bionotes - Chapter 1: The themes in the study of life...

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Chapter 1 : The themes in the study of life Living things can be recognized by what they can do [Fig. 1.2]: i. ordered structure ii. Reproduction iii growth and development iv. Energy processing v. response to stimuli vi. Homeostasis vii evolutionary adaptation Themes that Unify Biology 1. A hierarchical organization exists from atoms to the biosphere. [Fig. 1.3]. Each level builds on the level below it. Atoms Molecules Organelles Cells Tissue Organs Organisms Population Community Ecosystem Biosphere With each step properties emerge that were not present at the simpler levels. 2. Emergent Properties of Systems : New properties emerge at each level of the hierarchy of biological order. The structure at each level governs what it does. “Form fits Function”. Biologists study living systems using the strategy of reductionism and systems biology (modeling of the dynamic behavior of whole biological systems, in order to predict how a change in one or more variables will impact other components and the whole system). [Fig. 1.10]. Systems Biology relies on high-throughput technology, Bioinformatics, and interdisciplinary teams. 3. Organisms interact and exchange materials and energy with their living and nonliving environment [Fig. 1.4]. Organisms are open systems. Ecosystem Dynamics include 2 major processes: The cycling of nutrients and the flow of energy from sunlight to producers to consumers. 4. The cell is the basic structural and functional unit of life. [Fig. 1.5] It is the lowest level of structure that can perform all the activities of life. Two Main Cell Types : [Fig. 1.8] Prokaryotic (Bacteria and Archae): Simple and small, DNA not membrane bound no membrane bound organelles; most have tough external cell wall.
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Eukaryotic (All other forms of life): more complex; nuclear membrane; membrane-bound organelles suspended in the cytosol (both make up the cytoplasm). 5. Heritable information is in form of deoxyribonucleic acid (DNA) molecules. DNA is the substance of genes and consists of a sequence of Nucleotide bases [Fig. 1.7]. All forms of life employ the same genetic code . Inheritance depends on the copying of DNA and passing its sequence of nucleotides to the offspring via the sperm and the egg. The DNA replicates before each cell division [Fig. 1.6]. The genome consists of the entire “ library” of genetic instructions . Each gene codes for a specific protein and each protein has a unique function. 6. Feedback Regulation in Biological Systems to maintain homeostasis . Regulation of chemical reactions in biological systems involves Enzymes . Many Biological processes are self- regulated by Feedback: Negative feedback [Fig. 1.11] slows or stops processes and is more common; Positive feedback [Fig. 1.12] speeds processes.
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bionotes - Chapter 1: The themes in the study of life...

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