页数：129页文件大小：7.21 MB来源： 生物化学ppt课件
本课件为英文教材的第一章，依次讲生命系统的独特性质、构成生命的主要生物分子类型、由简单分子到超分子复合物的层次结构，以及生物分子的结构与功能适配关系；最后讲原核细胞与真核细胞的组织结构差异，并以病毒作为超分子组装的例子收尾。
1.1Distinctive Properties of LivingSystemsComplicated and highly organized
The Orion Nebula, a tremendous cloud of gas in which many hot, young stars are evolving rapidly toward cataclysmic cosmic explosions called supernovea. Energy released by nuclear explosions in such supernovea brought about the fusion of simple atomic nuclei, forming the more complex elements of which the earth, its atmosphere, and all living things are composed.
(a) Mandrill (Mandrillus sphinx), a baboon native to West Africa. (b) Tropical orchid (Bulbophyllum blumei), New Guinea.
Some characteristic of living matter.
Kaleidoscopes of life
Biological structures servefunctional purposes.
Microscopic complexity and organization are apparent in this colorized thin section
Living systems are actively engaged in energytransformationsCarnivores, Herbivores, PhotosynthesisFood pyramid
A prairie falcon acquires nutrients by consuming a smaller bird.
ATP and NADPH, two biochemically important energy-rich compounds.
Living systems have a remarkable capacity for self-replication.Living systems have aremarkablecapacityfor self-replication.
Biological reproduction occurs with near-perfect fidelity (zebra).
The DNA double helix. Two complementary polynucleotide chainsrunning in opposite directions can pair through hydrogen bondingbetween their nitrogenous bases. Their complementary nucleotidesequences give rise to structural complementarity.
The chemicalcomposition ofliving material,such as thisjellyfish(水母),differs from thatof its physicalenvironment,which for thisorganism is saltwater.
The elemental composition of livingmatter differs markedly from therelativeabundance of elements in the earth’s.Hydrogen,oxygen,carbon, andnitrogenconstitute more than 99% of theatoms inthe human body, with most of the H andO occurring as H2O.
水母Elements essential to animal life and health
Biomolecules Are CarbonCompounds
Aliphatic(脂肪族的, 脂肪质的)
Metabolites and MacromoleculesThe major precursors for the formation ofbiomolecules are water, carbon dioxide, and threeinorganic nitrogen compounds—ammonium (NH4+),nitrate (NO3-), and dinitrogen (N2). Metabolicprocesses assimilate and transform these inorganic
Some functional groups of biomolecules
1.3 • A Biomolecular Hierarchy:Simple Molecules Are theUnits for Building ComplexStructures
Prebiotic EvolutionThe finding that all biological macromolecules in all organism are made from the same three dozen subunits has provided strong evidence that modern organism are descended from a single primordial cell line whose fundamental chemistry would be recognizable even today.
Biomolecules first arose bychemical evolutionAleksandr I Oparin’s theory:Electrical energy from lightning discharges or heat energy from volcanoes cause ammonia, methane , water vapor, and other compounds of the primitive atmosphere to react, forming simple organic compounds.
These compounds then dissolved in the ancient seas, which over many millenia became enriched with a large variety of simple organic substances. In the warm solution(the “primordial soup”), some organic molecules had a greater tendency than others to associate into larger complexes.
Over millions of years, these in turn assembled spontaneously to form membranes and catalysts (enzyme), which came together to become precursors of earliest cells.
Chemical evolution can be simulated in the laboratory. A spark-discharge apparatus
RNA or related precursors may have been the first genes and catalystsIn modern organism, nucleic acids encode the genetic information that specifies the structure of enzymes, and enzymes have the ability to catalyze the replication and repair of nucleic acids, the mutual dependence of two classes of biomolecules bring up the perplexing question: which came first, DAN or proteins?
which came first, DAN or proteins?The answer may be: neither.The discover that RNA molecules can act as catalysts in their own formation suggests that RNA or similar molecules may have been the first gene and the first catalyst.
One possible “RNA world” scenario, showing the transition from the prebiotic RNA world(shades of yellow) to the biotic DNA world (orange).
The “RNA world” hypothesis is plausible but by no means universally accepted. The hypothesis does make testable prediction, and to the extent that experimental tests are possible within finite time, the hypothesis will be tested and refined.
Biological evolution began more than three and half billion years ago.
Ancient reefs in Australia contain fossil evidence of microbial life in the sea of 3.5 billion years ago. Bits of sand and limestone became trapped in the sticky extracellular coats of cyanobacteria, gradually building up these stromatolites(岩层)found in Hamelin Bay, Western Australia.
Microscopic examination of sections of such ancient rock reveals microfossils of filamentous becteria(b), interpreted as shown in the drawing(b).
