Muscle Contraction Mechanism Videos Quiz

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What type of components are cofactors in enzymes?

Carbohydrates

Proteins

Lipids

Inorganic ions (correct)

What causes a conformational change in troponin C during muscle contraction?

Release of sarcoplasmic reticulum

Binding of troponin I

Release of tropomyosin

Binding of Ca2+ (correct)

What is required for the catalytic activity of enzymes?

Proteolytic activation

Native protein conformation (correct)

Irreversible covalent modification

Noncovalent binding to regulatory proteins

What do coenzymes act as in enzymatic reactions?

Catalysts Signup and view all the answers

What did Eduard Buchner demonstrate in 1897 regarding enzymes?

Cell-free yeast extracts can ferment sugar to alcohol Signup and view all the answers

What do regulatory mechanisms of enzymes include?

Noncovalent binding to regulatory proteins and binding of allosteric modulators Signup and view all the answers

What is a prosthetic group in relation to enzymes?

A coenzyme or metal ion tightly bound to the enzyme protein Signup and view all the answers

Which inorganic ion serves as a cofactor for cytochrome oxidase enzymes?

Fe3+ Signup and view all the answers

Why do enzymes exhibit a very high degree of specificity?

They bind tightly to the transition state of reactions Signup and view all the answers

What is the main role of enzymes as biological catalysts?

Lower reaction activation barriers Signup and view all the answers

Where do enzyme-catalyzed reactions take place?

Active site Signup and view all the answers

Why are enzymes often regulated through multiple methods?

To allow for exquisite control of every chemical process in a cell Signup and view all the answers

What part of an enzyme together with its bound coenzyme and/or metal ions forms a holoenzyme?

Apoenzyme Signup and view all the answers

What is the function of troponin I in muscle contraction?

Inhibits muscle contraction Signup and view all the answers

What is the range of molecular weight for enzymes?

<12,000 to >1 million Signup and view all the answers

What occurs in the active sites of enzymes during catalysis?

Conversion of product to substrate Signup and view all the answers

In metal ion catalysis, how do metals assist in reactions?

By stabilizing transition states and mediating redox reactions Signup and view all the answers

What must be true for catalysis to occur?

The new pathway has a lower activation energy than the uncatalyzed pathway Signup and view all the answers

What do enzymes affect in a reaction?

Reaction rates Signup and view all the answers

What do metal ions do in metal ion catalysis?

Stabilize charged reaction transition states Signup and view all the answers

How are metal ions involved in metal ion catalysis?

They help orient the substrate and stabilize transition states Signup and view all the answers

What concept explains the catalytic power of enzymes by binding tightly to specific states?

Transition state theory Signup and view all the answers

What percentage of known enzymes require metal ions for catalytic activity?

Nearly 1/3 Signup and view all the answers

Which type of RNA can also catalyze reactions?

Ribozymes Signup and view all the answers

What does the term 'Transition state (‡)' represent in a reaction?

The stage where decay to substrate or product are equally likely Signup and view all the answers

What is the difference between ∆G‡uncat and ∆G‡cat in a reaction?

Activation energy for uncatalyzed and catalyzed reactions Signup and view all the answers

What is the starting point for either the forward or reverse enzymatic reaction?

Ground state Signup and view all the answers

What do catalysts do to the activation energy and the reaction rate?

Decrease activation energy and increase reaction rate Signup and view all the answers