• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

cell theory summary

Extracts from this document...

Introduction

2.1.1 Outline Cell Theory * All living things are made of cells. * Cells are the smallest unit of life. * Existing cells have come from other cells. * Stated in this way Cell Theory might be attributed to Schleiden and Schwann (1838). * Robert Hooke first coined the term 'cell' after observing the structure of cork in 1655. * The first observation of living cells was by Anton van Leeuwenhoek in 1674. * Retrospectively we regard the observations of Hooke and Leeuwenhoek as important contributions in the development of cell biology. However at the time the the microscope was regarded by many as a toy and not as a serious scientific instrument. The philosophy of science at this time was dominated by the physical sciences and 'reductionism' which held the view that all natural phenomena could ultimately all be best explained in terms of its constituent parts, namely molecules and atoms. Biology at this time was not established as a serious autonomous science, rather, physics and chemistry were regarded as 'science'. The dutch were regarded as the best lens makers of the time and it is there that the best telescopes and microscopes were being made. Newton himself was not appointed to the Royal Society until (December 21, 1671 ) the invention of his reflecting telescope. The work for which Newtonian became more famous followed this time and began with his discussion on how light is composed of a spectrum. The context and historical development of optics has been covered by in the outstanding BBC broadcast In Our Time. 2.1.2 Discuss the evidence of cell theory a. All living things are made of cells: When living things are observed under the microscope they consistently appear to be composed of cells. However, there are a number of examples of cells that do not conform to the standard notion of what a cell looks like at the microscopic level. ...read more.

Middle

Loxodonta africana (African elephant). This is the largest land living mammals. The adult African elephants can reach a length of 18-24 feet and a height of 10-13 feet. They weigh in at 8,800-15,500 pounds .Maximum size is reached at around 25 years of age. According to the calculations above the elephant should have a small surface are to volume ratio in comparison to smaller animals. Heat exchange ought to be quite slow which would be a problem for an animal living in a warm region. The elephant has evolved large ears to increase the surface area for heat exchange allowing the elephant to remain cool. * Small organisms have the opposite problem of a rapid rate of exchange with the environment. Sorex minutus (pygmy shrew) Size: Approximately 60mms from tip of nose to base of tail. The tail is around 40mms long. Mass: 4 grams. This shrew looses body heat so fast that it consumes food at a furious rate simply to produce heat from respiration. I understand that this particular species needs to eat every two hours to stay alive. This is a brief introduction to scaling in biological systems. There are a variety of other fascinating examples. 2.1.7 Multicellular organisms show emergent properties syllabus: 'Emergent properties arise from the interaction of the component parts; the whole is greater than the sum of the parts'. 'I define life as....a whole that this pre-supposed by all its parts' S. Coleridge Systems biologists attempt to put together the parts that make up a system and then observe the properties of that 'emerge' from the system but which could not have predicted from the parts themselves. As a model consider the electric light bulb. The bulb is the system and is composed of a filament made of tungsten, a metal cup, and a glass container. We can study the parts individually how they function and the properties they posses. ...read more.

Conclusion

The process of therapeutic cloning is shown in this diagram. It begins by taking a somatic (body) cell from the individual. The somatic cell is fused with an egg that has had its nucleus removed. The resulting cell is genetically identical to the individual because it contains the DNA from the individual's somatic cell. The new cell behaves like a fertilized egg and develops into a blastocyst. ES cells can be harvested from the blastocyst and grown in culture. These ES cells could be used to treat the individual without encountering resistance from his or her immune system. Notice that we do not not refer to this type of blastocyst as an embryo. This is because, technically speaking, an embryo is the result of the union of an egg and a sperm, which has not happened in this case. � 1. The patient requires the replacement of some diseased tissue. First we obtain a health cell from the same patient. 2. At the same time we require a human egg cell. This is mainly as the cell retains the tendency to divide unlike the sample tissue from the patient. 3. The nucleus is removed from the egg and discarded. The cell body itself is retained. 4. The nucleus of the patients cell is removed and retained. The cell body of the patients cell is discarded. 5. The nucleus from the patients cell is transferred to the enucleated cell body. 6. The cells then stimulated to divide forming a clone. 7. The cell mass forms a blastocyst. 8. The inner cell mass becomes a source of totipotent stem cells. Totipotent means they are capable of being stimulated to become one of any type of cell. 9. Cells are stimulated using differentiation factors to become the type of cell required for therapy. 10. Therapy would require the transfer of the new healthy cell to the patient. In therapeutic cloning these cells have the same immune system identity as the patient therefore there is not immune rejection problem. It is important that this technique is not confused with embryonic stem cell cultures or with reproductive cloning. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Biology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Biology essays

  1. Lion King-The Ecological study

    16. Rafike was referring to the changing ecosystem. There will be a new, fresh ecosystem to replace the collapsing one. This includes the revival of the plants, the returning of the herds and the thriving of the lion packs. In the movie itself, near the end of the movie, there is a raging thunderstorm, lots of lightning and bolts striking across the skies.

  2. biology extended essay - How different diets: vegetarian, vegan and a meat centered diet ...

    a year How many days are you absent from school when you have a cold? I still go to school even when I am sick I still go to school even when i am sick I still go to school even when i am sick A day or two I

  1. Environmental Factors affecting plant growth

    As mentioned earlier, the plants growing in 0% and 25% of sach solution grow or develop faster than the plants planted in 100%, 75% and 50% of complete sach solution which does not support my hypothesis. The plants for the last two treatments (25% s and 0%s)

  2. IB Genetic Unit Notes

    4.3.2: Determine the genotypes and phenotypes of the offspring of a monohybrid cross using a Punnet grid. The grid should be labelled to include parental genotypes, gametes, and both offspring genotype and phenotype. 4.3.3: State that some genes have more than two alleles (multiple alleles).

  1. Effect of Incandescent, Fluorescent and LED lights at 900 lumens on the concentration of ...

    at 900 lumens, LED light at 900 lumens and finally, fluorescent light at 900 lumens. The following is the ANOVA statistical test formula- the image was taken from (Statsdirect.com): This formula has been processed with the significance level of 0.05 which indicates that if p-value obtained from the calculation is

  2. Examine the correlation between soil moisture at different heights up the slope and the ...

    This measurement should be repeated 3 times in the exact same place so that an average for the light intensity at each of the 7 locations can be deduced. 7) For humidity, firstly some water should be inserted into the water cap inside the hydrometer.

  1. Sleep is a normal part of human life. Investigate the neurobiological basis of normal ...

    Thus, I certainly think that my anxiety, stress, and inability to function at school is a result of me going to bed late and only getting between 5-6 hours of sleep on school nights. You do feel the symptoms of sleep deprivation and it is not a good feeling whatsoever.

  2. Biotechnology Assignment: Genetic Screening/Testing

    but not others, and this may lead to differential usage of retail tests in different areas. At the federal level, an expert working group has been set up by Health Canada to look at the ethical and social issues surrounding genetic testing for late onset diseases.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work