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Honors Biology - Unit 4: Cell Membrane & Transport
More cell stuff?
Terms in this set (50)
What is exocytosis?
Moving of large particles out of the cell by vesicles that fuse with the plasma membrane.
_ involves moving large particles into the cell.
What are the three forms of endocytosis?
Pinocytosis, receptor mediated, phagocytosis
What is pinocytosis?
Taking in large liquid droplets or "cell drinking" and is the most common form of endocytosis taking in dissolved molecules as a vesicle.
What is receptor mediated endocytosis?
Some integral proteins have receptors on their surface to recognize and take in hormones, cholesterol, etc.
What is phagocytosis?
"Cell eating" and when large particles are engulfed and brought into the cell as vesicles.
_ _ that are manufactured in the cell are released through the cell membrane.
T/F: bulk transport requires energy.
Exocytosis and endocytosis are forms of _ _.
T/F: exocytosis and endocytosis require the molecule ATP.
Would a white blood cell (which is responsible for eating foreign invaders in your body) be high or low in number of mitochondria?
What is osmosis?
The diffusion of water across a cell membrane.
If water potential is high, solute concentration is _.
If water potential is low, solute concentration is _.
Water moves from _ concentration (water potential) to _ concentration (water potential).
What is an isotonic solution?
No net movement of water.
What is a hypotonic solution?
Water moves into the cell. Concentration of solute is more inside the cell than outside.
What is a hypertonic solution?
Water moves out of the cell. Concentration of solute is more outside the cell than inside.
What is plasmolysis?
Occurs whenever water moves out of a cell and the cell shrinks size.
What is cytolysis?
Occurs whenever water moves into the cells causing them to swell and burst.
What is homeostasis?
Balanced internal condition of cells. Also known as equilibrium.
How does the plasma membrane help maintain homeostasis?
Controls what enters and leaves the cell.
What are the seven functions of the plasma membrane?
Protective barrier, regulates transport/selectively permeable, cell recognition, anchor for cytoskeleton, binding site for enzymes, binds cells, contains the cytoplasm.
Phospholipids contain 2 fatty tails that are _.
The head is _ and contains a phosphate and glycerol.
T/F: the polar heads are hydrophobic while the non polar tails are hydrophilic.
False (hydrophilic; hydrophobic)
How does cholesterol help control membrane fluidity at warm temperature?
Less fluid at warm temperature by restraining the phospholipid movement.
How does cholesterol help control membrane fluidity at cold temperatures?
More fluid at lower temperatures by preventing close packing of phospholipids.
What are the six major functions of membrane proteins and examples of each?
Transport - glucose transporting in.
Enzymic activity - metabolism of ATP.
Signal transduction - insulin attached to receptor for cells to take in glucose.
Cell-cell recognition - white blood cells don't attack your cells.
Cell adhesion - stomach lining are cells all jointed together.
Cytoskeleton attachment - filaments.
T/F: materials soluble in lipids cane easily pass through the cell membrane.
Because the membrane is semipermeable, _ molecules and larger hydrophobic molecules can move through easily.
T/F: Ions and hydrophilic molecules are larger than water and large protein molecules do NOT move through the membrane on their own.
What is a fluid mosaic model?
Fluid because individual phospholipids and proteins can move side-to-side within the layer, like it's a liquid. Mosaic because of the pattern produced by the scattered protein molecules when the membrane is viewed from above.
What are three types of movement that can occur across cell membranes?
Simple diffusion, facilitated diffusion, active transport.
Passive transport does not require additional energy and moves materials from _ to _ concentration.
Why is diffusion considered a passive process?
No energy is used to make the molecules move.
Distinguish between a "solute" and a "solvent."
Solutes can be dissolved (ions, atoms, or molecules).
Solvents dissolve solutes.
What happens when solutes diffuse through a membrane?
They move from an area of high to low concentration if the membrane allows it.
Membranes have "_ _", meaning it only allows certain substances to cross it.
What is facilitated diffusion?
A type of passive transport because energy is not required. Uses transport proteins to help move materials from high to low concentrations.
What are two materials that move in or out of cells by facilitated diffusion?
Glucose and amino acids
Name two types of transport proteins found in cell membranes.
Channel and carrier
Describe channel proteins.
Proteins embedded in the cell membranes for materials to cross (like a bridge).
Describe carrier proteins.
Change shape to move materials from different sides of the membrane (like a boat). They bond and drag molecules through the membrane to release.
Some carrier proteins can change _ to move materials across the cell membrane.
_ transport requires additional energy to move materials.
Active transport uses cellular energy known as _.
T/F: active transport moves materials along the concentration gradient or from high to low concentration.
False (against; low to high)
How does a sodium potassium pump work?
Moves Na+ sodium ions out of the cell and K+ potassium ions are moved into the cell.
Na+ and K+ concentrations _ up on different _ of the membrane.
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