Quiz 2 Flashcards
What is primary protein structure?
The linear sequence of amino acids in a straight line. They have an NH3 (Amino) on one end and a COO (Carboxyl) on the other.
What is secondary protein structure?
The formation of a-helices or b-pleated sheets due to hydrogen bonding between the O of
a carbonyl group and the H of the amino group. B pleated sheets form when the peptide lies in a parallel or an antiparallel direction.
What are tertiary protein structures?
The arrangement of the peptide chain due to interactions between R-groups gives proteins a distinct shape. These can include hydrophobic interactions,van der Waals interactions, ionic bonds, hydrogen bonds, disulphide bonds
What are quaternary protein structures?
Results from the aggregation of two or more polypeptide subunits
What can change protein functions?
A change in primary structure
What determines protein structure?
Primary structure and physical and chemical nature can alter the structure. Alterations in pH, salt concentration, temperature or other environmental factors can cause a protein to unravel
What is denaturation?
The loss of a protein’s native structure. It is now biologically inactive.
What happens if a protein folds improperly?
Misfolded proteins can cause certain diseases like mad cow disease
What are chaperonins?
Proteins that assist with the folding of other proteins.
What are the steps of chaperonin actions?
An unfolded polypeptide enters the cylinder from one end, the cap attaches causing the cylinder to change shape to make a hydrophilic environment for folding. Then the cap come off and the properly folded protein releases
What are nucleic acids?
Contain coded information for cells to transmit to future generations that determine protein production. There are two types; DNA & RNA
What is a nucleotide made of?
A phosphate, sugar and nitrogenous base joined together
What are the different sugars in DNA and RNA?
DNA uses deoxyribose ( OH and H on the bottom and RNA uses ribose( 2 OH at the bottom)
What are the features of a nucleotide?
There’s a 5’ C phosphate group, a 1’ C base, 2 C’ OH in RNA and H in DNA, and a 3’ C OH for polymer function
What are pyrimidines?
Single six-sided ring nitrogenous base, Cytosine, Thymine and uracil
What are purines?
Six and Five sided rings fused, Adenine and Guanine
What are integral membrane proteins?
They are embedded in the bilayer due to the protein being hydrophobic
What are peripheral membrane proteins?
They are attached loosely to the surface of the membranes ( it usually interacts with the membrane proteins)
What are glycoproteins?
Membrane proteins that have sugar attached, important in cell recognition
What are glycoproteins?
Membrane lipids that have sugar attached
What is cholesterol?
Inserted between phospholipid molecules to increase membrane fluidity and permiablity
How do phospholipids move?
They move laterally or rarely flip-flip transversely
What does high temperature do to membrane fluidity
It increases fluidity and permiablity since gaps in the membrane will form if the temperature goes high enough
What happens when temperature changes in a membrane?
Phase change will change from solid to liquid or reverse
The temperature at which phase transition occurs depends on?
The length of the fatty acid Long=Solid, Short=Liquid. Shape; Saturated=solid, Unsaturated=liquid.Cholesterol acts as a fluidity buffer to maintain membrane fluidity at differing temperatures since it interferes with lateral movement and also prevents the packing of phospholipids at cooler temperatures.
What are the six major functions of membrane proteins?
Transport of molecules into or out of the cell, enzymatic reactions near the membrane, signalling via receptors, cell-cell recognition, intercellular attachment, attachment of the cell to extracellular matrix proteins
What are the three ways of transport in membranes?
Diffusion facilitated diffusion and active transport.
What is diffusion?
It occurs best with small hydrophobic molecules that are soluble in the bilayer and they spread out until equilibrium is reached. Uncharged can rarely pass through and charged never can.
What is osmotic lysis?
An influx of water in animal cells from an outside hypotonic solution
What is plasmolysis?
When a turgid (normal) plant cell shrivels and the membrane pulls away from the cell wall from a hypertonic solution and becomes plasmolyzed
What is facilitated diffusion?
When specific molecules are impeded by the membrane but are transported by specific proteins. Channel proteins only allow one type of molecule or ion to pass through, channel proteins are gated and can be turned on by specific stimulus. Carrier proteins undergo a slight change in shape to translocate a solute across the membrane, it can move in any direction but always down the concentraion gradient.
What is active transport?
It is used to move a substance against the concentration gradient, which is needed to; concentrate nutrients in the cells, expel waste, and establish voltage/chemical gradients, all these proteins are carrier proteins which are specific.
How do animals maintain a high internal concentration of K and NA?
A Sodium and potassium pump and a stored energy molecule called ATP ( Adenosine triphosphate, it breaks apart and releases energy)
What are the steps of active transport?
Cytoplasmic Na binds to the pump, which stimulates phosphorylation by ATP, this causes the protein to change shape expelling Na to the outside, K+ binds on the extracellular side and triggers the release of the phosphate group, loss of phosphate restores the protein’s original shape, K+ is released and the cycle repeats. 3 Na+ (in) + 2 K+ Start (out) + ATP
End 3 Na+ (out) + 2 K+ (in) + ADP + Pi this creates a more negtaive inside than outside which is membrane potential.
What forces drive diffusion?
A difference in concentration (chemical force), a difference in total charge (electrical force) which is the electrochemical gradient. Charged molecules flow down the electrochemical gradient.
What do electrogenic pumps do?
Create electrochemical gradients. Animals use K Na+ pump and plants use proton pumps.
What are cotransporters?
Couple the “downhill” transport of a solute to the “uphill” transport of a second substance against its own concentration gradient
