Geoscience Reference
In-Depth Information
that deoxyribonucleic acid (DNA) contains the instructions used in the
development and functioning of almost all known living organisms. Since
Gregor Mendel's groundbreaking late nineteenth-century inquiries into
plant heredity, biologists had wanted to understand how species achieve
intergenerational consistency (structural and functional) with phenotypical
variation. It was hypothesised that a 'particle' existed that, through species
reproduction, was (1) passed on to each generation yet somehow itself sub-
ject to variation, or (2) able to create variation in the resulting organisms.
Watson and Crick confirmed that this 'particle' was not only real but, in fact,
comprised a 'double helix' in the nucleus of cells - a helix itself composed
of four bases arranged along its (considerable) length.
Some decades later, molecular biologists made new and equally funda-
mental discoveries. From the late 1970s, they began to sequence the genome
(i.e. describe the entire genetic content) of different species. Watson and
Crick had only been able to identify the rudiments of DNA, namely its
'twisted ladder' structure of base pairs. It was another thing altogether to
describe in detail the coupling and relative position of hundreds of thou-
sands of bases - notably those in 'coding regions' that contain instructions
vital for organism development and functioning. To date, over 100 species
have been genomically sequenced, including humans. The HGP was one
of two international, high-profile and exceedingly expensive attempts to
produce a draft of humanity's genetic specificity, which famously came to
fruition in 2000, along with a similar privately funded project by Celera
If these and other discoveries have been exceedingly noteworthy and
newsworthy, so too have a set of biotechnological tools invented by molec-
ular biologists to intervene in the life processes they study. These tools are a
second reason why molecular biology today enjoys enormous influence and
prominence. The tools include the ability to isolate sections of DNA, copy it
and insert it into the cell nuclei of different organisms. Without these tools,
the hotly debated processes of 'genetic engineering' and 'cloning' would
not be possible. Genetically modified (GM) bacteria, insects, plants and ani-
mals are now widely employed in medical, pharmaceutical and agricultural
research - leading to product development, sale and use in a large and grow-
ing number of cases. The range of applications stretches from Oncomouse
(a life form designed by Harvard University research biologists to be suscep-
tible to cancer) to food crops engineered to be less vulnerable to things like
drought or disease. Many GM organisms are transgenic, meaning that their
DNA is a 'cut and paste' hybrid of genetic material that could not be recom-
bined through 'natural reproduction'. In the case of cloning (i.e. replicating
genetic material for the purposes of research and therapy), Dolly the sheep
remains without doubt the icon. Born in 1996, she was a Finn-Dorset ewe
created from nuclear DNA taken from a mammary gland cell belonging to a
full-grown ewe. Her birth and growth to adulthood showed that the nucleus
