Cell Communication Flashcards

Flashcards to review key concepts from a cell communication lecture.

What is the plasma membrane composed of?

A fluid mosaic of lipids and proteins, including a double layer of phospholipids.

What is the primary function of the plasma membrane?

To control traffic into and out of the cell.

What characteristic of the plasma membrane allows the passage of some substances more easily than others?

Selective permeability.

What type of molecules are phospholipids?

Amphipathic molecules (containing both hydrophilic and hydrophobic regions).

What part of the phospholipid is hydrophilic?

The head.

What part of the phospholipid is hydrophobic?

The tail.

What component found in animal cell membranes helps stabilize the membrane by reducing fluidity?

Cholesterol.

What determines many of the membrane's specific functions?

Proteins in the membrane.

What are integral proteins?

Transmembrane proteins embedded in the lipid bilayer.

What are peripheral proteins?

Proteins not embedded in the lipid bilayer, but attached to the surface.

What is active transport?

The pumping of solutes against their concentration gradients, requiring energy.

What is the significance of active transport for cells?

It allows cells to maintain internal concentrations of small molecules that differ from concentrations in the environment.

How do cells communicate through direct contact?

Via cell-surface molecules, cell junctions, intracellular joining, and cell-cell recognition.

What are plasmodesmata?

Channels that perforate cell walls of plant cells, allowing communication.

Name three types of intracellular junctions found in animal cells.

Tight junctions, desmosomes, and gap junctions.

How does cell-cell recognition occur?

Through carbohydrates (glycolipids and glycoproteins) on the cell surface.

What role do carbohydrates play in cell-cell recognition?

Sorting cells into tissues and organs in the embryo and recognizing/rejecting foreign cells.

What are the components of the animal extracellular matrix (ECM)?

Glycoproteins such as collagen fibers embedded in a network of proteoglycans.

What are fibronectins?

Glycoproteins that bind to integrins in the plasma membrane, linking the ECM to the cytoskeleton.

What is the role of integrins?

Receptor proteins in the plasma membrane that bind to fibronectins and microfilaments.

Briefly describe paracrine signaling.

A local signaling mechanism where a secreting cell releases local regulators that diffuse to nearby target cells.

Briefly describe synaptic signaling.

A local signaling mechanism involving nerve cells releasing neurotransmitters across a synapse to target cells.

Briefly describe endocrine signaling.

Long-distance signaling where endocrine cells release hormones that travel in the bloodstream to target cells.

What is a ligand (or first messenger)?

A signaling molecule that binds to a receptor protein.

What are the three main stages of cell signaling?

Reception, transduction, and response.

Define 'reception' in cell signaling.

The target cell's detection of a signaling molecule from outside the cell.

Define 'transduction' in cell signaling.

The change of the receptor protein that initiates the process of cellular response.

Define 'response' in cell signaling.

The cellular activity that results from the signal, such as catalysis or gene activation.

What happens to a receptor or protein when it is activated?

It is able to transfer the signal inside the cell.

Give examples of receptors.

G protein-coupled receptors, receptor tyrosine kinases, and ion channel receptors.

Where are intracellular receptors located?

In the cytoplasm or nucleus.

What is a protein kinase?

An enzyme that transfers phosphate groups from ATP to a protein.

What role do small molecules and ions play in transduction?

They act as second messengers, spreading the signal by diffusion.

Give examples of second messengers.

cAMP and calcium ions.

What ion's concentration is increased by neurotransmitters, growth factors and hormones?

Calcium ions.

Give examples of common responses to this increase in ion concentration.

Muscle contraction, secretion of substances, cell division.

Where can responses occur at the end of a pathway?

In the nucleus or in the cytoplasm.

What is the main function of the growth factor binding to the receptor at the start of signal transduction?

To start a phosphorylation cascade.

What biological process is the final step in a nuclear response to a signal?

Gene expression.

What are transcription factors?

Proteins that regulate the activity and synthesis of genes.