Cell Biology: Plasma Membrane Structure

<p>It helps stabilize the membrane structure (C)</p> Signup and view all the answers

<p>Small molecules move more easily due to their size (C)</p> Signup and view all the answers

<p>Hydrophilic regions are water-loving and face outward, hydrophobic regions are water-fearing and face inward (B)</p> Signup and view all the answers

<p>Ions and large polar molecules (A)</p> Signup and view all the answers

<p>Fluid Mosaic Model (C)</p> Signup and view all the answers

<p>To minimize energy by avoiding contact with water (B)</p> Signup and view all the answers

<p>Integral membrane proteins (D)</p> Signup and view all the answers

<p>Increases fluidity by preventing tight packing of phospholipids (D)</p> Signup and view all the answers

<p>They serve as distinctive cellular markers. (B)</p> Signup and view all the answers

<p>Osmosis (A)</p> Signup and view all the answers

<p>They maintain fluidity at lower temperatures. (A)</p> Signup and view all the answers

<p>Cholesterol assists in maintaining fluidity across temperature changes. (A)</p> Signup and view all the answers

<p>Tonicity also considers permeability of the membrane to solutes (B)</p> Signup and view all the answers

<p>Involves substances moving down their concentration gradient (C)</p> Signup and view all the answers

<p>They span the entire membrane and are involved in transporting substances. (D)</p> Signup and view all the answers

<p>They assist specific molecules in crossing the membrane (C)</p> Signup and view all the answers

<p>A small, single-layered sphere formed from phospholipids with small tails. (B)</p> Signup and view all the answers

<p>Hydrophobic core created by the arrangement of phospholipids (A)</p> Signup and view all the answers

<p>They are loosely attached and do not span the membrane. (C)</p> Signup and view all the answers

<p>The relative solute concentrations and their effect on cell membranes (B)</p> Signup and view all the answers

<p>Membrane proteins aiding in transport (C)</p> Signup and view all the answers

<p>Facilitating the diffusion of polar and charged molecules (B)</p> Signup and view all the answers

<p>They facilitate transport by changing shape to move target molecules. (D)</p> Signup and view all the answers

<p>To maintain proper sodium and potassium concentrations (C)</p> Signup and view all the answers

<p>The phosphorylation of the pump by ATP (B)</p> Signup and view all the answers

<p>Cotransport of molecules along with another molecule moving down its gradient (C)</p> Signup and view all the answers

<p>By actively transporting three sodium ions out and two potassium ions into the cell (A)</p> Signup and view all the answers

<p>It involves channel proteins and carrier proteins for passive transport. (C)</p> Signup and view all the answers

<p>It resets to its original shape, opening towards the cell interior. (D)</p> Signup and view all the answers

<p>Two potassium ions are released into the cytoplasm. (A)</p> Signup and view all the answers

<p>By moving 3 Na out and only 2 K in. (B)</p> Signup and view all the answers

<p>It couples the movement of sodium ions with other substances against their gradients. (B)</p> Signup and view all the answers

<p>Enclosing particles in vesicles made from the plasma membrane. (C)</p> Signup and view all the answers

<p>It establishes a concentration gradient for sodium ions. (C)</p> Signup and view all the answers

<p>Enclosing large particles in vesicles. (D)</p> Signup and view all the answers

<p>The voltage counterbalances the potassium’s concentration gradient. (D)</p> Signup and view all the answers

<p>To facilitate the transport of one substance uphill while another moves downhill. (A)</p> Signup and view all the answers

<p>To break down engulfed particles (D)</p> Signup and view all the answers

<p>Phagocytosis (D)</p> Signup and view all the answers

<p>By binding to specific target molecules and triggering endocytosis (C)</p> Signup and view all the answers

<p>Pinocytosis is often termed 'cell drinking' and involves the uptake of small amounts of extracellular fluid. (C)</p> Signup and view all the answers

<p>To remove waste and release substances from the cell (D)</p> Signup and view all the answers

<p>It allows for the uptake of molecules that are present in low concentrations. (B)</p> Signup and view all the answers

<p>It fuses with the lysosome for further processing. (D)</p> Signup and view all the answers

<p>It can inadvertently allow harmful particles, such as viruses, to enter the cell. (C)</p> Signup and view all the answers

The fluid mosaic model describes the structure of the plasma membrane as a dynamic and flexible arrangement of phospholipids, cholesterol, and proteins that can move freely within the membrane.

Phospholipids are the primary structural component of the plasma membrane. They have a hydrophilic head that interacts with water and a hydrophobic tail that repels water, creating a bilayer structure with the tails facing inwards.

Cholesterol is another lipid found interspersed within the phospholipid bilayer. It helps regulate membrane fluidity by preventing the phospholipids from packing too tightly at low temperatures or becoming too loose at high temperatures.

