BIOL 1000 Chapter 5 pt 2 Flashcards | Quizlet

Plasma membrane

Flexible boundary between cell and environment, regulates flow of material, proteins embedded in lipid bilayer, hydrophobic parts are in the membrane while hydrophilic parts protrude in or out of membrane

Fluid mosaic model

The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.

Selective permeability

A property of a plasma membrane that allows some substances to cross more easily than others.

Phospholipids in membranes

Spontaneously self assemble into membrane

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration. Spreads out in all available space, equilibrium reached

Passive transport

diffusion of substances across a cell membrane without the use of energy by the cell

Osmosis

Diffusion of water through a selectively permeable membrane. Water passes through membrane until concentration of solute is equal on both sides

Tonicity

the ability of a surrounding solution to cause a cell to gain or lose water

Isotonic

Equal concentration of solution, water enters and exits cell at same rate, in animals its the ideal solution while in plants this causes them to wilt

Turgor pressure

The pressure that water molecules exert against the cell wall

Hypotonic

Less solute in the environment, water rushes to cell to equalize concentration and the cell swells. In animals, too much swelling can cause it to burst while in plants/fungi, this is the normal as the rigid cell walls protect against bursting and when the cell walls swell, the wall exerts back pressure

Hypertonic

More solute in the environment as water moves out of cell. In animals, the cell will die and in plants, the rigid cell wall won't be able to change shape and the plant will die

Plasmolysis

Plasma membrane pulls away from ell wall

Osmoregulation

Control of water balance and regulation of solute concentrations in body

Facilitated diffusion

Diffusion through membrane with help of transport proteins, passive transport

Channel protein

Simple channel for molecules to pass

Carrier protein

Solute binds to protein causing it to change shape

Aquaporin

Allows passage of water

Active transport

cell expends energy to move solute across concentration gradient, ATP supplies energy

Active transport steps

1. solute binds to transport protein 2. ATP provides energy for change in protein shape 3. Solute released to opposite side 4. protein returns to original shape and more solute can bind

Exocytosis

Large molecules going out of cell, transport vesicle buds off from golgi apparatus and fuses with plasma membrane, contents are released from cell

Endocytosis

process where large molecule and fluid are taken up by cell. Particle packaged in vacuole which can fuse with lysosome to digest contents. How amoeba take in food and white blood cells take in pathogens

Phagocytosis

Cell eating

Pseudopodia

Extensions of membrane that engulf particle during endocytosis

Receptor mediated phagocytosis

Allows cell to acquire specific solutes, receptor proteins are embedded in membrane in an area lined by coat proteins, receptor proteins then bind solute and plasma membrane indents to form coated pit which pinches to form vesicle

What substances diffuse through cell membrane through passive transport?

Small non polar molecules, and ions and polar molecules diffuse using transport proteins