Chapter 3 Study Guide Flashcards
Name the 3 major parts of the cell
The Plasma Membrane (serves as a selective barrier), the Cytoplasm (consists of organelles in a fluid portion called cytosol), and the nucleus (a large organelle housing most of the cell’s DNA)
Describe the fluid mosaic model of the plasma membrane.
Proteins embedded in a sea of fluid lipids. The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid, but more like a ‘fluid’.
Know the three major lipid components of the membrane and their relative percentages
75% phospholipids, 20% chloresterol (a steroid), and about 5% glycolipids (lipids with carbohydrate attached)
Draw the structure of the lipid bilayer
the fatty acid tails are together in the interior of the membrane, with the heads pointed outward to the extracellular fluid and in the intracellular fluid. Double bonds put a kink in the fatty acid tails, preventing tight packing.
Describe the term amphipathic
Containing polar and non-polar regions
While part of a phsopholipid is polar and hydrophilic and which part is non-polar and hydrophobic?
the head, a phosphate group and glycerol, is hydrophilic, and the fatty acid tail is hydrophobic.
What is an integral membrane protein?
a protein that extends into and through the membrane bilayer
What is a peripheral membrane protein?
a protein that is loosely attached to the lipid bilayer on the outside of the cell
Know the functional classes of membrane proteins
ion channels, transporters, receptors, enzymes, linker proteins, cell identity markers
What is a cell identity marker?
Proteins unique to an individual’s cells. These are important in the immune system and are also a factor in transplantation of tissue from one person to another
What is an ion channel?
some integral proteins form ion channels, pore or holes that specific ions, such as potassium ions, can flow through to get into or out of the cell. most ion channels are selective; they allow only a single type of ion to pass through
What is a transporter?
In biology, an ion transporter, also called an ion pump, is a transmembrane protein that moves ions across a plasma membrane against their concentration gradient, in contrast to ion channels, where ions go through passive transport.
What is a receptor?
integral proteins called receptors sere as cellular recognition sites. each type of receptor recognizes and binds to a specific type of molecule. For instance insulin receptors bind the horomore insulin. A specific molecule that binds to a receptor is called a ligand of that receptor.
What is an enzyme?
some integral proteins are enzymes that catalyze specific chemical reactions at the inside or outside surface of the cell.
What is a linker protein?
an integral protein that anchors proteins in the plasma membranes of neighboring cells to one another or to the protein filaments inside and outside the cell.
What is meant by the term membrane fluidity?
double bonds put a kink in the fatty acid tails preventing tight packing => in motion
What is meant by the term membrane permeability?
the degree to which a substance can permeate (enter or pass through) the membrane.
What is meant by the term selective permeability?
Selective permeability allows for different concentrations of substances on either side of the membrane (concentration gradients). Selective permeability means that some substances can get through and others cannot.
Define the term: active transport
Transport requiring the assistance of ATP
Definet the term: passive transport
Transport done by virtue of a molecules own kinetic energy (without aid of ATP), like with water through the membrane down it’s concentration gradient
Define the term: concentration gradient
and area from highest to lowest concentration on a substance
Define the term: electrical gradient
There is a difference in distribution of postively charged ions across the membrane. This causes an electical gradient refferent to as the membrane potential.
Define the term: membrane potential
Electical gradient
Define the term: electrochemical gradient
Both concentration gradients and membrane potentials are set up as a result of selective transport across the membrane. The combined influence of concentration gradient and membrane potential (electical gradient) on movement of an ion is referred to as it’s electrochemical gradient.
Define the term: diffusion
movement of molecules or ions down a concentration gradient due to their kinetic energy until they reach equilibrium
Define the term: osmosis
passive movement of water molecules across a selectively permeable membrane from an area of higher to lower water concentration until equilibrium is reached
Define the term: facilitated diffusion
passive movement of a substance down its concentration gradient through the lipid bilayer by transmembrane proteins that function as channels or carriers
Define the term: endocytosis
material moves into cell in vesicles
Define the term: exocytosis
material moves ouf of cell in vesicles e.g. secretory vesicles releasing a horomore or enzyme