AP BIOLOGY

Detailed explanation-1: -Most genes contain the information needed to make functional molecules called proteins. (A few genes produce regulatory molecules that help the cell assemble proteins.) The journey from gene to protein is complex and tightly controlled within each cell. It consists of two major steps: transcription and translation.

Detailed explanation-2: -Scientists estimate that the human genome, for example, has about 20, 000 to 25, 000 protein-coding genes.

Detailed explanation-3: -Only about 1 percent of DNA is made up of protein-coding genes; the other 99 percent is noncoding. Noncoding DNA does not provide instructions for making proteins.

Detailed explanation-4: -Genes are small sections of DNA within the genome that code for proteins.

Detailed explanation-5: -mRNA codons are read from 5’ to 3’, and they specify the order of amino acids in a protein from N-terminus (methionine) to C-terminus. Translation involves reading the mRNA nucleotides in groups of three; each group specifies an amino acid (or provides a stop signal indicating that translation is finished).