(Unit 1.3) Gene Expression

• What is gene expression?

  It is the process of using information from a gene to synthesize a protein.
• How is phenotype determined?

  Phenotype is determined by the proteins that are made when genes are expressed.
• What is the relationship between genotype and phenotype?

  Genotype is made up of the sequence of bases in genes, while phenotype is what you physically look like.
• What are the two main stages of protein synthesis?

  The two main stages are transcription and translation.
• What is the role of mRNA in protein synthesis?

  mRNA carries the genetic code from DNA to the ribosome.
• What happens during transcription?

  During transcription, an mRNA strand is synthesized from a section of DNA.
• What is the function of RNA polymerase?

  RNA polymerase unwinds the DNA double helix and synthesizes mRNA from DNA.
• What is a codon?

  A codon is a triplet of bases on the mRNA strand that codes for a specific amino acid.
• What are introns and exons?

  Introns are non-coding regions, while exons are coding regions of the mRNA transcript.
• What is RNA splicing?

  RNA splicing is the process of removing introns and joining exons to form a mature mRNA transcript.
• How can the same primary mRNA transcript produce different proteins?

  Different regions can be treated as introns or exons, leading to different mature mRNA transcripts.
• What is the role of tRNA in translation?

  tRNA carries specific amino acids to the ribosome and matches them with the mRNA codons.
• What is a peptide bond?

  A peptide bond is the bond that links amino acids together to form a protein.
• What determines the function of a protein?

  The variety of shapes that proteins can take, determined by their amino acid sequence and interactions.
• What are the processes of transcription and translation in protein synthesis?

  • Transcription: Gene is copied into mRNA using RNA polymerase; introns are removed to form mature mRNA.
  • Translation: Mature mRNA attaches to ribosome; tRNA brings amino acids; peptide bonds form to create a protein.
• What is the stop codon in translation?

  The stop codon signals the end of protein synthesis.
• How do hydrogen bonds contribute to protein structure?

  Hydrogen bonds help hold the 3D shape of proteins together.
• Why is the shape of a protein important?

  The shape of a protein determines its function.
• What is the definition of gene expression

  the process by which specific genes are activated to produce a required protein. 
• what are the stages of transcription?

  1. RNA polymerase unwinds DNA and separates it into two strands
  2. Hydrogen bonds break between 2 strands
  3. RNA polymerase attaches RNA nucleotides to their complementary nucleotides on DNA template strand
  4. primary mRNA transcript is produced
  5. exons are coding and introns are non-coding. introns are removed and exons are retained.
  6. exons join together to form mature mRNA transcript which makes its way to ribosome via cytoplasm.
• what are the stages of translation?

  1. tRNA had an anticodon and amino acid attachment site which binds to specific amino acids and carries to ribosome
  2. anticodon on tRNA are complementary and temporarily bind to codons on the mature mRNA transcript
  3. there are start and stop codons that will begin and end the translation process, between these codons, amino acids are assembled by tRNA
  4. peptide bonds form between assembled amino acids and a polypeptide forms