Enzyme Activity and Regulation

These flashcards cover key concepts regarding enzyme activity, regulation, and metabolic pathways as discussed in the lecture.

What is an enzyme's activity defined as?

An efficiency metric measured by the amount of substrate converted to product.

What do competitive inhibitors do to enzyme activity?

They cause the enzyme's activity to diminish or decrease.

What is the measurement used to express substrate conversion to product?

Percentage of the total number of molecules.

What is the difference between reversible and irreversible inhibitors?

Reversible inhibitors can detach from the enzyme, while irreversible inhibitors permanently bind to the active site.

What is an allosteric inhibitor?

A molecule that attaches to an enzyme at a site other than the active site, causing a shape change that inhibits function.

How do cells regulate enzyme activity?

Cells can turn enzymes on or off to maintain homeostasis like using electrical switches.

What is feedback inhibition?

A regulatory mechanism where the end product inhibits an earlier step in the synthesis pathway.

What is an enzyme cascade?

A series of enzymatic reactions where the product of one reaction serves as the substrate for the next.

How does an increase in product concentration affect enzyme activity?

It may inhibit earlier enzymes in the cascade, stopping production.

What happens when the end product of a reaction reaches sufficient levels?

It allosterically inhibits the first enzyme, turning off the entire pathway.

What is the significance of the term 'Vmax'?

It represents the maximum rate of an enzymatic reaction when the enzyme is saturated with substrate.

What does a higher Km value indicate about enzyme saturation?

The enzyme is saturated with the inhibitor more quickly than with substrate.

How do competitive inhibitors function in drug discovery?

By binding to specific enzymes of pathogens, thus inhibiting their replication without affecting human enzymes.

What impact did the drug Secuinarivir have on HIV deaths?

It significantly reduced the annual death rate from HIV by inhibiting the virus's ability to replicate.

What is the primary characteristic of noncompetitive inhibitors?

They attach to a site different from the active site and do not compete with the substrate.

Why is it costly for cells to use irreversible inhibitors?

Such inhibitors can permanently inactivate enzymes, leading to resource wastage and cellular death.

What role does ATP play in enzymatic reactions?

It provides energy required for various biochemical processes by being phosphorylated.

What is the major difference between aerobic and anaerobic respiration?

Aerobic respiration uses oxygen and generates more ATP, while anaerobic respiration does not use oxygen and generates less.

How do fermentation processes help single-celled organisms?

They provide enough energy to survive under anaerobic conditions, converting sugar to acids or alcohols.

What is the importance of metabolic pathways in different organisms?

They show similarities in enzyme function and substrate usage across diverse species, including humans and bacteria.