Differential Gene Expression

• What did the Acetabularia Experiment find out?

  The nucleus controls development, using mRNA as a messenger molecule
• What happened during the Acetabularia Experiment?

  1. Acetabularia A and Acetabularia B have their hats removed and stalks swapped.
  2. Plants develop new hats with features of both species- the stalks and nuclei are different.
  3. If the intermediate hats are removed, the new hats correspond to the nulceus in the rhizoid- this demonstrates the role of the nucleus and mRNA in development.
• What did the Dolly the Sheep experiment show?

  All genetic information for making a complete organism is present in every cell.
• What happens during cloning?

  1. An egg cell from a donor has it's nucleus removed and the nucleus of a body cell of another mammal is inserted.
  2. The two are fused.
  3. A small electric shock is applied to make the cells divide.
  4. An embryo is formed and grown in culture.
  5. Embryo is inserted into the host/ surrogate mother
  6. Embryo develops and the offspring is genetically identical to the body cell donor
• What happens during differential gene expression?

  1. Correct stimulus is given to unspecialised cells.
  2. Some genes are activated
  3. mRNA is transcribed from active genes.
  4. mRNA moves from nucleus to ribosomes in cytoplasm, making the appropriate protein.
  5. the protein controls cell processes or determines cell structure
  6. cell has been modified to make it specialised.
• How does differential gene expression allow cells with the same genetic material to have different structures?

  Different genes are active in different cells.

  • active genes make mRNA
  • active genes make proteins
  • proteins control cell processes
  • this causes a permanent change to a cell
• What chemical stimuli lead to specialisation?

  Hormones and enzymes
• What happened in Dawid and Sargent's experiment ?

  mRNA was made in the blastula as it had active genes.

  The gastrula was more specialised so it had more active genes so more mRNA was made.

  2. mRNA was converted into cDNA by reverse transcriptase enzyme.

  3. cDNA from gastrula and mRNA from blastula were combined

  4. at the end, there was unpaired cDNA
• What did the unpaired cDNA at the end of the experiment show?

  This proves that more genes are active in specialised cells
• What is a gene probe?

  A short, single-stranded piece of DNA or RNA used to detect complementary sequences in a sample.
• If a gene probe is used to look for the insulin gene in all cells, what would be observed?

  Insulin would be found there because the insulin gene is present in all cells, however, it isn't active in all cells
• What is produced when a gene is active?

  mRNA- a probe complementary to the mRNA should be used in differential gene expression, to see if a certain gene is active as mRNA would be produced