Macromolecules

10 Key excerpts on "Macromolecules"

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  Man and His World/Terres des hommes

  The Noranda Lectures, Expo 67/Les Conferences Noranda/L'Expo 67

  • The Noranda Lectures/ Expo 67(Author)
  • 2019(Publication Date)
  • University of Toronto Press

    (Publisher)

  I was fascinated by the complexity of living organisms and the intri-cate ways in which they perform so many functions. I tried to understand these func-tions in a somewhat deeper way than is re-quired of a student, but I soon realized that I would first have to study chemistry, physics, and mathematics before trying to grapple with these complicated processes. I thus spent many years in the study of the exact sciences. When I felt that I had mastered, at least to a certain extent, some of the vast areas of these sciences, I returned to the study of life pro-cesses. Here I was fascinated by the large molecules, by the Macromolecules of the cell which play a most important role in determin-ing life processes. Proteins and nucleic acids are among the most important materials in the living organ-ism. The protein myosin forms our muscles, collagen -our skin, keratin -our hair. Fibrin determines the process of blood clotting. Se-rum albumin and haemoglobin abound in our blood. Some of the proteins are hormones, such as insulin, and others act as antibodies protecting us from micro-organisms. Last, but not least, all enzymes, i.e. the entire complex variety of catalysts of a living cell, are pro-teins. As for the nucleic acids, they store all the information of the cell. They actually keep the secrets of life in the best sense of the word. They direct the functions of the cell. They are responsible for all hereditary properties and govern protein biosynthesis. While considering proteins and nucleic acids, I could not help wondering why nature chose large molecules for the essential pro-cesses of the cell. Could nature not carry out these reactions with small molecules and make the life of a chemist and a physicist so much simpler? But I soon realized that the special quality of a large molecule is a structure which is essentially linear, made up of many hundreds of thousands of atoms in one long chain that can be folded into a large variety

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  Karp's Cell Biology

  • Gerald Karp, Janet Iwasa, Wallace Marshall(Authors)
  • 2018(Publication Date)
  • Wiley

    (Publisher)

  Substitute a sulfhydryl group (—SH), and you have formed CH 3 CH 2 SH, a strong, foul-smelling agent, ethyl mercaptan, used by biochemists in studying enzyme reactions. A Classification of Biological Molecules by Function The organic molecules commonly found within living cells can be divided into several categories based on their role in metabolism. 1. Macromolecules. The molecules that form the structure and carry out the activities of cells are huge, highly organized molecules called Macromolecules, which contain anywhere from dozens to millions of carbon atoms. Because of their size and the intricate shapes that Macromolecules can assume, some of these molecular giants can perform complex tasks with great precision and efficiency. The presence of macro- molecules, more than any other characteristic, endows organ- isms with the properties of life and sets them apart chemically from the inanimate world. Macromolecules can be divided into four major catego- ries: proteins, nucleic acids, polysaccharides, and certain lipids. The first three types are polymers composed of a large number of low-molecular-weight building blocks, or mono- mers. These Macromolecules are constructed from mono- mers by a process of polymerization that resembles coupling railroad cars onto a train (FIGURE 2.10). The basic structure and function of each type of macromolecule are similar in all organisms. It is not until you look at the specific sequences of monomers that make up individual Macromolecules that the diversity among organisms becomes apparent. The localiza- tion of these molecules in a number of cellular structures is shown in an overview in FIGURE 2.11. 2. The building blocks of Macromolecules. Most of the macro- molecules within a cell have a short lifetime compared with the cell itself; with the exception of the cell’s DNA, they are con- tinually broken down and replaced by new Macromolecules.

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  Visualizing Microbiology

  • Rodney P. Anderson, Linda Young, Kim R. Finer(Authors)
  • 2020(Publication Date)
  • Wiley

    (Publisher)

