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

Atoms Elemental units of which everything is made Atomic Diameters: one to a few hundred millionths of an inch

Molecules Atoms bonded together CO 2 : source of life’s carbon atoms O 2 : crucial to energy generation in most life forms H 2 O: 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 meter Millimeter = 1 x meter Micrometer = 1 x meter Nanometer = 1 x 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