1.4• Properties of BiomoleculesReflect Their Fitness to theLiving Condition
Biological Macromoleculesand Their Building BlocksHave a“Sense”orDirectionality
The macromolecules of cells are built of units—amino acids in proteins, nucleotides in nucleic acids, and carbohydrates in polysaccharides—that have structural polarity.That is, these molecules are not symmetrical, and so they can be thought of as having a “head” and a “tail.” Polymerization of these units to form macromolecules occurs by head-to-tail linear connections. Because of this, the polymer also has a head and a tail, and hence, the macromolecule has a “sense” or direction to its structure.
Biological Macromolecules Are Informational
Biological Macromolecules Are Informational
Biological Macromolecules Are Informational
Biomolecules Have Characteristic Three-Dimensional Architecture
G (IgG, Immunoglobulin G is a major type of circulating antibody. Each of the spheres represents an atom in the structure.
Weak Forces Maintain Biological Structure and Determine Biomolecular InteractionsCovalent bondshold atoms together so that molecules are formed. In contrast, weak chemical forces or noncovalent bonds, (hydrogen bonds, van der Waals forces, ionic interactions, and hydrophobic interactions) are intramolecular or intermolecular attractions between atoms.
Hydrogen bonds,Van der Waals forces,Ionic interactions, Hydrophobic interactions
Structural Complementarity Determines Biomolecular Interactions
This principle of structural complementarity is the very essence of biomolecular recognition. Structural complementarity is the significant clue to understanding the functional properties of biological systems. Biological systems from the macromolecular level to the cellular level operate via specific molecular recognition mechanisms based on structural complementarity: a protein recognizes its specific metabolite, a strand of DNA recognizes its complementary strand, sperm recognize an egg. All these interactions involve structural complementarity between molecules.
Biomolecular Recognition Is Mediated by Weak Chemical ForcesWeak Forces Restrict Organisms to a Narrow Range of Environmental Conditions The central role of weak forces in biomolecular interactions restricts living systems to anarrow range of physical conditions.
EnzymesThe sensitivity of cellular constituents to environmental extremes places another constraint on the reactions of metabolism.
Metabolic Regulation Is Achieved by Controlling the Activity of EnzymesThousands of reactions mediated by an equal number of enzymes are occurring at any given instant within the cell. Metabolism has many branch points, cycles, and interconnections.This metabolic regulation is achieved through controls on enzyme activity so that the rates of cellular reactions are appropriate to cellular requirements.
A glance at a metabolic pathway map
1.5 • Organization and Structure of Cellsprokaryotic eukaryotic
All living cells fall into one of two broad categories—prokaryotic and eukaryotic. The distinction is based on whether or not the cell has a nucleus. Prokaryotes are single-celled organisms that lack nuclei and other organelles; the word is derived from promeaning “prior to” and karyotmeaning“nucleus.” Eukaryotic cells have true nuclei and other organelles such as mitochondria, with the prefix eumeaning “true.”
Structural Organization of Prokaryotic Cells
A dividing Escherichia coli(E. coli )cell
Dividing Saccharomyces cerevisiae(baker’s yeast ) cell
Structural Organization of eukaryotic Cells
Nuclear pores
nucleusNuclear pores
chromosome
Structure of a mitochondrion
Structure of a chloroplast
Portion of a skeletal muscle cell(artificial color)
Collenchyma（厚角组织）cells of a plant stem
Human sperm cells (artificial color)
Mature human erythrocytes (artificial color)
Human embryo at the two-celled stage cells
1.6 • Viruses Are Supramolecular Assemblies Acting as Cell ParasitesVirusVirions, nonliving particles(outside of the host cells)Bacteriophages, simply phages, specific for the becteria.
HIV
(a) a bacterial virus, bacteriophage T4; (b) an animal virus, adenovirus (inset at greater magnification); (c) a plant virus, tobacco mosaic virus.
Orion NebulaCataclysmicKaleidoscopesCarnivoreHerbivorePrairieFidelityMaterialElementalAmmoniumMetaboliteHierarchyNew Words ReviewPrebioticPrimitiveApparatusPerplexingHypothesisPlausibleMicrobialCovalentParasiteinstant PriorErythrocytesVirusVirionPhenomenaReflectPropertiesAssemblyFitnessComplicatedTremendousAtmosphere
ComplementarityComplementComplementary CompositionGlycerolPolysaccharidesNucleotideAmino acidsSpontaneouslyCatalystPrecursorsimulated ScenarioMicrobialStromatolitesFilamentousRevealDirectionalityPolarityCarbohydratesSymmetricalArchitectureImmunoglobulinSphereLeukocyteErythrocytesEmbryoBacteriophageTobacco mosaic virus
The End ofChapter 1
Topics of Discussion1 What Are Distinctive Properties of LivingSystem?2 How Many Types of the ImportantBiomacromolecules?3 What Are Features of Biomolecules? 4 Talk About the Organization and Structure of Cells.
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