Cell-Cell Interactions in Biological Science

These flashcards cover key concepts related to cell-cell interactions, structures, and communication in biological sciences.

What are cell-cell interactions essential for in multicellular organisms?

They are essential for communication and cooperation among cells.

What is the plasma membrane primarily composed of?

A phospholipid bilayer studded with proteins.

What is the primary function of the plasma membrane?

To create an internal environment distinct from the external environment.

What material generally makes up the extracellular layer?

A fibre composite that helps define cell shape and attach cells to one another.

What predominant protein is found in the extracellular matrix (ECM) of animals?

Collagen.

What do proteoglycans in the ground substance of ECM do?

Attract water and help form a gel-like structure.

What are the characteristics of the primary cell wall in plant cells?

Long strands of cellulose organized into a crisscrossed network.

What is turgor pressure and why is it important in plant cells?

It helps maintain cell shape by counteracting water entry through osmosis.

What is the secondary cell wall in plants and its significance?

A wall secreted by mature cells that helps with tissue function and structure.

What structures in animal cells hold them together?

Tight junctions, desmosomes, and gap junctions.

What are tight junctions and their function?

Membrane proteins that fuse cells together, creating a watertight seal.

How do desmosomes contribute to tissue integrity?

They link cytoskeletons of adjacent cells and resist mechanical stress.

What are cadherins?

Attachment molecules in desmosomes that promote cell-cell adhesion.

How can an antibody affect cell adhesion?

By binding to adhesion proteins, preventing proper cell adhesion.

What is the function of gap junctions?

Allow ions and small molecules to pass between adjacent cells for communication.

What is the middle lamella in plant cells?

A layer of gelatinous pectins that glues the primary cell walls together.

What are plasmodesmata?

Channels in plant cell walls that connect the cytoplasm of adjacent cells.

How do hormones function in cell signaling?

By binding to specific receptors on target cells to initiate a response.

What changes can occur in signal receptors over time?

The number of receptors may change, and their sensitivity can also vary.

How do lipid-soluble hormones enter cells?

They can diffuse across the cell membrane and bind to internal receptors.

What is the process called when a cell converts an extracellular signal into an intracellular response?

Signal transduction.

What happens during signal amplification?

Many steps between the receptor and response increase the intensity of the signal.

What role do G proteins play in signal transduction?

They activate a second messenger when triggered by a signal receptor.

What are examples of secondary messengers?

Calcium ions (Ca2+) and cyclic AMP.

What is the function of receptor tyrosine kinases (RTKs)?

They are enzyme-linked receptors that catalyze reactions inside the cell.

What are the two general categories of cellular responses to signals?

Changes in gene expression and changes in the activation of existing proteins.

Why is signal deactivation important?

It ensures cells remain sensitive to small changes in signaling.

What is quorum sensing?

A signaling mechanism bacteria use to communicate based on population density.

What is a common example of a response to quorum sensing in bacteria?

Aggregating to form a biofilm, such as plaque on teeth.

What is the correct order of events in signal transduction?

Signal molecule binds to receptor, induces conformational change, activates enzyme, produces second messenger, phosphorylates target proteins.

What is the function of phosphatases in cell signaling?

They remove phosphate groups to deactivate signals.

What is the significance of the fibrous component of the extracellular matrix?

It provides structural support and helps with cell adhesion.

What defines the extracellular space between adjacent plant cells?

The primary cell wall of one cell, the middle lamella, and the primary cell wall of another cell.

What type of signaling molecules are often secreted from cells?

Hormones that circulate in the body to act on target cells.

How do cells in tissues connect and communicate?

Through physical connections and signaling pathways.

What happens to target cells when they receive a signal?

They may change gene expression or activate/deactivate existing proteins.

How do cells maintain a quick response to changes in signaling?

Through automatic mechanisms that deactivate signals rapidly.

What characterizes intercellular interactions in unicellular organisms?

They communicate about environmental changes and can respond based on density.