  MICROBIOLOGY INSIGHT Summary 71 The complexity of life begins at the simplest chemi- cal level. Bonding different types of atomic building blocks together is the first step in generating molecules essential for life. More sophisticated atomic aggregations produce the monomers used to assemble the four major categories of bio- chemical polymers. Interactions between proteins, carbohy- drates, lipids, and nucleic acids are ultimately responsible for initiating and maintaining the intricate processes of life. These basic chemical concepts will be revisited regularly in upcom- ing chapters and applied to the structure and life functions of diverse microorganisms. Summary 3.1 Proteins 46 • Proteins, the most structurally complex category of biochemi- cal polymer, are made up of 20 different amino acids. Proteins have four levels of structure from the primary structure, the lin- ear sequence of amino acids, to the three-dimensional quaterna- ry structure in which polypeptides combine. • Arranging 20 different amino acids in varying sequences can gener- ate an enormous number of functional proteins. Among their many functions, proteins act as enzymes and hormones, and they make up the contractile fibers of muscles and the oxygen-carrying hemo- globin of red blood cells. Protein function requires maintenance of their three-dimensional conformation to bind specific ligands. 3.2 Enzymes 53 • In enzyme action the substrate binds to the active site of an enzyme. Induced fit distorts the substrate into its most reactive state, which lowers the activation energy (E a ) and allows rapid conversion to product. • Regulating the rate of enzyme activity allows precise control of biochemical processes to conserve host resources. Reaction rate can be influenced by cofactors, coenzymes, and environ- mental conditions such as temperature and pH. Competitive enzyme inhibition decreases reaction rate because inhibitors compete with the substrate for access to the active site.

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  Single-Molecule Cellular Biophysics

  • Mark C. Leake(Author)
  • 2013(Publication Date)
  • Cambridge University Press

    (Publisher)

  For example, one physical form of pure carbon is diamond which is a highly stable structure, but this is not encountered in living cells. It is just as important for the cell to be able to break up biological molecules controllably as it is to be able to make them. Thus, some level of chemical instability could also be said to be a feature of biological molecules. Other important but less abundant atomic elements include nitrogen (a vital component of all proteins among several other types of molecule), phosphorus (for example, found in all nucleic acids such as DNA) and sulphur (present in some proteins, especially those with more structural functions), as well as sodium, potassium and chlorine (present in ionic form in all cells), calcium (very important in muscle cells, but also secreted into extra- cellular components such as bone by some cells), magnesium (plays a vital role in manipulating abundant phosphate-containing molecules in the cell), and more trace but still essential elements such as certain transition metals (for example iron and zinc to name only two out of about 30). Beyond this are more elements still found in less abundance in the cell, which are deemed non-essential per se but are still found in many cell types. 2.3 Cell structure and sub-cellular architecture Single biological molecules perform their physiological functions in the context of a living organism: either inside living cells, attached to their outer surface, or outside cells but in their vicinity in the so-called extra-cellular matrix which some cells secrete. Some organisms appear to consist just of a single cell, bacteria and yeast for example, whereas other cells are part of a more complex multi-cellular organism, for example the human body which contains over 200 different types of cell as defined by tissue of origin, with ~10 14 human cells in total in each of us.

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  Molecular Communication

  • Tadashi Nakano, Andrew W. Eckford, Tokuko Haraguchi(Authors)
  • 2013(Publication Date)
  • Cambridge University Press

    (Publisher)

  A DNA molecule, a storage of genetic information, responds to molecular signals in the cell by changing its state by switching on and off particular genes. A stem cell, a biological cell found in all multicellular organisms, responds to molecular signals in the environment by differentiating into specialized cell types with particular functions (e.g., muscle cells). m Å (10 –10 m) cm (10 –2 m) mm (10 –3 m) nm (10 –9 m) μm (10 –6 m) Organ/tissue structure Eukaryote Prokaryote Protein Atom Amino acid Virus Human Vesicle DNA/RNA Example bio-nanomachines Figure 2.1 Examples and length scales of nature-made bio-nanomachines. 22 Nature-made biological nanomachines In this chapter, we will briefly review the naturally occurring bio-nanomachines in terms of biochemical structures and functional roles in biological systems. Specific bio-nanomachines reviewed in this chapter include protein molecules, DNA and RNA molecules, lipid membranes and vesicles, as well as whole cells that consist of large numbers of bio-nanomachines. This chapter is written for communication engineers who have no prior knowledge of bio-nanomachines. For such communications engi- neers, basic biology terms that appear throughout this book as well as in other molecular communication literature are in bold the first time that they appear. 2.1 Protein molecules Proteins are one of the most basic building blocks of nature-made biological systems. We first review the biochemical structure of proteins and then look at the major roles of proteins in biological systems such as functioning as catalysts to induce chemical reactions, sensors to process molecular signals, and actuators to produce motion. 2.1.1 Molecular structure The molecular structure of a protein molecule is a linear chain of amino acids (Figure 2.2 left). An amino acid is made from one amino group (−NH 2 ), one carboxyl group (−COOH), and a side chain called an R group specific to each amino acid.

