1.4 + 1.6 - stem cells and mutations

• What is cell differentiation?

  the process by which a cell expresses certain genes to produce proteins characteristic for that type of cell, allowing it to carry out specialised functions
• embryonic stem cells are described as pluripotent
• tissue stem cells are described as multipotent
• What is a stem cell?

  an unspecialised cell which can self renew and differentiate into specialised cells by only expressing certain genes to produce specific proteins
• All genes can be switched on in a pluripotent cell
• certain genes can be switched on in a multipotent cell
• Research uses of stem cells?

  model cells for studying how diseases develop

  model cells for drug testing
• therapeutic uses of stem cells?

  repair of damaged/diseased organs/tissues for example regeneration of damaged skin or corneal repair
• Advantages of using embryonic stem cells?

  avoids animal/human testing

  can lead to effective treatments for disease
• disadvantages of using embryonic stem cells?


  involves destruction of an embryo
• What are the two main types of mutations?

  • single gene mutations
  • chromosome mutations
• What are the 3 types of single gene mutations?

  • substitution
  • insertion
  • deletion
• What are the 3 types of substitution mutations?

  • missense
  • nonsense
  • splice site
• A substitution mutation can be described as a point mutation
• Insertion and deletion mutations can be described as frame shift mutations
• What is a substitution mutation? (single gene mutation)

  one nucleotide is replaced for another in DNA
• What is an insertion mutation? (single gene mutation)

  adding nucleotides into the base sequence
• What is a deletion mutation? (single gene mutation)

  nucleotide is removed
• what type of organism has differentiated cells?

  multicellular eukaryotes
• compare a stem cell and a differentiated cell?

  a stem cell can self-renew whereas a differentiated cell cannot
• Where are meristems found?

  • between xylem and phloem
  • tips of roots and shoots
• Define gene expression?

  the process by which specific genes are activated to produce a required protein
• Define phenotype?

  the visible characteristics of an organism which occur as a result of its genes
• Define single gene mutation?

  alters a DNA nucleotide
• what is a missense mutation?

  changes one amino acid to another, changing the shape/function of the protein
• what is a nonsense mutation?

  changing an amino acid for a stop codon, shortening the protein and affecting/preventing it functioning
• What is a splice site mutation?

  results in some introns being retained/exons not being included in the mature mRNA transcript
• What kind of mutation is this?

  substitution

  
• what kind of mutation is this?

  insertion

  
• what kind of mutation is this?

  deletion

  
• chromosome structures affect whole chromosomes
• What are the 4 types of chromosome mutations?

  • deletion
  • translocation
  • duplication
  • inversion
• define deletion (chromosome mutation)?

  A section of a chromosome is removed
• define translocation (chromosome mutation)?

  a section of a chromosome is moved to another chromosome that is not its homologous partner
• Define duplication (chromosome mutation)?

  a section of a chromosome is moved to its homologous partner
• Define inversion(chromosome mutation)?

  a section of the chromosome is reversed
• chromosome mutations are often lethal to the organism
• why are duplication mutations important in evolution?

  they allow beneficial mutations to occur in the duplicated gene and the original gene can still be expressed to produce the coding protein
• what kind of mutation is this?

  deletion

  
• What kind of mutation is this?

  translocation