Transcript Chapter 01
Chapter 01 A Singular Theme • Basic structures and mechanisms that sustain life are common to all living creatures • All forms of life are connected to one another and to their predecessors Homologous Patterns • Common patterns in bones are signs of biological unity Cells • • • • Basic structural unit of all living things Gather fuel and building materials Produce usable energy Grow and duplicate Cells • Every living thing is a cell or is made of cells • All cells contain nearly the same molecules and undergo similar interactions Size and Speed • The smaller an object is, the faster it can move • Life depends on frequent and vigorous collisions of molecules Relative Sizes Relative Sizes Atoms • Elemental units of which everything is made • Atomic Diameters: one to a few hundred millionths of an inch Molecules • Atoms bonded together • CO2: source of life’s carbon atoms • O2: crucial to energy generation in most life forms • H2O: aids chemical events inside cells Molecules Simple Molecules • Sugars, nucleotides, amino acids • Food and/or building materials Chain Molecules • Long strings of simple molecules linked together • Protein: amino acid chain • DNA and RNA: nucleotide chains Molecular Structures • Chain molecules fit together in complex architectural arrangements • Form cell’s infrastructure Cell • Nucleus: contains most of DNA • Cytoplasm: surrounds nucleus; site of most active cell processes Animal Cell Microscopy • Mid 1600s: first evidence of existence of things smaller than the unaided eye could see • Robert Hooke: viewed a cork slice with a magnifying lens; named denselypacked empty chambers “cells” Measurement Units • Meter: standard metric system unit of length • Centimeter = 1 x 10-2 meter • Millimeter = 1 x 10-3 meter • Micrometer = 1 x 10-6 meter • Nanometer = 1 x 10-9 meter Light Microscope • Magnifies and focuses image formed when light passes through an object • Can’t distinguish objects smaller or closer together than the shortest wavelength of visible light (200 nm) Transmission Electron Microscope Scanning Electron Microscope • Use beam of electrons controlled by electric or magnetic fields • Possible to see details of cell surfaces and rough shapes of large molecular structures Scanning Electron Micrograph • The mitochondrion (M) is about the same size as a common bacterium (E. coli) Electron Micrograph • View of the nucleus (N), Golgi bodies (G), and vesicles (V) X-ray Diffraction • Used to study structural details of individual proteins • Technique contributed to discovery of DNA double helix structure and structure of hemoglobin X-ray Diffraction • Protein molecules isolated and crystallized so they stack regularly in a three-dimensional lattice • Beam of x-rays focused on protein crystal – regularly repeating atoms in crystal structure deflect x-rays at certain angles • X-rays produce pattern of exposure spots on photographic film placed behind protein sample X-ray Diffraction • X-ray diffraction pattern of DNA captured by Rosalind Franklin • The X is an indicator of a helical molecular shape Scientific Process • Observe an interesting event or phenomenon • Identify a particular aspect of it that can be stated as a problem • Produce an hypothesis that explains the event • Test the hypothesis by experiment Scientific Method • Conclusions scientists arrive at after testing many hypotheses are statements that have probability of reflecting reality; they are never certainties • An idea becomes substance only if it fits into a dynamic accumulating body of knowledge Ultracentrifuge • Used to separate and compare sizes of cell components • A rotor spins tubes containing materials from broken cells at speeds of up to 80,000 rpm • Cell components separate out according to size The Way Life Works Central Characters • DNA: information The Way Life Works Central Characters • Protein: machinery Your Itinerary Patterns Energy and Information Machinery and Feedback Community and Evolution