T8 The control of gene expression

• What is the main topic of Miss Estrich's biology video?

  Gene expression and gene technologies
• What should students do if they want more detailed explanations?

  Watch individual topic videos
• What is the cost of GCSE tuition at Medicate?

  £24 per hour
• How does Medicate match students with tutors?

  Based on exam board and study preferences
• What is a gene mutation?

  A change in the DNA sequence of a gene
• When do gene mutations mainly occur?

  During DNA replication in interphase
• What can increase the frequency of gene mutations?

  Exposure to mutagenic agents
• What can a gene mutation result in?

  A different amino acid being coded for
• How does a mutation affect protein structure?

  It can change the tertiary structure
• What can happen if a mutation occurs in a gene controlling the cell cycle?

  It could result in cancer
• What are the six types of gene mutations?

  1. Addition
  2. Deletion
  3. Substitution
  4. Inversion
  5. Duplication
  6. Translocation
• What is an addition mutation?

  One extra nucleotide is added to the sequence
• What happens to codons in an addition mutation?

  All subsequent codons shift by one position
• What is a deletion mutation?

  A base is removed from the sequence
• How does a substitution mutation affect the DNA sequence?

  One base is swapped for another
• What is an inversion mutation?

  A section of bases is reversed in order
• What is a duplication mutation?

  A base is duplicated in the sequence
• What is a translocation mutation?

  A section of bases moves to a different chromosome
• What are stem cells?

  Undifferentiated cells that can divide and specialize
• What are the types of stem cells based on differentiation abilities?

  Totipotent, pluripotent, multipotent, unipotent
• What can totipotent stem cells produce?

  Any type of body cell
• Where are pluripotent stem cells found?

  In embryos, excluding placenta cells
• What is the role of induced pluripotent stem cells?

  To overcome ethical issues in stem cell use
• How do transcription factors control gene expression?

  They bind to DNA to turn genes on or off
• What happens when a transcription factor binds to DNA?

  Transcription of the gene can begin
• How does estrogen initiate transcription?

  It binds to a receptor on the transcription factor
• What is epigenetics?

  Heritable change in gene function without DNA change
• How does increased methylation affect transcription?

  It inhibits transcription by condensing DNA
• What is the effect of decreased acetylation on transcription?

  It inhibits transcription by tightly coiling DNA
• What is RNA interference (RNAi)?

  Inhibition of translation by destroying mRNA
• How does small interfering RNA (siRNA) function?

  It binds to mRNA and destroys it
• What can mutations in genes regulating mitosis lead to?

  Uncontrolled cell division and cancer
• What is a benign tumor?

  A non-cancerous tumor that grows slowly
• How do malignant tumors differ from benign tumors?

  Malignant tumors grow quickly and metastasize
• What is metastasis?

  Spread of cancer cells to other tissues
• What is the significance of a tumor having its own blood supply?

  It receives oxygen and glucose for respiration
• What is the role of transcription factors in gene expression?

  They regulate the transcription of target genes
• How do transcription factors enter the nucleus?

  They move from the cytoplasm into the nucleus
• What is the role of histone proteins in DNA packaging?

  They help condense DNA into chromatin
• What is euchromatin?

  Less tightly coiled DNA allowing transcription