week 1

• Hypothesis


  A testable statement that explains something observed
• Experiment


  Allows researchers to test the effect of a factor on a particular phenomenon
• Prediction


  A measurable or observable result that must be correct if a hypothesis is valid
• Hypothesis


  1. X (explanatory/independent variable)

  2. affects/impacts

  3. Y (response/dependent variable)

  4. Does not imply direction
• Prediction


  1. X (explanatory/independent variable)

  2. increases/decreases

  3. Y (response/dependent variable)

  4. Implies direction
• Louis Pasteur's hypothesis: Cells arise from cells, Cells do not arise by spontaneous
• Louis Pasteur hypothesized that microbes come from microbes and are not spontaneously generated
• Pasteur's experiment


  1. Filled two flasks with broth and boiled the broth, killing all the microbes it contained

  2. One flask had a straight neck and one had a swan neck

  3. The straight-neck flask allowed dust particles with microbes to enter

  4. The swan-neck flask did not

  5. Therefore, there was only one variable -- in this case, the shape of the neck of the flask
• Special Creation (aka natural theology)

  1. all species were created separately, and thus, are unrelated to one another; 2. Each species is unchanging, and there is little variation within each
• In 1858, Charles Darwin and Alfred Russel Wallace made two claims regarding the natural world: 1. All species are related by common ancestry, 2. Characteristics of species can be modified from generation to generation (descent with modification)
• Microevolution


  Species changing over time
• Macroevolution


  Species splitting and diverging
• Evolution


  A change in a population over time
• Population

  A group of individuals of the same species living in the same area at the same time
• Natural selection


  The most famous mode of evolution proposed by Darwin and Wallace
• For natural selection to occur in a population

  • Individuals must vary in traits that are heritable—can be passed on
  • In a particular environment, certain versions of these heritable traits help individuals reproduce more than other versions
• Natural selection acts on individuals and evolutionary changes occur in populations
• When certain heritable traits lead to increased success in producing offspring, they become more common in a population over time. This allows the population's characteristics to evolve due to natural selection acting on individuals
• Speciation


  Occurs when populations diverge to form new species
• Fitness

  The ability for an organism to produce offspring. Higher fitness = producing many surviving offspring
• Adaptation


  A heritable trait that increases the fitness of an individual in a particular environment
• The chromosome theory of inheritance was proposed in 1902 by Walter Sutton and Theodor Boveri
• Hereditary or genetic information

  Encoded in genes
• Genes


  Units located on chromosomes
• In the 1950s, chromosomes are molecules of deoxyribonucleic acid, or DNA
• DNA is the hereditary material
• Genes


  Segments of DNA that code for cell products
• The Central Dogma: The flow of information in cells

  1. Genes in DNA code the information necessary to produce a functional product, often a protein

  2. DNA is transcribed into an RNA message

  3. The RNA message can then be translated into a protein
• DNA is copied to pass genetic information from cell to cell or from one organism to its offspring
• Copying DNA is highly accurate
• DNA sequence changes


  • May lead to changes in proteins
  • May cause changes in outward appearance
• At individual level, changes in DNA expression might be associated with an increase or decrease in fitness (ability to survive or reproduce)
• At population level, changes in DNA sequence lead to heritable variations that underlie diversity of life and make evolution possible
• The theory of evolution states that all organisms are related by common ancestry
• Natural selection is a well-tested explanation for why species change through time and why they are so well adapted to their habitats
• The chromosome theory of inheritance states that genes are located on chromosomes
• A chromosome consists of a molecule of DNA – the hereditary material. Genes, located on chromosomes, consist of specific segments of DNA that code for products in the cell

  
• The flow of information from DNA to RNA to protein is called the central dogma

  
• Organisms are highly diverse in how they acquire and use energy
• Phylogeny


  The actual genealogical relationships among all organisms