Biology Chapter: Plasma Membrane Structure

The plasma membrane is a thin, flexible barrier that surrounds the cell, separating the internal contents from the external environment.

Phospholipids are molecules with both water-attracting (hydrophilic) heads and water-repelling (hydrophobic) tails, allowing them to form a bilayer.

Cholesterol is a molecule that helps maintain the fluidity and stability of the plasma membrane.

Glycolipids are lipids with attached sugar molecules, found on the outer surface of the plasma membrane. They help cells recognize each other and interact with the environment.

The fluid mosaic model describes the plasma membrane as a flexible structure with proteins moving within a fluid lipid bilayer.

Membrane proteins are embedded within or attached to the plasma membrane, performing various functions like transporting molecules or signaling.

Peripheral proteins are loosely attached to the surface of the membrane and are not embedded within the lipid bilayer. They often work as enzymes or in signaling.

Integral proteins are embedded within the lipid bilayer of the membrane, playing crucial roles in transport, signaling, and other cellular processes.

Proteins that are embedded within the cell membrane, spanning or penetrating the lipid bilayer.

Proteins that form channels or pores through the membrane, allowing selective passage of specific molecules.

Proteins that bind to specific molecules on one side of the membrane and change shape to transport them to the other side.

Proteins that bind to signaling molecules, triggering a cellular response, like hormones or neurotransmitters.

Membrane proteins that act as catalysts for chemical reactions on the membrane's surface or within the membrane itself.

Proteins that enable cells to stick to each other or to the extracellular matrix, essential for tissue formation.

Proteins that act like identification tags for cells, crucial for the immune system to recognize self from non-self.

The ability of a membrane to control which substances can pass through it.

The movement of molecules from a region of high concentration to a region of low concentration without the need for energy. This occurs directly through the lipid bilayer.

A specific type of diffusion where water moves across a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

The passive movement of molecules across a membrane with the help of carrier proteins or channel proteins. This process does not require energy.

A type of facilitated diffusion where specific carrier proteins bind to the molecule being transported, undergo a conformational change, and release the molecule on the other side of the membrane.

Specialized channel proteins that allow specific ions (such as Na⁺, K⁺, Ca²⁺, Cl⁻) to pass through the membrane. Ion channels can be gated, opening or closing in response to signals.

The sodium-potassium pump (Na⁺/K⁺ ATPase) is an active transport mechanism that moves three sodium ions (Na⁺) out of the cell and two potassium ions (K⁺) into the cell against their concentration gradients, using energy from ATP. This pump maintains the electrochemical gradient crucial for nerve impulse transmission and muscle contraction.

The movement of molecules across a membrane from a region of low concentration to a region of high concentration, requiring energy. This process usually involves protein pumps.

The difference in electrical potential between the inside and outside of a cell membrane, essential for nerve impulse transmission and muscle contraction.

Transport mechanism that relies on the energy stored in an electrochemical gradient, often created by primary active transport, to move molecules across the membrane.

A type of secondary active transport where both molecules move across the membrane in the same direction using the energy from an electrochemical gradient.

A type of secondary active transport where molecules move across the membrane in opposite directions, driven by the energy from an electrochemical gradient.

Movement of a single type of molecule or ion across the membrane, without the use of ATP or an electrochemical gradient.

A process where cells engulf large particles, fluids, or other cells by encasing them in a vesicle formed from the plasma membrane.

A process where cells release materials from inside the cell into the extracellular space by fusing a vesicle containing the materials with the plasma membrane.

A combination of endocytosis and exocytosis, where materials are transported across the interior of a cell.

A process that involves the movement of large particles, fluids, or other cells across the membrane using vesicles.

A specialized protein found in the plasma membrane that actively pumps sodium ions (Na+) out of the cell and potassium ions (K+) into the cell, using energy from ATP. This process is essential for maintaining the electrochemical gradient and nerve and muscle function.

This type of transport moves substances across the cell membrane against their concentration gradient, requiring energy expenditure.

The engulfing of large particles or cells by the plasma membrane, involving a process where the membrane folds inward and encloses the material, forming a vesicle.

This process involves the movement of substances across the plasma membrane, down their concentration gradient, without requiring energy.

The movement of water molecules across a semi-permeable membrane from a region of high water concentration to a region of low water concentration.

The maintenance of a stable internal environment within a cell, despite changes in the external environment.

A difference in electrical charge across the plasma membrane, vital for nerve impulse transmission and muscle contraction.

The potential energy stored across the plasma membrane due to the difference in ion concentrations.

High blood sugar levels (hyperglycemia) can lead to the sugar molecules attaching to proteins, a process called glycation. This can alter the protein's function, potentially damaging the sodium-potassium pump.

The sodium-potassium pump is a protein that uses energy to move sodium ions out of the cell and potassium ions into the cell, maintaining the cell's electrical charge. This process is crucial for nerve and muscle cell function.

When the sodium-potassium pump is not functioning properly, cells cannot maintain their electrical charge. This leads to issues with muscle contraction, nerve impulse transmission, and overall cell function.

Dehydration occurs when the body loses more fluids than it takes in. It can further exacerbate issues with ion transport by making it harder for the sodium-potassium pump to work efficiently.

Managing diabetes effectively means controlling blood sugar levels to prevent further glycation of proteins, ensuring the sodium-potassium pump functions properly.

Electrolyte imbalances, especially potassium levels, are a major concern in patients with impaired sodium-potassium pump function. Close monitoring and treatment are crucial to prevent complications like heart rhythm problems.

The patient can benefit from rehydration to address dehydration and support proper cellular function.

The patient may benefit from dietary modifications that include adequate intake of electrolytes, particularly sodium and potassium, to support the proper function of ion channels and transporters in the plasma membrane.