General Biology 2 - Long Exam 1

• Biology is the scientific study of life
• Questions biologists ask


  • How does a single cell develop into an organism?
  • How does the human mind work?
  • How do living things interact in communities?
• Biology is a subject of enormous scope
• Five unifying themes of the study of life

  • Organization
  • Information
  • Energy and matter
  • Interactions
  • Evolution
• Organization


  • New properties emerge at successive levels of biological organization
• Levels of biological organization

  • Biosphere
  • Ecosystems
  • Communities
  • Populations
  • Organisms
  • Organs and organ system
  • Tissues
  • Cells
  • Organelles
  • Molecules
• Life in general is complex
• Emergent properties


  Result from the arrangement and interaction of parts within a system
• Knowing the function of something provides insight into its structure and organization
• Cell


  Lowest level of organization that can perform all activities required for life
• Types of cells


  • Eukaryotic - with nucleus
  • Prokaryotic - no nucleus

  
• Genetic information


  Life's processes involve the expression and transmission of genetic information
• Chromosomes


  Contain genetic material in the form of DNA (deoxyribonucleic acid)
• Cell division


  DNA is first replicated, or copied, and each of the two cellular offspring inherits a complete set of chromosomes, identical to that of the parent cell
• Genes


  Units of inheritance
• DNA molecule


  Made up of two long chains, called strands arranged in a double helix, each chain is made up of four kinds of chemical building blocks called nucleotides, abbreviated A, T, C, and G
• Protein-encoding genes


  Control protein production indirectly, using a related molecule called RNA as an intermediary
• Energy and matter


  Life requires the transfer and transformation of energy and matter
• Consumers


  Organisms like animals that feed on other organisms or their remains
• When an organism uses chemical energy to perform work, some energy is lost to the surroundings as heat
• Chemicals cycle within an ecosystem, where they are used and then recycled. These chemicals will be returned to the environment by decomposers, such as bacteria and fungi that break down waste products, leaf litter, and the bodies of dead organisms

  
• Interactions


  From molecules to ecosystems, interactions are important in biological systems
• Feedback regulation


  The output or product of a process regulates that very process
• Negative feedback


  A loop in which the response reduces the initial stimulus
• Positive feedback


  An end product speeds up its own production
• Ecosystem interactions


  Interactions between organisms include those that are mutually beneficial and those in which one species benefits and the other is harmed
• Evolution accounts for the unity and diversity of life
• The scientific explanation for both the unity and diversity of organisms is the concept that living organisms are modified descendants of common ancestors
• Theodosius Dobzhansky: 'Nothing in biology makes sense except in the light of evolution'
• Diversity of life


  Biologists have so far identified and named about 1.8 million species of organisms
• Taxonomy


  Branch of biology that names and classifies species that increasing in breadth
• Three domains of life

  • Bacteria
  • Archaea
  • Eukarya

  
• Kingdoms in the domain Eukarya

  • Plantae
  • Fungi
  • Animalia
  • Protists

  
• LUCA


  Last universal common ancestor
• Similarities between organisms are evident at all levels of the biological hierarchy
• Charles Darwin's theory of natural selection

  Explained the duality of unity and diversity
• Darwin's three observations from nature

  • Individuals in a population vary in their traits, many of which seem to be heritable
  • A population can produce far more offspring than can survive to produce offspring of their own, so competition is inevitable
  • Species generally are suited to their environments - they are adapted to their circumstances

  
• Natural selection


  The natural environment consistently "selects" for the propagation of certain traits among naturally occurring variant traits in the population
• Natural selection results in the adaption of organisms to their environment
• Darwin's proposal


  Natural selection could cause an ancestral species to give rise to two or more descendent species