GenBio

• Oparin and Haldane Chemical Theory of Life


  The atmosphere of the early Earth must have contained methane CH4, ammonia NH3, hydrogen H2, and water vapor; chemical reactions in the said mixture of gases must have produced organic molecules, and this could have given rise to the first living cells.
• Miller-Urey Experiment


  Aimed to simulate the conditions of early Earth's atmosphere and test the hypothesis that the building blocks of life could have formed spontaneously; simple organic molecules, such as amino acids, could be synthesized under conditions resembling early Earth. This provided evidence that the basic building blocks of life could have emerged spontaneously from non-living matter.
• Reasons why early Earth did not contain oxygen

  • Geological Record: rocks and sediments that formed billions of years ago, indicate the absence of oxygen
  • Abundance of Redox-Sensitive Elements: abundance of certain elements in ancient rocks, such as iron and sulfur, indicates that the atmosphere lacked oxygen
  • Biomarkers and Fossil Evidence: anaerobic bacteria and certain archaea in these ancient ecosystems suggests an environment devoid of oxygen
  • Chemical Reactions: Oxygen is a highly reactive gas that readily reacts with other elements and compounds. Given the presence of abundant reactive substances on early Earth, if oxygen had been present, it would have reacted with them and left clear chemical signatures.
• Evolution


  Changes in living organisms over time; explains how modern organisms have descended from ancient organisms
• Evolution


  • Explains the Unity of Life: similarities between all living things
  • Explains the Diversity of Life: variety of different creatures on Earth
• Geological Time Scale


  Tabular presentation of the history of life based on geologists' study of rocks and fossils
• Charles Darwin


  British naturalist who proposed a way how evolution works - by natural selection
• Voyage of the HMS Beagle


  Main mission was to chart South American coastline; Darwin made many observations of nature, including stopping in the Galapagos Islands
• Galapagos Islands were formed by volcanic activity and the animals on the Galapagos live nowhere else in the world, but they look like species living on the South American mainland
• Evidence that creatures have changed over time


  • Species variations in beaks
  • Natural selection for the most fit
  • Adaptation to environment with offspring inheriting successful traits
  • Common Ancestry and Speciation
• Lamarckism


  Evolution by acquired traits - creatures developed traits during their lifetime and gave those traits to their offspring
• Lamarckism is not accepted as a valid theory of evolution
• 5 Principles of Natural Selection


  • Heritable Variation: variation exists in populations
  • Over-production of offspring: more offspring than the environment can support
  • Competition: for food, mates, nesting sites, escape predators
  • Differential Survival: successful traits = adaptations
  • Differential reproduction: adaptations become more common in population
• Adaptations


  Traits that help an organism fit the environment better to survive & reproduce; Fits an organism to its environment or way of life
• 3 Types of Adaptations


  • Behavioral Adaptations: things an animal does to survive
  • Structural Adaptations: physical features that allow an organism to survive
  • Physiological Adaptations: internal/cellular features of an organism that enable them to survive
• Descent with Modifications/Evolution


  Each species has descended, with changes, from other species over time
• Evidence Supporting Evolution


  • Fossil record: shows change over time
  • Anatomical record: comparing body structures
  • Molecular record: comparing protein & DNA sequences
  • Artificial selection: human caused evolution
• Fossil record

  Layers of rock contain fossils that show a series of organisms have lived on Earth over a long period of time; the Law of Superposition states that the deeper you dig, the farther back in time you go, with the bottom layer being the oldest
• DNA Technology


  Set of methods and techniques used to manipulate, analyze, and modify DNA molecule
• The evolution of birds is evidenced by the fossil of Archaeopteryx, which lived about 150 million years ago and links reptiles and birds
• DNA Technology


  • Revolutionized Fields: Molecular Biology, Genetics, Biotechnology
• The 2006 fossil discovery of an early tetrapod with 4 limbs provided a missing link from sea to land animals
• Applications of DNA Technology

  • Medicine
  • Agricultural
  • Forensics
  • Environmental Science
• DNA Sequencing


  1. Determine the exact sequence of nucleotides

  2. Can help identify genes responsible for specific traits or diseases
• Homologous Structures


  Structures that come from the same origin, such as the forelimbs of humans, cats, whales, and bats, which have the same underlying structure but different functions
• PCR (Polymerase Chain Reaction)


  1. Amplify a specific DNA sequence

  2. Creating millions of copies of a DNA segment

  3. Understanding the function of a protein
• Analogous Structures


  Structures that look similar on the outside but have different structure and development on the inside, and different evolutionary origin, such as the adaptations of dolphins and fish to aquatic life
• PCR


  • Diagnose infectious diseases, such as COVID19
• Vestigial Organs


  Structures on modern animals that have no function, but are remains of structures that were functional in ancestors, providing evidence of change over time
• Gel Electrophoresis


  1. Separate DNA fragments based on their size and charge

  2. Uses an electric field to pull fragments

  3. Often used in DNA research to separate DNA fragments by size
• Gel Electrophoresis


  • Analyze PCR products to confirm the presence of a specific DNA fragment
• Comparative Embryology


  The development of embryos tells an evolutionary story, as animals with different structures on the surface have similar structures during development, indicating common ancestry
• CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)


  Gene editing tool that allows precise changes
• Molecular record


  Comparing DNA and protein sequences, including the universal genetic code, allows building "family trees" of phylogenetic relationships between species
• CRISPR


  • Correct mutations
  • Introduce new traits
• Artificial Selection


  Human-caused evolution through selective breeding, leading to unexpected consequences like pesticide, antibiotic, and insecticide resistance
• Genetic drift is a process that can lead to insecticide resistance becoming more common in a population
• DNA Microarray Analysis


  Simultaneously analyze the expression levels of thousands of genes
• DNA Microarray Analysis


  • Compare the gene expression profiles of healthy and diseased tissues
  • Identify potential disease markers
• DNA Cloning


  Make multiple copies of a DNA fragment, by inserting it into a vector such as a plasmid