Study Questions #4 Flashcards
Septemer 17-21
What is the difference between cilia and flagella?
Cilia - usually has many, but shorter and they beat like oars. Can also be used for sensing what’s going on outside cell
Flagella, one or a few, longer, undulating motion that generates movement
What functions are performed by cilia and flagella?
movement
what makes cilia and flagella move
cilia beat perpendicular to the membrane and flagella use breast strokes. Both have a rigid stroke and limp recovery
What is the extracellular matrix and what sorts of cells have it?
mix of different proteins made in Golgi that occupies space between animal cells
cell wall in plants
What are the two classes of molecules used to express cell identity?
Glycolipids and glycoproteins
What are major histocompatibility complex proteins?
glycoproteins used by cells to identify themselves to their own immune system
why are heart transplant patients treated with drugs which suppress the immune system
so the body doesn’t reject the foreign organ
What are the three types of cellular junctions found in animal tissues?
Tight, Anchoring, and communicating
What are desmosomes and what do they do?
type of anchoring junction-cadherin that joins the cytoskeleton to that of the next cell
What is cadherin and what does it do?
connects cytoskeletons of adjacent cells
What are adherens junctions?
integrins that join cells to extracellular matrix
What are integrins and why is it important for the to be attached to the extracellular matrix?
…
What is a connexon?
sodium channel embedded in the plasma membrane that allows sodium to move from one cell to its neighbor
What are plasmodesmata?
Gap junctions in plants where the ER extends between cells.
Why must all cells have a plasma membrane?
keeps what you want in, in and what you want out, out
Why do we say that membranes are semipermeable and why is this important?
They regulate what goes in and out of the cell to make sure it’s appropriate. Cells need to be semipermeable to allow the transfer of nutrients, waste, and information.
Why do phospholipids form bilayers in water?
The hydrophilic head is attracted to water while the hydrophobic tail repels water.
Why must membranes be fluid to function?
allows for semi-permeability
turn corners
seal proteins
fuse and form vesicles
What are 3 methods cells use to adjust membrane fluidity?
Changing fatty acids
changing the head group
adding cholesterol
What sorts of molecules can pass through lipid bilayer membranes?
gasses
small uncharged particles
some water
Why do cells need integral membrane proteins?
to allow polar molecules to come in
What is the general model for the structure of biological membranes?
fluid mosaic model
what keeps integral membrane proteins from leaving the membrane
the part inside the membrane has to be hydrophobic and the parts exposed to the surface have to be hydrophilic
how do we know that proteins can diffuse within membranes
they are evenly dispersed within the membrane
how can proteins form holes through membranes?
hydrophilic amino acids line the channel and hydrophobic aminos face the bilayer
What is special about the structure of the plasma membrane and what sorts of proteins do you find in it?
sugar coating on the outside
physically attached to cytoskeleton
transmembrane proteins, peripheral proteins
What are the functions of the plasma membrane
physical isolation, regulation of exchange with the environment, sensitivity to the environment, structural support
What is osmosis and why does it occur
movement of water across membrane
goes from higher concentration to lower concentration
what kinds of cells want to be isosmotic and what kinds want to be hyper osmotic
animal cells want to be isosmotic and plants want to be hyper osmotic
why do cells shrink when placed in a hyper osmotic solution?
the water all rushes out of the cell to be at the lower concentration
Why do red blood cells explode when you place them in distilled water?
the water rushes in and the cells swell and burst
What is turgor pressure and what is it used for
osmosis pushes the membrane against the cell wall to make the structure rigid
How is bulk transport accomplished?
via vesicles
What is the difference between endocytosis and exocytosis
endocytosis brings things in and exocytosis brings things out
what is the difference between phagocytosis and pinocytosis?
phagocytosis is large objects and pinocytosis is several small objects
What is receptor-mediated endocytosis?
plasma membrane proteins bind to specific objects and when enough bind, pits become vesicles
What are the differences between bulk transport and selective transport?
Bulk transport - Vesicles move large objects across the Plasma membrane by endocytosis and exocytosis. Requires some energy
Selective transport - The plasma membrane proteins move specific items across but saves energy in the process. However they are specific (1 Item / carrier)
What is selective transport and what substances do cells move by selective transport?
Proteins embedded in the membrane whose job is to bring in ONE type of molecule across the membrane
polar molecules and positively charged molecules are brought in by selective transport.
How do aquaporins prevent the passage of molecules other than water?
They are a tight channel. Only few objects can fit through it.
It has 2 positive charges on one side, so anything with a charge will not go through. (+ charges are repelled, - charges get stuck. Water doesn’t have a charge and it’s
relatively small so it fits though fine.
how can ion channels tell the difference between one type of ion and another
by size and charge
How are ion channels regulated?
open and closed like a gate
what are the differences between ion channels and facilitated diffusion?
ion channels are like a gate whereas facilitated diffusion binds with certain things and changes shape to help get them across the membrane
why is facilitated diffusion saturable whereas channels are not?
Channels - are somewhat specific but not completely. It depends on the size and the charge of the substance, but can anything that matches. They are controlled by “opening and closing” so a whole lot of material can pass through at one time when it opens
Facilitated diffusion - Is specific to a certain molecule.
the plasma membrane has to bind it, carry it through the dump it out. This is a longer slower process therefore not saturated
what are the differences between facilitated diffusion and active transport?
facilitated doesn’t require energy and active does
how can you tell if a substance is moved by active transport?
ATP was used
How can cells have 35 fold higher concentrations of K+ inside than in the surrounding blood?
the plasma membrane has a pump that exchanges sodium and potassium
how do cells remove sodium
thought the na/k pump
why does the toxin from poison arrow frogs kill you slowly and painfully
it freezes the Na/K pump and cells burst because there’s too much sodium
why are cardiac glycosides useful for treating heart patients
at the right dosage, it stimulates the heart
what is the difference between active transport and coupled channels?
active transport only brings in one chemical whereas coupled channels bring in more by piggy backing
why are coupled channels often called secondary active transport
it brings in a secondary particle
what is the difference between symport and antiport
a symport imports things and anti ports export them
Why do cells lining the small intestine have two different kinds of glucose transport proteins?
there’s proteins that require energy and some that don’t
What are ionophores and why are they so deadly?
they dissipate the concentration gradient so all the work was done for nothing and things can move freely
What are contractile vacuoles and what is their function
Contractile vacuoles are membrane-bound organelles that pump water out of the cell. They work to maintain a solvent/solute balance in the cell through a process called osmoregulation.
why did you get a larger diameter circle with lugol’s than with Brilliant Blue G?
it had smaller molecules that were able to diffuse earlier
