Unit 2B Cells & Cell Transport

Cell

basic unit of structure and organization of all living organisms

Plasma (Cell) Membrane

flexible, selectively permeable boundary that helps control what enters and leaves the cell

Eukaryotic Cell

unicellular organism with membrane-bound nucleus and organelles; generally larger and more complex than a prokaryotic cell

Prokaryotic Cell

microscopic, unicellular organism without a nucleus or other membrane-bound organelles

Selective Permeability

property of the plasma membrane that allows it to control movement of substances into or out of the cell

Phospholipid Bilayer

plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside

Transport Protein (aka carrier protein)

protein that moves substances or wastes through the plasma membrane

Cytoplasm

semifluid material inside the cell's plasma membrane

Cell Wall

in plants, the rigid barrier that surrounds the outside of the plasma membrane, is made of cellulose, and provides support and protection to the cell

Diffusion

net movement of particles from an area of higher concentration to an area of lower concentration

Dynamic Equilibrium

condition of continuous, random movement of particles but no overall change in concentration of materials

Facilitated Diffusion

passive transport of ions and small molecules across the plasma membrane by transport proteins

Osmosis

diffusion of water across a selectively permeable membrane

Isotonic Solution

a solution with the same concentration of water and solutes as inside a cell, resulting in the cell retaining its normal shape because there is no net movement of water

Hypotonic Solution

a solution that has a lower concentration of solute outside the cell than inside, causing water to flow into the cell by osmosis

Hypertonic Solution

a solution that has a higher concentration of solute outside the cell than inside, causing water to leave the cell by osmosis

Active Transport

energy-requiring process by which substances move across the plasma membrane against a concentration gradient

Endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

Exocytosis

release of substances out a cell by the fusion of a vesicle with the membrane.

Protein pump

The term applied to a protein channel/transport protein that is working to move substances against the concentration gradient with the help of cell energy (ATP).

Hydrophobic

Having an aversion to water; tending to coalesce and form droplets in water. (water-fearing)

Hydrophilic

Having an affinity for water. (water-loving)

Polar

describes a molecule in which the positive and negative charges are separated

Nonpolar

a molecule in which all atoms have equal positive & negative charge distribution

Solvent

A liquid substance capable of dissolving other substances. Typically this is water.

Solute

A substance that is dissolved in a solution. (ex: salt or sugar)

Cholesterol

A lipid that forms an essential component of animal cell membranes that keep the fatty acid tails from sticking together.

Homeostasis

process by which organisms maintain a relatively stable internal environment

Electrolytes

minerals that help maintain the body's fluid balance (major examples in animal cells are sodium and potassium)

Solution

Homogeneous mixture where one substance (the solute) is uniformly dissolved in another substance (the solvent)

Cell theory

Fundamental biological principle that states all living organisms are composed of cells, the cell is the basic unit of structure and function in all living things, and all cells arise from pre-existing cells

Nucleus

Control center of the cell; A part of the cell containing DNA and RNA and responsible for growth and reproduction

Ribosome

Organelle which synthesizes (makes) proteins.

Endoplasmic reticulum

A system of membranes that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids.

Golgi apparatus

Cell organelle which modifies, sorts, and packages proteins and other materials within the cell.

Vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

Mitochondria

Powerhouse of the cell, organelle that is the site of respiration which produces ATP (energy).

Cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell; found in plant cells.