This chapter discusses carbohydrates, which are an important source of rapid energy production for living cells,the structural building blocks of cells, and the components of numerous metabolic pathways. The chapter refers to sugar polymers linked to proteins and lipids which, it states, are now recognized as a high-density coding system. Their vast structural diversity is exploited by living organisms to produce the immense informational capacity required for living processes. The chapter describes the structures and chemistry of typical carbohydrate molecules found in living organisms. Carbohydrates are the most abundant biomolecules in nature and are a direct link between solar energy and the chemical bond energy of living organisms.
Chapter
Carbohydrates
Chapter
Carbohydrate Metabolism
This chapter reviews the crucial roles carbohydrates play in the metabolic processes of living organisms as they serve as energy sources and structural elements in living cells. It looks at the role of carbohydrates in energy production, focusing on its synthesis, degradation, and storage as the monosaccharide glucose is a prominent energy source in almost all living cells. The term metabolism is used to describe the thousands of enzyme-catalysed biochemical reactions that sustain life in living organisms. The chapter analyses how biochemical reactions are spatially and temporally organised into complex, interconnected networks. It classifies all biochemical reaction pathways into three major categories: signal transduction pathways, genetic regulatory pathways, and core metabolic pathways.
Chapter
The basic molecular themes of life
This chapter talks about living cells. These obey the laws of physics and chemistry. Energy is derived in cells from the breaking down of food molecules and released in a form that can drive chemical and physical work. The chapter considers adenosine triphosphate (ATP) as the universal energy currency in life. Energy from food breakdown is used to synthesize ATP from adenosine diphosphate (ADP) and phosphate. ATP breakdown can then be coupled to carry out biochemical work. The chapter analyses biological molecules which are based on the carbon atom bonded mainly to hydrogen, oxygen, nitrogen, and other carbon atoms. Noncovalent bonds are weak in comparison with covalent bonds but important in allowing interactions between molecules.
Chapter
General properties of viruses
This chapter describes viruses as small organisms that retain infectivity after passage through filters small enough to hold back bacteria. Bacteria are measured in terms of the micrometre (μm), which is 10-6 of a metre. For viruses, the nanometre (nm) is used as the unit, which is a thousand times smaller. The chapter points out that viruses are totally dependent on living cells, either eukaryotic or prokaryotic, for their replication and existence, and possess and carry enzymes of their own. Viruses cannot reproduce and amplify and translate into proteins the information in their genomes without the assistance of the cellular architecture and protein translation machinery, namely ribosomes. The chapter discusses viruses that possess only one species of nucleic acid, either DNA or RNA, and have a component for attaching or ‘docking’ to cells so that they can commandeer the cells as virus production factories.
Book
Trudy McKee and James R. McKee
Biochemistry begins with an introduction to the topic. Discussions covered include living cells, the importance of water to life, energy, and amino acids, peptides, and proteins. The book also contains chapters on carbohydrates, carbohydrate metabolism, aerobic metabolism, and lipids and membranes. The text goes on to examine photosynthesis, nitrogen metabolism, nucleic acids, and genes. Finally, it looks at protein synthesis.
Chapter
Introduction to cell biology
This chapter recounts the first discovery of living cells by the Dutch linen merchant Leeuwenhoek, who observed unicellular organisms in pond water, and later blood cells, oral bacteria, and spermatozoa. It mentions the first use of the term ‘cell’ in 1665 by a curator of the Royal Society of London, who described the empty cell walls of a cork. It also considers cells as the basic structural and functional unit of all organisms, which are grouped into archaea, eucarya, and bacteria. The chapter cites the theory that life began with a group of molecules that were capable of catalyzing their self-replication. It explains that cells are largely composed of water and a variety of inorganic minerals and organic constituents.
