cell structure Flashcards
eukaryotic cell vs prokaryotic cell
eukaryotic - complex and include all animal and plants cell, as well as all cells in algae and fungi
prokaryotic - smaller and simpler eg bacteria
animal cell contains
plasma cell surface membrane rough endoplasmic reticulum nucleolus nucleus smooth endoplasmic reticulum lysosome ribosome nuclear envelope golgi apparatus cytoplasm mitochondrion
plant cell contains
plasma cell surface membrane chloroplast rough endoplasmic reticulum plasmodesma mitochondrion golgi apparatus vacuole smooth endoplasmic reticulum cytoplasm nucleolus nucleus ribosome cell wall
algal and fungal cells
algal - like plant cells - have same organelles
fungal - like plant cells but cell wall made of chitin and don’t have chloroplasts
homogenisation what?
breaking up the cells
homogenisation steps
can be done in several ways eg vibrating the cells, grinding the cells in a blender
this breaks up the plasma membrane and releases the organelles into solution
solution must be an ice cold isotonic buffered solution
cold - reduce the activity of enzymes
isotonic - same concentration of chemicals as the cells being broken down to prevent damage to organelles
buffered solution - maintain the pH
filtration what?
getting rid of the big bits
filtration - steps
homogenised cell solution is filtered through a gauze to separate any large cell debris or tissue debris
The organelles are much smaller than the debris, so they pass through the gauze
ultrafiltration - what
separating the organelles
ultrafiltration - step 1
the cell fragments are poured into a tube - the tube is put into a centrifuge and is spun at a low speed - the heaviest organelles get flung to the bottom of the tube by the centrifuge
they form a thick sediment at the bottom - the pellet
the rest of the organelles stay suspended in the fluid above the sediment - the supernatant
ultrafiltration - step 2
the supernatant is drained off, poured into another tube, and spun in the centrifuge at a higher speed
again, the heaviest organelles form a pellet at the bottom of the tube
the supernatant containing the rest of the organelles is drained off and spun in the centrifuge at an even higher speed
ultrafiltration - step 3
this process is repeated at higher and higher speeds, until all the organelles are separated out
each time, the pellet at the bottom of the tube is made up of lighter and lighter organelles
