Protein synthesis

• What are the two stages of protein synthesis?

  Transcription and Translation

  
• What is produced during transcription?

  An mRNA molecule is produced

  
• What is the role of mRNA in protein synthesis?

  It transfers information from DNA in the nucleus to the cytoplasm

  
• Which enzyme is required for mRNA production?

  RNA polymerase

  
• Where does transcription occur in the cell?

  In the nucleus

  
• What happens to the DNA molecule during transcription?

  Part of the DNA unwinds and exposes the gene to be transcribed

  
• What is the complementary base pairing for adenine in RNA?

  Uracil
• What is the sugar-phosphate backbone of the mRNA formed by?

  Bonding of sugar-phosphate groups of RNA nucleotides by RNA polymerase

  
• What happens to the mRNA molecule after transcription?

  It leaves the nucleus via a pore in the nuclear envelope

  
• Why can't DNA make the journey out of the nucleus?

  Because it is too big to fit through the pores in the nuclear envelope
• What is the difference between the coding strand and the template strand of DNA?

  The coding strand carries the genetic code, while the template strand is transcribed
• What is the stability of DNA attributed to?

  Hydrogen bonding between bases and strong phosphodiester bonds
• How does the stability of DNA affect transcription?

  It allows single DNA strands to act as reliable templates for transcription

  
• How many protein-coding genes are there in the human genome?

  Approximately 20,000
• What is gene expression?

  It is the process of switching certain genes on or off to match the requirements of the cell
• What happens to genes that are not expressed?

  They are 'switched off' and do not undergo transcription or translation
• Where does translation occur in the cell?

  In the cytoplasm
• What is a polypeptide?

  A sequence of amino acids covalently bonded together
• What is the role of ribosomes in translation?

  They facilitate the binding of mRNA and tRNA to synthesize proteins

  
• What are the two subunits of a ribosome made of?

  Proteins and ribosomal RNA (rRNA)
• How do tRNA molecules contribute to translation?

  They bring specific amino acids to the ribosome based on codon-anticodon pairing

  
• What is a codon?

  A sequence of three mRNA bases that codes for a specific amino acid

  
• What is an anticodon?

  A sequence of three tRNA bases that are complementary to a codon

  
• What is the significance of stop codons in translation?

  They signal the end of translation when the polypeptide chain is complete

  
• How does complementary base pairing occur in translation?

  Between codons on mRNA and anticodons on tRNA

  
• What is the analogy used to describe transcription and translation?


  • Transcription is like converting text from one language to another (e.g., English to French).
  • Translation is like converting text from a Western language to a language with a different alphabet (e.g., English to Japanese).

  
• What is the genetic code based on?

  A triplet (three-letter) code of DNA nucleotide bases
• How many different amino acids are there that cells use to make proteins?

  There are 20 different amino acids
• What does it mean that the genetic code is degenerate?

  Multiple codons can code for the same amino acids
• What does it mean that the genetic code is universal?

  Almost every organism uses the same code for amino acids
• What is the role of start and stop signals in the genetic code?

  They tell the cell where individual genes start and stop
• How does the non-overlapping nature of the genetic code affect reading the DNA?

  Each base is only read once in the codon it is part of
• How many different codons are possible in the genetic code?

  There are 64 different codons
• What is the significance of the degenerate nature of the genetic code?

  It can limit the effect of mutations
• What is the relationship between the genetic code and protein synthesis?

  The genetic code determines the sequence of amino acids in proteins
• What do start and stop signals in DNA indicate?

  They tell the cell where individual genes start and stop.
• How do start and stop signals affect protein production?

  They ensure the cell reads the DNA correctly and produces the correct amino acid sequences.
• What is the nature of the genetic code?

  The genetic code is non-overlapping.
• What does it mean that the genetic code is non-overlapping?

  Each base is only read once in the codon it is part of.
• How many different codons are possible in the genetic code?

  There are 64 different codons possible.