2. Cell theory
• Smallest unit of life
• Smallest structures capable of surviving on
their own
• All living organisms composed of cells.
multicellular organisms(human) +
unicellular(bacteria)
3. Importance of sa-v ratio as a factor of
limiting cell size
• Substances need to be taken into the cell to
fuel these reactions and the vast products of
the reactions need to be removed
• Surface area affects the rate at which particles
can enter and exit the cell
• volume affects the rate at which material are
made or used within the cell
• volume of the cell increases so does the
surface area
4. State multilcellular organisms show
emergent properties
• E.g
• Cells form tissues> tissues form organs>organs
form organ systems>organ system form
multicellular organisms.
• Cells working as a unit e.g lungs. That are
composed of many cells functioning to be
efficient at their job i.e ventiliation.
5. Outline stem cells
• Stem cells are unspecialised cells that have
two key qualities:
• 1. Self renewal: They can continuously divide
and replicate
• 2. Potency: They have the capacity to
differentiate into specialised cell types
• Derived from embryos or placenta
6. 1 therapeutic use of S-cells
• Retinal cells: Replace dead cells in retina to
cure diseases like glaucoma and macular
degeneration
9. Cell wall
• Protects the cell from the outside
environment
• maintains the shape of the cell.
• It also prevents the cell from bursting if
internal pressure rises.
10. Plasma membrane
• Semi-permeable membrane that controls the
substances moving into and out of the cell. It
contains integral and peripheral proteins.
Substances pass through by either active or
passive transport.
11. Cytoplasm
• Contains many enzymes used to catalyze
chemical reactions of metabolism
• it also contains the DNA in a region called the
nucleoid.
• Ribosomes are also found in the cytoplasm.
13. flagella
• Made of a protein called flagellin.
• Helps bacteria move around by the use of a
motor protein that spins the flagellum like a
propeller.
14. ribosomes
• They are the site of protein synthesis.
Contributes to protein synthesis by translating
messenger RNA.
• 70s in prok
• Consist of ribosonal rna + proteins
• 3 trna binding sites- E(exit site) p(Peptidyl) and
A(aminoacidyl)
• Large+small subunits
15. nucleoid
• Region containing naked DNA which stores the
hereditary material (genetic information) that
controls the cell and will be passed on to
daughter cells.
18. RER
• Can modify proteins to alter their
function/destination
• Synthesize proteins to be excreted from cell
19. Lysosome
• Contains many digestive enzymes to hydrolyze
macromolecules such as proteins and lipids
into their monomers.
20. Golgi apparatus
• Receives proteins from the rough
endoplasmic reticulum and may further
modify them.
• It also packages proteins before the protein is
sent to it’s final destination which may be
intracellular or extracellular.
25. Outline Two roles of extracelular
components
• Plants- cellulose secreted from cell wall.
• -provides support/strength for cell(keep cell
shape)
• -barrier against pathogens
• Animals-ECM is made of glycoproteins
secreted from cell:
-provides support/anchorage for cells
• -segregates tissue from one another
27. Explain how the hydrophobic and hydrophilic properties of
phospholipids help to maintain the structure of cell membranes.
• Hydrophilic / hydrophobic layers restrict entry and exit of
substances
• Hydrophobic tail regions face inwards and are shielded from
the surrounding polar fluid while the two hydrophilic head
regions associate with the cytosolic and extracellular
environments respectively
28. Function of membrane proteins
hormone binding sites
Electron carriers
Pumps for active transport
Channels for passive transport
29. • Diffusion is the passive movement of particles
from a region of high concentration to a
region of low concentration.
• Osmosis is the passive movement of water
molecules, across a partially permeable
membrane, from a region of lower solute
concentration to a region of higher solute
concentration.
