chap 12 molecular genetics

• what is DNA?

  deoxyribonucleic acid is a molecule that carries genetic information that is important for all cellular functions (like cell division and cell differentiation)
• what is the basic unit of DNA ?

  nucleotide, made up of : sugar, phosphate group, nitrogenous base
• what are the 4 different nitrogenous bases and their base pairings ?

  guanine - cytosine

  adenine - thymine
• what is 1 ?

  phosphate group

  
• what is 2 ?

  nitrogenous base

  
• what is 3 ?

  sugar

  
• how is a polypeptide/ protein made ?

  1. message from a small segment in the DNA molecules (gene) is used to produce a polypeptide
  2. the message in the gene is copied into a molecule called mRNA in the nucleus through the process called transcription
  3. mRNA travels from the nucleus to the cytoplasm and attaches to a ribosome
  4. the ribosome moves along the mRNA, synthesising a polypeptide, which is released when the ribosome leaves the mRNA, through the process called translation
• describe the process of producing transgenic bacteria that manufactures insulin

  1. obtains the fragment of DNA in human chromosome containing insulin gene and cut it out using a restriction enzyme
  2. it cuts the restriction site at 2 ends to produce sticky ends
  3. obtain a plasmic from a bacterium and cut it with the same restriction enzyme, producing sticky ends complementary to the ends of insulin gene
  4. mix the plasmid with DNA fragment containing human insulin gene and they will be by complementary base pairing between sticky ends
  5. add DNA ligase to seal the ends, forming recombinant plasmid
• how does the recombinant plasmid enter the bacterium again to produce insulin ?

  1. mix recombinant plasmid and bacetirum, apply temporary heat or electric shock which opens up the pores in the cell membrane for the plasmid to enter
  2. transgenic bacteria is grown in fermenters under optimal conditions to produce large quantities of human insulin
• benefits of genetic engineering

  • low- cost production of medicines
  • production of crops that grow in extreme conditions
  • development of foods designed to meet specific nutritional goals
• ethical considerations of genetic engineering ?

  • new proteins in GM foods might cause allergies in humans
  • animals are often used in research, raising concerns for the welfare of animals
  • people may deliberately create new combinations of genes which they may use in chemical or biological warfare