes?

Question 17

Ideal temperature: 37 C=98.6 F= 310 K Ideal pH for most enzymes: 7.4 …gastric enzymes : around 2 ;………For pancreatic enzymes, around 8.5

Answer 17

What is the ideal temperature for most enzymes in the body? The ideal pH?

Question 18

Simply involves occupancy of the active site. Substrates cannot access enzymatic binding sites if there is an inhibitor in the way. Competitive inhibition can be overcome by adding more substrate so that the substrate -to-inhibitor ratio is higher. Adding a competitive inhibitor does not alter the value of Vmax because if enough substrate is added, it will outcompete the inhibitor and be able to run the reaction at maximum velocity.

Answer 18

What is competitive inhibition?

Question 19

• Bind to an allosteric site instead of the active site, which induces a change in enzyme concentration. Allosteric sites are non-catalytic regions of the enzyme that bind regulators. Because the two molecules do not compete for the same site, inhibition is considered noncompetitive and cannot be overcome
• Adding a noncompetitive inhibitor decreases the measured value of Vmax because there is less enzyme available to react; it does not however, alter the value of Km because any copies of the enzyme that are still active maintain the same affinity for their substrate.

Answer 19

What is noncompetitive inhibition?

Question 20

• It results when an inhibitor can bind to either the enzyme or the enzyme-substrate complex.
• Mixed inhibition do not bind at the active site, but an allosteric site. Mixed inhibition alters the experimental value of Km depending on the preference of the inhibitor for the enzyme vs the enzyme-substrate complex

Answer 20

What is Mixed inhibition ?

Question 21

Uncompetitive inhibitors bind only to the enzyme-substrate complex and essentially lock the substrate in the enzyme, preventing its release. This can be interpreted as increasing affinity between the enzyme and substrate.

Answer 21

What is uncompetitive inhibition?

Question 22

No it isn’t active but a allosteric site. The impact on Km is unchanged. The impact on Vmax decreases

Answer 22

When it comes to noncompetitive inhibition, is the binding site active? What happens to Km and Vmax?

Question 23

It isn’t active but a Allosteric site, and the impact on Km increases or decreases. The impact on Vmax Decreases

Answer 23

When it comes to Mixed inhibition, is the binding site active? What happens to Km and Vmax?

Question 24

It isn’t active, and the impact on Km decreases and so does the impact on Vmax

Answer 24

When it comes to uncompetitive inhibition, is the binding site active? What happens to the Km and Vmax ?

Question 25

A real world example is aspirin. Acetylsalicyclic acid(aspirin) irreversibly modifies cyclooxygenase-1. The enzyme can no longer bind its substrate (arachidonic acid) to make its products (prostaglandins) which are involved in modulating pain and inflammatory responses.

Answer 25

Give a real life example of irreversible inhibition?

Question 26

It catalyzes oxidation-reduction reactions, that is the transfer of electrons between biological molecules. Enzymes with a dehydrogenase or reductase in their names are usually oxidoreductases.

Answer 26

What is the enzyme Oxidoreductase?

Question 27

Enzymes that have multiple binding sites. The active site is present, as well as at least one other site that can regulate the availability of the active site.

Answer 27

What is allosteric sites

Question 28

Alternate between an active and inactive form. Inactive Form can’t carry out the enzymatic reaction. Molecules that bind to the allosteric site may be either activators or inhibitors.

Answer 28

What are Allosteric Enzymes ? Allosteric activators and inhibitors?

Question 29

Through phosphorylation or dephosphorylation

Answer 29

Enzymes are often subject to covalent modification, how are they activated and deactivated?

Question 30

The covalent attachment of sugar moieties(one of two parts) is another covalent enzyme modification. And Glycosylation can tag an enzyme for transport within the cell, or can modify protein activity and selectivity

Answer 30

What is Glycosylation?

Question 31

An enzyme that is secreted in an inactive form and must be activated by cleavage; common examples are digestive enzymes like trypsin. If release in the pancreas in a uncontrolled manner, it can digest the whole organ itself. That’s why we have trypsinogen which is a zymogen to avoid that kind of danger.

Answer 31

Whatare zymogens?

Question 32

Enzymes are often subject to regulation by products further down a given metabolic pathway in which there is a process. Feed-forward regulation is less often when enzymes may be regulated by intermediates that precede the enzyme in the pathway

Answer 32

What is feedback regulation ? Feed-forward regulation?

Question 33

Yes it is active and the impact of Km increases. For Vmax it is unchanged

Answer 33

When it comes to competitive inhibition is the binding site active? What is the impact on Km and Vmax?