Unit 3 Notes

Active Transport

Process by which molecules are dragged across the membrane against concentration or pressure gradients using energy (ATP).

Membrane Pumps

Proteins that capture and pump molecules against their concentration gradients. Example includes the Sodium Potassium Pump.

Cotransport

Also known as coupled transport; occurs when active transport of one solute indirectly drives transport of another solute.

Bulk Transport

Large molecules transported into or out of the cell via vesicles or vacuoles, requiring energy.

Endocytosis

Process where the cell membrane engulfs material to bring it into the cell.

Exocytosis

Process where vesicles fuse with the outer membrane to release contents outside of the cell.

Phagocytosis

A type of endocytosis involving solid particles, often referred to as 'cell eating'.

Pinocytosis

A type of endocytosis involving liquids, commonly referred to as 'cell drinking'.

Receptor-Mediated Endocytosis

Endocytosis that occurs when a specific ligand binds to a receptor, stimulating vesicle formation.

Sodium Potassium Pump

A specific membrane pump that moves Na+ ions out of the cell and K+ ions into the cell, crucial for generating electrical signals in muscle and nerve cells.

Brownian Motion

The constant random movement of molecules, even in a solid, due to thermal energy.

Net Movement

The movement of molecules in a specific direction caused by imbalances in pressure, temperature, or concentration.

Percent Concentration

The ratio of solute and solvent in a solution, which always adds up to 100%.

Molarity

A measure of the concentration of solute in a solution, higher molarity indicates more solute.

Concentration Gradient

The process of molecules moving from an area of high concentration to an area of low concentration.

Passive Transport

The movement of molecules across a membrane without the use of energy, typically from high to low concentration.

Active Processes

Transport mechanisms that require energy, moving substances against their concentration gradient (from low to high concentration).

Simple Diffusion

The process where molecules spread evenly into available space, moving from high concentration to low concentration until equilibrium is reached.

Dialysis

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

Osmosis

The diffusion of water across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration.

Tonicity

The relative concentration of solutes in two solutions separated by a membrane.

Hypertonic Solution

A solution with a higher concentration of solutes compared to another solution.

Hypotonic Solution

A solution with a lower concentration of solutes compared to another solution.

Isotonic Solution

A solution that has the same concentration of solutes as another solution.

Crenation

The process by which cells shrink in a hypertonic solution due to loss of water.

Lysis

The swelling and bursting of cells in a hypotonic solution due to an influx of water.

Facilitated Diffusion

The process by which large molecules pass through a membrane via protein channels without requiring energy.

Channel Proteins

Proteins that form tubes in the plasma membrane to allow ions or polar molecules to pass through.

Carrier Proteins

Proteins that bind to specific substances and transport them across the membrane.

Cell Membrane

Surrounds the cell and is at its most basic a lipid bilayer bubble filled with fluid.

Phospholipid Bilayer

A structure consisting of two rows of phospholipids with their tails pointing towards the inside, forming a hydrophobic inner layer.

Cholesterol

A steroid lipid embedded in the membrane that provides stability and affects membrane fluidity.

Fluid Mosaic Model

The concept that membranes are not rigid but fluid, allowing lateral movement of phospholipids and proteins.

Extracellular Environment

The fluid environment outside a cell.

Intracellular Environment

The fluid environment inside a cell.

Membrane Proteins

Proteins that perform various functions, including transport, adhesion, and signaling.

Transport Proteins

Proteins that assist specific ions or molecules in crossing the membrane, either passively or actively.

Glycoproteins

Carbohydrate chains attached to membrane proteins that serve various functions.

Glycolipids

Carbohydrate chains attached to phospholipids that function as identification tags for the cell.

Extracellular Structures

Structures that exist outside the cell membrane, such as walls in plant cells and the extracellular matrix in animal cells.

Pectin

A sticky substance that 'glues' the walls of adjacent plant cells together.

Plasmodesmata

Channels that connect neighboring plant cells, allowing for communication and transport.

Extracellular Matrix (ECM)

A network of glycoproteins that fill the space between adjacent animal cells, aiding in cell adhesion.

Glycoproteins

Carbohydrate/protein complexes found in the extracellular matrix that play a critical role in cell recognition and adhesion.

Collagen fibers

Structural proteins in the ECM that provide strength and support to tissues.

Tight Junctions

Connections between adjacent animal cell membranes that create leak-proof tissues.

Densosomes

Protein structures that strongly connect neighboring cells' cytoplasm in sheets, important for muscle cell integrity.

Gap Junctions

Complex channels made of connexin proteins that connect the cytoplasm of neighboring animal cells and can open or close.

Connexins

Proteins that make up gap junctions, allowing for communication between heart cells.

Fimbriae

Sticky extensions that help cells adhere to surfaces.

Nucleoid

Open area in prokaryotic cells containing the DNA.

Cell wall

A non-living, stiff covering that surrounds the plasma membrane and protects internal cell structures.

Cytoskeleton

A series of protein tubes that support the cell, involved in cell shape, movement, and division.

Microtubules

Cytoskeletal proteins that support the cell and involved in organelle movement.

Flagellum

A long structure made of microtubules that spins in a circle to move the entire cell.

Cilium

Short, hair-like structures made of microtubules that propel liquids or move the cell.

Plasma Membrane

A biological membrane that separates and protects the interior of all cells.

Glycocalyx

An outer coating in prokaryotic cells, including a protective capsule or slime layer.

Rough Endoplasmic Reticulum (Rough ER)

A type of endoplasmic reticulum studded with ribosomes that synthesizes proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

A type of endoplasmic reticulum that is involved in lipid synthesis and detoxification.

Plasmids

Circular pieces of DNA found in bacteria that can be transferred between cells.

Centrioles

Paired bundles of microtubules that play a role in mitosis.

Chloroplast

An organelle found in plant cells that conducts photosynthesis.