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  Science for Students of Leather Technology

  The Commonwealth and International Library: Technology Division a Modern Course in Leather Technology

  • R. Reed(Author)
  • 2016(Publication Date)
  • Pergamon

    (Publisher)

  Little information is at present available regarding the Type C Macromolecules, which in the solid state have a unique molecular shape of great compactness and complexity. Most members of this class are the globular proteins and the nucleoproteins, all of which apparently retain their complexity of structure even in the aqueous systems of living cells. Hence it is likely that such Macromolecules will remain essentially unchanged in general form when placed in aqueous environments. PROTEINS Proteins are naturally occurring Macromolecules consisting of one, or in some cases, several polypeptide chains. Such polypeptide chains can be considered to be built from -amino acids which are linked by the condensation of the amino group of one acid with the carboxyl group of another, with the formation of the peptide link —NH—CO—. When many amino acids are thus linked together, the resulting structures are linear Macromolecules represented either by the general formula : NH 2 —CH—CO—NH—CH—CO—NH ... NH—CH—COOH I I I Ri R 2 R„ Macromolecules: Proteins and Carbohydrates 13 or by —NH—CH—CO—1 I L R L where « is a large integer and —NH—CH—CO— I R is called the general amino acid residue. The atoms in bold type, i.e. the repeated sequence of N—C—C atoms, form the backbone or main chain of the macromolecule, which thus has the same pattern in all proteins. The R 1? R 2 , ...,R n are various groups which project from the main chain and hence are called side-chains. The structure NH 2 —CHRj—CO—, bearing a free amino group, is called the N terminal residue whilst —NH—CHR^—COOH, bearing a free carboxyl group, is called the C terminal residue. Evidence for the peptide link in joining the monomeric amino acids comes from several sources.

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  Biology for AP® Courses

  • Julianne Zedalis, John Eggebrecht(Authors)
  • 2018(Publication Date)
  • Openstax

    (Publisher)

  protein, including interactions between secondary structural elements; formed from interactions between amino acid side chains fat formed artificially by hydrogenating oils, leading to a different arrangement of double bond(s) than those found in naturally occurring lipids process through which messenger RNA forms on a template of DNA RNA that carries activated amino acids to the site of protein synthesis on the ribosome process through which RNA directs the formation of protein fat molecule; consists of three fatty acids linked to a glycerol molecule long-chain hydrocarbon that has one or more double bonds in the hydrocarbon chain lipid made of a long-chain fatty acid that is esterified to a long-chain alcohol; serves as a protective coating on some feathers, aquatic mammal fur, and leaves CHAPTER SUMMARY 3.1 Synthesis of Biological Macromolecules Proteins, carbohydrates, nucleic acids, and lipids are the four major classes of biological Macromolecules—large Chapter 3 | Biological Macromolecules 131 molecules necessary for life that are built from smaller organic molecules. Macromolecules are made up of single units known as monomers that are joined by covalent bonds to form larger polymers. The polymer is more than the sum of its parts: it acquires new characteristics, and leads to an osmotic pressure that is much lower than that formed by its ingredients; this is an important advantage in the maintenance of cellular osmotic conditions. A monomer joins with another monomer with the release of a water molecule, leading to the formation of a covalent bond. These types of reactions are known as dehydration or condensation reactions. When polymers are broken down into smaller units (monomers), a molecule of water is used for each bond broken by these reactions; such reactions are known as hydrolysis reactions. Dehydration and hydrolysis reactions are similar for all Macromolecules, but each monomer and polymer reaction is specific to its class.

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  Methods in Molecular Biophysics

  Structure, Dynamics, Function

  • Igor N. Serdyuk, Nathan R. Zaccai, Joseph Zaccai(Authors)
  • 2007(Publication Date)
  • Cambridge University Press

    (Publisher)

