Chapter 13: Techniques In Biotechnology

Question 1

• What is biotechnology
• What’s the human genome project?
• What’s a genome?
• Describe the structure of DNA
• What are the 4 nitrogenous bases in a DNA molecule?
• What’s the effect on the order of nitrogen bases in DNA molecules?
• What does each nucleotide consist of?
• What is link between the nitrogen bases?
• What is DNA sequencing?
• Explain Sanger’s method of determining a DNA sequence.

Answer 1

• Using biological processes to produce useful products.
• An international effort to map the location of the genes in all 46 chromosomes in the human genome.
• The complete set of genetic info of an organism.
• DNA molecules consists of 2 strands of alternating sugars and phosphates with pairs of nitrogen bases forming cross-links between the sugar molecules in the 2 strands. The molecule is twisted into a spiral known as a double helix.
• Adenine, Thymine, Cytosine and Guanine.
• Determines the structure of the cell and the way it functions.
• A phosphate group and a nitrogenous base.
• A weak hydrogen bond
• Determining the precise order of nucleotides in a sample of DNA.
• Each new nucleotide is bonded to the hydroxyl group (OH) of the previous nucleotide. Sanger’s method uses synthetic nucleotides that lack this OH group and are added to the growing strand, stopping the elongation of the sequence because there is no OH group for the next nucleotide to attach to. This then allows the strands to be compared.

Question 2

• Explain the process of electrophoresis
• Explain the process of polymerase chain reaction (PCR)
• What is recombinant DNA technology?
• What are transgenic organisms?
• What is a recognition site?
• What are restriction enzymes?

Answer 2

• Special enzymes are used to cut DNA at specific base sequences that vary from person to person, and are then placed in a special gel. An electric current is passed through the electrodes at either. The DNA which is negatively charged moves through the gel towards the positive electrode. The smaller pieces move faster resulting in a pattern of bands often called a DNA fingerprint.
• A process of artificially multiplying segments of DNA. It involves a thermal cycle carried out by a specialised machine. 1st, denaturing occurs: the double stranded DNA section is heated at 96°, separating it into 2 strands. Next, annealing occurs: temp lowers to 55° enabling the primers to attach to each strand. 3rd, extending occurs: temp raises to 72° and Taq polymerase enzyme creates new DNA strand.
• Introducing DNA into a cell from a different type of organism.
• Organisms whose genome has been altered by the transfer of a gene from another organism.
• A specific sequence of nucleotides at which an enzyme cuts a strand of DNA.
• Enzymes that cut strands of DNA at a specific of nucleotides.

Question 3

• What are the 2 types of cuts produced by restriction enzymes?
• How do the names of each restriction enzyme reflect its origin?
• What is DNA ligase?
• What is ligation?
• Explain the process of making a recombinant DNA molecule.
• What are the 2 commonly used vectors?
• What are plasmids?

Answer 3

1. Straight cuts: Clean breaks across the 2 strands of DNA producing a blunt end, terminating in a base pair.
2. Staggered cuts: Results with fragments with sticky ends of unpaired nucleotides in the DNA molecule that overhang at the break in the strands.
   - The 1st letter of the name comes from the genus of the bacterium from which it was isolated, while the 2nd 2 letters comes from the species. The numbers listed after the name indicate the order in which the enzymes were isolated from the single strains of bacteria.
   - An enzyme capable of combining 2 small components of single-strand DNA into 1 single structure.
   - The process of joining short strands of DNA during replication.
   - 1st the gene of interest is isolated and restriction enzymes cut the DNA on either side of the gene producing a section of DNA with sticky ends. Next a plasmid from a bacterial cell is isolated and cut using the same type of restriction enzyme as before. The plasmid now has a section missing with sticky ends. The DNA section with the interested gene is connected to the plasmid by ligase enzymes. The recombinant plasmid is put back in the bacterium and the bacterium itself multiples producing more of the recombinant DNA.
   - Bacterial plasmids and phage viruses.
   - Small circular strand of DNA distinct from the main bacterial genome; it is composed of only a few genes and is able to replicate independently within a cell.

Question 4

• Explain how recombinant DNA technology has had success for diabetes treatment.
• Explain what Haemophilia A is, how it was treated and how recombinant DNA technology has helped patients.
• What are hereditary diseases?
• What is gene therapy?
• What is cystic fibrosis?
• What is Huntington’s disease?

Answer 4

• Using recombinant DNA techniques, the human gene that has the code for insulin production was introduced into bacterial cells. These bacteria became insulin factories and are now cultured in vats where they produce insulin that can be used to treat diabetes.
• It’s a inherited disorder where patients do it have sufficient factor VIII (blood clotting protein). Patients therefore needed injections of factor VIII which were obtained by and required thousands of donors, putting patients after risk of transmission of viral diseases. The production of factor VIII by recombinant DNA techniques overcame this problem by producing Factor VIII that is free of other dangerous plasma proteins.
• Diseases transmitted from parents-children by defective genetic info.
• Used to treat or cure genetic abnormalities by replacing faulty genes with healthy ones.
• A genetic recessive disorder affecting the lungs and pancreas. It is characterised by thick sticky secretions of mucus which may clog up air passages, trapping bacteria increasing chance of Infections. CF can also prevent secretions of digestive enzymes affecting nourishment of patents.
• A single gene disorder of chromosome 4 called IT15, resulting in damage of brain nerve cells, causing physical, mental, and emotional changes. The disease is characterised by occasional unintentional flailing movements of the arms and legs and difficulty making voluntary limb movements.

Question 5

• What are stem cells?
• What is cell replacement therapy?
• Gel electrophoresis is used in DNA profiling. Does the DNA molecules move toward to the negative or positive electrode?

Answer 5

• Undifferentiated cells capable of repeated mitosis divisions for long periods of time and given the right conditions, can differentiate into specialised cells.
• The replacement of damaged cells with healthy ones.
• DNA molecules move towards the negative electrode.