How is dna sequence used to make proteins?

Answer 1

to get from DNA to protein there are two stages before you understand them you must know the basics about DNA structure. It is a long sequence made from the chemicals adenin, thymine, cytosine and gaunine , represented by the letters letters A, T, C, and G. you also need to know that a gene is a small section of the DNA sequence, which has a definable start and end. When 'reading' DNA we go from one end of the DNA strand to the other in a specific direction, 5 prime to 3 prime.

Transcription

An enzyme known as DNA dependant RNA polymerase (often shortened to RNA polymerase) uses DNA near to the start of gene to determine where the gene starts. It then 'transcribes' (creates a copy of) the DNA into RNA, the sequence of RNA is like the mirror image of the DNA. for example a 'C' in the DNA becomes a 'G' in RNA. In addition to this there are no 'T's' in RNA instead there are U's

After an RNA copy of the DNA has been made it is modified in the cell by adding an unreactive 'cap' to one end which protects it from being broken down in the cell and also a tail of repeating 'A's' it is now known as mRNA.

Translation

Once the 'mRNA' has been produced it moves from the nucleus of the cell into the cytoplasm. A cell componant known as the ribosome associates with the mRNA and begins to translate it. The ribosome reads 3 bases (letters) in the RNA sequence at one time 'a codon'. each codon gives information on one amino acid in the finished protein sequence. For example the first codon the ribosome looks for is the start codon. In humans this is often AUG. Once found the ribosome uses this as the 'beginning' of the gene. The mRNA is read and the ribosome adds molecules called tRNAs to it which have one of 20 amino acids attached to them, so we have:

3bases in RNA --> linked to 1 'tRNA' molecule --> which in turn is linked to one amino acid.

As the ribosome contines to translate the mRNA the amino acids added earlier at the 5 prime end link up to form a protein. It is in this way that DNA--> RNA --> Protein (the central dogma of genetics)

Answer 2

The sequence of nitrogen bases in DNA determines the sequence of amino acids in a protein. The sequence of amino acids determines the structure and function of the protein.

Answer 3

Most simply put, DNA first has to be turned into RNA with the process of transcription. This pre-RNA is processed and sent out of the nucleus, where it is then translated into a protein.

Answer 4

gene expression