Protein Synthesis

• What is the process by which genetic information stored in DNA is copied into RNA?

  Transcription
• What type of RNA serves as a template for protein synthesis?

  Messenger RNA (mRNA)
• What is the key enzyme responsible for synthesizing mRNA?

  RNA polymerase
• In which direction can RNA polymerase add nucleotides?

  5' to 3' direction
• What are the three main steps of transcription?

  • Initiation: RNA polymerase binds to the promoter.
  • Elongation: RNA polymerase unwinds DNA and adds RNA nucleotides.
  • Termination: Transcription stops at a termination sequence.
• If a DNA template strand has the sequence 5'-ATGCTAGC-3', what would be the corresponding mRNA sequence?

  3'-UACGAUCG-5'
• What is the process of synthesizing a polypeptide based on mRNA called?

  Translation
• What are the key features of the genetic code?

  • Triplet code: Each codon corresponds to an amino acid.
  • Degeneracy: Multiple codons can code for the same amino acid.
  • Universality: The genetic code is nearly identical across organisms.
• What is the role of transfer RNA (tRNA) in translation?

  Bringing amino acids to the ribosome
• What does the anticodon on tRNA do?

  Base-pairs with the mRNA codon
• What are the steps of translation?

  • Initiation: Small ribosomal subunit binds to mRNA and recognizes the start codon.
  • Elongation: tRNAs bring amino acids, forming peptide bonds.
  • Termination: Stop codon is reached, and release factors cause the polypeptide to be released.
• What is the start codon in translation?

  AUG
• What does the mRNA sequence AUG-CCU-GAA-UGA code for?

  Methionine-Proline-Glutamic acid
• What is the difference between free and bound ribosomes?

  • Free ribosomes: Synthesize proteins for use within the cell.
  • Bound ribosomes: Produce proteins for secretion or incorporation into membranes.
• How does protein synthesis differ between prokaryotes and eukaryotes?

  Prokaryotes can transcribe and translate simultaneously, while eukaryotes separate these processes.
• What does the primary structure of a protein refer to?

  The linear sequence of amino acids in the polypeptide chain
• Why is the primary structure of a protein crucial?

  Because a single amino acid change can significantly alter a protein's function
• How can students deduce amino acid sequences from mRNA sequences?

  • Use a codon table to translate mRNA codons into amino acids.
  • Example: mRNA sequence 5'-AUGCCUUUUGAGUGA-3' translates to Methionine-Proline-Phenylalanine-Glutamic acid.
• How can students perform reverse translation from amino acids to DNA?

  • Given an amino acid sequence, deduce possible mRNA and DNA sequences.
  • Example: Methionine-Serine-Lysine corresponds to mRNA 5'-AUG-UCU-AAA-3' and DNA 3'-TAC-AGA-TTT-5' (template strand).
• Why might there be multiple correct mRNA and DNA sequences for a given amino acid sequence?

  Due to the degeneracy of the genetic code
• Why is mastering protein synthesis important for students?

  • It provides a foundation for understanding complex biological phenomena.
  • It has applications in genetic engineering and biotechnology.
• What are proteins composed of?

  Long chains of amino acids
• What are the components of an amino acid?

  • Central alpha carbon
  • Amine group
  • Carboxyl group
  • Variable side chain (R)
• How many different amino acids are there?

  20 different amino acids
• What distinguishes the 20 amino acids from one another?

  Their variable side chains
• What are essential amino acids?

  Amino acids that cannot be synthesized by the body
• How many essential amino acids are there?

  Nine essential amino acids
• What are some sources of essential amino acids?

  • Meat
  • Fish
  • Eggs
  • Dairy products
  • Quinoa
  • Soy products
  • Legumes
  • Nuts and seeds
  • Whole grains
• What are non-essential amino acids?

  Amino acids that can be synthesized by the body
• What are conditional amino acids?

  Amino acids that can be produced by the body but may be essential under certain conditions
• How does protein deficiency affect health?

  It varies based on which amino acids are lacking
• Why is special attention needed in certain diets regarding protein?

  To ensure all essential amino acids are consumed
• What is a dipeptide?

  A molecule formed by two amino acids linked together
• How are dipeptides formed?

  Through condensation reactions that release water
• What is a peptide bond?

  The bond formed between the amine and carboxyl groups of adjacent amino acids
• What are polypeptides?

  Long chains of amino acids
• How can polypeptides be broken down?

  Through hydrolysis reactions that require water
• What are the functions of proteins?

  • Structure: Collagen, spider silk
  • Hormones: Insulin, glucagon
  • Immunity: Antibodies
  • Transport: Protein channels
  • Sensations: Rhodopsin
  • Movement: Actin, myosin
  • Enzymes: Rubisco, amylase
• What is denaturation of proteins?

  A structural change in a protein that results in the loss of its biological properties
• What causes denaturation of proteins?

  Heat and pH changes