The Science behind CSI Speyside
Whilst working together to solve the murder of Ms Wilson you have all learned some very important Science – here is a summary of all you have learned:
Microscopes:
Scientists use microscopes can be used to view tiny things – such as hairs, fibres and cells. Stains, like Iodine, can be used to make cells easier to see.
To work out the magnification, multiply the magnification of the lens by the magnification of the eye piece i.e. 10 x 10 = 100.
Cells:
Plant and animal cells look very different from each other.
Plant Cell
Animal cell
Part of cell / Job in the cell / Where this is foundAnimal cells / Plant cells
Cell membrane / Surrounds the cell, controlling what can enter and leave the cell / Y / Y
Cell wall / Surrounds plant cells – makes them strong. / Y
Cytoplasm / Jelly-like filling inside the cell – this is where all the chemical reactions happen in the cell. / Y / Y
Nucleus / Control centre for the cell. Also stores the chromosomes made of DNA. / Y / Y
Vacuole / Sap-filled bag in the centre of the plant cell which helps to make it strong. / Y
Chloroplast / Used by plant cells to turn sunlight into food. / Y
Chromosomes, Genes and DNA:
We all look very different from each other – eye colour, hair colour, hair type, which hand we write with, our fingerprints, etc.
These differences are controlled by chromosomes which are inherited from our parents.
Chromosomes are found in the nucleus of the cell and you get half from your mother and half from your father.
These chromosomes are made of a chemical called DNA (Deoxyribonucleic Acid) and divided up into sections called genes. Which genes you get will decide what you look like.
DNA fingerprinting:
DNA can be taken out of the cells and tested to tell who it came from. DNA is like a code, made up of 4 letters (A, T, C and G), and everyone has a slightly different version of the code.
When a crime is committed the scientists can collect the DNA and cut it up with enzymes – rather like special scissors – which cut the DNA every time it sees a certain combination of letters, e.g. TATC. Exactly where the enzymes cut the DNA will be slightly different from one person to another.
Scientists can then separate the DNA out by a process called electrophoresis, where the DNA is put inside a special jelly and electricity is passed through. The electricity separates out the chunks of DNA – with small bits moving the furthest. This produces a “DNA fingerprint” – which is unique (unless you have an identical twin!). Police can then compare the DNA fingerprint from a suspect with the DNA fingerprint found at the crime scene.
This shows the DNA gel being loaded. The picture above shows a DNA fingerprint from a crime scene. You can match the pattern of lines from the crime scene with the pattern of lines from the suspects.
Solubility
When you add a solid (e.g. a powder) to water it will either dissolve or not.
When a solid dissolves in a liquid it is called soluble. Solids that do not dissolve in a liquid are called insoluble.
When a solid dissolves in a liquid it creates a solution. A solution is made up of the solute (the solid powder) and the solvent (the liquid).
Flame testing:
You can use flame testing to tell different solutions apart.
Solutions that contain different metals burn with different coloured flames.
Paper chromotagraphy of inks:
Black ink is made of a combination of several different coloured inks.
These can be separated using a process called chromatography.
During chromatography the ink dissolves in the water (solvent) and moves up the paper. The different colours separate out and create a unique pattern for each pen.
What you need to know: