Ch. 5 Structure & Function of Plasma Membranes

What are the four functions of the plasma membrane?

What are the four functions of the plasma membrane?

• Defining the outer border of all cells and organelles

• Managing what enters and exits the cell

• Receiving external signals and initiating cellular responses

• Adhering to neighboring cells

What is the second major component of membranes that can be transporters, receptors, enzymes, or can function in binding and adhesion?

protein

What type of protein is integrated completely into the bilayer?

integral protein

What are integral proteins that pass completely through the phospholipid bilayer?

transmembrane proteins

What type of proteins occur only on the surface?

peripheral proteins

What is the third major component of membranes located on the exterior surface of the plasma membrane bound to either proteins or lipids?

carbohydrates

What are three things that affect membrane fluidity?

• phospholipid type

• temperature

• cholesterol

What is it when the plasma membrane allows some molecules to pass through but not others?

selective permeability

What is it when molecules can cross the phospholipid bilayer?

permeant

What three things can pass through the phospholipid bilayer?

• gasses

• hydrophobic/nonpolar molecules

• small polar molecules

What two things cannot pass through the phospholipid bilayer?

• large polar molecules

• ions/electrically charged molecules

What are the two types of transport?

passive and active

What type of transport requires no added energy?

passive

What type of transport requires energy (ATP)?

active

What is the simplest type of passive transport that occurs when a substance from an area of high concentration moves down its concentration gradient?

diffusion

What five factors affect diffusion rates?

• concentration rates

• mass of the molecules

• temperature

• surface area

• pressure

What moves substances down their concentration gradients through transmembrane, integral membrane proteins?

facilitated diffusion

What are the two types of facilitated transport proteins?

channel and carrier proteins

What type of facilitated transport protein’s top, bottom, and inner core are composed of hydrophilic amino acids that attract ions &/or polar molecules?

channel proteins

What type of facilitated transport protein binds to a substance that changes shape and carries it to the other side?

carrier proteins

What is the diffusion of water across a membrane?

osmosis

What describes how an extracellular solution can change the volume of the cell by affecting osmosis?

tonicity

What three things describe the osmolarity of the cell to that of its extracellular fluid?

• hypertonic

• hypotonic

• isotonic

What is it when extracellular fluid that has lower osmolarity than the cytosol (water leaves the cell)?

hypertonic

What is it when extracellular fluid has the same osmolarity than the cytosol (water does not move)?

isotonic

What is it when extracellular fluid that has higher osmolarity than the cytosol (water enters the cell)?

hypotonic

What is it when there is pressure exerted by the plasma membrane against the cell wall?

turgor pressure

What is it when the plasma membrane detaches from the cell wall?

plasmolysis

What is needed any time an ion or molecule is transported through a membrane protein?

active transport

What are the two types of active transport?

primary and secondary

What arises from the combined effects of concentration and electrical gradients; where cytoplasm contains more negatively charged molecules than the extracellular fluid?

electrochemical gradient

What type of pump carries one molecule or ion?

uniporter

What type of pump carries two different molecules or ions in the same direction?

symporter

What type of pump carries two different molecules or ions in different directions?

antiporter

What moves an ion or molecule up its concentration gradient using energy from ATP hydrolysis?

primary active transport

What uses an electrochemical gradient created by primary active transport to move a different substance against its concentration gradient?

secondary active transport

What type of active transport requires energy for cells to import or export molecules/particles that are too large to pass through a transport protein?

bulk transport

What is importing by bulk transport?

endocytosis

What is exporting by bulk transport?

exocytosis

What are the three types of endocytosis?

• phagocytosis

• pinocytosis

• receptor-mediated endocytosis

What is cell eating; the cell membrane surrounds a particle and engulfs it?

phagocytosis

What is cell drinking; the cell membrane folds inwards surrounding a small volume of fluid and pinches off?

pinocytosis

What is it when the uptake of a specific substance is targeted by binding to receptors on the external surface of the membrane?

Receptor-mediated endocytosis

What is the