Enzyme Regulation and Function

Flashcards covering key concepts related to enzyme function, regulation, and the role of enzymes in biological processes.

Enzymes are __ that are highly specific and powerful, increasing reaction rates by 106 or more.

catalysts

Enzymes lower the __ barriers for reactions by creating a lower energy transition state between substrate and product.

activation energy

Isoenzymes differ in amino acid sequence but catalyze the __ chemical reaction.

same

Regulatory strategies of enzymes include __, covalent modification, feedback inhibition, and allosteric control.

multiple enzyme forms

Apoptosis is a process of programmed cell death that occurs in __ organisms.

multicellular

Caspases are responsible for the __ activation that plays a key role in apoptosis.

proteolytic

Many enzymes are stored in zymogen granules as inactive __ in pancreatic cells.

zymogens

Phosphorylation involves the addition of a __ to an amino acid with an OH group.

phosphate group

Feedback inhibition occurs when the first reaction in an enzyme pathway is inhibited by the __ product.

end

Allosteric control involves regulation of an enzyme by binding an effector molecule at a site other than the enzyme's __ site.

active

Haemoglobin is considered a classical allosteric protein due to its cooperative binding of __.

oxygen

Sickle cell anemia results from a point mutation in the __ of the hemoglobin gene.

DNA

The primary function of cell membranes is to provide a _______ barrier for the cell

permeable

The two key components of phospholipids in the membrane are _______ tails and a _______ head group

Fatty acid and polar

Cholesterol _______ the flexibility of fatty acid side chains, which _______ membrane fluidity.

decreases and reduces

The two main classes of membrane transport proteins are _______ and _______

Transporters and channels

A transporter moves solutes by alternating between _______ , whereas a channel forms a _______ for passive diffusion

Conformations and pore

Transporter-mediated diffusion reaches a maximum (Vmax) when the transporter is _______

saturated

Active transport is driven by transporters coupled to an _______ source, such as ion-concentration gradients or ATP hydrolysis

Energy

The Na+/glucose symporter transports glucose into the cell by using a _______ gradient

Na+ (Sodium)

The four main mechanisms of membrane transport are simple _______, channel-mediated transport, transporter-mediated transport, and _______ transport

Diffusion and active

G-protein coupled receptors (GPCRs) communicate signals from the _______ to the _______ via G-proteins

Extracellular medium and cytosol

A G-protein becomes activated when ligand binding causes the receptor to change _______ , allowing the alpha subunit to exchange _______ for _______

Conformation, GDP and GTP

A G-protein consists of three subunits: _______, _______, and _______

Alpha, Beta and Gamma

In GPCR signaling via phospholipids, two second messengers are produced: _______ and _______

Diacylglycerol (DAG), inositol 1,4,5-trisphosphate (IP3)

Cyclic AMP (cAMP) functions in GPCR signaling by activating _______ , which phosphorylates target proteins

Protein kinase A (PKA)

CREB plays a role in transforming short-term signals into long-term cellular changes, which is important for _______ and _______

Learning and memories