BIOLOGY 1510 CHP 5.

Researched, and information pulled from lecture slides.

Phospholipid bilayer

Consists of phospholipids arranged in two layers with exterior facing hydrophilic polar heads and interior hydrophobic, non-polar tails.

Selective permeability

The ability of a cell membrane to regulate which substances can enter or leave the cell, allowing some molecules through while blocking others. (Lipids and small nonpolar molecules ex: O₂ and CO₂

Phospholipids are

Selective permeability

Transmembrane proteins

integral membrane protein that spans the entire lipid bilayer, typically using hydrophobic. Functions in transport, signaling, adhesion, or enzymatic activity. They are embedded in phospholipid bilayer

Proteins

Are important for function of cell membrane (1.Transport, 2. Enzymes, 3. Cell surface receptors, 4. Cell surface identity marker, 5. cell to cell adhesion, 6. Attachment to the cytoskeleton, 7. Affect membrane structure)

Transporter

Enzyme

Cell surface receptor

Cell surface identity marker

Cell-to-cell adhesion

attachment to the cytoskeleton

Transport proteins

allows for the movement of polar molecules into/ out of the cell (Are selectively permeable)

Enzymatic proteins

Allow the cell to perform certain, specific functions internally

Receptor proteins

Bind external chemical singals to trigger internal action (Shape specific)

Cell surface markers

Molecules, typically proteins or carbohydrates, that are embedded in or attached to the outer layer of the cell membrane. (Identification as recognized or foreign, characteristic of each cell type)

Cell-cell adhesion proteins

Enable cells to bind to each other or to the Extracellular matrix, forming the structural and signaling basis of tissues.

Order of the cell membrane

1. Phospholipids, 2. transmembrane proteins, 3. Interior protein network 4. Cell surface markers

Passive transport

movement of substances across a cell membrane from high to low concentration without using cellular energy (ATP), and it includes diffusion, facilitated diffusion, osmosis and filtration

Active transport

Energy-requiring process in which cells use ATP to move molecules, or ions across membranes from low to high concentration (EX: Sodium potassium pump)

Passive transport properties

Simple diffusion: NONE, Facilitated diffusion: Channels proteins, osmosis, carrier proteins

Active transport properties:

(EX: h+ pumps & Sodium potassium pump) Secondary active transport: Symport, antiport. Endocytosis, exocytosis

Diiffusion

Passion movement of molecules or particles from a region of higher concentration to a region of lower concentration, continuing until equilibrium is reached.

Simple diffusion

Moves freely through cell membrane (ex: gases)

Facilitated diffusion

A form of passive transportation in which membrane proteins move particles across a membrane down concentration gradient

Proteins that accomplish facilitated diffusion

Carrier, channel

Carrier proteins

Bind a single molecule at a time (ex: glucose and amino acids)

Channel proteins

Allow for the passage of ions and water (Ion channels - ions, Aquaporins - water)

Osmosis

The diffusion of water across a semipermeable membrane from high to low concentration

Hypertonic examples

High solute outside, cellsize shrinks

Hypotonic examples

Low solute outside, cell size swells

Isotonic examples

Equal solute outside, cell size stays the same`

Hypertonic

Solution or environment with a higher solute concentration than another

Hypotonic

Solution with a lower solute concentration than another solution, causing water to move into cells, or a muscle with lower resting tone

isotonic

solution that has the same solute concentration as the fluid inside a cell; results in no net movement of water across the cell membrane

Secondary Active transport

Uses energy produced from passive transport to fuel other molecules to move against their concentration gradient

Symport

The transported solute moves in the same direction as the gradient of the driving ion

Antiport

The transported solute moves in the direction opposite from the gradient of the driving ion

Exocytosis

Cells use vesicle to transport fluids and large particles out of the cell

Endocytosis

Cell engulfs fluids and large molecules

Types of membrane transport

passive, active