more things im forgetting ill probably delete this deck later x Flashcards
why is substrate concentration able to stop being a limiting factor in a reaction
the enzymes can become saturated, and will be working at their maximum possible rate
name the type of proteins that are translated in ribosomes on the RER and enter its lumen
transmembrane proteins
what are the fates of lipids that are synthesised in the ER
they can become part of cytosolic lipid droplets and stored or transported to the ER for secretion. they are fats
what changes would result in a decrease in the affinity of haemoglobin for oxygen
increased temperature and decreased pH
what is the name of the covalent bond that stabilises the teritiary structure of a protein
disulphide
state which form of post translational modification can cause reversible conformational change in proteins
addition or removal of a phosphate
give examples of cellular proteins where their activity is affected by the conformational change following phosphorylation
enzymes and receptors
state the type of interactions that are disrupted in the unphosphorylated protien
ionic interactions
give five ways in which the r groups of an amino acid can vary
- size
- shape
- charge
- hydrogen bonding capacity
- chemical reactivity
state how a phospholipid differs to a triglyceride
former has 2 fatty acids, latter has 3
name the proteins that interact extensively with the hydrophobic region of the membrane phospholipids
integral membrane proteins
state which r groups peripheral membrane proteins contain on their surface
hydrophilic
give two interactions that bind peripheral membrane proteins to the surface of the membrane
ionic and hydrogen bonds
state which molecules the phospholipid bilayer is a barrier to
ions and most uncharged polar molecules
name the different types of transporter proteins and their functions
- aquaporins - passage of water through cells
- GLUT - glucose transport
- sodium channels - sodium in the cell
- potassium channels - only allow potassium ions to pass through them
- calcium channels - specific for calcium ions only
state what the sodium potassium pump accounts for a high proportion of in animal cells
the basal metabolic rate
describe glucose symport.
- the glucose transporter responsible for glucose symport transports sodium ions and glucose at the same time and in the same direction.
- the sodium ions enter the cell down their concentration gradient; the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient
what combines to form the electrochemical gradient
concentration gradient and electrical potential difference
describe how transporter proteins transfer the solute across the membrane
the transporter proteins bind to the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane. the transporters alternate between two conformations so that the binding site for a solute is sequentially exposed on one side of the bilayer and then the other.
describe what is meant by a pump protein
transporter proteins coupled to an energy source
give a feature of channel proteins that make them able to allow or prevent diffusion
they are gated, and can change conformation
give a feature of channels
they are highly selective
name the type of transmembrane protein that allows for passive transport
channel protein
how do signals reach the cytosol
via signal transduction pathways
in hydrophilic signalling, describe the process that changes the behaviour of the cell
the conversion of extracellular ligand binding to intracellular signals
describe the results of insulin binding to its receptror
conformational change triggers the phosphorylation of the receptor. intracellular signalling cascade that triggers recruitment of glut4 transporter proteins to the cell membrane of fat and muscle cells
describe how insulin stimulate the uptake of glucose into cells
the insulin binding to its receptor results in the receptor changing conformation. this triggers an intracellular signalling cascade, which results in glut4 containing vesicles being transported to the cell membrane of muscle and fat cells
what is meant by signal transduction
signal molecules cant enter the cell through the membrane. they are instead transduced via receptors, which then initiates the response.
how is membrane potential maintained
sodium potassium pump
name the molecule that receptors are made from
ligands
name the signal that is sent down the axon
action potential
what happens to rhodopsin when retinal absorbs a photon of light
changes conformation to photoexcited rhodopsin
photoexcited rhodopsin activates a g protein called…
transducin
what affects the function of ion channels in the membrane of rod cells
the reduction in the concentration of cyclic GMP as a result of its hydrolysis.
describe the series of events that triggers nerve impulses in neurons in the retina
- retinal absorbs photon of light.
- rhodopsin becomes photoexcited
- this activates transducin
- transducin activates PDE
- PDE catalyses the hydrolysis of cyclic GMP
- the reduction in concentration of cyclic GMP results in a closure of ion channels in the membrane of the rod cells
- this triggers nerve impulses in neurons in the retina
