School of Clinical Laboratory Sciences
Genetics

• The human body is made of millions of cells, in the nucleus of each cell are the chromosomes There are 22 pairs of "normal chromosomes" plus two sex chromosomes either a pair of X chromosomes in females or one X plus one Y in males • Chromosomes are made of DNA coding for each gene and the "switches" to turn the genes on and off • This means that different genes are turned on in different parts of the body to make teeth, hair blood etc • When a gene is switched on a small message is copied from the correct part of the chromosome • This message is short and can move from the nucleus to the protein-making machinery of the cell • Each message is called a "messenger RNA" it is written in genetic code • The code is made up of chemicals called nucleotides there are 4 sorts Gs As Us and Cs • Each gene and its message is just a string of these nucleotides in a row • Each messenger RNA is decoded by the protein-making machinery of the cell • Proteins are then made containing different ammo-acids depending on what the code specifies. • Three letters in the genetic code for each amino-acid , long chains of amino-acids joined together make proteins • Each amino-acid has a different name which is represented by a letter of the alphabet (but there are only 20 different ones of them) • Each protein is like a long word made of the letters • Each different type of amino-acid gives the protein different properties For example proteins with lots of Ps in them are springy as in curly hair or knee joints Proteins with Cs and Hs in them make coloured proteins like those in blood and eyes, other proteins can act as enzymes like those in saliva that break down starches and sugars in our food • The proteins form part of the cells in different parts of the body and give them the correct properties (making livers different to toenails and tongues different to eyelids)

Getting familiar with the genetic code • Below is the genetic code written out • To get used to the code we will use it to build up simple "protein words" made of amino-acids • In real life proteins are made up of hundreds of amino-acids but by making short protein words you can learn the code • All living creatures from microbes to marigolds to mammoths to man use this code in their cells

Make a genetic code friendship bracelet You are given a set of different coloured beads that represent the Gs As Us and Cs, some string and a copy of the genetic code in colour. Use these to build up a genetic friendship bracelet. Remember that the amino-acids are like letters of the alphabet but a few are missing, you can't do words containing B, J, 0, U, X or Z. So for example Genetics would be GGC GAA AAC GAG ACA AUC UGC UCA You will find that use can use more than one code for some letters, that's OK. If you want to make multiple words put a "stop" code between each new word If you like you can use a marker pen to write the Gs As Us and Cs onto the beads of the finished bracelet. Keep this paper so you know the code forever. Wear the bracelet to remind you that genetics is a friendly topic!

Genetic Code (amino-acids in black)

	UUU F UUC F UUA L UUG L	UCU S UCC S UCA S UCG S	UAU Y UAC Y UAA stop UAG stop	UGU C UGC C UGA stop UGG W
	CUU L CUC L CUA L CUG L	CCU P CCC P CCA P CCG P	CAU H CAC H CAA Q CAG Q	CGU R CGC R CGA R CGG R
	AUU I AUC I AUA I AUG M	ACU T ACC T ACA T ACG T	AAU N AAC N AAA K AAG K	AGU S AGC S AGA R AGG R
	GUU V GUC V GUA V GUG V	GCU A GCC A GCA A GCG A	GAU D GAC D GAA E GAG E	GGU G GGC G GGA G GGG G