Chapter 10 Terms Flashcards

(18 cards)

1
Q

Activity at one functional site affects the activity at others.

A

Cooperativity

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2
Q

Catalysis by aspartate carbamoylase of the first step in pyrimidine biosynthesis is inhibited by cytidine triphosphate, the final product of that biosynthesis.

A

Feedback (end-product) inhibition

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3
Q

A site distinct from the active site at which substrate binds where a regulatory molecule may bind to.

A

Allosteric (regulatory) site

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4
Q

The effects of substrates on allosteric enzymes are referred to as _______ effects.

A

Homotropic effect

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5
Q

Where the change in the enzyme is “all or none”; the entire enzyme is converted from T into R, affecting all of the catalytic sites equally.

A

Concerted mechanism

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6
Q

Assumes that the binding of ligand to one site on the complex can affect neighboring sites without causing all subunits to undergo the T-to-R transition.

A

Sequential model

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7
Q

The effects of nonsubstrate molecules on allosteric enzymes (such as those of CTP and ATP on ATCase) are referred to as ______ effects.

A

Heterotrophic effect

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8
Q

Are enzymes that differ in amino acid sequence yet catalyze the same reaction. Usually, these enzymes display different kinetic parameters, such as Km, or respond to different regulatory molecules.

A

Isozyme (isoenzyme)

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9
Q

The covalent attachment of a molecule to an enzyme or protein that can modify its activity.

A

Covalent modification

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10
Q

The enzymes catalyzing phosphorylation reactions.

A

Protein kinase

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11
Q

A sequence pattern derived from the alignment of multiple sequences that represents the nucleotide or amino acid most likely to occur at each position in a sequence.

A

Consensus sequence

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12
Q

These enzymes reverse the effects of kinases by catalyzing the removal of phosphoryl groups attached to proteins. The enzymes hydrolyze the bond attaching the phosphoryl group.

A

Protein phosphatase

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13
Q

Is activated by cAMP; it alters the activities of target proteins by phosphorylating specific serine or threonine residues.

A

Protein kinase A (PKA)

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14
Q

A sequence that matches the consensus sequence for phosphorylation except for the presence of alanine in place of serine. This thereby prevents the entry of protein substrates.

A

Pseudosubstrate sequence

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15
Q

Inactive precursor enzymes, waiting cleavage to become activated.

A

Zymogen (proenzyme)

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16
Q

Are often employed in biochemical systems to achieve a rapid response. An initial signal institutes a series of steps, each of which is catalyzed by an enzyme. At each step, the signal is amplified.

A

Enzymatic cascade

17
Q

This clotting pathway is activated by exposure of anion surfaces on rupture of the endothelial lining of the blood vessels.

A

Intrinsic pathway

18
Q

This clotting pathway is activated when trauma exposes tissue factor, an integral membrane glycoprotein. Exposure generates small amounts of thrombin. This is the most crucial pathway in blood clotting.

A

Extrinsic pathway