Chapter 1.1: Cellular Foundations

• Life arose on Earth around 4 billion years ago.
• The first life was simple microorganisms that extracted energy from chemical compounds and sunlight. They used this energy to make biomolecules from the simple elements and compounds on Earth's surface.
• Cells are the fundamental unit of life.
• Although cells can vary in complexity and can be highly specialized for their environment or function within a multicellular organism, they share remarkable similarities.
• Cells use a relatively small set of carbon based metabolites to create polymeric machines, supramolecular structures, and information repositories. The structures of these components define their cellular function.
• The collection of molecules made by a cell carry out a program, the end result of which is reproduction of the program and self perpetuation of that collection of molecules.
• Living organisms exist in a dynamic steady state, never at equilibrium with their surroundings.
• Following the laws of thermodynamics, living organisms extract energy from their surroundings and employ it to maintain homeostasis and do useful work.
• Essentially, all the energy obtained by cells comes from the flow of electrons, driven by sunlight or metabolic redox reactions.
• Cells have the capacity for precise self replication and self assembly using chemical information stored in the genome.
• A single bacterial cell placed in a sterile nutrient medium can give rise to a billion identical daughter cells in 24 hours. Each cell is a copy of the original with its construction entirely directed by the information in the genetic material.
• The progeny of vertebrate animals share a striking resemblance to their parents as a result of the inheritance of parental genes.
• Living organisms change over time by gradual evolution.
• Evolution has led to an enormous diversity of life forms that are fundamentally related through shared ancestry, which can be seen at the molecular level in the similarity of gene sequences and protein structure.
• Biochemistry is the chemistry behind the biological phenomenon shared by all living organisms.
• Diagram

  A) Prokaryote

  B) Eukaryote

  C) Plasma membrane

  D) Ribosomes

  E) Cytoplasm

  F) Nucleus

  
• The plasma membrane is a thin, flexible, hydrophobic barrier that defines the periphery of the cell.
• The plasma membrane is composed of lipid and protein molecules that contains embedded transport proteins, receptor proteins, and membrane enzymes.
• Cytoplasm is the internal volume enclosed by the plasma membrane.
• Cytoplasm is composed of cytosol and a variety of suspended particles, like mitochondria, chloroplasts, ribosomes, and proteasomes.
• Cytosol is a highly concentrated solution that contains enzymes, RNA, amino acids, nucleotides, coenzymes, and inorganic ions.
• Cytosol does not contain membranous organelles, such as mitochondria.
• The genome is a complete set of genes composed of DNA.
• Bacteria and archaea, formerly grouped as prokaryotes, store their genome in a nucleoid.
• Eukaryotes store their genome in a membrane enclosed nucleus.
• Cells are microscopic.
• Animal and plant cells can be 5 to 100 micrometers in diameter.
• Unicellular microorganisms can be 1 to 2 micrometers.
• The upper limit of cell size is likely set by the rate of transportation and the need to deliver oxygen to all parts of the cell. As the size increases, the surface area to volume ratio decreases.
• All cells have a plasma membrane.
• The three domains are bacteria, archaea, and eukarya.
• Bacteria inhabit soils, surface waters, and the tissues of other living or decaying organisms.
• Archaea inhabit extreme environments.
• Eukarya are all eukaryotic organisms. They are more closely related to archaea that bacteria.
• Aerobic organisms need a plentiful supply of oxygen because they transfer electrons from fuel to oxygen for energy.
• Anaerobic organisms do not use oxygen and transfer electrons to nitrate, sulfate, or carbon dioxide for energy.
• Obligate anaerobes die when exposed to oxygen.
• Facultative anaerobes can live with or without oxygen.
• You discover a new single celled organism in a salt lake. Subsequent laboratory experiments show that the organism is able to live in the presence or absence of oxygen. This means that the organism would be classified as a facultative anaerobe in the Archaeal domain.
• Phototrophs trap and use sunlight.