Protein synthesis
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Protein Synthesis. By: Sophie gollan. In this experiment we modelled the structure of DNA and the processes involved in protein synthesis from the information in the DNA. DNA structure. DNA - a double stranded helix molecule which consists of subunits called nucleotides.

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Protein Synthesis

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Protein synthesis

Protein Synthesis

By: Sophie gollan

Protein synthesis

  • In this experiment we modelled the structure of DNA and the processes involved in protein synthesis from the information in the DNA

Dna structure

DNA structure

  • DNA - a double stranded helix molecule which consists of subunits called nucleotides.

  • Each nucleotide contains a sugar, a phosphate, and a base.

  • There are four bases:

  • adenosine

  • thymine

  • cytosine

  • guanine

  • Alternate sugar and phosphates form the sides, and the bases are connected to the sugars making “rungs” like a ladder.

  • The chemical structure of the bases allow them each to pair up with only one other base, thus they form complementary pairs.

  • The complementary pairs are:

  • Adenosine and thymine

  • Cytosine and guanine

Protein synthesis1

Protein synthesis

  • The information about the number, type and sequence of amino acids, needed to make a protein molecule, is found as a code in DNA.

  • The code- a sequence of bases.

  • One gene sequence codes for one polypeptide (a single chain of many amino acids)

  • A set of 3 bases (a codon) codes for one amino acid of a polypeptide.

  • A protein is one or more polypeptides.



  • 42 toothpicks

  • 18 milk bottles cut in half (36 halves) – sugar

  • 18 raspeberry lollies cut in half- phosphate

  • 25 jelly beans cut in half (5 of each 5 colours)- bases:

  • Adenosine- orange

  • Thymine- purple

  • Cytosine- pink

  • Guanine- green

  • Uracil- blue

  • 4 jelly snake, aproxx. 6cm long, different colours

  • A4 white paper representing a cell

  • Colored paper circle, 6cm diameter- a ribosome

  • Clean sharp knife

  • Cutting board

  • Gloves

  • Scissors

  • Marking pen

  • Heinemann Biology textbook



  • A gene length of DNA unwinds in the nucleus. This is the area containing the information about the protein to be made.

Protein synthesis

  • RNA polymerase enzyme moves along the exposed single DNA strand linking complementary RNA nucleotides together to form a mRNA strand.

  • RNA contains the base uracil where thymine is found in DNA. (uracil replaces thymine)

  • The ‘start’ codon and the ‘stop’ codon control the length of the mRNA strand

Protein synthesis

  • The mRNA strand is then modified so that it only consists of the base sequence that will code for the protein. It removes the non-coding regions, introns, while still in the nucleus by splicing the coding regions, exons, together.

  • The modified mRNA then moves from the nucleus into the cytoplasm

Protein synthesis


  • In the cytoplasm, an enzyme attaches amino acids to tRNA molecules. Each type of amino acid is attached to its specific tRNA.

Protein synthesis

  • mRNA passing out of the nuclear pores into the cytoplasm

  • triplet codons of tRNA with amino acids in the cytoplasm of the cell



  • The start codon (AUG) end of the mRNA strand binds onto a ribosome. A tRNA carrying the amino acid methionine at one end and anticodon (UAC) at the other, binds to the mRNA start codon within the ribosome.

Protein synthesis

  • A second tRNA binds to the next codon. Its amino acid links to the polypeptide bond of the first amino acid.

  • The first tRNA is released from the ribosome. The ribosome moves along the mRNA strand one codon at a time. Two tRNAs at a time are temporarily bound within the ribosome and their amino acids linked together


Amino acid forming polypeptide bond (jelly snakes)

mRNA strand

DNA strand

Triplet codon of tRNA

Protein synthesis

  • A polypeptide chain forms (jelly snakes)

Snakes form the polypeptide chain

Protein synthesis

  • When a ‘stop’ codon is reached the polypeptide chain is released into the cytoplasm

Polypeptide chain

Protein synthesis

  • A polypeptide chain is only the primary structure of a protein. Each protein has a particular shape formed by the twisting or folding of its polypeptide chains

  • Proteins are vital components of a cell.

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