I did your corrections. I just wanted to know if all the sentences are correct from a scientific point of view. Thank you.
1) DNA contains instructions which decide which proteins a cell will make and consequently determines the whole chemistry of the cell.
2) DNA is found in chromosomes and it is one of the most important kinds of molecules found in living things.
DNA molecules are made up of two long chains of smaller molecules called nucleotides. So DNA is a polynucleotide.
3) The two chains of nucleotides wind around one another in a helix. The shape of a DNA molecule is a double helix.
4) There are four different kinds of nucleotides in a DNA molecule. They are known by the letters A, which stands for Adenine, T (Thymine), C (Cytosine) and G (Guanine).
5) The nucleotides can be arranged in any order along one of the DNA strands. The order of the nucleotides determines the kinds of proteins which the cell will make. Chemical bonds between opposite nucleotides hold the two strands together.
6) DNA carries the genetic code.
Proteins are chains of amino acids. There are about 20 kinds of amino acids in a protein chain. The sequence of these different amino acids in a protein chain determines what kind of protein it is.
7) A part of a DNA molecule which gives instructions for making one kind of protein is called a gene. It carries the instructions in the form of a code, called the genetic code. The code is a “three letter” code.
8) The letters are the nucleotides on one of the DNA strands in the double helix. A row of three nucleotides is a “code-word”, which stands for a particular amino acid.
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