Membrane proteins are embedded within the plasma membrane and play a variety of roles, including transporting molecules across the membrane, acting as receptors for signaling molecules, and providing structural support.

Carbohydrate groups are attached to the outer surface of the plasma membrane, either to proteins (forming glycoproteins) or lipids (forming glycolipids). These groups can be involved in cell recognition and signaling.

Hydrophilic regions of phospholipids, such as the phosphate group and the attached R group, are attracted to water and face outwards towards the aqueous environment both inside and outside the cell.

Hydrophobic regions of phospholipids are the fatty acid tails, which are repelled by water and buried inside the membrane core, away from the aqueous environment.

Due to their amphipathic nature, phospholipids spontaneously form a bilayer in aqueous environments. The hydrophobic tails face inwards, shielding themselves from water, while the hydrophilic heads interact with the water.

The tendency of phospholipids in water or aqueous solutions to arrange themselves with hydrophobic tails facing inwards and hydrophilic heads facing outwards.

A small, single-layered sphere formed by phospholipids with small tails, where the hydrophobic tails face inwards and the hydrophilic heads face outwards.

A hollow droplet of bilayer membrane formed by phospholipids with bulkier tails, where the hydrophobic tails face inwards and the hydrophilic heads face outwards.

Proteins embedded within the plasma membrane, usually with hydrophobic regions anchoring them to the hydrophobic core.

Proteins found on the outer and inner surfaces of membranes, loosely attached to integral proteins or phospholipids.

Integral membrane proteins that span the entire membrane, with parts exposed to both the outer and inner regions. They can act as channels for ions or transport molecules.

Carbohydrates attached to proteins or lipids on the outer surface of cell membranes. They act as cellular markers and play a role in cell recognition.

The ability of the cell membrane to maintain a fluid-like state, allowing movement and flexibility.

Cholesterol helps keep membranes fluid at low temperatures by preventing phospholipids from packing tightly, and it helps reduce fluidity at high temperatures.

The net movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration.

The total concentration of solutes in a solution.

A solution with a low osmolarity has fewer solute particles per unit volume. A solution with a high osmolarity has more solute particles per unit volume.

The ability of an extracellular solution to make water move into or out of a cell by osmosis.

The movement of a substance down its concentration gradient, meaning from an area of higher concentration to an area of lower concentration.

The ability of a membrane to allow certain substances to pass through while blocking others.

Facilitated diffusion involves the movement of substances across a membrane with the assistance of membrane proteins. It's still a passive process, meaning the cell doesn't expend energy. Channels and carrier proteins are two types.

The sodium-potassium pump moves sodium ions out of the cell and potassium ions into the cell, maintaining a concentration gradient. This process requires energy and uses ATP.

The movement of potassium ions out of the cell down their concentration gradient helps establish the membrane potential. This makes the inside of the cell negative relative to the outside.

This type of transport uses the energy stored in concentration gradients created by primary active transport to move other substances across the membrane.

Large particles or quantities of smaller particles are moved across the cell membrane in this process.

A type of endocytosis where the cell engulfs solid particles, forming a phagosome that fuses with a lysosome for digestion.

A type of endocytosis where the cell takes in fluids and dissolved substances, forming a pinosome that fuses with a lysosome for digestion.

A type of endocytosis where specific molecules bind to receptors on the cell surface, triggering the formation of a vesicle.

A process where cells release substances from the inside to the outside by fusing with the plasma membrane.

A type of membrane transport that requires the assistance of membrane proteins to move molecules across the cell membrane.

A type of facilitated diffusion that involves membrane proteins forming hydrophilic channels through which molecules can pass. These channels are selective, allowing only specific molecules to pass through.

A type of membrane transport that utilizes energy to move molecules against their concentration gradient (from an area of low concentration to an area of high concentration).

A type of active transport that directly uses energy from ATP hydrolysis to move molecules across the membrane. It's like using a pump to move water uphill.

A type of active transport that uses the energy stored in the electrochemical gradient of one molecule to move another molecule against its concentration gradient. It's coupling the movement of one molecule with the movement of another.

A type of secondary active transport where two molecules move in the same direction across the membrane. One molecule moves down its concentration gradient, providing the energy for the other molecule to move against its concentration gradient.

A type of secondary active transport where two molecules move in opposite directions across the membrane. One molecule moves down its concentration gradient, providing the energy for the other molecule to move against its concentration gradient.

The fusion of a food vacuole with a lysosome, an organelle containing enzymes that break down the engulfed material into usable components.

Coat proteins that contribute to vesicle formation by shaping the vesicle and aiding its detachment from the membrane.

Membrane-bound sacs that transport substances within and out of the cell, often formed by endocytosis or exocytosis.