The polymerase chain reaction (PCR) is a technique for rapid copying and amplification a selected region of DNA. Most commonly where

the sequence at both 5' and 3' ends is known.

This is useful when large amounts are needed for analysis.

Thermal Cycler

4.4.1Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA

Campbell:382

It is a method used to separate fragments of DNA according to their size and charge. DNA is placed on a thin sheet

of GEL with an electric field and depending on the charge of the particle, they move towards a specific end of the GEL sheet.

GEL electrophoresis is most commonly used in DNA profiling also known as DNA fingerprinting ( such in criminal investigation).

4.4.2-4.4.3 State that, in gel electrophoresis, fragments of DNA move in an electric field and are separated according to their size. 4.4.3 State that gel electrophoresis of DNA is used in DNA profiling.

Campbell:384

4.4.4: Describe the application of DNA profiling to determine paternity and also in forensic investigation

Campbell:396 Forensic investigation

Outcome: Knowledge of number of

human genes 19,599 confirmed protein-

coding genes 2,188 DNA segments

predicted to be protein-coding genes

Location of specific genes Locus: the fixed position of

a gene on a chromosome

Discovery of proteins and their function Functions include:

Enzyme, Structural, Transport, Movement, Hormones, Defense

Human Genome Project An international

cooperative venture established to sequence the complete human genome. Completed April 2003

Human Genome: the sequence of chemical base pairs which make up DNA

4.4.5 Analyze DNA profiles to draw conclusions about paternity or forensic investigations.

Make it easier to study how genes influence human development

Allow easier identification of genetic disease

Allow production of new drugs based on DNA base sequences of genes or the structure of proteins coded by the gene

New insight into origin, evolution and migration of humans

4.4.6 outline three outcomes of the sequencing of the complete human genome

Campbell:386

4.4.7

when genes are transferred between species, the amino acid sequence of polypeptides translated from them is unchanged because the genetic code is universal.

Genetic code is universal: The same sequence of bases (codons) will always code for the same amino acid in any animal or plant. All living organisms

use the same code

State that, when genes are transferred between species, the amino acid sequence of polypeptides translated from them is unchanged because the genetic code in universal.

Campbell:307-308

The use of E. Coli in gene technology is well documented. Most of its DNA is in one circular chromosome but it also has plasmids (smaller circles of DNA helix). These plasmids can be removed and cleaved by restriction enzymes at target sequences. Originally developed by bacteria for defense against viruses, restriction enzymes cut DNA only at specific sequences, allowing two different DNA strands to be cut with the same restriction enzyme and reattached. DNA fragments from another organism are then cleaved by the same restriction enzyme as described previously and these pieces can be added to the open plasmid and spliced together by DNA ligase. These new plasmids are called recombinant DNA, as they are a combination of genetic material from more than one species. The recombinant plasmids formed can be inserted into new host cells, typically a bacteria due to their rapid reproduction rate, and copied by the host. Host cells often also serve to test if the DNA recombination has been successfully conducted by adding onto the recombinant strand some gene sequence that will cause the host to display an easily observable characteristic. Such a sequence that is often used codes for phosphorescence, causing the host cell to glow if the transfer has been completed successfully.

4.4.8: Outline a basic technique used for gene transfer involving plasmids, a host cell (bacterium,), restriction enzymes and DNA ligase

Campbell:376 and 378

4.4.9: State two examples of the current uses of genetically modified crops or

animals

Salt Tolerance In Tomato Plants

Herbicide Resistance In Crop Plant

Economic Benefit: allow them to grow in

overly irrigated farmlands

Economic Benefit: allow crops to fight of diseases and prevent bugs from killing them

Campbell:399

Potential Benefits of Bt Maize

Possible Harmful Effects of Bt Maize

1. Less pest damage and therefore higher crop yields to help to reduce food shortage

2. Less land needed for crop production, so some could become areas for wildlife conservation

3. Less use of insecticide sprays, which are expensive and can be harmful to farm workers and to wildlife

1. Humans or farms animals that eat the genetically modified maize might be harmed by the bacterial DNA in it, or by the Bt toxin

2. Insects that are not pests could be killed. Maize pollen containing the toxin is blown into wild plants growing near the maize. Insects feeding on the wild plants, including monarch butterfly caterpillar are therefore affected even if they do not feed on the maize

3. Population of wild plants might be changed Cross-pollination will spread Bt gene into some wild plants but not others. These plants would then produce the Bt toxin and have an unfair advantage over other wild plants in the struggle for survival.

4.4.10: Discuss the potential benefits and possible harmful effects of one example of genetic modification

Clone: A group of genetically identical organisms or a group of cells derived from a single parent cell.

4.4.11 Define Clone

Campbell:375

1. Udder cells were taken from a donor sheep. The cells were cultured in a low nutrient medium to make them become dormant.

2. Unfertilized cells were taken from another sheep

3. The nucleus was removed from each egg cell using a micropipette.

4. The egg cells without nuclei were fused with the donor cells using a electricity

5. The fused cells developed like zygote and become embryos

6. The embryos were implanted in to another sheep who became the surrogate mother.

7. One lamp was born success fully and was named Dolly. Dolly is genetically identical to the sheep whose udder cells were used.

Fun Facts: • cloning is very useful to produce more organisms with desirable characteristics• Plants can be cloned easily while animals can not• Twins are natural clones

Campbell:408 and 379

4.4.12 Argument For and Against Cloning HumansArgument for Cloning in Humans

Argument against Cloning in Humans

1. Happens naturally when identical twins are formed

2. Cloning of embryos would make screening of embryos for genetic disease easier

3. Infertile couples might have more chances of success with IVF if their embryos were cloned

1. Groups of genetically identical people might suffer from problems of identity

2. Cloning using differentiated cells would often cause suffering because it carries a high risk of fetal abnormalities and a high rate of miscarriage

3. DNA taken from differentiated cells has already begun ageing and humans cloned from it might therefore grow old more quickly than is usual

4.4.13: Discuss the ethical issues of therapeutic cloning in humans

Therapeutic Cloning: The creation of an embryo to supply embryonic stem cells for medical use.

Some people believe that the embryo is a child and therefore by using it a way just to obtain embryonic stem cells mean that the scientist are killing people in order to obtain material for a science experiment.

Campbell:394 and 409-410

Key Words to Know:

Genetic Engineering

Biotechnology

Gene Cloning

Restriction Enzyme

Restriction Fragments

Sticky Ends

Gel electrophoresis

PCR ( polymerase chain reaction)

Human Genome Project

Gene Therapy

Campbell: 375-399