Cell membrane and cell transport test

based on study guide

diffusion

movement of particles from high concentration to low concentration

osmosis

diffusion of water across a membrane from high water (low solute) to low water (high solute)

osmotic pressure

pressure caused by water moving into a solution by osmosis

turgor pressure

pressure of water inside a plant cell pushing against the cell wall (keeps plants firm)

plasmolysis

when a plant cell shrinks as water leaves it

hypertonic

solution with higher solute concentration than the cell (water leaves cell)

hypotonic

solution with lower solute concentration than the cell (water enters cell)

isotonic

solution with equal solute concentration (no net water movement)

phagocytosis

cell “eats” large particles by engulfing them

pinocytosis

cell “drinks” liquids and small particles

endocytosis

process of bringing materials into the cell

exocytosis

process of releasing materials out of the cell

solute

substance being dissolved (like salt in water)

solvent

substance doing the dissolving (like water)

concentration

amount of solute in a given amount of solution

facilitated diffusion

movement from high to low concentration with help of proteins (no energy needed)

active transport

movement from low to high concentration using energy

examples of active transport

sodium-potassium pump, nutrient absorption in the gut, mineral uptake in plant roots, and endocytosis/exocytosis for transporting large particles

channel proteins

form tunnels for substances

carrier proteins

change shape to move substances

protein pumps

use energy to push substances

receptor proteins

receive signals

recognition proteins

identify cells

enzymatic proteins

speed up reactions

membrane structure and function

thin, flexible barrier that controls what enters and leaves the cell

phospholipid bilayer

two layers with heads out (hydrophilic heads and hydrophobic tails)

fluid mosaic

proteins move within the membrane

cholesterol role in cell membrane

keeps membrane stable

selective permeability

allows some substances in/out but not others

osmosis in plants

water moves into or out of plant cells depending on surroundings

high turgor pressure

cell is firm when water enters (plant stands upright)

low turgor pressure

cell is weak when water leaves (plant wilts)

plasmolysis

cell shrinks as water leaves (remember: “plasma pulls away”)

saline solution

salt water that is hypertonic to onion cells (more solute outside)

hypertonic solution

causes water to leave the cell

osmosis example in onion and saline solution

water moves out of onion cells into the salt solution

turgor pressure

decreases as water leaves (cell loses firmness)

plasmolysis

cell membrane pulls away from the cell wall as it shrinks (key result in onion cells)

cell membrane

a thin, flexible, semipermeable barrier found in all living cells that separates the cell's interior from the outside environment

vacuole

a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.

cytoplasm

becomes more concentrated as water leaves

cell wall

a rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria.

tonicity effect

salt outside “pulls” water out of the cell (remember: “salt sucks water out”)