Cell Structure and Membrane Transport

These flashcards cover key concepts related to cell structure and various types of membrane transport mechanisms.

What is the structure of the phospholipid bilayer?

Composed of two layers of phospholipids with hydrophilic heads outward and hydrophobic tails inward.

What is the function of gap junctions?

They provide cytoplasmic channels between cells, allowing communication, and the passage of small molecules.

What role do carbohydrates play in cell signaling?

They act as receptors and co-receptors, facilitating cell recognition and triggering reactions.

What is the main function of cholesterol in the cell membrane?

Cholesterol reduces membrane fluidity at moderate temperatures and hinders solidification at low temperatures.

How does phagocytosis function?

Cells engulf particles through the plasma membrane, forming a food vacuole that fuses with a lysosome.

What are integral proteins?

Proteins that penetrate the hydrophobic interior of the lipid bilayer, allowing passage of hydrophilic substances.

What is facilitated diffusion?

A passive transport mechanism that uses channel and carrier proteins to move substances across the membrane.

What is a proton pump and its function?

A transport protein that pumps hydrogen ions out of the cell to generate voltage, primarily in plants and bacteria.

What are aquaporins?

Channel proteins that facilitate the rapid transport of water molecules across the cell membrane.

What do peripheral proteins do?

They are loosely attached to the membrane and act as receptors for signals, transmitting them into the cell.

What is the structure of the phospholipid bilayer?

Composed of two layers of phospholipids with hydrophilic heads outward and hydrophobic tails inward.

What term describes molecules with both hydrophilic and hydrophobic regions, like phospholipids?

Amphipathic

What is the function of gap junctions?

They provide cytoplasmic channels between cells, allowing communication, and the passage of small molecules.

In what types of animal tissues are gap junctions commonly found?

Gap junctions are common in animal cells, particularly in tissues requiring rapid communication like heart muscle.

What role do carbohydrates play in cell signaling?

They act as receptors and co-receptors, facilitating cell recognition and triggering reactions.

What are glycolipids and glycoproteins?

Glycolipids are carbohydrates covalently bonded to lipids, and glycoproteins are carbohydrates covalently bonded to proteins, both found on the extracellular surface of the plasma membrane.

What is the main function of cholesterol in the cell membrane?

Cholesterol reduces membrane fluidity at moderate temperatures and hinders solidification at low temperatures.

How does cholesterol affect membrane fluidity at different temperatures?

At high temperatures, cholesterol restrains phospholipid movement, reducing fluidity; at low temperatures, it maintains fluidity by preventing tight packing.

How does phagocytosis function?

Cells engulf particles through the plasma membrane, forming a food vacuole that fuses with a lysosome.

What type of endocytosis is 'cellular eating'?

Phagocytosis is a type of endocytosis where a cell engulfs large particles or other cells, often called 'cellular eating'.

What are integral proteins?

Proteins that penetrate the hydrophobic interior of the lipid bilayer, allowing passage of hydrophilic substances.

What are the two main types of membrane proteins?

Integral proteins penetrate the hydrophobic interior of the lipid bilayer, while peripheral proteins are loosely bound to the surface of the membrane.

What is facilitated diffusion?

A passive transport mechanism that uses channel and carrier proteins to move substances across the membrane.

Is facilitated diffusion an active or passive transport process?

Facilited diffusion is a passive transport process because it does not require metabolic energy to move substances down their concentration gradient.

What is a proton pump and its function?

A transport protein that pumps hydrogen ions out of the cell to generate voltage, primarily in plants and bacteria.

What type of active transport protein is a proton pump?

A proton pump is an electrogenic pump that actively transports protons (H^+) out of the cell, generating an electrochemical gradient.

What are aquaporins?

Channel proteins that facilitate the rapid transport of water molecules across the cell membrane.

Do water molecules cross cell membranes solely via aquaporins?

While water can slowly cross the lipid bilayer directly, aquaporins greatly increase the speed and efficiency of water transport across cell membranes.

What do peripheral proteins do?

They are loosely attached to the membrane and act as receptors for signals, transmitting them into the cell.

How are peripheral proteins associated with the cell membrane?

Peripheral proteins are typically bound to the surface of the membrane, often to integral proteins or directly to phospholipids, rather than embedded within