PLTL Cell Membranes & Transport Workshop

Plasma Membrane & Concentrations

100

What is the fluid mosaic model?

Model or term used to describe the plasma membrane given that it's made up of multiple different kinds of molecules (mosaic part) and that the plasma membrane is always moving, never static (fluid part).

200

The membrane is made up of which type of lipid? Describe it's structure.

Phospholipid - made up of a polar/hydrophilic head and a non-polar/hydrophobic tail

300

What is a hypertonic, isotonic, and hypotonic solution?

Hypertonic: solution that is high in concentration relative to a cell.

Isotonic: solution concentration is equal to the cell or balanced.

Hypotonic: solution that is low in concentration relative to a cell.

400

What happens if I placed a cell in a hypertonic, isotonic, and hypotonic solution?

Hypertonic - cell shrinks due to water exiting

Isotonic - cell remains stable

Hypotonic - cell swells and bursts (lysis) due to water entering

500

Using this figure, where will the water move? What is this process called?

Water will go down its concentration gradient so into the right side of the tube through osmosis. Osmosis is the movement of water towards a solute across a semi-permeable membrane.

water likes to go where the party is.

Transport Mechanisms

100

What is passive transport? What are the 2 kinds of passive transport?

Passive transport: transport of molecules down their concentration gradient without the use of energy / ATP

1. Simple diffusion: diffusion of solute through a membrane without any help - molecule moves thru the membrane

2. Facilitated diffusion: diffusion of a solute through a membrane using the help of transport proteins

200

What is the difference between active and passive transport?

Active transport requires energy (ATP) to move molecules against their concentration gradient

Passive transport doesn't require ATP and molecules move down their concentration gradient

300

What type of transport is demonstrated in the figure? Endocytosis or exocytosis? Define this process.

Endocytosis: the process of molecules entering the cell by using the cell membrane to form a vesicle around the molecule. 

ex. Cholesterol is picked up by liver cells using endocytosis

hint: endo = inside/within

400

What transport mechanism is illustrated in the figure below? Endocytosis or exocytosis? Describe this process.

Exocytosis: when the cell releases molecules by forming a vesicle around the molecules (within the cell), which will fuse into the membrane and exit the cell.

ex. neurons release chemical signals called neurotransmitters using exocytosis so that they can communicate with other neurons/cells

exo = exit

500

What is the difference between pinocytosis and phagocytosis?

Both are a type of endocytosis. 

Pinocytosis involves the cell engulfing water/liquids, while phagocytosis involves the cell engulfing pathogens like bacteria and then digesting them (cell eating).