Function - Site of DNA replication and transcription , Contains the genetic code for each cell
Endoplasmic Reticulum
Structure - Both have folded membranes, RER has ribosomes
Function - RER - Protein synthesis SER - Synthesis and stores lipids and carbs
Lysosomes
Structure - Bag of digestive enzymes
Function - Hydrolyses phagocytic cells, breaks down dead cells, Exocytosis, Digests worn out organelles for reuse of materials
Golgi apparatus and vesicles
Structure - Folded membranes making cisternae, Secretary vesicles pinch of from the cisternae
Function - Adds carbs to protein to form glycoproteins, Produces secretory enzymes, Secretes carbs, Transport, modify and store lipids, Forms lysosomes, Fuse with membrane and contents is released
Mitochondria
Structure - Double membrane, Inner membrane called cristae, Fluid centre called matrix, Loops of mitochondria DNA
Function - Site of aerobic respiration, Site of ATP production, DNA to code
Vacuole
Structure - Filled with fluid surrounded by a single membrane called a tonoplast
Function - Makes cells turgid - Provides support, Temp store of sugar and amino acids
Ribosomes
Structure - Made up of protein tRNA, 80s - Larger - Eukaryotic, 70s - Smaller - Prokaryotic - Mitochondria - Chloroplasts
Function - Site of protein synthesis
Chloroplasts
Structure - Surrounded by a double membrane, Contains thylakoids, Found is plant cells, Contains enzymes for photosynthesis
Function - Site of photosynthesis
Cell Wall
Structure - In plant and fungi cells, Plant - Made of microfibrils of the cellulose polymer, Fungi - Made of chitin a nitrogen containing polysaccharide
Function - Provides structural strength
Plasma membranes
Structure - Found in all cells, Phospholipid bilayer - molecule embedded within and attached on the outside
Function - Controls the entrance and exit of molecules
Eukaryotic cells enter the cell cycle and divide by either mitosis or meiosis
Prokaryotic cells divide by binary fission
Viruses do not undergo cell division as they are non living. They replicate in side host cells
The cell cycle
Interphase (G1,S,G2)
Nucleardivision
Cytokinesis
Interphase
The longest stage and is when the organelles double. The cell grows and the DNA replicates
Nuclear division
Can be either mitosis, creating 2 identical diploid cells, or meiosis, creating 4 genetically different haploid cells
Cytokinesis
The final stage is where the division of the cytoplasm creates the new cells
Mitotic index 

Number.of.cells/Total.number.of.cells.X.100
Stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
Prophase
Chromosomes condense and become visible
centromeres separate and move to opposite poles
nucleolus disappears
Metaphase
Chromosomes line up along the equator of the cell
The spindle fibres released form the poles now attach to the centromere and chromatid
Anaphase
The spindle fibres pull the centromere and chromatids to opposite poles this causes the centromere to split in two
The individual chromatids are puled to each pole. They are now known as chromosomes
Telophase and cytokinesis
The chromosomes are now at each pole of the cell and become longer and thinner again
The spindle fibres disintegrate and the nucleus starts to reform again
The final stage in the cell cycle is when the cytoplasm splits in two to create the two new genetically identical cells
Magnification
Refers to how many times larger the image is compared to the object
Resolution
Is the minimum distance between two objects in which they can still be viewed as separate. The resolution in an optical microscope is determined by the wavelength of light, and the wavelength of the beam of electrons determines the resolution in electron microscope
Eye piece graticule 

This can be sued to measure the size of the object
Calibration
A stage micrometre is used to calibrate the eye piece graticule. This is a glass slide with a scale on it which you place on the stage
Optical microscopes
A beam of light condensed to create the image
poorer resolution due to light having a longer wavelength
Lower magnification
Colour images
Can view living samples
Electron microscopes
A beam of electrons is condensed to create the image. Electromagnets are used to condense the beam
Higher resolving power as electrons have a short wavelength
Higher magnification
Black and white images
Sample must be in a vacuum and therefore non-living
Transmission electron microscope
Extremely this specimens are stained and placed in a vacuum. An electron gun produces a beam of electrons that pass through the specimen. Some parts absorb the electrons and appear dark. The image produced is 2D and shows detailed images on the internal structure of cells
Scanning electron microscope
The specimens do not need to be thin, as the electrons are not transmitting through instead, the electrons are beamed onto the surface and the electrons are scattered in different ways depending on the contours this produces a 3D image
Magnification equation
Image=ActualsizeXMagnification
Cell fractionation
Used to isolate different organelles so they can be studied
This enables individual organelle structures and functions to be studied
Cells are broken open to release the contents and the organelles are then separated
The cells must be prepared in a cold, isotonic and buffered solution
Why must the cell be prepared in a cold solution for cell fractionation
To reduce enzyme activity when the cell is broken open enzymes are released which could damage the organelles
Why must the cell be prepared in a isotonic solution for cell fractionation
The organelles must be the same water potential as the solution to prevent osmosis as this could cause the organelles to shrivel or burst
Why must the cell be prepared in a buffered solution for cell fractionation
The solution has a PH buffer to prevent damage to the organelles
Step 1 cell fractionation - Homogenisation
The cells must be brokenopen and this is done using a blender the cells are blended in the cold, isotonic and buffered solution then filtered