Lecture 4: Basic Genetics Mechanism

• What is the central molecule for protein synthesis?

  DNA
• What role does DNA play in protein synthesis?

  It acts as a template for replication
• What are the two main processes through which DNA directs protein synthesis?

  Transcription and translation
• What are chromosomes composed of?

  DNA wrapped around histone proteins
• Where are chromosomes found in the cell?

  In the nucleus
• What forms the double helix structure of DNA?

  Two long polynucleotide chains
• What are the components of a nucleotide?

  Phosphoric acid, deoxyribose, and a nitrogenous base
• Which nitrogenous bases are found in DNA?

  Adenine, thymine, guanine, and cytosine
• How do adenine and thymine pair in DNA?

  Adenine bonds with thymine (A-T)
• How do guanine and cytosine pair in DNA?

  Guanine bonds with cytosine (G-C)
• What is semiconservative replication?

  Each original strand serves as a template
• What is the result of DNA replication?

  Two DNA molecules with one original strand
• What enzyme unwinds the DNA during replication?

  DNA helicase
• What do single-stranded binding proteins (SSBPs) do?

  They prevent the separated strands from rejoining
• What is the role of topoisomerase during DNA replication?

  It prevents the supercoiling of DNA
• In which direction does DNA polymerase add nucleotides?

  5' to 3' direction
• What is the leading strand in DNA replication?

  The strand synthesized continuously
• What is the lagging strand in DNA replication?

  The strand synthesized in fragments
• What are Okazaki fragments?

  Fragments on the lagging strand
• What enzyme joins Okazaki fragments?

  DNA ligase
• What is a gene?

  A segment of DNA with information
• What is transcription?

  Copying a gene’s nucleotide sequence into RNA
• What sugar does RNA use?

  Ribose
• How does ribose differ from deoxyribose?

  Ribose has an extra hydroxyl group
• What replaces thymine in RNA?

  Uracil
• What is the function of messenger RNA (mRNA)?

  It carries genetic code to ribosomes
• What is the structure of mRNA?

  Long, single RNA strands
• What are codons in mRNA?

  Three-nucleotide sequences specifying amino acids
• What is the function of transfer RNA (tRNA)?

  It transports activated amino acids to ribosomes
• What is the structure of tRNA?

  Cloverleaf shape
• What is an anticodon in tRNA?

  A sequence that pairs with mRNA codon
• What is the function of ribosomal RNA (rRNA)?

  Forms the ribosome for protein synthesis
• What percentage of the ribosome's structure is rRNA?

  60%
• What is the role of microRNA (miRNA)?

  Regulates gene expression
• How do miRNAs affect mRNA?

  They lead to degradation or inhibit translation
• What is the first step of transcription?

  RNA polymerase attaches to a promoter
• In which direction does RNA polymerase move during elongation?

  5' to 3' direction
• What happens during the termination phase of transcription?

  Transcription stops and mRNA is released
• What are introns in pre-mRNA?

  Sequences that do not code for proteins
• What are exons in mRNA?

  Coding sequences that remain in mRNA