Thank Me With TEA!

BioTech Lecture 2

Resources

Important

  • Elements on the exam – Only about 12 elements from the periodic table will appear on your exam.
  • Atomic number – All atoms of the same element will always have the exact same number of protons.
  • Neutrons – The number of neutrons in an atom typically equals the number of protons, with the exception being isotopes.
  • Mass number – This is calculated by adding the number of protons to the number of neutrons.
  • Valence electrons – These are the electrons found in the outermost shell, and they ultimately determine the chemical behavior of an atom.

Core concepts

  • Chemical bonds: Interactions that hold molecules together, including ionic bonds (easily dissolved bonds between metallic and non-metallic atoms), covalent bonds (tight bonds sharing at least one pair of valence electrons), hydrogen bonds (weaker attractions between an electronegative atom and a hydrogen atom covalently bonded to another electronegative atom), and Van der Waals interactions (attractions between transiently positive and negative regions of molecules),,,.
  • Organic chemistry basis: Organic chemistry is the study of carbon compounds,. Carbon’s unique ability to bond to four other atoms allows for immense molecular diversity through variations in chain length, branching, double bonds, and ring formations,,.
  • Four major classes of macromolecules: The human body relies on carbohydrates (sugars/starches for energy and structure), lipids (fats, oils, and phospholipids for energy storage and membranes), proteins (amino acid chains acting as enzymes, antibodies, and structural supports), and nucleic acids (DNA and RNA for genetic information),,,,,,,.
  • DNA structure and function: DNA forms a double helix of nucleotide chains held together by hydrogen bonds between specific base pairs (Adenine pairs with Thymine, Guanine pairs with Cytosine),,. Because the strands are complementary, each strand acts as a template for reconstructing the other during DNA replication,.
  • Chromosome structure: To fit roughly 2 meters of DNA into a single cell nucleus, eukaryotic DNA wraps tightly around histone proteins to form nucleosomes (“beads on a string”), which then arrange into thicker fibers, looped domains, and ultimately highly packaged chromosomes,,.
  • Gene definition: A gene is a specific sequence of nucleotide bases carried on a DNA molecule that provides the exact genetic instructions needed for constructing specific proteins, which in turn determine physical and functional traits.
  • Emergent properties: New properties that arise at each level of the biological hierarchy as a result of the specific arrangement and interaction of parts within a system.
  • Isomerism: Occurs when molecules have the exact same gross chemical formula (e.g., C2H6O) but completely different structural arrangements, which can drastically alter their biological function and specificity,.
  • Functional groups: Specific chemical groups (such as hydroxyl, carbonyl, or amino groups) attached to a carbon skeleton that participate in chemical reactions and heavily influence the molecular shape and function of biological molecules,.

Theories and Frameworks

  • Shell Model of Atoms: A model describing how electrons move in orbitals (volumes of space) around an atomic nucleus, where the first shell holds up to 2 electrons and the second shell holds up to 8 electrons,.
  • Central Dogma of Molecular Biology: The directional flow of genetic information in an organism, proceeding from DNA to RNA (via transcription) and from RNA to Protein (via translation), which ultimately dictates the phenotype,.
  • Classical Genetics vs. Molecular Genetics: Classical genetics focuses on observable traits and how their inheritance patterns pass from parents to offspring, whereas molecular genetics focuses on the specific DNA sequences, genes, and proteins that mechanically underlie those inheritance patterns,.

Notable Individuals

  • Werner Heisenberg: University of Leipzig physicist and academic ancestor.
  • Jean-Marie Lehn: Stated that chemistry serves as a bridge between physics and biology.
  • Albert Lehninger: Noted the fundamental concept that living things are composed of lifeless molecules.
  • F. Scott Fitzgerald: Quoted observing that a first-rate intelligence possesses the ability to hold two opposed ideas in mind at the same time.
  • Democritus: Ancient Greek philosopher who posited that nothing exists except atoms and empty space.
  • Gregor Mendel: A monk who deduced the basic laws of inheritance in the 1860s by observing traits in pea plants.
  • James Watson, Francis Crick, and Maurice Wilkins: Announced the discovery of DNA’s double-helix structure in 1953 and were awarded the 1962 Nobel Prize in Physiology or Medicine,.

Time for Review

  • What are the four most abundant elements in living systems?
    • Answer: Carbon (C), Oxygen (O), Hydrogen (H), and Nitrogen (N).
  • What determines the chemical behavior of an atom?
    • Answer: Electrons. Specifically, the valence electrons in the outermost shell are what determine an atom’s chemical behavior.
  • What is a covalent bond?
    • Answer: A covalent bond is formed by the sharing of valence electrons between atoms.
  • What is a chemical reaction?
    • Answer: A chemical reaction is the making and breaking of chemical bonds, which leads to changes in the overall composition of matter.
  • What are the four main types of macromolecules (organic molecules)?
    • Answer: Carbohydrates, Lipids, Proteins, and Nucleic Acids.
  • The 4 most abundant elements (making up 96.3% of body mass):
    • Carbon (C)
    • Oxygen (O)
    • Hydrogen (H)
    • Nitrogen (N)
  • The other major elements in the human body (making up 3.7% of body mass):
    • Calcium (Ca)
    • Phosphorus (P)
    • Potassium (K)
    • Sulfur (S)
    • Sodium (Na)
    • Chlorine (Cl)
    • Magnesium (Mg)
  • Other familiar or trace elements mentioned throughout the lecture as examples include Helium (He), Iron (Fe), Iodine (I), Gold (Au), Silver (Ag), and Aluminum (Al). Because the exact list of 12 is not explicitly spelled out, you may want to focus your studying on the 11 major biological elements listed above, as well as review your own class notes to see if your professor highlighted a specific 12th element.