Unit 1.2 gene expression

• What are the main differences between DNA and RNA in terms of location?

  DNA is found in the nucleus, while RNA is found in the nucleus and cytoplasm.
• How many strands does DNA have?

  DNA has 2 strands.
• How many strands does RNA have?

  RNA has 1 strand.
• What sugar is found in the nucleotide of DNA?

  The sugar in DNA nucleotides is deoxyribose.
• What sugar is found in the nucleotide of RNA?

  The sugar in RNA nucleotides is ribose.
• Which base pairs with adenine in DNA?

  Thymine pairs with adenine in DNA.
• Which base pairs with adenine in RNA?

  Uracil pairs with adenine in RNA.
• What are the two stages of protein synthesis?

  • Transcription
  • Translation
• What is the purpose of protein synthesis in cells?

  Cells express their genes by converting the genetic message into protein.
• What occurs during transcription?

  1. RNA polymerase unwinds the DNA double helix.

  2. Hydrogen bonds between base pairs break, allows unzipping of double helix

  3. As RNA polymerase breaks the bonds it synthesizes a primary transcript of mRNA, using RNA nucleotides which form hydrogen bonds with the exposed DNA stand by complementary base pairing to the DNA nucleotide.

  4. The primary transcript is spliced to produce mature mRNA.

  5. Mature mRNA leaves the nucleus to travel to the ribosome.
• Where does transcription take place?

  Transcription takes place in the nucleus.
• What is the role of RNA polymerase during transcription?

  RNA polymerase moves along the DNA, unwinding the double helix and synthesizing mRNA.
• What happens to the primary transcript of mRNA after it is synthesized?

  The primary transcript is spliced to produce a mature mRNA transcript.
• What is the final destination of mature mRNA after transcription?

  Mature mRNA travels to the ribosome.
• What is the process of converting the primary transcript to a mature mRNA transcript called?

  Splicing
• What is the section of mRNA produced during transcription called?

  The section of mRNA produced is called the primary transcript.
• What is the significance of complementary base pairing during transcription?


  Complementary base pairing ensures that RNA nucleotides correctly match with the exposed DNA strand.
• What initiates the translation of mRNA?

  A start codon
• What do tRNA molecules carry to the mRNA during translation?

  Specific amino acids
• How does the genetic code get translated into a sequence of amino acids?

  By tRNA molecules bonding to mRNA codons
• What forms between amino acids during translation?

  Peptide bonds
• What happens to each tRNA molecule after it has delivered its amino acid?

  It leaves the ribosome
• What is formed after the translation of mRNA?

  A polypeptide chain
• When does translation end?

  At a stop codon
• What are the main steps of translation in protein synthesis?

  1. Translation begins at a start codon.

  2. Anti-codons on tRNA bond to mRNA codons by complementary base pairings. 3. tRNA molecules carry specific amino acids, this translates the genetic code into a sequence of amino acids .

  4. Peptide bonds form between amino acids.

  5. Each tRNA molecule leaves the ribosome And a chain of polypeptide is formed

  6. Translation ends at a stop codon.