Membrane Function and Signaling

Flashcards covering membrane transport, osmosis, protein types, and signaling mechanisms.

Cell Membrane Function

Controls movement of substances in and out of cells.

Diffusion

Movement of molecules from high to low concentration without energy input.

Osmosis

Net movement of water from low to high solute concentration across a membrane.

Amphipathic

Having both hydrophilic and hydrophobic parts, allowing integration into lipid bilayers.

Integral Membrane Proteins

Proteins that integrate into lipid bilayers due to amphipathic properties.

Channel Proteins

Proteins that contain channels or pores facilitating the transfer of specific compounds.

Carrier Proteins

Proteins that change shape to transfer molecules, ensuring specificity.

Facilitated Diffusion

Transfer through channels and carriers driven by concentration gradient, not energy input.

Gated Protein Channels

Proteins regulated to open or close channels in response to environmental signals.

Active Transport Pumps

Allow molecules to be transported against concentration gradients using energy.

Pumps in Active Transport

Moves molecules from low to high concentrations, creating imbalances for other cell processes.

Sodium-Potassium Pump

The Sodium-Potassium pump moves sodium ions out of the cell and potassium ions into the cell, against their concentration gradients.

Cell Signaling

Cells use chemical messengers such as adrenaline and growth factors.

Local Signaling

Communication by direct contact between cells through gap junctions or cell junctions.

Tight Junctions

Form watertight seals between epithelial cells.

Gap Junctions

Enable shared cytoplasm between animal cells.

Paracrine Signaling

Signaling molecules travel short distances to interact with cells in the local vicinity.

Synaptic Signaling

Occurs between nerve cells where neurotransmitters diffuse across the synapse.

Endocrine Signaling

Specialized cells release hormones that travel through the bloodstream to reach target cells.

Signal Transduction Pathway

A series of relay molecules that transduce a signal.

Kinase Enzymes

Enzymes add phosphate groups to other proteins.

Phosphorylation Cascade

Allows signal amplification and fine control, requiring energy.

Cellular Response to Signals

The cell's response to many signals is to switch on specific genes.