Transport and trafficking Flashcards
what is compartmentalisation?
division of eukaryotic cewlls into smaller compartments (organelles) that increases the speed of reactions and allows increased diversity in the way cells are organised
what are the five functions of membranes in cells?
- Controlling transport
- Concentrating enzyme activity
- Controlling cell communication
- Connecting cells
- Recognising cells
How thick are membranes?
5-10 nm (2 cells) thick
what is the most abundant membrane lipid?
phospholipids
what molecules can easily pass through membranes?
hydrophobic (non-polar) molecules (eg: hydrocarbons) as they can dissolve in the lipid bilayer
what molecules need specific transport mechanisms to pass through membranes?
polar molecules (eg: sugars)
what are types of passive transport?
- diffusion
- facilitated diffusion
what are the two types of proteins that allow for facilitated diffusion?
- channel proteins
- carrier proteins
what are the two types of transport across cell membranes?
- passive transport
- active transport
why do animal cells have Na+/K+ pumps?
to regulate the cell to prevent it from bursting
what are the three main ways to transport proteins around a cell?
- Gated transport e.g. nuclear pore (between compartments)
- Transmembrane transport e.g. mitochondria (between compartments)
- Vesicular transport e.g. motor proteins (within compartments)
What is a nuclear envelope?
two centric membranes which are perforatred by nuclear pores
what is transported through nuclear pores?
- proteins imported into the nucleus
- mRNA exported out of nucleus
how many nuclear pore complexes does a typical mammalian cell contain?
3000-4000
how do nuclear pore complexes recognise which proteins can be actively transported through to thr other side?
nuclear locatisation signals
How does transmembrane transport in mitochondria work?
- protein translocator is activated by a specific signal sequence
- protein translocator opens up to allow protein to pass through to the ER lumen
how many types of motor proteins are there?
three
- myosin
- kinesin
- dynein
which motor proteins transport along actin filaments?
myosin (towards the positive end)
which motor proteins transport along microtubules?
- kinesin (towards the positive end)
- dynein (towards the negative end)
what is the structure of motor proteins? (from the top down)
- tail (attaches to cargo)
- stalk
- head (attach to microtubules or actin)
what do motor proteins need to move?
ATP
what is myosin most commonly used for?
muscle contraction
