IE-Study

❤️HUMAN RESPONSE
TO THE ENVIRONMENT ❤️

Advantages of cloning

 Therapeutic cloning can replace damaged tissue e.g. skin, heart cells and bone marrow, so helping to save human lives.

 Genetic diseases could be prevented.

 Superior animals may be bred to improve food supply and quality. The process of cloning

 Research in any form improves skills and could open other avenues due to spin-off technologies which could help mankind in the future.

The process of cloning

 Sheep A is the superior animal to be cloned. Sheep B is inferior, but hardy, so it can survive the harvesting of eggs.

 An egg cell from sheep B is taken and the nucleus is removed.

 A body (somatic) cell from the genetically superior sheep (sheep A) is collected.

 The nucleus with DNA from cell A is removed and placed into the “empty” egg cell B.

 The egg cell is stimulated with a shock so that it starts dividing by mitosis.

 The egg cell now has DNA from the superior sheep A and will grow into an embryo.

 The embryo is then placed into the uterus of a surrogate or foster mother (sheep C) and should develop to full term.

The baby (lamb) is clone of sheep A meaning it will be an exact copy of sheep A.

Cloning

Cloning is the natural or artificial process of creating a genetically identical copy of an organism or biological material (e.g. tissue). The organism produced in this way is called a clone.

Cloning happens naturally when asexual reproduction takes place or a plant is selfpollinated or when identical twins are formed from a single zygote.
These processes all give rise to individuals with DNA identical to that of the parent. Biotechnology has enabled cloning to produce a new individual that is an exact copy of the organism from which the body cell was taken.

Advantages of cloning

 Therapeutic cloning can replace damaged tissue e.g. skin, heart cells and bone marrow, so helping to save human lives.

 Genetic diseases could be prevented.

 Superior animals may be bred to improve food supply and quality. The process of cloning.

 Research in any form improves skills and could open other avenues due to spin-off technologies which could help mankind in the future.

Disadvantages of GMO’s

 GMO’s contain glyphosate due to extensive spraying of herbicide.

 They are expensive so only ‘rich’ countries can benefit.

 The possibility of error is great as the process is complex.

 There has been no long-term safety testing as it is a relatively new technology.

 People may be allergic to the inserted gene e.g. brazil nut gene in soya beans.

 Widespread use of GMO crops may lead to a loss of biodiversity.

 New pathogens could be made for biological warfare.

 Ethically there is a fine line between what can be done and what should be done.

Advantages of genetically modified plants

 Pest resistance – the plants no longer taste good to insects.

 Herbicide tolerance – the crop plant is immune to poison, so large amounts can be used to kill the weeds.

 Disease resistance – these plants are hardy and do not get affected by diseases.

 Improved food quality – do not have damage due to pests or diseases so look good.

 Cold tolerance – rice and to***co have been engineered to be unaffected by sudden drops in temperature.

 Drought or salinity tolerance – this helps plants grow in areas previously unsuitable for agriculture.

 Nutritionally enhanced – for example adding vitamin A to rice (a staple food in Asian countries) by introducing a gene from a daffodil.

 Incorporating vaccines into bananas/potatoes – this means that vaccines are made by the plant which can then be transported to countries easily without having to be refrigerated.

Genetic engineering

Genetic engineering is used to alter the genome of a living cell for medical, industrial or agricultural purposes.

This results in a genetically modified organism (GMO) or transgenic animal (animal with DNA from more than one species).

GMO’s are used …

 to breed more productive crops or animals so that more food can be made

 to produce drugs or hormones (e.g. insulin) which have fewer side-effects and is cheaper

 to ‘infect’ cells to cure diseases (gene therapy) such as brain tumours and cystic fibrosis One process used to produce a GMO is recombinant DNA technology. It can be used to manufacture human insulin using E. coli bacteria.

The process can be summarised as follows:

Biotechnology.

Humans have used artificial selection to breed the best food crops, farm animals and pets (think of all the different varieties of dogs that exist today).

With modern science, however, humans can manipulate the actual DNA of organisms. Biotechnology is the use of organisms (e.g. bacteria) or biological processes to improve the quality of human life, as for example, in DNA profiling, genetic engineering, stem cell technology and cloning.

Gene mutations

Gene mutation occur during replication if a base pair is added, left out or doubled up. This changes the sequence of bases in DNA.

Examples of gene mutations are haemophilia, colour-blindness, sickle cell anaemia, albinism.

 Haemophilia and colour blindness are sex-linked gene mutations on the Xchromosome.

 Sickle cell anaemia is an autosomal disease common in Central Africa, India and South America. It is caused by a gene mutation which results in a faulty haemoglobin molecule being formed. The red blood cells which are made have a half-moon shape (hence the term ‘sickle’). Not only can these cells not carry enough oxygen (resulting in anaemia), but the shape means that the cells stick to each other blocking small capillaries. This causes damage in organs such as the brain and kidneys.

Mutations

A mutation is caused by a permanent change to the DNA of a cell.

Mutations can be harmless, harmful or useful. Harmless mutations mostly

 involve changes to the non-coding DNA (which makes up 98,5% of the DNA).
 This DNA is not involved in making proteins.

Mutations can occur in genes or chromosomes.

Pedigree diagrams

A pedigree diagram (also called a family tree) is used to study the inheritance of characteristics in a family over a number of generations.

The pedigree diagram below shows inheritance of eye colour in humans over three generations of a family. Brown eye colour (B) is dominant over blue eye colour (b).

 Squares represent males and circles represent females

 The horizontal line between a square (Joshua) and a circle (Ronel) shows that they have mated.

 The vertical line flowing from the horizontal line represents the offspring (Sarah and Peter) of the two parents (Joshua and Ronel).

Phenotypic ratio: 9:3:3:1