From DNA to Protein - A Storyboard

Fill-in exercise

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DNAstructure.jpgThe genetic code of a cell is carried in , which is located in the of the cell. The DNA molecule has four nitrogenous bases, A (), T (), G () and C (). These bases pair along the inside of the "double " of the DNA molecule. The base Adenine always pairs with , and Guanine always pairs with . There are about three of these base pairs in the human genome, coding for an estimated 40,000 genes. The outside backbone of the double-stranded molecule is made up of deoxyribose molecules and charged groups.

DNA is copied by a process known as . The process is semi-, which means that in each new DNA molecule, there will be one old strand and one strand.replicationl.gif

RNA.gifSince protein production takes place in the , which are located in the cytoplasm, the genetic code must be exported there before protein can be produced. This is done in the form of RNA, also called mRNA. mRNA is made from the DNA template by a process called . There are several difference between RNA and DNA.

  1. RNA is -stranded
  2. RNA contains the sugar (instead of deoxyribose in DNA)
  3. RNA contains the base U () instead of the base Thymine

mRNA undergoes some processing and then leaves the . In the ribosomes the process of making from mRNA, called , takes place. The ribosomes read bases of mRNA at a time. The three-base sequences are called , and each "translates" to a particular amino acid. Molecules of RNA (tRNA), possessing the -codons of the mRNA, bring amino acids that build the protein chain. For instance, the mRNA codon GGG would attract a tRNA with the anti-codon . The process begins with a "" codon (AUG) which puts the amino acid methionine in place, and continues until the ribosome reaches a "" codon, at which point the process terminates. The completed protein is released into the (ER).Protein.jpg