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Flashcards in Membrane Structure And Function Deck (25):
1

Integral proteins

Penetrate the hydrophobic core

2

What are the different effects of steroid cholesterol on membrane fluidity at different temperatures?

Warm temperature: cholesterol restrains movement of the phospholipids

Cool temperature: maintains fluidity by preventing tight packing

3

What are the six major functions of membrane proteins?

-Transport
-Enzymatic activity
-Signal Transduction
-Cell-cell recognition
-Intercelluar joining
-Attachment to cytoskeleton and ECM

4

Peripheral proteins

Bound to the surface of the membrane

4

MHCs

Determines how your tissue works with you (such as blood type)

5

Fluid Mosaic model

States that a membrane is a fluid structure with a "mosaic" of various proteins embedded in it

6

What dissolves in the lipid bilayer and pass through membrane rapidly?

Hydrophobic (nonpolar) molecules, such CO2, and O2

7

Transport proteins (channel proteins)

Allow passage of hydrophilic substances across the membrane

8

Aquaporins

Facilitate the passage of water

9

Diffusion

Tendency for molecules to spread out evenly into the available space

10

Passive transport

Diffusion of a substance across a biological membrane. No energy is expended by the cell to make this happen

11

Osmosis

Diffusion of water across a selectively permeable membrane

12

Which direction do substances diffuse?

Down their concentration gradient (from high to low concentration)

13

Isotonic solution

Solute concentration is the same as inside the cell; still movement but no net movement

14

Hypertonic solution

Solute concentration (amount of non-water particles) is greater than that inside the cell; cell loses water and shrivels (plasmolyzed)

15

Hypotonic solution

Solute concentration (amount of non-water particles) is less than that inside the cell; cell gains water (turgid; lysed (ruptured))

16

Osmoregulation

Control of salute concentration and water balance, is a necessary adaptation for life in such environments
(A paramecium pumps water out of the cell due to living in hypotonic solution)

17

Facilitated diffusion

Transport proteins speed the passive movement of molecules across the plasma membrane
(Aquaporins, ion channels)
Still PASSIVE

18

Active transport

Moves substance against their concentration. Requires energy, usually in the form of ATP.
Performed by specific proteins (or pumps) in the membranes

20

Bulk transport

Large molecules, such as polysaccharides and proteins, cross the membrane in bulk via vesicles
Requires energy

21

Endocytosis

The cell takes in macromolecules by forming vesicles from the plasma membrane

22

What are the three types of endocytosis?

Phagocytosis-cell "engulfs"
Pinocytosis-cell "gulps"
Receptor-mediated endocytosis

23

Receptor-mediated endocytosis

Binding of ligands to receptors triggers vesicle formation

24

Ligand

Any molecule that binds specifically to a receptor site of another molecule

25

What is an example of an ACTIVE transport system? (Requires energy)

Sodium-potassium pump
(Remember: 3 sodium for every 2 potassium)