Day: May 13, 2010

Question

Discuss the reasons why it is often impossible or more difficult to use bacteria as transgenic organisms to make many human proteins.

Answer

Many human genes are very large, with many intron regions in the gene. Bacterial DNA does not contain introns and amount of DNA which can be inserted is limited.

Introns would have to be removed from human gene to make it small enough to fit into the plasmid. Protein required may need further processing beyond assembly of amino acids. Bacterial cells do not have machinery to carry out secondary and tertiary processes in creating a complex protein.

Question

Research is involved in the production of transgenic plants to incorporate characteristics which make some of the very rare plants hardier to a wider range of conditions. Many of the medicinal plants are dicotyledonous, which means that Agrobacterium can be used as a vector in the production of these transgenic plants.

Describe why these plants are called transgenic plants and explain the human need and demand which is driving this research. Discuss the scientific basis for concerns which some groups have for the production of such transgenic organisms.

Transgenic plants contain introduced genes artificially from another species or additional gene which is not part of it’s original genome. Human need and demand driving research is people in third countries need the plants to maintain health – not enoufh plants are left and they are in risk of becoming extinct, cutting off this resource for these people.

Traditional breeding processes are very slow and seeds may not grow in areas where the plants are needed. New plants creased to meet specific need using genes from other or similar species to create chracteristics desired for growing purposes.

Concerns

Creation of super weeds by making weedkiller-resistant varieties, cross breeding with vigorous closely related weed species could allow genes to be transfered.

Using the R genes as markers in the bacterial vectors could lead to transfer of resistance within bacterial species by transformation. It will create antibiotic resistance in super bug.

Cross pollination with wild relatives will destroy the wild genome.

Question

Forensic scientists often use PCR before they carry out DNA profiling. Discuss the human need and demand for this process, its particular usefulness in forensic science and how scientists have to ensure that the evidence is admissible in court.

Procedure can begin with only a minute amount of DNA- DNA can be obtained from a crime scene from myriad of sources and only small amounts required. Contamination of DNA from any sources must be restricted or accounted for, since contaminant will also be multiplied/replicated.

Question

Discuss how DNA profiling can be used to help scientists study the mating and breeding of the blue duck.

Answer

To avoid inbreeding, scientists would ensure mating between genetically unrelated individuals – increasing gene pool, reduces change of expression of deleterious/lethal genes. By identifying DNA profiles, most successful adult breeders can be identified (their offspring will carry successful breeders’ DNA markers) – scientists would preferentially use these birds to build species numbers.

Question

Female salmon prefer the biggest male as a breeding partner. Discuss how this preference would affected the spread of the growth gene through a wild salmon population if genetically modified salmon were accidentally released.

Answer

Genetically modified male salmon have same survivorship chances and same reproductive success as wild salmon. Females will not necessarily choose only GM salmon, as not all would be the ‘biggest’. Of those chosen, the genes for increased growth would spread rapidly through population, since those males carrying increased growth genes reach maturity quicker and thus have less exposure to predation, disease etc..

GM salmon have same fitness and reproductive sucess as non-GMsalmon and females equally choose GM salmon and non-GM salmon based on size.

Question

Some inherited genetic diseases were caused by the lack of an essential protein. Biotechnology may be used to treat individuals affected by these genetic diseases. Research into genetic diseases caused by the lack of an essential protein can focus on using biotechnology in two ways:

1. Produce the protein cheaply and affectively using microorganisms so that the patient can be regularly dosed with the protein.

2. Cure the affected person by inserting functioning genes so that the person is capable of producing the required protein.

Discuss difficulties that could occur when delivering a gene into a patient. These are things that researchers would need to consider, and check for, and ensure were not a problem before the patient could be said to be ‘cured’ and able to produce their own essential protein.

Answer

A faulty gene is isolated and replaced by a healthy/active gene. Isolation of gene of interest inserted into DNA of a suitable vector using vector using restriction enzymes and ligation and then cloned. Correct gene delivered back into the human, enabling coding of required protein.

Problems may arise with type of vector used, immune system may attack it/ may elicit an allergic response. Testing is needed to make sure the gene delivered works to correct cells and is incorporated into nucleus for protein synthesis. The quantity of protein made would have to be sufficient to effect a cure – needed to deliver enough gene to do this and genes must remain in patient long enough to have an effect.

Question Two

Discuss why the procedures used to ‘sex’ the bones of the Moa were harder than just identifying that they belonged to the same species. In your discussion, say why procedures were needed and why the researchers used DNA from closely related living birds for comparison.

Answer

The species can be identified using the mitochondrial DNA in cells. The karytype of living species of related birds is known and can be used to identify sex of Moa bones were from. Sex chromosome is need to identify the sex of Moa.

However, there are more mitochondria/mitochondrial DNA in cells compared to chromosomes/nuclear/sex chromosome DNA because there is only one of them in a cell. This is the reason why the ‘sex’ of the Moa is harder to identify.