Cell Biology Flashcards
which organelles in a eukaryotic cell contain 2 membranes surrounding them
nucleus (called nuclear envelope) and mitochondria
What is the RER and what is it’s function. how is it different from SER
RER: rough endoplasmic reticulum: location of synthesis and/or modification of secretory, membrane-bound and organelle proteins. aka packaging station
SER: smooth endoplasmic reticulum: site of detoxification and glycogen breakdown in liver.
role of golgi apparatus
sorting and traficking station:
modification of proteins made in RER
sorting of proteins to their correct destinations.
peroxisomes degrade what type of macromolecule?
lipids
T/F: all of the proteins that enter the secretory pathway contain an ER signal sequence, generally at the N-terminus
true
Flowchart of secretory vs non secretory pretien pathways and their signals
can a secretory protein be modified during its travel to the PM or lysozome
no, proteins in the secretory pathway are inaccessible to cytoplasmic proteases
splicing occurs in nucleus or cytoplasm
nucleus
Match the type of organism to the main component in its membrane:
fungi
bacteria
plants
peptidoclygan
titin
cellulose
fungi: titin
bacteria: peptidoglycan
cellulose: plants
fluid mosaic model refers to
called fluid because its components are free to move back and forth laterally like a fluid. cannot flip upside down though. only exception is those proteins anchored to cytoskeleton
called mosaic because it is comprised of a variety of components
which has greater membrane fluidity and why?
- phospholipid bilayer composed more of saturated fatty acids
- phospholipid bilayer composed of more unsaturated fatty acids
unsaturated because the kinks allowing for less van der walls forces allowing more proteins and gases to pass freely within it
the ionizability factor (aka van’t Hoff factor) measures what?
how many ions that one unit of a substance will produce in a solution when it dissociates where 1= no ions.
e.g. C6H12O6 won’t dissociate so i=1
NaCl will make Na+ and Cl-, so i=2
colligative properties refers to:
a property of a solvent that is changed with the addition of a solute where the change is dependent on the number of solute particles rather than on the type of particle.
what is vapor pressure and the colligative property of vapor-pressure depression
it is the pressure exerted by the gaseous phase of a liquid that evaporated from the exposed surface of the liquid
volatility : higher the vapor pressure : the more easily it evaporates : the weaker its intermolecular forces
so, when you add a solute, this strengthens the intermolecular forces of the solvent because the solute molecules are attached to solvent molecules > lower vapor pressure
what effect does a solute have on the boiling point of a solvent and why?
elevates it (colligative property)
because solutes are attached to solvent particles, making it more difficult for them to break free during boiling (entry into gas phase)
the increase in boiling point : increase in number of solutes
what effect does solute have on the freezing point of a solution and why?
depresses it (colligative property)
this occurs because when things freeze, they form solid orderly lattices. solutes disrupt the formation of solid lattices so freezing point is more difficult to acheive and will occur further along the freezing process (ie lower temperature)
increase number of solutes : decrease freezing point
osmotic pressure is defined as
the pressure it would take to stop osmosis from occurring. I.e the pressure that must be overcome by solvent in order to move towards concentration equiliubrium
diffusion vs osmosis
diffusion refers to any type of movement to fill an available volume in such a way that entropy is increased. Osmosis is a subgroup of diffusion in which the membrane separating the 2 chambers is semipermeable (only permeable to water, not solute)
what characteristic allows steroid hormonse to move freely back and forth across the membrane
hydrophobicity
T/F: the eukaryotic plasma membrane does not have any pores
true.
this would destroy its function. they exist in the nuclear membrane, the outer mitochondrial membrane, and gram-negative bacterial membrane
how do the kinetics of simple diffusion differ from that of facilitated diffusion?
since facilitated diffusion depends on carrier/channel proteins, which are limited in number so they reach saturation
how is primary active transport coupled with secondary active transport?
primary active transport uses ATP to fuel transport of molecules against their concentration gradient. This ends up creating a electrochemical gradient. the flow of a molecule along its electrochemical gradient is then coupled with transport of a molecule that must travel against its concentration gradeint
e.g. Na/K pump and glucose transport
T/F: when the Na/K pump breaks down and water is drawn into the cell
true, because the net result of the pump is to get 1 positive ion out, thus if this breaks down, that solute particle will stay in the inside and therefore water will move into the cell by the rules of osmosis
flowchart of transport mechanisms in cell
what is the fate of particles ingested in cell by phagocytosis
they will be fused with lysosome and therefore broken down
T/F: clathrin can recognize and bind to lipoproteins
false - it’s on the intracellular side and because a coat on the outside of the endosome
clathrin coated pits famously transport what type of macromolecule
large lipoproteins
e.g. cholesterol
receptor mediated endocytosis is associated with what protein?
clathrin
it helps sequester cargo and supports proper budding of endosome
ligand-gated ion channels open an ion channel upon binding a ______
neurotransmitter ligand
most common example: acetylcholine binds to a receptor, allowing Na+ entry into the cell which rapidly depolarizes it
An enzyme-linked receptor, also known as a catalytic receptor, is a transmembrane receptor, where the binding of an extracellular ligand causes
enzymatic activity on the intracellular side. Hence a catalytic receptor is an integral membrane protein possessing both enzymatic catalytic and receptor functions.
e.g. kinase (eg insulin receptor) that phosphorylates a protein to activate it.
a kinase _________ a the proteins 1_____, 2______, and 3_____
phosphorylates
- serine
- threonine
- tyrosine
all G-protein linked receptors binds a G-protein which binds ___________
GTP, which actives the G protein allowing it to move to activate the next molecule in the signal transduction cascade
T/F: a G-protein linked receptor can be inhibitory or excitatory
true
