Cellular control

• What are gene mutations?

  Changes in the DNA sequence
• What is the role of DNA helicase in transcription?

  It unzips DNA by breaking hydrogen bonds
• What do free RNA nucleotides do during transcription?

  They form hydrogen bonds with complementary bases
• What is the function of RNA polymerase in transcription?

  It catalyzes the formation of the sugar phosphate backbone
• What is the first step in translation?

  tRNA binds to codon on mRNA
• What happens after tRNA binds to the codon during translation?

  It brings the corresponding amino acid
• What forms between amino acids during translation?

  A peptide bond forms between amino acids
• What are the types of point mutations?

  • Silent mutation
  • Missense mutation
  • Nonsense mutation
• What is a silent mutation?

  Triplet code changes but amino acid remains the same
• What is a missense mutation?

  It changes the amino acid sequence
• What is a nonsense mutation?

  It alters the triplet to a stop codon
• What are INDEL mutations?

  Insertions or deletions of nucleotide base pairs
• What is the effect of INDEL mutations on the genetic code?

  They cause a frameshift in the code
• What is an operon?

  • A group of genes functioning as a single transcription unit
  • Controls gene expression in prokaryotes
• What happens in the lac operon when lactose is not present?

  Repressor protein blocks transcription of structural genes
• What occurs in the lac operon when lactose is present?

  Lactose binds to repressor, allowing transcription
• What do transcription factors do?

  They control gene expression by aiding or inhibiting RNA polymerase
• What happens to introns during RNA processing?

  Introns are removed from primary RNA
• What is post-transcriptional gene regulation?

  Introns are removed, only exons are translated
• What is the role of signaling molecules in post-translational regulation?

  They bind to receptors and activate proteins
• What are the steps in apoptosis?

  1. Enzyme breaks down cytoskeleton
  2. Cytoplasm becomes dense with organelles
  3. Blebs form
  4. Chromatin condenses and DNA fragments
  5. Cell breaks into vesicles for phagocytosis
• What is a homeobox sequence?

  A sequence of 180 base pairs regulating development
• What is the function of a repressor protein in transcriptional regulation?

  It turns off gene expression by blocking transcription
• What is the difference between introns and exons?

  Introns are non-coding, exons are coding sequences
• What is the role of pKa in post-translational regulation?

  It catalyzes phosphorylation of proteins
• What causes genetic variation?

  • Random mating
  • Random fertilization
  • Mutations
  • Non-disjunction
• What is aneuploidy?

  Chromosome number is not a multiple of haploid
• What is polyploidy?

  Diploid gamete fertilized by haploid gamete
• What is deletion mutation?

  A part of chromosome is lost
• What is duplication mutation?

  A piece of chromosome is duplicated
• What is inversion mutation?

  A section of chromosome breaks and flips 180 degrees
• What is translocation mutation?

  A piece of chromosome attaches to another chromosome
• What are the types of variation in genetics?

  • Continuous variation: quantitative, wide range
  • Discontinuous variation: qualitative, narrow range
• What is dihybrid inheritance?

  • Involves two gene loci
  • Alleles inherited independently
• What is codominance?

  Both alleles contribute to phenotype in heterozygotes
• What determines blood groups?

  Three alleles on a single gene
• What is the difference between homogametic and heterogametic?

  Homogametic has same sex chromosomes, heterogametic has different
• What is haemophilia A?

  Inability to clot blood due to mutated allele
• How is colour blindness inherited?

  It is linked to the X chromosome
• What is epistasis?

  Interaction where one gene masks another's expression