   Biological Macromolecules, although they are made up of a concatenation of subunits, have evolved to fulfil specific functions and have specific properties that are very dif- ferent from those of classical polymers.  All the molecules in a living organism either are proteins or can be considered as products of protein action.  Proteins are made up of properly folded polypeptides of amino acid residues, and may include prosthetic groups with specific properties (such as the haem group, which binds oxygen). 62 A Biological Macromolecules and physical tools  Colour in proteins (e.g. the red in haemoglobin, or green in chlorophyll binding proteins) is always due to a prosthetic group, because amino acids absorb in the UV region.  There are 20 main amino acids in natural proteins, with a variety of chemical characteristics: acid and base, polar and non-polar, aliphatic and aromatic.  Primary structure is the subunit sequence in the macromolecule; secondary structures are favoured local chain conformations arising from chemical and steric constraints; tertiary structure is the three-dimensional conformation of the macromolecular chain (given by the coordinates of the constituent atoms); quaternary structure is the organi- sation of different or similar chains in a macromolecular complex.  The secondary structures of proteins can be expressed on a Ramachandran plot in terms of angles of rotation of the peptide planes in the chain around the so-called alpha-carbons, to which the amino acid side-chains are bound.  α-helices and β -sheets are the main secondary structures found in proteins.  The tertiary structure results from weak (non-covalent, except for the disulphide bond between two cysteines) interactions between the amino acids in the polypeptide chain.  Protein domains with distinct features have been identified in the solved tertiary struc- tures.

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  The Sciences

  An Integrated Approach

  • James Trefil, Robert M. Hazen(Authors)
  • 2022(Publication Date)
  • Wiley

    (Publisher)

  • The consumption of a healthy diet is a challenge in both developing and developed countries. • In developing countries, access to potable water and adequate caloric intake is often an issue. • In developed countries such as the United States, the combination of sedentary lifestyles and the overconsumption of calorie-dense foods has led to the current obesity epidemic. Summary Organic molecules share the following characteristics: (1) they are based on carbon, (2) they usually form from only a few elements, (3) they are generally modular structures (that is, no matter how large or complex they are, they are formed from a few simple building blocks), and (4) their chemical function is largely determined by their geometri- cal shape. Three important types of biological molecules are proteins, carbohydrates, and lipids. Proteins form from chains of amino acids to make many of the body’s physical struc- tures, such as hair and muscle. Proteins in cells also function as enzymes, which are mol- ecules that increase reaction rates between other molecules but are themselves unaffected by the reaction. Proteins thus mediate many of life’s chemical reactions. Carbohydrates are modular molecules built from sugars, which are relatively simple molecules built from carbon, oxygen, and hydrogen atoms. Carbohydrates provide an essential source of energy for all animals, and they provide much of the solid structure in the cellulose of plants. Lipids, including fats and oils, are molecules that will not dissolve in water. If the car- bon atoms form single bonds, the lipid is saturated, whereas molecules on which adjacent carbon atoms form double bonds are unsaturated. All cell membranes are constructed from bilayers of lipids, which are terminated by one end that attracts water and the other end that repels water.

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  Methods in Molecular Biophysics

  Structure, Dynamics, Function for Biology and Medicine

  • Nathan R. Zaccai, Igor N. Serdyuk, Joseph Zaccai(Authors)
  • 2017(Publication Date)
  • Cambridge University Press

    (Publisher)

  Macromolecules as Physical Particles 34 encountered in glycobiology (a term coined in 1988 to recognize the combination of the traditional discipline of carbohydrate biochemistry with the modern understand-ing of the role of complex sugars in cellular and molecular biology). Biological carbohydrates are divided into monosacchar-ides (single sugar subunits, e.g., glucose , from the Greek “ glycys , ” “ sweet ’ ; -ose is the generic nomenclature ending chosen for the monosaccharides), disaccharides (two cova-lently bound sugar subunits, e.g., sucrose ), oligosaccharides ( “ a few ” or several covalently bound sugar subunits), and polysaccharides ( “ many ” covalently bound sugar subunits) – the division between the oligo-and polysaccharide groups being fairly loose. Cellulose , a large linear polymer of glucose subunits, is the principal structural component in plants and the most common natural polysaccharide. Glycogen (from “ sweet ” and the root of “ gennaein , ” “ to produce ” or “ give birth ” ) is a complex branched polysaccharide of glucose subunits, stored as an energy source in liver and muscle cells. Linear and branched polysaccharide mixtures compose the starch (from the old English “ stercan ” meaning “ to stiffen ” ) gran-ules, which represent the main energy storage mechanism in plants. All cell types and many biological Macromolecules carry complex arrays of oligosaccharide chains called glycans , which also occur as free-standing entities. Most glycans are bound to excreted Macromolecules or to pro-tein or lipid molecules on the outer surfaces of cells, which are surrounded by a speci fi c carbohydrate-rich “ shell ” called the glycocalyx (from the Greek “ kalyx , ” a covering, not from the Latin “ calix , ” a cup). Glycans participate in speci fi c cell – cell and cell – macromolecule recognition events, cell matrix interactions in higher organisms, and interactions between different organisms, such as the ones between a parasite and its host.

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