Biology Chapter 5 Flashcards
the membranes that encase all living things are made of ___.
lipids
The lipid found in membranes is a ___
phospholipid
What is the phospholipid membrane made of?
- Glycerol (a 3 carbon polyalcohol)
- 2 fatty acid chains (non polar hydrophobic)
- phosphate group (polar hydrophilic)
What happens when you put phospholipids in water? Describe the process.
they form a lipid bilayer - the bilayer is formed by hydrophobic exclusion, the non polar tails align and face inwards while the polar heads align and face outwards
The lipid bilayer is fluid/not fluid.
fluid
The lipid bilayer is held together by ___ from the water.
hydrogen bonding
Describe why the lipid bilayer is fluid.
The hydrogen bonds in water keep the lipid bilayer in place, but does not keep the phospholipid molecules in place. Therefore the phospholipid molecules are free to move around in the bilayer.
What part of the lipid bilayer determines the fluidity of the membrane? What makes a membrane more or less fluid?
the fatty acid chains determine the fluidity of the membrane; the more double bounds the chains have the more fluid as opposed to the the chains without double bonds
Which makes membranes less fluid, saturated fatty acids or unsaturated fatty acids?
Saturated fatty acids
What prevents double bonds from packing tightly?
kinks
___ can increase or decrease membrane fluidity, depending on temperature. An example is cholesterol.
sterol
The warmer the temperature, the more/less fluid the membrane is.
more
What is the fluid mosaic model?
The model that lipid bilayer consists of proteins that are embedded in the plasma membrane as opposed to on top of the bilayer which would crush the membrane. The proteins float on the plasma membrane like a boat on a pond.
What are the 4 components of a cell membrane?
- lipid bilayer
- transmembrane proteins
- supporting fiber
- exterior proteins and glycolipids
__are proteins that are inserted in the membrane; they have a huge variety of functions
transmembrane proteins
__ are fibers attached to transmembrane proteins, which help cell maintain its shape
supporting fibers
__ is a special molecule made in the ER made up of carbohydrates and lipids, used for cell recognition and other cell identity
glycocalyx
List the 6 kinds of transmembrane proteins.
- transporters
- enzymes
- receptors
- surface identity markers
- cell adhesion
- cytoskeleton attachment
these proteins are used to move molecules in and out of a cell
transporter transmembrane protein
What are 3 types of transporter proteins?
Channels, Carriers and pumps
these proteins allow certain molecules to diffuse into the cell
channels and carriers
these proteins are used for active transport when the cell needs to expend energy
pumps
type of protein that many of the biochemical reactions are carried out by and are attached to the plasma membrane
enzyme
these type of proteins are very sensitive to specific chemicals, once chemical attaches to this protein a series of chemical reactions are initiated in the cell
receptor
type of protein used to identify molecules/cells; glycocalyx is attached
surface identity markers
cells are able to attach to each others surface through this protein
adhesion protein
this protein is the anchoring point for actin fibers of the cytoskeleton
attachment protein
has 7 transmembrane domains forming a structure within the membrane through which protons pass during the light driven pumping of protons
bacteriorhodopsin
the net movement of a substance from an area of high concentration to a lower concentration; no energy required
diffusion or passive transport
What are two types of facilitated diffusion?
1 -the use of ion channels which allow hydrophilic ions to pass through the cell
2- the use of carriers which attach to the molecule and is passes through the plasma membrane
net diffusion of water across a membrane toward a higher solute concentration
osmosis
water needs a special channel protein called __ to diffuse in and out of the cell
aquaporins
the concentration of all the solute in the water
osmotic concentration
a solution w/a higher osmotic concentration (hypertonic)
hyperosmotic
a solution w/a lower osmotic concentration (hypotonic)
hypoosmotic
a solution with equal osmotic concentration
isosmotic
cells in hyper osmotic solutions __ water, and cell sin hypo osmotic solutions __ water.
loose; gain
the pressure that must be applied to stop the osmotic movement of water across a membrane
osmotic pressure
Water should move into the cell via osmosis. The pressure of the water moving in is ___ and the pressure from the water in the cell is the ___
osmotic pressure; hydrostatic pressure
The plasma membrane cannot tolerate high pressures, cells need to maintain ___ relative to the internal environment.
isosmotic conditions
a method used to solve osmosis problems; used by single cell organisms through which the organisms are hyper osmotic and are constantly taking in water
extrusion
often organisms that live in hyper osmotic environments can adjust by allowing their cells to maintain the same concentrations as the seawater
isosmotic solutions
plant cells use this; the cells are hyper osmotic and take on lots of water and the plasma membrane is pressed against the cell wall
turgor
is a process whereby the plasma membrane envelopes something and forms a vacuole; the movement of a substance into a cell
endocytosis
What are the different types of endocytosis?
1- phagocytosis, taking in a particular matter
2- pinocytosis, taking in liquid
3- receptor mediated endocytosis, many receptors on plasma membrane fill w/molecules and eventually forms a vacuole and is brought into a cell
used in plants to export cell wall material; molecules are ejected from the cell by fusion of a vesicle with the plasma membrane
exocytosis
requires the cell to expend energy; the only way for a cell to transport a molecule against a diffusion gradient; moves a molecule from an area of low concentration to high concentration
active transport
moves 1 molecule at a time in active transport
uniporter
moves 2 molecules in the same direction
symporter
moves 2 molecules in opposite directions
antiporters
More than __ of the energy used by a cell is used to actively transport sodium out and potassium into the cell, which is done by the protein __
1/3; sodium-potasium pump
is a pump that moves protons across a membrane and are powered by electrons
proton pump
Proton pumps are critical for the manufacturing __
ATP
