AP Bio Unit 2.4-5

Why do phospholipids spontaneously form membranes?

hydrophilic heads block water from reaching hydrophobic tails by forming membranes around them.

What type of proteins do not interact with water?

certain regions of integral proteins

What makes the membrane fluid and mosaic?

fluid because its constantly moving & fatty acids changing from saturated to unsaturated and mosaic because of its combined structure

How do channel/carrier proteins “find” their target molecules?

the random movement of molecules, but molecules with certain glycoproteins can enter

Why don’t animal molecules have a cell wall?

it would limit movement

Why do the cell walls of plants, fungi, and bacteria have different compositions? (plants = cellulose, fungi = chitin, peptidoglycan = prokaryote)

different environments require different adaptions

Plasmodesmata

small pores in cell walls that allow the movement of water, nutrients, and waste between plant cells

Facilitated Diffusion

movement of a molecule across the membrane through a protein

What molecules can’t pass through membranes freely?

polar, hydrophilic, and ionic molecules

Glycoprotein

cell marker

What is the purpose of glycolipids?

communication

How does cholesterol reinforce the cell membrane?

it holds phospholipids together

Signal Transduction

molecules give signals to other cells that signal for activity

Peripheral Protein

loosely bounded to the membrane surface (hydrophilic)

Integral Protein

span into the membrane (whole or part) and are amphipathic

Amphipathic

hydrophobic and hydrophilic regions of the same cell (phospholipids)

In what environment do phospholipids form membranes?

aqueous environments