10/03 Flashcards
What structure do plants have that is different from animals?
Cell wall
Plants have a cell wall which provides structure and support, unlike animals that have a skeletal system.
What is the main function of membranes in cells?
Compartmentalization and regulation
Membranes separate cell contents and organelles from their environment and control movement between cells and surroundings.
What happens if there is no cell membrane?
No multicellular organisms and no organs.
What is the hydrophobic part of a membrane?
Water repelling, non-polar region
The hydrophobic part cannot form hydrogen bonds with water.
What is the hydrophilic part of a membrane?
Water attracting, charged or polar region
The hydrophilic part can form hydrogen bonds with water.
What is the role of cholesterol and sterols at high temperatures?
Restrains the movement of phospholipids.
What is the role of cholesterol and sterols at low temperatures?
Maintains fluidity by preventing tight packing of phospholipids.
What does the term ‘mosaic’ refer to in membrane structure?
Collage of proteins embedded in the membrane.
What are peripheral proteins?
Bound to membrane surface by anchoring molecules.
What are transmembrane integral proteins?
Proteins that penetrate hydrophobic core and span across the lipid bilayer.
What does selectively permeable mean?
Membranes repel polar molecules but not nonpolar molecules.
What factors influence membrane permeability?
- Lipid solubility
- Electrical charge
- Size
What is passive transport?
Movement of molecules through the membrane without energy required.
What is simple diffusion?
Movement through phospholipids.
What is protein-mediated transport?
Movement through proteins.
What is active transport?
Movement against concentration gradient using energy (ATP).
What is the Na+/K+ Pump?
Moves 3 Na+ out of the cell and 2 K+ into the cell against their concentration gradient.
What is the electrochemical gradient?
Combination of electrical gradient and chemical gradient.
What is osmosis?
Movement of water across membranes to regions of highest solute concentration.
What is isotonic solution?
Equal solute concentration.
What occurs in a hypertonic solution for animal cells?
Cells lose water and shrivel up (crenate).
What happens to animal cells in a hypotonic solution?
Cells swell up and may burst (lyse).
What is the normal state of a plant cell in a hypotonic solution?
Normal state due to hydrostatic pressure.
