B6A1Intro - The Science of Life What are the...

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Unformatted text preview: The Science of Life What are the “Characteristics of Life” BIOLOGY n ÿ bios - Gr.: “way of life” ÿ logos - Gr.: “words” ÿ -logia: “ a collection of writings and speeches” ÿ “a body of knowledge” Complexity & Order n Regulation n Respond to changes in environment – Homeostasis – Physiology – Behavior – Evolution n Harness energy - metabolism Growth and reproduction n Cellular structure - “Cell Theory” n – Inheritance - DNA - “Gene Theory ” Biochemical Complexity & Order n Living cells carry out millions of chemical reactions that rearrange matter in significant ways •Biological molecules have many atoms bound precisely in complex forms. •How does the right rearrangement of the right bond at the right time happen? Basic metabolic pathways Beta-carotene Biochemical Complexity & Order n Vitamin A (2 molecules) Emergent Systems Analysis: attempting to map all interactions within the holistic living complex CELL Molecular machines Nucleus Cytoplasm Outer membrane and cell surface Fig. 1.12 A systems map of known interactions among 3500 proteins in a fly cell Heyer 1 The Science of Life Structural Complexity & Order n Structural Complexity & Order Cellular complexity n Organismal complexity What are the “Characteristics of Life” Structural Complexity & Order n n Complexity & Order n Regulation n Respond to changes in environment – Homeostasis Structure correlates with function! – Physiology – Behavior – Evolution n Harness energy - metabolism Growth and reproduction n Cellular structure - “Cell Theory” n – Inheritance - DNA - “Gene Theory ” Biochemical Complexity & Order n Basic metabolic pathways – Each step tightly regulated in rate, time & location Regulation by feedback mechanisms n Steady-state regulation: negative feedback loops Fig. 1-13a Amplification: positive feedback loops Fig. 1-13b Negative feedback – A W Enzyme 1 Enzyme 4 B Excess D blocks a step D D Positive feedback + X Enzyme 5 Enzyme 2 D C Enzyme 3 Excess Z stimulates a step Z Y Z Z Enzyme 6 Z D (a) Negative feedback Heyer n (b) Positive feedback 2 The Science of Life Homeostasis - maintaining an ideal constant Homeostasis - maintaining an ideal constant internal environment internal environment Life is dynamic The Marine Environment n Stable – Near constant temp; unlimited water availability; buoyant fi do not need to regulate internally \ can “get away with ” an extreme diversity of body forms n Constant exchange between internal and external environments What are the “Characteristics of Life” The Terrestrial Environment n Harsh & Variable – Wide variations in temp & water availability; gravity fi need to strongly regulate internally \ Only few body forms have necessary homeostatic mechanisms to succeed ¸ Vascular plants, arthropods, & vertebrates n Complexity & Order Regulation n Respond to changes in environment n – Homeostasis – Physiology – Behavior – Evolution n Harness energy - metabolism Growth and reproduction n Cellular structure - “Cell Theory” n – Inheritance - DNA - “Gene Theory ” Heyer 3 The Science of Life Respond to Stimuli Respond to Stimuli Integration & Cognition sensor effector stimulus response What are the “Characteristics of Life” Environmental Selection n These complex systems have been adjusted and refined by natural selection n Complexity & Order Regulation n Respond to changes in environment n – Homeostasis – Physiology – Behavior – Evolution n Growth and reproduction n Cellular structure - “Cell Theory” – Inheritance - DNA - “Gene Theory ” Organisms and their Environment Interconnect Energy Flow n n Heyer Harness energy - metabolism n NOTE: Biological evolution applies to populations, not to an individual organism. But the specific structures exhibited by an individual organism reflex the selection upon its ancestors for that structure ’s functions. Chemical Cycling Energy Flow 4 The Science of Life What are the “Characteristics of Life” n Complexity & Order Regulation n Cellular Reproduction Respond to changes in environment n – Homeostasis – Physiology – Behavior – Evolution n Harness energy - metabolism n Growth and reproduction n Cellular structure - “Cell Theory” – Inheritance - DNA - “Central Dogma ” Organismal Reproduction Fig. 1-7 Molecular Inheritance: double- stranded D eoxyribo -N ucleic Acid (dsDNA ) Sexual and/or asexual n Sequence of bases (A,T,C, or G) along the DNA molecule are the “Genetic Information” Fig. 1-7 “telescoping generations ” in aphids — born already pregnant! What are the “Characteristics of Life” The Central Dogma of Biology n Complexity & Order Regulation n Respond to changes in environment n – Homeostasis – Physiology – Behavior – Evolution n Harness energy - metabolism Growth and reproduction n Cellular structure - “Cell Theory” n – Inheritance - DNA - “Central Dogma ” Heyer 5 The Science of Life Early views of cells The Cell Theory 1. 2. 3. The cell is the basic unit of life. All organisms are constructed of cells. All cells derive from previous cells. n n n Plasma membrane “Nucleus” ( “center”) – filled with “chromatin” (“colored stuff”) “Cytoplasm” (“cell fluid”) EUKARYOTIC CELL Membrane Better microscopes and stains stained PROKARYOTIC CELL DNA (no nucleus) Membrane Cytoplasm Contrasting eukaryotic and prokaryotic cells in size and complexity – Electron microscope. n “Cytoplasm” and “chromatin” much more complicated, structured, and dynamic than previously appreciated. 5 µm Organelles Nucleus (contains DNA) Selective isolation from environment (plasma membrane) n Energy (ATP) n Instructions (DNA) n Machinery to carry out instructions and regulate processes (proteins) n Compartmentalization of incompatible or specialized activities (organelles) Heyer 1 µm Biology: Levels of Organization What does a cell need? n 50µ m Two major types of cells Modern v iews o f c ells n unstained human cheek cell n Cells: the basic units of life Top mystery of Biology: Irreducible Complexity and the Origin of Life — the first cell(s)? 6 The Science of Life Another great mystery of biology n Differentiation of genetically identical cells into a coordinated, integrated, holistic multicellular organism Biology: Levels of Organization Physiological levels: n Tissues n Organs n Organ Systems Fig. 1-9 Biology: Levels of Organization n Organism: the living individual Biology: Levels of Organization Ecological levels: n Population n n Biology: Levels of Organization n Biosphere: the Earth as a living system Community Ecosystem Biology: Levels of Organization n n n n n n n n n n Heyer Molecules and Atoms Cells Tissues Biol-6A Organs Organ Systems Organisms Populations Communities Ecosystems Biosphere Biol-6B Biol-6C 7 ...
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This note was uploaded on 09/02/2011 for the course BIOL 6a taught by Professor Staff during the Fall '10 term at DeAnza College.

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