Central Dogma of Genetics

• Initiation begins when the initiator tRNA carrying methionine attaches to the rRNA of the small ribosomal subunit.

  Together, they bind to the 5' end of the mRNA by recognizing the 5' cap. Then, they "walk" along the mRNA in the

  5’ to 3' direction, stopping when they reach the start codon on the mRNA (usually AUG).

  The initiator tRNA binds to the start codon of the mRNA. The large ribosomal subunit then attaches. The initiator

  tRNA sits in the P site on the ribosome. Together, the complete ribosome, the tRNA, and the mRNA are known as the initiation complex
• What does the central dogma of molecular biology describe?

  The flow of genetic information in cells

  
• What is the sequence of events in the central dogma?

  DNA → mRNA → protein

  
• Where does DNA transcription occur?

  In the nucleus

  
• What is the role of mRNA after transcription?

  It travels to the ribosomes for translation

  
• What is the significance of the S phase of Interphase?

  DNA replication occurs during this phase
• What does the central dogma provide evidence for?

  The common ancestry of all life forms
• What is an exception to the central dogma involving retroviruses?

  They transcribe RNA into DNA
• What enzyme do retroviruses use to transcribe RNA into DNA?

  Reverse transcriptase
• How do primitive viruses differ in their genetic material?

  They use only RNA to produce proteins
• What is the new exception to the central dogma discovered with prions?

  Protein → Protein replication
• Why are retroviruses and prions not considered "alive"?

  They do not follow the central dogma
• What is the primary function of DNA?

  To code for the body’s proteins
• What does the one gene-one polypeptide hypothesis state?

  A single gene codes for one polypeptide
• What is transcription?

  The process of making mRNA from DNA

  
• Why is transcription important?

  It allows DNA to be used for protein synthesis

  
• How does transcription differ from replication?

  Transcription occurs gene by gene
• What are the three major phases of transcription?

  Initiation, Elongation, Termination

  
• What happens during the initiation phase of transcription?

  Transcription factors attach to the promoter region

  
• What is the TATA box?

  A specific part of the promoter region
• What does RNA polymerase do during transcription?

  It assembles new RNA molecules

  
• What is the template strand in transcription?

  The DNA strand used to build RNA

  
• In which direction is the new RNA molecule built?

  5’ to 3’ direction
• What is the primary transcript?

  The newly formed RNA molecule

  
• What signals the end of transcription?

  A stop or terminator sequence in DNA

  
• What happens to RNA polymerase after transcription is complete?

  It unbinds from the DNA

  
• How do prokaryotic and eukaryotic RNA processing differ?

  Prokaryotic RNA can act as mRNA immediately
• What are the steps of RNA processing in eukaryotic cells?

  1. 5’ modification: Add GTP cap
  2. 3’ modification: Add Poly A Tail
  3. Splicing: Remove introns, retain exons

  
• What is alternative splicing?

  Choosing which exons to include in mRNA

  
• How does alternative splicing affect protein diversity?

  It allows multiple proteins from one gene

  
• How many protein-coding genes do human cells contain?

  Approximately 20,000
• How many different proteins can humans produce?

  Over 100,000 different proteins
• What role do introns play in gene expression?

  They allow for microRNA regulation
• What are the four important types of RNA?

  • mRNA: Carries information from DNA
  • tRNA: Delivers amino acids to ribosomes
  • rRNA: Forms ribosomes with proteins
  • snRNA: Involved in RNA processing

  
• What role do introns play during meiosis?

  They may regulate crossing over.
• What are the four important types of RNA?

  • Messenger RNA (mRNA)
  • Transfer RNA (tRNA)
  • Ribosomal RNA (rRNA)
  • Small nuclear RNA (snRNA)

  
• How does the sequence of RNA bases affect its function?

  It determines the RNA molecule's function.

  
• What is the function of mRNA?

  It carries information from DNA to ribosomes.

  
• What does tRNA do during translation?

  It delivers specific amino acids to ribosomes.

  
• What is the role of rRNA in cells?

  It forms the functional building blocks of ribosomes.