B1.4 Protein synthesis

• What is the process of making proteins called?

  Protein synthesis
• What are the two main steps of protein synthesis?

  Transcription and translation
• What happens during transcription?

  A gene of DNA is copied into mRNA
• What is the role of ribosomes in protein synthesis?

  They produce proteins using mRNA
• What does mRNA stand for?

  Messenger RNA
• Why can't DNA leave the nucleus?

  Because DNA is too large
• What is the structure of mRNA compared to DNA?

  mRNA is shorter and single-stranded
• What base does mRNA contain instead of thymine?

  Uracil
• What enzyme initiates transcription?

  RNA polymerase
• What happens to the DNA strands during transcription?

  They separate to expose bases
• How do mRNA bases pair with DNA bases?

  They are complementary to each other
• What does the template strand refer to in transcription?

  The DNA strand used to make mRNA
• What is a codon?

  A group of three bases
• How many different amino acids do cells use?

  20 different amino acids
• What is the role of tRNA in translation?

  It brings amino acids to the ribosome
• What is the anticodon on tRNA?

  A sequence of three complementary bases
• How does the ribosome know which amino acid to add next?

  It reads the codons on mRNA
• What happens after the ribosome joins two amino acids?

  The ribosome moves along the mRNA
• What occurs at the end of translation?

  The amino acid chain detaches and folds
• What are the steps of transcription?

  1. RNA polymerase binds to DNA
  2. DNA strands separate
  3. RNA polymerase reads DNA bases
  4. mRNA strand is formed
  5. mRNA detaches and leaves the nucleus
• What are the steps of translation?

  1. mRNA binds to ribosome
  2. tRNA brings amino acids
  3. Ribosome reads mRNA codons
  4. Amino acids are joined together
  5. Completed protein chain detaches
• Compare the roles of mRNA and tRNA in protein synthesis.

  • mRNA: Carries genetic information from DNA
  • tRNA: Brings specific amino acids to ribosome
• What are the differences between DNA and mRNA?

  • DNA: Double-stranded, contains thymine
  • mRNA: Single-stranded, contains uracil
• What is the significance of codons in protein synthesis?

  • Codons code for specific amino acids
  • Each amino acid has a unique codon
• What is the function of RNA polymerase in transcription?

  • Binds to DNA
  • Synthesizes mRNA from DNA template
• What is the importance of the ribosome in translation?

  • Site of protein synthesis
  • Joins amino acids in correct order
• Give 3 ways mRNA is different to DNA.

  1. mRNA is shorter than DNA.
  2. mRNA is single-stranded, whereas DNA is double stranded.
  3. mRNA contains Uracil (U), where DNA contains Thymine (T).
• Where does mRNA go once it has been transcribed?

  It goes to the ribosome.
• Summarise transcription in a single sentence.

  Transcription is the process of copying a single gene of DNA to mRNA.
• Where does transcription take place?

  Transcription takes place in the nucleus.
• Summarise translation in a single sentence.

  Translation is the process by which a ribosome combines amino acids together to form a protein, using the 'instructions' of mRNA.
• What is the function of a ribosome?

  To carry out protein synthesis (assemble amino acids to form a protein).
• What is a polypeptide?

  A polypeptide is a chain of amino acids.
• How many bases are needed to code for one amino acid?

  3.