Enzymes and Membranes

Set of flashcards covering key terms and concepts related to enzymes, membrane functions, hormone classification, and signaling pathways.

Functions of Membranes

1. Define cell/organelle boundaries (compartmentalization) 2. Selective permeability (controls what enters/leaves) 3. Transport (channels, carriers, pumps) 4. Signal reception/transduction (receptors) 5. Cell recognition/adhesion + structural support (glycocalyx/anchors)

Factors Affecting Enzymatic Reaction Rate

1. Substrate concentration ([S]) 2. Enzyme concentration ([E]) 3. Temperature 4. pH 5. Inhibitors/activators (including required cofactors/metals)

Transition State in Enzymatic Reactions

Enzymes bind to and lower the transition state's activation energy (Ea) by stabilizing it.

Km Values and Binding Affinity

Small Km means strong binding and high Km means weak binding.

Isomerase Group of Enzymes

Catalyze transfer of groups within molecules.

Micelles

Monolayer structure of lipids.

Membrane Transport Systems

Three classes: Channels, carriers, pumps.

Phases of Membrane Bilayer

Gel phase and Liquid-crystalline (fluid) phase.

Charge Inside the Cell

Typically negatively charged.

Fluid Mosaic Model Components

Carbohydrates are always found attached towards the outside of a membrane.

Epinephrine Classification

Catecholamine hormone.

Receptor Definition

A protein that binds a signaling molecule (ligand) triggering a cellular response. Examples: β-adrenergic receptor, Insulin receptor, Glucocorticoid receptor.

Steroid Hormones Composition

Made from cholesterol.

Epinephrine Receptor in Signaling Pathway

Binds to beta adrenergic receptor.

Insulin Hormone Classification

Peptide hormone.

b-cell Insulin Secretion Process

1. Glucose enters β-cells via GLUT2 2. Glucose is phosphorylated by glucokinase 3. ATP increases and closes KATP channels 4. Membrane depolarizes 5. Voltage-gated Ca²⁺ channels open 6. Ca²⁺ influx triggers exocytosis of insulin granules.

Three Classes of Mammalian Hormones

Peptide/protein, Steroid, and Amino-acid–derived hormones.

Effects of Insulin

Increases activity of glycogen synthase, glucokinase in liver, and promotes translocation of GLUT4 into muscle.