Biochemistry and Cellular Foundations

Key Milestones in Biochemistry and Cellular Foundations

• 1896: Eduard Buchner demonstrates alcoholic fermentation in yeast cell extracts, marking the first complex biochemical process outside of a cell.
• 1953: James Watson and Francis Crick discover the double helical structure of DNA.
• 1953: Hans Adolf Krebs discovers the biochemical steps of the Krebs cycle in carbohydrate metabolism.
• 1957: Daniel Bovet receives Nobel Prize for developing antihistamines.
• 1959: Severo Ochoa and Arthur Kornberg receive Nobel Prize for discoveries on DNA and RNA synthesis.
• 1970: Hamilton Smith reports the discovery of the first restriction enzyme.
• 1975: Cesar Milstein, Georges Kohler, and Niels Kai Jerne develop the technique for making monoclonal antibodies.
• 1995: FDA approves the first protease inhibitor for AIDS treatment.
• 1997: First complete nucleotide sequence of a eukaryote's chromosomes (yeast) reported.
• 2001: NIH-funded human fetal ventral mesencephalic transplant clinical trials yield negative results.
• Principles 1 and 2: Cells are the fundamental unit of life and use a small set of metabolites to create structures and information repositories.
• Principle 3 and 4: Living organisms are in a dynamic steady state, not at equilibrium, and extract energy from their surroundings to maintain homeostasis.

Key Concepts in Biochemistry

• Trace elements, essential to life, are vital for the function of specific proteins and enzymes.
• Carbon is the central element in biomolecules, forming stable single bonds with up to four other carbon atoms.
• Carbon can form covalent single, double, and triple bonds, with the ability for free rotation around single bonds and limited rotation around double bonds.
• Biomolecules are derivatives of hydrocarbons with functional groups such as alcohols, amines, aldehydes, ketones, and carboxylic acids, each conferring specific chemical properties.
• Many biomolecules are polyfunctional, containing multiple types of functional groups, determining the compound's chemical characteristics and reactions.
• Cells contain a universal set of small molecules, including amino acids, nucleotides, sugars, and carboxylic acids, with secondary metabolites being specific to the organism.
• Macromolecules, such as proteins, nucleic acids, and polysaccharides, are the major constituents of cells, with proteins also functioning as enzymes, structural elements, and more.
• Proteins, nucleic acids, and some oligosaccharides serve as informational macromolecules, with the proteome representing the sum of all proteins in a cell.
• Nucleic acids, including DNA and RNA, store and transmit genetic information, while some RNA molecules have structural and catalytic roles in supramolecular complexes.
• Polysaccharides serve as energy-rich fuel stores, rigid structural components, and extracellular recognition elements, while lipids function as structural components of membranes and energy-rich fuel stores.
• Three-dimensional structure in biochemistry is described by configuration and conformation, with stereochemistry playing a crucial role in the interaction between biomolecules.
• Geometric isomers, or cis-trans isomers, have distinct biological roles despite their similar chemical makeup, exemplified by the visual pigment in the vertebrate eye, rhodopsin, containing retinal, a vitamin A–derived lipid.

Cellular Diversity and Organization

• Organisms are distinguished by their habitats and sources of energy, such as aerobic, anaerobic, obligate anaerobes, and facultative anaerobes.
• Bacteria and Archaea share common features but differ in their cell envelopes, with Gram-positive bacteria having a thick peptidoglycan layer and Gram-negative bacteria having an outer membrane composed of a lipid bilayer.
• Eukaryotic cells contain various membranous organelles, including mitochondria, endoplasmic reticulum, golgi complexes, peroxisomes, lysosomes, vacuoles, and chloroplasts.
• Subcellular fractionation involves disrupting cells and centrifuging the homogenate to isolate organelles enriched in specific enzymes, aiding in enzyme purification.
• The cytoplasm is organized by the dynamic cytoskeleton, consisting of actin filaments, microtubules, and intermediate filaments, which provide structure and organization to the cell.
• The endomembrane system segregates metabolic processes and facilitates transport mechanisms like exocytosis and endocytosis.
• Supramolecular complexes are held together by noncovalent interactions, such as hydrogen bonds, ionic interactions, van der Waals interactions, and the hydrophobic effect, producing unique structures.
• Studying isolated cellular components in vitro may overlook important interactions that occur in living cells, as molecules may behave differently in vivo and in vitro.
• Cells use a relatively small set of carbon-based metabolites to create polymeric machines, supramolecular structures, and information repositories.
• The observed universality of chemical intermediates and transformations supports the understanding that all organisms share a common evolutionary origin.
• The four most abundant elements in living organisms are hydrogen, oxygen, nitrogen, and carbon, which make up more than 99% of the mass of most cells, due to their ability to efficiently form strong bonds.
• The lightest elements form the strongest bonds, and the biochemical unity is based on the shared evolutionary origin of organisms.

Test your knowledge of key milestones in biochemistry and cellular foundations with this quiz. From the discovery of the double helical structure of DNA to the development of monoclonal antibodies, explore important events that have shaped our understanding of cellular processes and biochemical pathways.