Chapter 5 Biology 1

What are the mechanisms of endocytosis and how do they differ?

3 mechanisms Phagocytosis: the uptake of solids into cell "eating" Pinocytosis: the uptake of liquids into cell "drinking" Receptor-Medicated Endocytosis: Ligand binds into receptor

What does active transport require?

ATP and a transport protein

Phospholipids are said to be amphipathic; What does amphipathic mean?

Amphipathic means some parts are polar and some are non-polar. Like the fatty acid tails are non-polar and the phosphate heads are polar.

Why is the plasma membrane called a "Fluid-Mosaic" model?

Because it's integral proteins are the "mosaic tiles" and cannot be released from membrane walls unless chemically dissolved.

Which molecules diffuse easily across the bilayer? (Small-uncharged molecules or Large-charged molecules)

Gases and small uncharged molecules

How do plant cells react in an isotonic solution, a hypotonic solution, and a hypertonic solution?

Hypotonic: turgid/normal Isotonic: flaccid/wilting Hypertonic: dead

What factors contribute to the fluidity of the plasma membrane bilayer?

Kinks formed in the hydrocarbon chain can make the plasma membrane more fluid

What is osmosis?

Movement of water across membranes to balance solute concentrations

How does cholesterol contribute to the fluidity of the bilayer (either positively or negatively)?

Negatively. It tightly packs the membrane making it more viscous

What is the difference between simple diffusion, facilitated diffusion, and active transport.

Simple and facilitated diffusion do not require ATP, whereas active transport does.

Which movement is not energetically favorable?

The flip-flop.

How do phospholipids move in the bilayer and which movements are energetically favorable?

They can move rotationally, laterally, or flip-flop. Only the former two are energetically favorable.

What is the function of the plasma membrane?

cell to cell recognition, cell signaling, adhesion to the extracellular matrix, attachment to the cytoskeleton, and transport.

What is the optimal solution for a plant cell?

hypotonic

What is exocytosis?

material from inside the cell is packaged into vesicles and excreted outside the cell