AQA · GCSE · Biology

    Course version: 8461 · Version from Sept 2018

    (HT only) Proteins are synthesised on ribosomes, according to a template.

    Full specification wording

    DNA structure (biology only): (HT only) Proteins are synthesised on ribosomes, according to a template.

    Protein synthesis occurs on ribosomes, which are the cell's protein factories.

    Checked against the AQA 8461 specification (opens in a new tab) on .

    • Point 11 of 19
    • 4 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Protein synthesis occurs on ribosomes, which are the cell's protein factories. The template is a molecule of messenger RNA (mRNA) that carries a copy of the gene's base sequence from the DNA in the nucleus to the ribosome. The ribosome binds to the mRNA and reads its bases in groups of three (codons). Each codon specifies one amino acid. Transfer RNA (tRNA) molecules bring the correct amino acids to the ribosome, where they are joined in the order dictated by the mRNA codons. In this way, the base sequence of the gene determines the amino acid sequence of the protein. For example, the codon AUG on mRNA codes for the amino acid methionine, so the ribosome will place methionine at the start of the protein chain. The process is called translation.

    What earns the marks

    • Ribosomes are the site of protein synthesis in the cell.
    • The template used by the ribosome is messenger RNA (mRNA), which is a copy of the gene's base sequence.
    • mRNA is transcribed from DNA in the nucleus and travels to the ribosome.
    • The ribosome reads the mRNA bases in groups of three, called codons.
    • Each codon codes for a specific amino acid.
    • Transfer RNA (tRNA) molecules bring the correct amino acids to the ribosome.
    • The amino acids are joined together in the order specified by the mRNA codons to form a polypeptide chain.

    Common mistakes and how to put them right

    • Thinking that proteins are made on the DNA itself.

      Put it right: Proteins are made on ribosomes, using mRNA as the template.

    • Confusing the roles of mRNA and tRNA.

      Put it right: mRNA carries the genetic message from DNA to the ribosome; tRNA brings amino acids to the ribosome.

    • Believing that the ribosome reads the DNA directly.

      Put it right: The ribosome reads mRNA, which is a copy of the DNA base sequence.

    Exam tips

    • Use the terms 'mRNA', 'codon' and 'tRNA' accurately in your answers.
    • When describing the process, state clearly that the ribosome moves along the mRNA and that amino acids are joined in the order of the codons.
    • If asked why the process is called translation, explain that the base sequence of mRNA is translated into the amino acid sequence of a protein.

    Try the lesson

    The start of the DNA structure (biology only): (HT only) Proteins are synthesised on ribosomes, according to a template. lesson, made from checked teaching notes for this specification point.

    Have a go first

    During protein synthesis on ribosomes, what is the role of the template molecule?

    Listen

    Protein synthesis occurs on ribosomes, which are the cell's protein factories. The template is a molecule of messenger RNA (mRNA) that carries a copy of the gene's base sequence from the DNA in the nucleus to the ribosome. The ribosome binds to the mRNA and reads its bases in groups of three (codons). Each codon specifies one amino acid. Transfer RNA (tRNA) molecules bring the correct amino acids to the ribosome, where they are joined in the order dictated by the mRNA codons. In this way, the base sequence of the gene determines the amino acid sequence of the protein. For example, the codon AUG on mRNA codes for the amino acid methionine, so the ribosome will place methionine at the start of the protein chain. The process is called translation. A strong answer earns marks for these points. Ribosomes are the site of protein synthesis in the cell. The template used by the ribosome is messenger RNA (mRNA), which is a copy of the gene's base sequence. mRNA is transcribed from DNA in the nucleus and travels to the ribosome. The ribosome reads the mRNA bases in groups of three, called codons. A common slip: Thinking that proteins are made on the DNA itself. Instead, proteins are made on ribosomes, using mRNA as the template. Exam tip: Use the terms 'mRNA', 'codon' and 'tRNA' accurately in your answers.

    See it

    A top-to-bottom flowchart with eight boxes joined by arrows. The first box says DNA in the nucleus and points to a box saying mRNA carries a copy of the gene's base sequence. That points to mRNA travels to the ribosome, which points to ribosome reads mRNA bases in groups of three (codons). This points to each codon specifies one amino acid, which points to tRNA brings the correct amino acids to the ribosome. That points to amino acids joined in the order of the codons, which finally points to polypeptide chain formed.
    It shows the sequence of translation, from mRNA carrying the gene's base sequence to the ribosome building a polypeptide chain in codon order.

    Put it in order

    Put these steps in the order they happen.

    1. 1. Each codon specifies one amino acid
    2. 2. Polypeptide chain formed
    3. 3. tRNA brings the correct amino acids to the ribosome
    4. 4. DNA in the nucleus
    5. 5. mRNA carries a copy of the gene's base sequence
    6. 6. Amino acids joined in the order of the codons
    7. 7. mRNA travels to the ribosome
    8. 8. Ribosome reads mRNA bases in groups of three (codons)

    Key words

    Say what each word means before you turn the card.

    Ribosomes

    Try answering aloud or in your head before turning the card.

    Messenger RNA

    Try answering aloud or in your head before turning the card.

    Translation

    Try answering aloud or in your head before turning the card.

    Codons

    Try answering aloud or in your head before turning the card.

    See every definition
    Ribosomes
    The site of protein synthesis in the cell, where proteins are synthesised according to a template.
    Messenger RNA
    A copy of the gene's base sequence that carries the genetic message from the DNA in the nucleus to the ribosome.
    Translation
    The process in which the base sequence of mRNA is translated into the amino acid sequence of a protein.
    Codons
    Groups of three mRNA bases read by the ribosome, each specifying one amino acid.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-to-bottom flowchart with eight boxes joined by arrows. The first box says DNA in the nucleus and points to a box saying mRNA carries a copy of the gene's base sequence. That points to mRNA travels to the ribosome, which points to ribosome reads mRNA bases in groups of three (codons). This points to each codon specifies one amino acid, which points to tRNA brings the correct amino acids to the ribosome. That points to amino acids joined in the order of the codons, which finally points to polypeptide chain formed.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

    There is more to this lesson

    The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.

    Carry on with the full lesson

    A week of Premium from your first lesson · Then the free plan continues · No card, no charge

    Test your understanding of DNA structure (biology only): (HT only) Proteins are synthesised on ribosomes, according to a template.

    Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.

    Take topic quiz

    A week of Premium from your first lesson · Then the free plan continues · No card, no charge

    Start free

    Cookies on MasteryMind

    Essential cookies keep you signed in.

    Analytics and advertising cookies stay off unless you accept.

    Read our Privacy Policy.