Chapter 01
Jan 13, 2016
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 densely-packed 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 MicroscopeScanning 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 WorksCentral Characters
• DNA: information
The Way Life WorksCentral Characters
• Protein: machinery
Your ItineraryPatterns
Energy and Information
Machinery and Feedback
Community and Evolution