Astronomy 141 -- Winter 2012 
Quiz 2 Study Guide

What is Life
    Biological definition of life
    6 basic characteristics for life
    Order and Structure
    Reproduction and growth/development
    Energy utilization
    Response to environment
    Adaptation to environment by evolving
    Natural Selection

Cells
    Cell membranes
    Carbon Chemistry - what makes carbon special
    Proteins and enzymes
    Amino Acids - only 22 in Earth life, all left-handed
    Chirality (handedness)
    Nucleic acids - RNA and DNA
    Prokaryotes
    Eukaryotes
    Phylogenetic Tree of Life
    Three Groupings: Bacteria, Archaea, and Eukarya

Chemistry of Life
    Main elements: CHON plus sulfur (S) and phosophorus (P)
    Metabolism
    ATP cycle
    Sources of carbon: Autotrophs vs. Heterotrophs
    Sources of energy: chemical and sunlight
    Photosynthesis
    Chemosynthesis
    Crucial role of liquid water as the ideal solvent medium of biochemistry

DNA, RNA, and Heredity
    Use of DNA to store and transmit cellular operating instructions
    DNA structure - sugar and phosphate backbone, 4 nucleotides base-pairs
    AT and GC
    Base pair sequences and how the code for amino acids for proteins
    Double-helix structure and replication
    RNA structure - sugar and phosphate backbone, AUGC pairs
    Role of RNA (transcription, translation, catalyze protein synthesis)
    Copying errors and mutations
    Mutations are molecular basis of evolution by providing genetic variation

Life on the Edge: Extremophiles
    Main Types: thermophiles, psychrophiles, halofiles, acidophiles 
    Thermophiles - why is heat bad, how have thermophiles adapted
    Environment of thermophiles, metabolism, first forms of life?
    Psychrophiles - why is cold bad, how have psychrophiles adapted
    Halophiles - why is salinity bad
    Acidophiles - why is acidity bad
    Radiation-resistant organisms
    Endoliths
    Life not possible without liquid water

Origin of Life on Earth
    What are the requirements for life?
    What is Abiogenesis
    Miller-Urey Experiment
    Sources of Amino Acids
    Role of Lipid vesicles as proto-cell membranes
    RNA World model of life's origin
    Metabolism First model of life's origin

Earliest forms of Life
    Challenges of finding the oldest fossils
    Stromatolites - fossil and present-day, oldest form of life
    Microfossils - fossil cells, challenges and oldest microfossils
    Carbon Isotope ratios - why a marker for life, challenges
    Which came first, photosynthesis or chemosynthesis?
    Were extremophiles the first forms of life?

History of Life on Earth
    Proterozoic Eon - rise of oxygen, first eukaryotes
    Phanerozoic Eon - first multicellular animals.
    Cambrian Explosion of animal diversity
    Plants and fungi colonize land (why not earler?)
    Animals colonize land
    Emergence of mammals and dinosaurs
    K-T event and rise of mammals
    Emergence of hominids and humans

Extinction and Impacts
    Role of mass extinctions in the history of life
    The K-T (Cretaceous-Tertiary) event and death of dinosaurs
    What is the evidence that the K-T event was an asteroid impact?
    Other mass extinctions in geological history
    Current-day hazards from asteroidal impacts
    What was the Tunguska Event?