3-5 -> 3-8: Biology

characteristics of molecules that get through the cell membrane

non-charged, nonpolar, and small

what is this

cell membrane

phospholipid head

hydrophilic

phospholipid tail

hydrophobic

molecules that get through the cell membrane

oxygen and carbon dioxide

aquaporin

get water through the membrane

functions of proteins in the membrane

transportation, cell structure, enzymes (do cell work), cell recognition, intercellular joining, signal transduction

bifacial cell membrane

the inside and outside are different, it saves energy; proteins have specific orientations and carbohydrates are only on the outsides

main macromolecules in cell membranes

phospholipid and proteins

proteins

helps charged, large, polar molecules through the membrane

passive transport

no energy needed (ex. diffusion, facilitated diffusion, osmosis)

active transport

energy needed (ex. endocytosis, exocytosis)

diffusion

passive, moves high to low on the concentration gradient

facilitated diffusion

passive transport, diffusion with a carrier protein

osmosis

the process of water diffusing across a membrane

isotonic

same amount of solute on both sides of the membrane, good for animal cells, bad for plant cells (they become inelastic, or flaccid)

hypertonic

more solute outside, makes animals and plant cells shrink

hypotonic

less solute outside, bad for animal cells (the cell may burst), good for plants cells

active transport

moving molecules against their concentration gradient (low to high) requires energy

what is this

diffusion

what is this

facilitated diffusion

what is this

active transport

endocytosis

active transport, cell takes in large molecules

exocytosis

vesicles (membrane sacks sent from the golgi) send large particles out of the cell

stages of c.s

reception (receiving the signal), transduction (passing on the signal), response ( cellular changes because of the signal)

signal molecules

the actual chemical signal that travels from cell to cell; water soluble, and too big to go through the membrane, is usually on the outside

intracellular signals

proteins located in the cytoplasm or nucleus that receive a signal that CAN pass through the cell membrane (ex. steroids (hormones) and nitric oxide)

transduction

the further amplification and movement of a signal in the cytoplasm

celluar responses

production of proteins, production of lipids cell division, apoptosis, increase metabolism

apoptosis

programmed cell death; uses cell signaling pathways, DNA is chopped up, cell shrinks and becomes lobed, pieces are digested by specialized scavenger cells

positive feedback loop

amplifies a response

negative (balancing) feedback loop

returns an organism to its original state

local signaling

paracrine signaling, synaptic signaling (neurons)

synaptic signaling

long distance, fast

long distance (hormonal) signaling

tells what to do and how to respond; long distance, sustained (longer, but slower)