Genetics - Chapter Ten

Question 1

Where is DNA technology used

Answer 1

• Medicine
• Agriculture
• Criminal justice
• Research

Question 2

What is DNA technology

Answer 2

• Manipulation of genes for some practical purpose
• Purpose could be linked to :

1. Solving genetic problems
2. Trying to cure diseases
3. Discovering new species
4. Forensics and solving crimes

Question 3

What is biotechnology

Answer 3

Artificial methods to modify the genetic material of living organisms or cells

Question 4

Why is biotechnology needed

Answer 4

• To produce novel compounds or to perform new functions.
• Biotechnology has been used for improving livestock and crops since the beginning of agriculture through selective breeding.
• As our knowledge of the structure of DNA has increased, biotechnology has become synonymous with the manipulation of organisms’ DNA at the molecular level.

Question 5

What can biotrchnology used for

Answer 5

• Extraction and identification
• Cloning
• Disease diagnostics
• Gene therapy
• Gene manipulation

Question 6

How is DNA technology useful

Answer 6

• Can prevent suffering
• Can improve the environment
• Criminal justice

Question 7

Explain DNA technology being useful in preventing suffering

Answer 7

• Medicine - gene therapy to cure or treat diseases, identification of disease causing alleles, stem cell therapy or manipulation of gene expression
• Agriculture - nutrition – increasing food production or increasing the quality of food – improving diets of people at risk

Question 8

Explain DNA technology improving the environment

Answer 8

• Ecological resilience –identifying plant and animal species at risk to extinction,
• Clean up pollutants – use of genetically modified organisms to make pollutants unavailable

Question 9

Explain DNA technology for criminal justice

Answer 9

• Solving crimes – DNA matching
• Solving issues of paternity

Question 10

What are the broad regions that DNA technology has a role in advancing science

Answer 10

• Detect harmful bacteria
• Identify viruses
• Test for inherited diseases
• Paternity testing
• Identify a species
• Detect species in water
• Connect people to crime scenes
• Learn about human history
• Learn about extinct species

Question 11

Explain the human genome project

Answer 11

• 3.2 billion base pairs in the human genomes
• 25 000 protein encoding genes, our cells can produce 400 000 different proteins
• 1.5% of Genome encodes for proteins
• One gene can produce multiple proteins depending on the introns that are removed
• 98.5% of our genome does not encode proteins
• Some of it regulates protein synthesis – promoters, enhancers
  • Some of the DNA is transcribed into rRNA, tRNA and microRNA
  • Pseudogenes are also present but are not translated into proteins – leftovers from ancestors
  • Tandem repeats – may differ from person to person
  • Human Genome Project

Question 12

What are the tools needed in DNA technology for DNA sequencing

Answer 12

• Extraction
• Isolation of DNA
• Polymerase Chain Reaction
• When we sequence a sample we want to find out the order of nucleotides on a particular

Question 13

Explain isolation and amplication of DNA

Answer 13

• Most nucleic acid extraction techniques involve steps to:

1. Break open the cell, and then the use of enzymatic reactions to destroy all undesired macromolecules.
2. Cells are broken open using a detergent solution containing buffering compounds.
3. To prevent degradation and contamination, macromolecules such as proteins and RNA are inactivated using enzymes.
4. The DNA is then brought out of solution using alcohol. The resulting DNA, because it is made up of long polymers, forms a gelatinous mass.

Question 14

Explain electrophoresis for ordering the fragments of different lengths

Answer 14

The process involves:

1. Cutting of DNA with restriction enzymes
2. Separation of fragments through electrophoresis
3. An agarose or polyacrylamide gel is poured into a mould and allowed to set
4. Wells (holes into which cut DNA solution can be placed) is made a short distance from one end
5. The gel is place in a gel tray and covered with an electrolyte solution
6. An electrical current is passed through the system from the side of the wells —Due to the fact that the DNA (or RNA) carries charges the current will pull the DNA fragments along
7. Cut DNA of known lengths will be put in one well in order to determine the sizes of the different fragments
8. The smallest fragments will move faster that the larger ones
9. The gel is stained with ethidium bromide which binds to the DNA and can be seen under UV-light

Question 15

What are DNA fragments differnt lengths

Answer 15

If DNA has replicated under lab conditions

Question 16

Explain DNA processing for sequencing and how to increase the amount of DNA in a sample

Answer 16

• Polymerase chain reaction (PCR) is a technique used to rapidly increase the number of copies of specific regions of DNA
• Use the components below to make complementary copies of the DNA sample – similar to DNA replication – but achieved in a laboratory
  • DNA polymerase – enzyme that adds nucleotides according to base pairing rules
  • Primers – required as DNA polymerase can not start a new strand
  • Normal nucleotides – to build the complementary copies
  • Terminator nucleotides – tagged with fluorescent labels, when added to a strand it stops the strand from growing any further

Question 17

Explain PCR purposes in laboratories

Answer 17

1) The identification of the owner of a DNA sample left at a crime scene

2) Paternity analysis

3) The comparison of small amounts of ancient DNA with modern organisms

4) Determining the sequence of nucleotides in a specific region

Question 18

What is needed for a PCR to run

Answer 18

1. The isolated DNA,
2. Nucleotides,
3. Primers that will identify specific sequences on the parent DNA to which it will anneal
4. A heat-resistant DNA-polymerase which are found in a bacterium in hot-water springs
   • The process is done in an apparatus called a thermal cycler (PCR machine) which will automatically perform the following process

Question 19

Explain the procedure for a PCR to run

Answer 19

• Mixture is heated to about 96°C to allow the DNA strands to separate
• Cooling of the mixture allows for the primers to attach to specific sequences on the -DNA template and the Taq-polymerase will attach nucleotides according to the base-pairing rule
• The mixture is heated again and all the DNA present will separate to form templates for new DNA strands
• Cooling is done again and the above process repeated
• Each cycle allows for the doubling of the DNA present and after about 20 cycles we will have about a million copies of the specific DNA sequence