Lecture 19a

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At what substrate concentration is the rate of reaction more sensitive?

Above Km

More than 10 times the Km

Below Km (correct)

Equal to Km

What does the elasticity coefficient measure in an enzyme with Michaelis-Menten kinetics?

Temperature sensitivity

Substrate specificity

Rate of reaction

Responsiveness to substrate concentration (correct)

What is the effect of increasing substrate concentration above the Km on enzyme activity?

Nearly saturates the enzyme with substrate

No effect on enzyme activity (correct)

Increases enzyme activity

Decreases enzyme activity

In what condition does an enzyme have an elasticity coefficient close to 0?

[S] > Km Signup and view all the answers

What can lead to the activation of AMP-activated protein kinase (AMPK)?

Elevated [AMP] Signup and view all the answers

What determines if a reaction is near-equilibrium or far from equilibrium?

[Q] compared to [Keq] Signup and view all the answers

What is the primary effect of AMPK activation on metabolism in extra-hepatic tissues?

Promotes the use of fatty acids as a fuel Signup and view all the answers

Which enzymes are highlighted as appropriate targets for regulating glycolytic flux?

Hexokinase and phosphofructokinase Signup and view all the answers

How does increased hexokinase activity affect glucose metabolism?

Activates glucose Signup and view all the answers

What is the main function of enzymes that catalyze reactions far from equilibrium in metabolic pathways?

Control flux through the pathway Signup and view all the answers

Which of the following statements about allosteric effectors is correct?

They convert hyperbolic kinetics to sigmoid kinetics. Signup and view all the answers

What is the relationship between the Hill coefficient and the effect of substrate concentration on reaction rate for allosteric enzymes?

A higher Hill coefficient indicates greater cooperativity and a lower change in substrate concentration is required to increase the reaction rate from 10% to 90% of Vmax. Signup and view all the answers

Which amino acid residues are typically phosphorylated in protein regulation?

Serine, Threonine, and Tyrosine Signup and view all the answers

What is the role of regulatory protein subunits in enzyme regulation?

They affect the specificity of enzymes by creating unique substrate binding sites. Signup and view all the answers

Which of the following statements about enzyme kinetics is true?

An allosteric enzyme with a Hill coefficient of 4.0 exhibits greater cooperativity than an enzyme with a Hill coefficient of 2.0. Signup and view all the answers

What is the key characteristic of proteins that undergo rapid turnover?

They are energetically expensive, but can adapt to new conditions faster Signup and view all the answers

Which of the following statements about the N-end rule is true?

It determines the half-life of proteins based on their N-terminal amino acid sequence Signup and view all the answers

In a metabolic pathway, what is true about the net rates of all enzymes at steady state?

They operate at the same net rate, but different rates of forward and reverse reactions Signup and view all the answers

Which statement accurately describes the relationship between protein half-life and energy expenditure?

Rapid turnover of proteins with a short half-life is energetically expensive Signup and view all the answers

What is the significance of near-equilibrium and non-equilibrium steps in a metabolic pathway?

Non-equilibrium steps are potential sites of regulation, while near-equilibrium steps are not Signup and view all the answers