C1L1 - Introduction to Biology

• Biology - study of life
• Characteristics of Life

  • Order
  • Homeostasis
  • Adaptation
  • Metabolism
  • Reproduction
  • Response to Stimuli
  • Growth and Development
• Organization reveals the principle of reductionism.
• As complexity of life increases, emergent properties arise due to the interaction of different subunits.
• Systems biology - a field of life science that studies the interaction of biological systems.
• Levels of biological organization

  • Atom
  • Molecule
  • Macromolecule
  • Organelle
  • Cell
  • Tissue
  • Organ
  • Organ System
  • Organism
  • Population
  • Community
  • Ecosystem
  • Biosphere
• According to Cell Theory, developed in the 1800s, the cell is the basic unit of life.

  • Prokaryotic - lack membrane-bound organelles and nucleus
  • Eukaryotic - does have membrane-bound organelles and nucleus
• Chromosomes - structures containing genetic material in the form of DNA.
• Gene - A particular section of DNA, the basic unit of inheritance
• Genomics - a branch of biology that applies systems biology approach.
• Genomics - this is the large-scale analysis of DNA sequence.
• Genome - the entire set of genetic material in an organism, including all the genes and the DNA that controls them.
• Genome Sequence - the entire sequence of nucleotides for a representative member of a species.
• Proteomics - studies organism’s sets of proteins and their properties.
• Proteome - the entire library of proteins that an organism expresses.
• The main source of energy comes from the sun.

  Energy flows one-way, but the chemicals are cycled.
• Feedback Regulation - the output or product of a process regulates that very process.
• Positive Feedback Loop - rarely happens, the end product speeds up its own production.
• Negative Feedback Loop - a loop in which the response reduces the initial stimulus.
• Evolution - the change in the inherited characteristics of a population over time.
• Evolution accounts for the:

  • Unity of life - through shared traits coming from a common ancestor; and
  • Diversity of life - through differences because of adaptation
• According to Theodosius Dobzhansky, a founder of modern evolutionary biology, “Nothing in biology makes sense except in the light of evolution.”
• According to Charles Darwin in his book:

  1. Evolution is descent with modification

  • Species accumulate differences from ancestors
  • 2. Natural selection causes evolution
  • individuals with inherited traits that are better adapted are more likely to survive and reproduce than less adapted individuals.
• Phylogenetic Trees - a diagram that highlights the evolutionary relationships
• Phylogenetic trees consists of nodes and branches.