DNA contains all of an organisms's genetic material - the chemical instructions it needs to grow and develop. DNA is arranged into chromosomes.
Chromosomes are long molecules of coiled up DNA. The DNA is divided up into short sections called genes.
DNA is a double helix (a double-stranded spiral). Each of the two DNA strands is made up of lots of nucelotides joined together in a long chain - this makes DNA is a polymer.
Each nucleotide contains a small molecule called a "base". DNA has just four different bases.
The bases are A (adenine), C (cytosine),G (guanine) and T (thymine).
Each base forms cross links to a base on the other strand. This keeps the two DNA strands tightly wound together.
Aalways pairs up with T, and Calways pairs up with G. This is called complementary base-pairing.
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Step 3
Use the coarse adjustment knob to move the stage up to just below the objective lens. Then, looking down the eyepiece, move the stage downwards (so that you don't accidently crash the slide into the lens) until the specimen is just about in focus.
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Step 4
Then, still looking down the eyepiece, adjust the focus with the fine adjustment knob, until you get a clear image of your specimen.
DNA contains all of an organism's mapquest driving directions genetic material, which are the chemical instructions it needs to grow and develop. Chromosomes are groups of DNA.
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