The Structure of Cells and Microscopy

• Cell tissue is cut up and kept in isotonic solution.
• The tissue is then broken down in a homogeniser to release the organelles
• It is spun in an ultracentrifugue
• Heaviest sediemnt falls the bottom and the supernantant is removed
• Process is repeated for Mitochondria, Lysosomes and Ribosomes.

These are formed when Vesicles by Golgi contain enzymes like protease and lipease. They isolate potentially harmful enzymes from the cell. Functions are...

• Break down material from Phagocytic (White Blood Cells)
• Releas enzymes (Exocytosis)
• Digest worn out organelles so useful chemials are made.
• Complete break down of dead cells

Small cytoplasmic granules in all cells, they are either in cytoplasm or with Rough Endoplasmic Reticulum. 80s type. They have 2 subunits each containing ribosomal DNA and protein up to 25% of a cell and are important for protein synthesis.

3D system of sheet like membranes in the cytoplasm. It's continuous with the outer membrane.

Rough ER -> have ribosomes on the outer have large surface area for gylcoprotein & protein synthesis.

Smooth ER -> no ribosomes, tubular in appearance. They synthesise, store and transport lipids and carbohydrates.

Consists of a stack of membrane of flattened stacks or cisternae. Proteins & lipids produced by ER are passed through and modified they

• add carbohydrates to proteins = glycoprotein
• produce secretory enzymes
• secrete carbohydrates
• transport modify & store lipids
• from lysosomes

The Nucleus contains the DNA and controls substances in and out of the cell

• Envelope - double membrane that surrounds the nucleus
• Pores- aloowspassage of large molecules
• Nucleoplam - Jelly -like material bulks out the cell
• Chrmatin - DNA found within the nucleoplam
• Nucleous - Sphereical body within
• Nucleoplasm - Manufactures ribsosomes

Rod Shaped between 1 and 10 micrometre in length made from...

• A double membrane that surrounds and controls in and out.
• Cristae are sehlf like extensions increasing the surface area for attaching enzymes that for respiration
• Matrix contain protein, lipids and tiny amounts of DNA controlling the production of proteins

Filtrate -> the solution that does not contain cell debris or broken cells

Homogenate -> a liquid that containsall cell contents due to it being broken

Isotonic -> solutions that posses the same amont of water as the cell

Organelle -> structure found within the cytoplasm of a cell

Sediment -> the heavy cell organisms found at the bottom of the tube

Supernatant -> the liquid left when suspended particles have been sperated .

The SEM directs a beam of electrons onto the surface of a speciemen from above. A 3D image is produced as the electrons are scattered.

Advantages

• 10x better reolving power than a light microscope
• Any thickness specimen can be used
• False colour ca be added

Limitations

• The system is a vacuum, no living organisms can be looked at
• The image is black and white
• Lower resolution than TEM
• Only a picture of the image is made

THe TEM consists of an electron gun that produces a beam of electrons it's focused by a condenser magnet. The beam is passed through. If the specimen image is dark the specimen is thick. It can be imaged by a photomicrograph.

Advantages.

• Have a higher resolution than SEM
• Short wavelength

Limitations

• The system is a vacuum and cannot be used to look at living speciemens
• The specimen has to be thin

The Magnification Equations.

Magnification = Image of specimen / actual object size.

Step 1

Write out the formula

Step 2

Gather the measurements

Step 3

Convert to m

Step 4

Do the Maths