Biochemistry Chapter 1

Cellular Foundations

• Biochemistry is the study of the chemical substances and processes that occur in plants, animals, and microorganisms.
• Living organisms are made up of biological molecules, which can be grouped into four major classes: carbohydrates, proteins, lipids, and nucleic acids.
• Cells are the structural and functional units of all living organisms.
• The cell membrane is a barrier to the free passage of inorganic ions and most other charged or polar compounds.
• Transport proteins in the plasma membrane allow the passage of certain ions and molecules.
• Receptor proteins transmit signals into the cell, and membrane enzymes participate in some reaction pathways.
• The internal volume enclosed by the plasma membrane is composed of an aqueous solution, the cytosol, and a variety of suspended particles with specific functions.
• Most cells are microscopic, invisible to the unaided eye.
• Animal and plant cells are typically 5 to 100 mm in diameter, and many unicellular microorganisms are only 1 to 2 mm long.
• Eukaryotic cells contain a variety of membrane-bounded organelles and large particles.
• All living organisms fall into one of three large groups (domains) that define three branches of the evolutionary tree.

Chemical Foundations

• Biomolecules are compounds of carbon with a variety of functional groups.
• Cells contain a universal set of small molecules.
• Elements essential to animal life and health include bulk elements (such as carbon, oxygen, and nitrogen) and trace elements (such as iron, copper, and zinc).
• Macromolecules are the major constituents of cells.
• The ABCs of biochemistry include amino acids, nitrogenous bases, sugars, and phosphate ions.

Physical Foundations

• Living cells and organisms must perform work to stay alive and to reproduce themselves.
• The synthetic reactions that occur within cells require the input of energy.
• Living organisms exist in a dynamic steady state, never at equilibrium with their surroundings.
• Maintaining this steady state requires the constant investment of energy.
• Organisms transform energy and matter from their surroundings.
• The flow of electrons provides energy for organisms.
• Creating and maintaining order requires work and energy.
• Energy coupling links reactions in biology.

Genetic Foundations

• The structure of DNA allows for its replication and repair with near-perfect fidelity.
• The linear sequence in DNA encodes proteins with three-dimensional structures.
• The central issue in bioenergetics is the means by which energy from fuel metabolism or light capture is coupled to a cell's energy-requiring reactions.

Evolutionary Foundations

• Nothing in biology makes sense except in the light of evolution.
• Changes in the hereditary instructions allow evolution.
• Biomolecules first arose by chemical evolution.
• Chemical evolution can be simulated in the laboratory.
• RNA or related precursors may have been the first genes and catalysts.
• Biological evolution began more than three and a half billion years ago.
• The first cell was probably a chemoheterotroph.
• Eukaryotic cells evolved from prokaryotes in several stages.