Chapter 1 and 19.1 Lecture

• Studying Life
• Chapter 1 Key Concepts

  • 1.1 Living Organisms Have a Common Origin and Share Similarities
  • 1.2 Genetics and Evolution Are Fundamental Principles of Biology
  • 1.3 Biologists Investigate Life through Experiments That Test Hypotheses
  • 1.4 Understanding Biology Is Important for Health, Well-Being, and Public-Policy Decisions
• Biology


  The scientific study of organisms, living and fossil
• Goal of biology


  Discovering and understanding the diversity and the complex processes that make up life
• 8 Common Features of Living Organisms

  • Made of a common set of chemical compounds
  • Made up of cells
  • Use molecules from the environment to make new biological molecules
  • Extract energy from the environment and use it to do work
  • Contain genetic information that enables them to develop, function, and reproduce
  • Use a universal genetic code to build proteins
  • Regulate their internal environments
  • Exist in populations that evolve over time
• Genetic info


  Population evolves
• All Life Has a Common Ancestry


  • Common characteristics lead to the conclusion that all life has a common ancestry
  • If life had multiple origins, then we would expect to see a much greater diversity in chemical composition, cell structure and function, and genetic code than has been observed in all life to date
  • The vast abundance of evidence instead supports the theory of a single origin of life on earth
• Processes of evolution over ~4 billion years


  Generated the enormous diversity of life on Earth that began with the Last Universal Common Ancestor (LUCA)
• Life evolved 600 million years or more later


  Earth formed 4.6 to 4.5 billion years ago
• The history of Earth can be pictured as a 30-day month
• At first, nonliving, but eventually:

  1. Temps cooled

  2. Surface water formed

  3. Smaller chemical building blocks randomly associated to form more complex molecules

  4. Nucleic acids = molecules that can reproduce themselves and be template to make proteins

  5. Proteins = large molecules with complex but stable shapes

  6. 20+ amino acids (vs 4 bases in both DNA and RNA) provides extreme functional diversity

  7. Extreme functional diversity of proteins allowed for evolution of intricate and complex control over all cellular functions
• Nucleic acids


  • DNA (ATCG)
  • RNA (AUCG)
• Proteins


  20 standard amino acids associated with Universal Genetic Code
• Membranes enclosed complex biological molecules

  1. Internal environment separate from external: regulation

  2. Fatty acids form most of membrane

  3. Don't dissolve in water

  4. Form liposomes (fig 1.3)

  5. Chemical reactions inside cells

  6. Cells could reproduce
• 2 Types of cells

  • Prokaryotes = unicellular, single outer membrane (Fig 1.3)
  • Eukaryotes later = Outer membrane + internal membranes at organelles
• Domains of life


  • Bacteria
  • Archaea
  • Eukarya = PROTISTS
  • PLANTS
  • ANIMALS
  • FUNGI
• Eukaryotic cells


  • Some formed colonies
  • Cellular specialization: multicellular eukaryotes have cells specialized for certain function, like reproduction
  • Organisms increased in size and more efficient getting resources and adapting
• Photosynthesis


  1. Energy of sunlight into chemical energy

  2. Make large molecules (glucose sugar)

  3. Cyanobacteria probably the first organism to use photosynthesis

  4. Also, released O2 as byproduct
• Metabolism


  • All chemical reactions of cell or organism
  • Small molecules used to make larger molecules (takes energy)
  • Break glucose to release energy for work
• Anabaena in lab
• Evolution of Photosynthesis


  Enabled life
• The atmosphere of early Earth had no O2 until photosynthesis evolved
• Photosynthesis produced oxygen


  • Early Earth no oxygen
  • O2 toxic to many organisms
  • Mass extinction
• Aerobic metabolism


  Biochemical process that uses O2 to extract energy from nutrient molecules, very efficient!
• Anaerobic metabolism


  Does not use O2, less efficient
• Ozone, O3, in atmosphere absorbs sun's UV radiation
• Thick ozone layer built over 2 billion years
• 500million years ago, organisms could leave water to live on land
• DNA


  Consists of long sequences of nucleotides
• Genes


  Segments of DNA that encode information to build proteins
• Nucleotide Sequence


  Genetic Code
• Gene


  Specific segment of DNA that encodes the info cell uses to build proteins
• Proteins


  • Made of amino acid building blocks
  • Sequence of nucleotides give sequence of amino acids in protein
• Genetic info


  1. Transcribed from DNA to RNA, ribonucleic acid

  2. RNA translated to amino acids in protein
• Protein


  Has unique shape and function for chemical reactions and structure!
• Multicellular Organisms


  • All cells have same genome, BUT use different parts
  • Called gene expression
  • So blood cells different from skin cells, etc
  • Genome = thousands of genes
• Mutations


  • Errors in genome
  • Some spontaneous
  • Some induced by chemicals, radiation
  • Most harmful or no effect
  • Some improve function for its environment
• Mutation = yellow
• Evolution


  The change in genetic composition of populations over time
• Evolutionary change is observed in lab experiments, natural populations, and the fossil record