Animal cell (eukaryotic cell)

HideShow resource information
Preview of Animal cell (eukaryotic cell)

First 408 words of the document:

Aleena James
Microscopy is research using microscopes
The magnification of an object is how many times the bigger the image is when
compared to the object. The material is put under microscope (object). And the
appearance of this material when viewed under microscope is referred as image
size of image
Magnification= size of object
size of image
Therefore size of object = magnification
Example, an object is actually 100nm in length and 10mm long. Find magnification
size of image
size of object
100nm = 10*1000000nm
100nm = 100000
1 = X 100000 times
Therefore magnification is x100000 times
Resolution or resolving power of microscope is the minimum distance apart that two
objects can be in order for them to appear as separate items. Resolving power
depends on the wavelength or form of radiation used. For e.g. in a light microscope it is
about 0.2 micro metres, this means that any two objects closer than 0.2 m will appear
as a single object. GREATER RESOLUTION MEANS GREATER CLARITY i.e. the image
produced is clearer and more precise
Increasing the magnification will increase the size of the image, but DOES NOT
always increase the resolution. The object while appearing larger, will just be
more blurred
CELL FRACTIONATION is the process where cells are broken up and the
different organelles they contain are separated out.
Before cell fractionation can begin, the tissue is placed in a cold, isotonic (it has the
same water potential as the original tissue) buffered (a solution which maintains pH)
solution because:
Cold- to reduce enzyme activity that might break down the organelles
Isotonic- to prevent organelles bursting out or shrinking as a result of osmotic
gain or loss of water.
Buffered- to maintain pH
HOMOGENISATION- cells are broken up by a homogeniser (blender). This
releases organelles from the cell. The resultant fluid is known as homogenate, is then
filtered to remove any complete cells and large pieces of debris
ULTRACENTRIFUGATION- it is the process by which the fragments in the
filtered homogenate are separated in a machine called and ultracentrifuge. This spins
tubes of homogenate at very high speed in order to create a centrifugal force. For
animal cells, the process is:

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Aleena James
Tube of filtrate is placed in the ultracentrifuge and spun at a low speed
The heaviest organelle (nuclei) are forced to the bottom of the tube, where
they form a thin sediment or pellet
The fluid at the top (supernatant) is removed and transferred to another tube
and spun in the ultracentrifuge at a higher speed than before
Then the next heaviest organelle (mitochondria) is forced at the bottom of the
tube and the process continues.…read more

Page 3

Preview of page 3

Here's a taster:

Aleena James
Lens is electromagnetic (as electrons are Lens is made up of glass
­vely charged the beam can focus using
Ultrastrcuture of the cell means each cell type has an internal structure that suits for
its job
EUKARYOTIC CELLS have a distinct nucleus and possess MEMBRANE
BOUND ORGANELLES. E.g. epithelial cells.
Prokaryotic cells don't have membrane bound organelled. E.g. bacteria
NUCLEUS- it contains the organism's hereditary material and controls the cell's
activities.…read more

Page 4

Preview of page 4

Here's a taster:

Aleena James
DOUBLE MEMBRANE- the outer membrane controls movement of material in and
out of organelles. Inner membrane is folded to form extensions known as cristae
CRISTAE- inner folded membrane. these provide large surface area for the
attachement of enzymes involved in the respiration
MATRIX- a semi rigid material containing proteins, lipids and traces of DNA that
allows the mitochondria to control the production of their own proteins.…read more

Page 5

Preview of page 5

Here's a taster:

Aleena James
SMOOTH ENDOPLASMIC RETICULUM (SER)- lacks ribosomes on its
surface and is often more tubular in appearence. FUNCTIONS ARE :-
Synthesise, store and transport lipids and carbohydrates
GOLGI APPARATUS- similar to SER in structure except it is more compact.…read more

Page 6

Preview of page 6

Here's a taster:

Aleena James
Completely breaks down the cell after they've died (autolysis)
Phagocytosis- mechanism by which cells engulf particles to form a vesicle or a vacuole.
RIBOSOMES- small cytoplasmic granules found in all cells. They may occur in the
cytoplas or associated with RER. They are two types:- 80s (found in eukaryotic cells, is
around 25 nm in diameter) and 70s (found in prokaryotic cells, is slightly smaller)
They have two subunits (1 large and 1 small), which contains ribosomal RNA and
proteins.…read more

Page 7

Preview of page 7

Here's a taster:

Aleena James
They contain carbon, hydrogen and oxygen
The proportion of oxygen to carbon and hydrogen is smaller than in
They're insoluble in water
They're soluble in organic solvemts such as alcohols and acetone
The main groups of lipids are triglycerides, phospholipids and waxes
ROLES OF LIPIDS- the main role is in plasma membrane. Phospholipids contribute
to the flexibility of membranes and the transfer of lipids-soluble substances
across them.…read more

Page 8

Preview of page 8

Here's a taster:

Aleena James
They form a bilayer sheet.…read more



This is a concise set of notes with clear diagrams and micrographs which would be useful to all A level biology students studying cell structure. It would be useful to make your own set of flashcards from this information that could be downloaded and used to test yourself with. 


Excellent set of well detailed notes, proving to be a huge help in my revision efforts! :D

Similar Biology resources:

See all Biology resources »See all resources »