unsw press seeds of concern the genetic manipulation of plants

[...]... years This is the measurement of the amount of DNA that plant cells characteristically possess The ‘C-value’ is the amount of DNA belonging to a haploid nucleus, expressed in picograms (10–12 g) This is an indicator of the size of the nuclear genome It has become clear that the size of the genome has often increased as flowering plants (Angiosperms) evolved.34,35 However, the magnitude of the differences... stored in seeds, are tissue and organ specific, and produced nowhere else in the plant Lack of organ specificity in gene expression has been a major problem for 34 • SEEDS OF CONCERN genetic engineers A prime example of this kind of imprecision is the production of a toxic Bt-protein in pollen grains as well as in every other part of transgenic maize plants (Chapter 6) Sometimes the aim of genetic modification... adapted from J D 18 • SEEDS OF CONCERN Watson’s book The Double Helix9 The Watson–Crick model laid the foundation for breaking the genetic code For a sequence of bases in one strand of DNA to specify the sequence of amino acids in a polypeptide, various kinds of ribonucleic acid (RNA) are first synthesised from template DNA: messenger RNA (mRNA), which moves between the DNA and the ribosomes where polypeptides... for their amino acid substrates.12 At the ribosomes, the appropriate tRNA molecules sequentially pair with the codons in mRNA, and the amino acids are then joined to form a polypeptide; this process is called ‘translation’ So by governing the base sequences in mRNA and tRNA molecules, portions of the DNA ultimately determine the sequences of the various amino acids in polypeptides The synthesis of nucleic... remained the nucleus, but the term ‘cytoplasm’ now presents difficulties Light microscopists still tend to call the transparent parts of the cell the cytoplasm, but strictly the soluble phase of the cytoplasm should now be called the ‘cytosol’ The term ‘cytoplasm’ is historically important, and retained in the phenomenon of cytoplasmic inheritance encountered by plant breeders (see below) The conclusion... SEEDS OF CONCERN Having two sets of homologous chromosomes is the normal condition for vegetative cells throughout a plant The number of chromosomes in a set is called the haploid number, n, and double this, the diploid number, is 2n Egg cells and sperm cells are reduced to the haploid number by meiosis (reduction division) during their formation, then the diploid condition is recovered on fusion of. .. from the air (‘les germes qui flottent dans l’air’).8 So the clear meat broth did not spontaneously generate the organisms responsible for its breakdown DNA AND THE GENETIC CODE How can something as small as the nucleus of a cell control the metabolic activity and properties of that cell, and ultimately the properties of a complex, multicellular organism? The answer lies at the molecular level, below the. .. brief overview of the various procedures currently used to introduce new genes into plant cells, leading to the production of transgenic plants In the popular press there is a great deal of misunderstanding as to what is involved It is pointless blaming the media Journalists print what people tell them, and myths soon take hold Misinformation has often been put forward by proponents of the new technology,... SEEDS OF CONCERN published a further treatise on plant anatomy in 1682, and was one of the first to study the varied shapes and sizes of pollen grains Details of cell structure have emerged progressively since the beginning of the 19th century Although a general ‘cell theory’ is often attributed to Matthias Schleiden (1804–1881) and Theodor Schwann (1810–1882) because of their pronouncements in 1839,... good example is the blocking of an enzyme necessary for ethylene synthesis Ethylene is a gaseous plant hormone that promotes senescence, wound healing or fruit ripening Preventing the synthesis of ethylene is useful for extending the vase-life of cut flowers, as in the ‘Moon’ series of Florigene carnations,14 or for delaying the ripening of fruits such as tomatoes The latter application of gene technology . class="bi x0 y0 w0 h0" alt="" SEEDS OF CONCERN This page intentionally left blank SEEDS OF CONCERN THE GENETIC MANIPULATION OF PLANTS David R Murray UNSW PRESS A UNSW Press book Published in Australia,. sweep of the double helix. They proposed that the bases of one strand form complementary pairs with the bases of the opposite strand, so that adenine always pairs with thymine 16 • SEEDS OF CONCERN (A–T),. addressed to the publisher. National Library of Australia Cataloguing-in-Publication entry: Murray, David R. (David Ronald), 1943– . Seeds of concern: the genetic manipulation of plants. Includes