3.2.2 all cells arise from other cells Flashcards
what is cell fractionation?
the process where cells are broken up and organelle are separated out
what is lysis?
breaking down he membrane of the cell
what happens in cell lysis?
some lysosomes are broken open, proteins inside the cell are exposed to the external solution, organelles are exposed to external solution
why are the cells placed in a buffer solution?
used for the purpose of breaking open cells, endures organelle are not damaged
what factors need to be controlled in a buffer solution?
temperature, pH and amount of water
why does the buffer solution have to be ice cold?
slows down the enzyme activity (less kinetic energy) but doesn’t denature them , no damage to organelle but cells can still respire
why do buffer solutions have to be buffered?
maintains the same pH, prevents proteins from being denatured altering cell structure
why do buffer solutions have to be isotonic?
same water potential as cytoplasm, prevent water entering or leaving organelle by osmosis, prevents osmotic lysis
what are the two stages to cell fractionation?
homogenation and ultracentrifugation
what is homogenation?
disrupting the tissue and cells
what is ultracentrifugation?
separating the organelle in a centrifuge
what happens in homogenation?
using high frequency sound or detergent to form a homogenate, must be in a buffer solution to stop damage to the organelle (mitochondria)
what happens in ultracentrifugation?
crush and filter homogenate to remove debris, spin at low speed and force which forms a pellet at the bottom containing structures of the same density, spin at higher and higher speeds and force, making sure you filter between each time, until you get the desired structure in the pellet
how can you predict which pellet an organelle will be in?
based on the density of the organelle
what is the supernatant?
homogenate that is taken out and spun again
why must the homogenate be filtered before spinning in a centrifuge each time?
so that the sample isn’t contaminated- all that is left is the organelle you are separating
what is the cell cycle?
a regular cycle of cell division, separated by periods of cell growth
what is the cell cycle needed for?
differentiation (cells becoming specialised), growth and repair e.g. in muscle cells
what is the first stage of the cell cycle?
interphase
what is the second phase of the cell cycle?
the mitotic phase
what is the third phase of the cell cycle?
cytokinesis
what are the three parts to the interphase?
growth and normal metabolic roles (G1), DNA replication (Synthesis) , growth and preparation for mitosis (G2)