Molecular and cell biology Flashcards
5 reasons why you need cell transport?
1) fuel for metabolism and export of waste products
2) transport between cytosol and organelles
3) protein secretory system
4) signalling between cells
5) proteins targeted to different cells
what are channel proteins called in invertebrates?
innexins
what are channel proteins called in vertebrates?
connexins
what are plasmodesmata?
pores/channels through plant cell walls
name 3 features of plasmodesmata?
1) they can dilate to allow larger molecules such as RNA to fit through
2) tube or endoplasmic reticulum passing through them
3) enable cytoplasmically interconnected fields of cells know as symplasm
brief explanation of gorter and grendel experiment
using known surface area of a red blood cell they extracted the lipids and measure when lipids form monolayer on water - surface area was double that of red blood cell proving bilayer
unsaturated hydrocarbon tails cause the bilayer to be what and why?
more fluid because kinks at double cc bonds means the hydrocarbons can’t pack as closely together
what molecules can easily pass through the cell membrane?
hydrophobic molecules
which molecules can’t pass through the cell membrane?
ions
which molecules pass less easily through the cell membrane?
uncharged polar molecules
what are aquaporins?
membrane channels for transport of uncharged molecules
what are two places where aquaporins are very abundant?
the kidneys and plant roots
whats the difference between passive and active transport?
passive favourable concentration gradient and active requires energy against concentration gradient
what are 3 ways or driving active transport?
1) light driven photon pumps
2) coupled transporter
3) ATPases
what are ion channels?
very particular pores which open and close by being voltage gated
what do electrogenic pumps do?
generate voltage across a membrane which can store energy
describe the process of the sodium potassium linked transporter
sodium binds to the pump stimulating phosphorylation causing the protein to change shape expelling sodium and potassium binds triggering release of a phosphate group restoring the pumps original shape
how is hydrochloric acid secreted in the stomach?
cells secrete protons and chloride which join to form hydrochloric acid
describe the active transport of sucrose entering the phloem
sucrose/proton co transporter - protons come from ATPase making high proton concentration to drive movement of sucrose
