Diffusion, Water Potential, and Organelles Flashcards
(55 cards)
Cell membrane
Allows substances to enter or exit the cell
Cell wall
Provides structure in plants, made of cellulose and prevents the cell from bursting.
Cytoplasm
Organelles are suspended in this, consists of cytosol (semi liquid, contains ions and small molecules). Most reactions take place there.
Nucleus
DNA storage, control center of the cell.
Ribosome
Links amino acids to make proteins, can be attached to the ER or free floating.
Endoplasmic reticulum
Synthesis, folding, modification, and transport of proteins. Continuous channel.
Smooth Endoplasmic reticulum
No ribosomes, produces lipids, hormones, and steroids, breaks down toxic chemicals.
Rough Endoplasmic reticulum
Attached to the nucleus and studded with ribosomes, produces proteins that can be transported across the cell membrane or used to build organelles.
Golgi Complex
Modify, process, and sort proteins. They are packaged in sacs (vesicles) for transport.
Mitochondria
Powerhouse of the cell, converts energy from organic molecules into energy for the cell (ATP).
Lysosome
Contains digestive enzymes that break down old organelles, debris, or large particles (clean up crew).
Vacuole
Store water, food, wastes, salts, or pigments.
Chloroplast
Contain chlorophyll, involved in photosynthesis.
Selectively Permeable
All cells have highly selective membranes that only allow certain substances to enter, and sometimes requires assistance. Whether a substance can enter or leave is determined by the membrane’s permeability.
How are molecules that cross the membrane selected? (4)
- Size- some molecules are too large
- Polarity- polar or nonpolar, can be determined by shape. Small nonpolar (O2), small polar (H2O) molecules cross on their own, while large polar molecules (glucose) require assistance.
- Electrical charge- ions (Ca, Na, K) can’t pass freely across the membrane.
- Lipid solubility- the membrane is made of phospholipids, and polar molecules typically aren’t soluble.
Passive Transport
Doesn’t require cell to use its own energy supply to transport across the membrane. Includes diffusion, osmosis, and facilitated diffusion.
Diffusion
Molecules move down a concentration gradient (from areas of high to low concentration). Matter is constantly in motion during diffusion, even during equilibrium at equal rates.
Facilitated Diffusion
Helps to transport ions down concentration gradient using ion channels or transport proteins. Charge on either side of the membrane is important. Aquaporins are water specific channels.
Osmosis
Diffusion of water down a concentration gradient, can serve to dilute a solution.
Hypertonic
More dissolved solutes than the cell (solution is more concentrated than the cell’s cytoplasm). The cell will lose water in this environment.
Hypotonic
Less dissolved solutes than the cell (solution is less concentrated). The cell will gain water and can burst (in animals).
Isotonic
Solute concentrations are equal.
How do plants encourage uptake of water?
By maintaining a concentrated vacuole (hypertonic condition). Entrance of water creates hydrostatic/turgor pressure.
Active Transport
Characterized by movement of material against concentration gradient (low to high concentration). Expenditure of the cell’s energy- transport proteins use ATP. Demonstrated by sodium potassium pumps.
