Bio topic 8

• 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 along
• What is a deletion mutation?

  A base is removed from the sequence
• What is a substitution mutation?

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

  A section of bases is inverted in the sequence
• What is a duplication mutation?

  One 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 totipotent stem cells?

  Cells that can produce any body cell type
• Where are pluripotent stem cells found?

  In embryos, excluding placenta cells
• What are multipotent stem cells?

  Cells that can form a limited number of cell types
• What are unipotent stem cells?

  Cells that can only become one type of cell
• What are induced pluripotent stem cells?

  Adult cells reprogrammed to pluripotent state
• How do transcription factors control gene expression?

  They bind to DNA to turn genes on or off
• What role does estrogen play in transcription?

  It binds to receptors on transcription factors
• 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 tightening 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 result from mutations in genes regulating mitosis?

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

  A non-cancerous tumor that grows slowly
• What is a malignant tumor?

  A cancerous tumor that grows quickly
• What is metastasis?

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

  It receives oxygen and glucose for respiration
• Why is brain surgery considered very high risk?

  It involves cutting through the skull.
• What characterizes malignant tumors?

  They are cancerous and grow much quicker.
• What happens to the cell nucleus in malignant tumors?

  It becomes very large.
• What is metastasis in relation to tumors?

  It is the spread of tumor cells to other tissues.
• Why do malignant tumors grow rapidly?

  They develop their own blood supply.
• What supplementary treatments are often needed after tumor removal?

  Radiotherapy and chemotherapy.
• What is a common cause of tumor development?

  Gene mutation in tumor suppressor genes or oncogenes.
• What is the role of tumor suppressor genes?

  They control the cell cycle and slow division.