Biochemistry Chapter 5 Quiz

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Questions and Answers

What primarily determines whether a chemical reaction can occur?

The activation energy of the reaction.

The collision frequency between reactant particles.

The speed of the particles involved in the reaction.

The Gibbs energy change of the reaction. (correct)

How is the rate of a chemical reaction generally defined?

The total amount of products formed over the course of the reaction.

The Gibbs energy change divided by the duration of the reaction.

The change in the mass of reactants or products per unit of time. (correct)

The number of collisions between reactant molecules in a given time.

In the reaction $3H_2 + N_2 \rightarrow 2NH_3$, how would the rate of reaction be expressed in terms of the change in concentration of hydrogen ($H_2$)?

$v = -\frac{[H_2]}{time}$

$v = \frac{[H_2]}{time}$

$v = -\frac{1}{3} \frac{[H_2]}{time}$ (correct)

$v = -3 \frac{[H_2]}{time}$

According to collision theory, what factor directly influences the rate of a reaction?

The number of active collisions between reactant molecules per unit of time. Signup and view all the answers

What is the correct expression for the reaction rate of a monomolecular reaction, such as $N_2O_4 \rightarrow 2NO_2$?

$v = k[N_2O_4]$ Signup and view all the answers

What is the primary function of the active site of an enzyme?

To provide a location where substrates bind and reactions occur. Signup and view all the answers

What characterizes isoenzymes?

They are enzymes with the same function but different structure and properties. Signup and view all the answers

According to the Michaelis-Menten equation, what does a high KM value indicate?

A low affinity of the enzyme for its substrate. Signup and view all the answers

Under what condition is the velocity of an enzyme-catalyzed reaction proportional to the substrate concentration?

When the substrate concentration is very low compared to KM. Signup and view all the answers

What does the unit 'catal' (cat) measure?

The amount of substrate converted by an enzyme per unit of time. Signup and view all the answers

What is the role of modulators in allosteric enzymes?

To attach to the allosteric site and influence the enzyme's affinity for its substrate. Signup and view all the answers

In homotropic regulation of allosteric enzymes, what acts as a modulator?

The substrate molecule itself. Signup and view all the answers

What is the significance of acetylcholinesterase cleaving 25,000 molecules of acetylcholine in one second?

It illustrates the enzyme's ability to accelerate a reaction extremely rapidly. Signup and view all the answers

What is the primary function of thermogenin?

To facilitate the transfer of protons, bypassing ATP synthase. Signup and view all the answers

Why are substances like thermogenin referred to as 'uncouplers'?

Because they separate oxygen consumption from ATP production. Signup and view all the answers

Which type of gland does not utilize a duct system for the release of its secretions?

Simple tubular glands Signup and view all the answers

What is a key by-product of the action of thermogenin in brown adipose tissue?

Heat generation Signup and view all the answers

What is the function of the striated duct within a compound gland?

To connect the intercalated duct to the interlobular duct. Signup and view all the answers

What is the consequence of using dinitrophenol as a weight loss drug?

It is very difficult to prescribe safely. Signup and view all the answers

What is characteristic of serous secreting cells?

They are typically basophilic due to peptide hormones, proteins or enzymes. Signup and view all the answers

When ATP production stops normally in mitochondria, what occurs?

The respiratory chain’s proton pumping stops due to the built-up proton gradient. Signup and view all the answers

Which type of secretion is commonly associated with tubular cells?

Mucinous secretion Signup and view all the answers

What is the function of the main duct in a compound gland?

To be the final duct before secretion exits the gland. Signup and view all the answers

If a secretion is described as basophilic, it is most likely produced by which type of cells?

Serous cells Signup and view all the answers

What specific feature of mucinous secretion makes it stainable by PAS dye?

Its content of polysaccharides. Signup and view all the answers

What is NOT a typical function of the ducts in glands?

Primary secretion creation. Signup and view all the answers

Which enzyme catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate?

Phosphofructokinase-1 Signup and view all the answers

During which step of glycolysis is NADH produced?

The conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate Signup and view all the answers

Which of the following enzymes is responsible for converting dihydroxyacetone phosphate (DHAP) to glyceraldehyde-3-phosphate (Gra-3-P)?

Triose phosphate isomerase Signup and view all the answers

How many ATP molecules are consumed in the first phase of glycolysis (up to the formation of two three-carbon molecules)?

2 Signup and view all the answers

Which enzyme catalyzes the reaction where water is removed from 2-phosphoglycerate to form phosphoenolpyruvate?

Enolase Signup and view all the answers

Which of the following is NOT a function of mitochondria?

Synthesis of proteins encoded by nuclear DNA Signup and view all the answers

What is the primary role of porins located within the outer mitochondrial membrane?

To facilitate the movement of all molecules smaller than 10 kDa Signup and view all the answers

Which characteristic of the inner mitochondrial membrane is crucial for its selective permeability?

It contains a high proportion of proteins Signup and view all the answers

Where are the enzymes of the Krebs cycle primarily located within the mitochondria?

In the mitochondrial matrix Signup and view all the answers

How do chaperones assist in the import of proteins into the mitochondria?

By keeping proteins unfolded allowing them to pass through translocator complexes Signup and view all the answers

What is a key difference between mitochondrial DNA (mtDNA) and nuclear DNA?

mtDNA is inherited maternally, while nuclear DNA is inherited from both parents Signup and view all the answers

Which of these conditions represents a mitochondrial disease caused by a mutation in a gene that codes for an abnormal protein?

Diabetes and deafness (DAD) Signup and view all the answers

Why is the CRISPR method ineffective for directly editing mitochondrial DNA?

CRISPR enzymes cannot enter the mitochondrial matrix due to membrane impermeability Signup and view all the answers

What is the primary purpose of mitochondrial fusion?

To mix contents, replenish proteins, repair mtDNA, and distribute metabolic intermediates Signup and view all the answers

Which of the following statements best describes the evolutionary origin of mitochondria?

Mitochondria originated from a symbiosis of a bacteria (rickettsia) with an archaea cell. Signup and view all the answers

In the context of mitochondrial diseases, what does heteroplasmia refer to?

The presence of multiple types of mitochondrial DNA in the same cell Signup and view all the answers

Why are mitochondria described as semi-autonomous organelles?

Because they are only capable of producing some of their own proteins. Signup and view all the answers

What is the role of the SAM protein complex in mitochondrial protein import?

It keeps proteins integrated into the outer mitochondrial membrane. Signup and view all the answers

Which of the following is most likely to cause cell edema due to insufficient mitochondrial activity?

Disruption of the membrane's ability to selectively regulate permeability. Signup and view all the answers

What is the significance of cardiolipin in the inner mitochondrial membrane?

It aids in membrane elasticity Signup and view all the answers

Study Notes

Course 2: Metabolism

This document is a table of contents for Course 2: Metabolism.
The course is taught by Stanislav Skamene, Svatava Vyhnánková, Filip Otepka, and Dominika Kubátová.
Course materials were translated by Kamila Kočí.
The document covers a variety of topics in metabolism, including metabolic reactions, enzymes, coenzymes, vitamins, trace elements, and the role of molecules in various organs and systems.

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Description

Test your knowledge on key concepts in biochemistry, including chemical reaction rates, enzyme activity, and modulation. This quiz covers essential topics such as collision theory, the Michaelis-Menten equation, and the role of active sites in enzyme function. Prepare to dive deep into the fascinating world of biochemical processes!