Biol1002 Notes Usyd

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The Nature of biology and science
Cell theory:
* All organisms are made of cells and the products of cells * All cells come from pre-existing cells
* The cell is the smallest organisational unit
Cells have an outer membrane, encloses fluid contents of cell (cytoplasm) Robert Hooke (1665): observed dead cells from bark Anton van Leeuwenhoek: described living cells Matthias Schleiden: plant issues Theodor Schwann: animal tissues Bacteria found without nucleus and lacking other membrane-bound organelles: prokaryotes Cells with a nucleus and other membrane-bound organelle: eukaryotes Origin of life:

* Life form can replicate itself pass on cellular information * Capacity to alter cellular information change overtime and adapt to new environments * Metabolic activity occurs with chemical reactions building and breaking down complex molecules * All these functions are concentrated&contained in space, surrounded by a barrier/membrane

A reducing environment: formation of organic molecules without the input of as much energy as it would in today’s oxygen-rich atmosphere Stanley Miller + Harold Urey: energy can generate spontaneously RNA polymers first molecules to store information and reproduce: * RNA: ribonucleic acid: polymer made up of a number of identical subunits—(nucleotide monomers). They are polymers that can: * Store information in the sequence order of their different nucleotide monomers * Possess a wide range of catalytic activities capable of providing metabolic function * Errors and mutations occur during RNA copying leads to changes in catalytic functions: can be advantageous or disadvantageous Concentration and containment of molecules in cell-like compartments: * Spontaneous generation of polymers, replication of more complex molecules, required high [monomers], templates and catalysts and the retention of new metabolic products * RNA is now replaced by DNA: deoxyribose nucleic acid, more stable and easier to replicate hereditary information * Key event: evolution of life was the concentration and containment of these and other molecules in cell-like compartments (lipid-based membranes) * Vesicles: naturally grow and divide as more lipids are added

DNA: basis of life:
* High level of structural and functional organisation – relies on stored information: all stored within DNA * During reproduction: DNA contains hereditary info info then transmitted in gamete cells * Characteristics of an organism: cytosine, guanine, thymine, adenine * Discovery of DNA identifying genetic genomes allows for modification to create altered or new gene functions Live evolves: the theory of natural selection:

* Charles Darwin (1809-1882): proposed life on earth has evolved and continues to evolve over time Darwin and Alfred Wallace (1823-1913): theory of evolution by the process of natural selection * Variation exists between individuals in populations * ‘fitter’ individuals make a greater relative contribution of offspring to the next generation * Populations can become better adapted to their environment over time * Evidence? Fossil records

Evolutionary relationships determined in biological classifications: * Light and electron microscopes = discovery of DNA and techniques to sequence the order of bases = biologists compare organisms * THREE KINGDOMS:

* Super kingdom, ‘domains’
* Bacteria, Archaea (two major groups of prokaryotes) * Eukarya (all forms of eukaryotes)
The practice of science:
* Scientific method
* Making observations: qualitative or quantitative
* Important to minimise value judgements
* Testing hypothesis by experiments: a possible explanation for an observed phenomenon; used to make certain predictions * Experimental design: two fundamental principles
* must have a control...
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