chapter 5 Flashcards
fluid mosaic model
Diverse protein models suspended in a fluid phospholipid bilayer
The presence of cholesterol keep phospholipids from packing too tightly
Attachment Protein
proteins that attach to the ECM (fibers of extracellular matrix) and cytoskeleton help support the membrane and can coordinate external and internal changes
Receptor Protein
bind signaling molecules and relay the message by activating other molecules in the cell (signal transduction)
Active Transport Protein
allow specific ions or molecules to enter or exit the cell
Junction Protein
form intercellular junctions that attach adjacent cells
Glycoprotein
serve as ID tags that are recognized by membrane proteins of other cells
Enzymes
to assist reactions in the cell?
evolution of membranes
Phospholipids among the first organic molecules formed
Can spontaneously self assemble into simple membranes
purposes of cell membrane
encloses assembly of molecules
regulates chemical exchanges w/ environment
what kind of energy do molecules have
thermal energy, because of their constant motion
diffusion
particles moving from an area of high to low concentration
passive transport
diffusion across a biological membrane down a concentration gradient (high to low)
Osmosis
diffusion of water
isotonic solution
solute concentration equal between solution and cell
Hypotonic solution
solute concentration is lower than in the cell
is the water filled cell
Hypertonic solution
solute concentration is higher than in the cell
is the small, shriveled cell
osmoregulation
preventing excessive uptake or excessive loss of water
plasmolysis
cell loses water
facilitated diffusion
use of channel proteins to move substances across a membrane
(when molecules still have a net movement of a high concentration to a low concentration but they may be too large or have other characteristics that prevent them from directly traveling across the selective cell membrane, therefore they have to go through a protein channel
active transport
molecules go against concentration gradient, powered by ATP
ATPs role in active transport
ATP energizes transport protein
endocytosis
the cell fuses with the molecules it’s taking in, in order to bring it inside, form vesicles that can be taken inside the cell
exocytosis
used to get rid of cell waste and getting valuable materials out, vesicle fuses with membrane
Phagocytosis
pods stretch out around what they are going to engulf, and then it pulls it in, “cell eating”