Biology Lecture 1 PDF

Lecture 1 Biology; the study of life Outline Defining Life - Emergent Properties – Chemical materials and Energy – Reproduction and Development – Adaptations and Natural Selection Biosphere Organization – Biodiversity – Classification The Scientific Method Live is divers...

Lecture 1 Biology; the study of life Outline Defining Life - Emergent Properties – Chemical materials and Energy – Reproduction and Development – Adaptations and Natural Selection Biosphere Organization – Biodiversity – Classification The Scientific Method Live is diverse Living things: – Comprised of the same chemical elements – Obey the same physical and chemical laws The cell is the smallest, most basic unit of all life – Familiar organisms are multicellular – Some cells are independent – single-celled organisms Life is diverse 15-30 million species Biodiversity Biodiversity: – The total number of species (est. 15-30 million) – Variation of their genes, and the ecosystems in which they live Biological organization – Levels range from extreme micro to global – Each level up: more complex than preceding level Extinction: – The death of the last member of a species – Estimates of 400 species/day lost worldwide Levels of biological organization Levels of biological organization; cont. Organisms share the same characteristics of life Order Response to stimuli Regulation of internal environment Acquisition of materials and energy Reproduction and development Genetic inheritance Evolutionary adaptations Order: Organisms are highly organized structures that consist of one or more cells. Even very simple, single-celled organisms are remarkably complex. Inside each cell, atoms make up molecules. These in turn make up cell components or organelles. Multicellular organisms, which may consist of millions of individual cells, have an advantage over single-celled organisms in that their cells can be specialized to perform specific functions, and even in certain situations for the good of the organism as a whole. How these specialized cells come together to form organs such as the heart, lung, or skin in organisms like the toad shown in following Figure Toad represents a highly organized structure consisting of cells, tissues, organs, and organ systems. (credit: "Ivengo (RUS)"/Wikimedia Commons Living things: respond to stimuli Living things detect changes in environment Response often involves movement – Microroganisms follow light or chemicals – leaves of plants follow sun – Iguanas basking in the sun Responses collectively constitute behavior Response to stimuli: plants respond to light Regulation of internal environment: Iguanas basking in the sun Living things: acquire & process food Energy - the capacity to do work – The sun: Ultimate source of energy for nearly all life on Earth Drives photosynthesis – Metabolism - all the chemical reactions in a cell Homeostasis - Maintenance of internal conditions within certain boundaries  Living Things: Adapt to Change Adaptation: any modification that makes an organism more suited to its way of life – Organisms become modified over time – However, organisms very similar at basic level Suggests living things descended from same ancestor Descent with modification – Evolution caused by natural selection  Natural selection When a new variation arises that allows certain members of a species to capture more recourses, these members tend to survive and to have more offspring that the other, unchanged members. Therefore, each successive generation includes more members with the new variation. In the end, most members of a species have the same adaptation to their environment. Classification is necessary due to the huge number of species Taxonomy: – Hierarchical levels (taxa) based on hypothesized evolutionary relationships – Levels are, from least inclusive to most inclusive: Species, genus, family, order, class, phylum, kingdom, and domain A level usually includes more species than the level below it, and fewer species than the one above it Scientific Names Binomial nomenclature (two-word names) Universal Latin-based – First word represents genus of organism – Second word is specific epithet of a species within the genus – Always Italicized as Genus species (Homo sapiens) Three domains/and four established Kingdoms Prokarya – Archaea – Kingdoms still being worked out – Bacteria - Kingdoms still being worked out Eukarya – Kingdom Protista – Kingdom Fungi – Kingdom Plantae – Kingdom Animalia Domains: The Bacteria Domains: The Achaea In an ecosystem: Chemicals cycle and energy flows Because energy flows and does not cycle, ecosystems could not stay in existence without constant input of solar energy and ability of photosynthesizers to absorb it. This explains why nearly all living things depend on plants for their existence. We, humans, are bad!! Ecosystems negatively impacted by human populations – Destroyed for agriculture, housing, industry, etc. – Degraded and destabilized by pollution However, humans depend upon healthy ecosystems for – Food – Medicines – Raw materials – Other ecosystem processes  A flow diagram for the scientific method The scientific method is a method of research with defined steps that include experiments and careful observation. The Scientific Method: Experimentation Experimentation – Purpose is to challenge the hypothesis – Designed through deductively reasoning – Often divides subjects into a control group and an experimental group – Predicts how groups should differ if hypothesis is valid The Scientific Method: Results – Observable, objective results from an experiment – Strength of the data is expressed in probabilities The probability that random variation could have caused the results Low probability (less than 5%) is good Higher probabilities make it difficult to dismiss random chance as the sole cause of the results The Scientific Method: Conclusion and Review The results are analyzed and interpreted Conclusions are what the scientist thinks caused the results Findings must be reported in scientific journals Peers review the findings and the conclusions Other scientists then attempt to duplicate or dismiss the published findings Elements of scientific research paper 1. Summary (abstract) 2. Introduction 3. Materials and methods 4. Results 5. Discussion and conclusion 6. References DNA barcoding of life may become a reality The consortium for the Barcode of Life (CBOL): an international initiative devoted to developing DNA barcoding as the global standard in taxonomy. The idea is an organism body remnant could be put into a barcoder and instantly we know what species is. Benefits include but is not limited to – A farmer who needs to identify which pest attacking his crop – A physician who needs to know the correct anti- venom for a snake bitten victim