生物化学英文课件Biochemistry-chapter 1(英文2)

Orderliness:
A glance at a metabolic pathway map.
1.5.4 Biochemistry and Evolution
➢All cells on Earth appear to have evolved from a common ancestry that existed more than 3 billion years ago.
Diverse living organisms
1.5.5 The Cell Is the Basic Unit of Life
( Structure multilevel )
1.5.1 The Chemical Elements of Life
★ The elemental composition of living matter differs markedly from the relative abundance of elements in the earth’s. ★ Only six nonmetallic elements-- carbon, Hydrogen, oxygen, nitrogen, phosphorus, and sulfur—account for more than 97% of the weight of most organisms. ★ Water is a major component of cells and accounts for the high percentage of oxygen.
1.5 Basic Phenomena of living systems
➢1.5.1 The Chemical Elements of Life ➢1.5.2 Many Important Biomolecules Are
Polymers ➢1.5.3 The Energetics of Life ➢1.5.4 Biochemistry and Evolution ➢1.5.5 The Cell Is the Basic Unit of Life
Living systems have a remarkable capacity for self-replication.So biological reproduction occurs with near-perfect fidelity .
In the DNA double helix, two complementary polynucleotide chains running in opposite directions can pair through hydrogen bonding between their nitrogenous bases. Their complementary nucleotide sequences give rise to structural complementarity.
The most important elements.
A total of 29 different elements are commonly found in living organisms.These include five ions that are essential in all species: Ca+, K+, Na+, Mg+ and Cl-.
Photosynthesis is one of the key biochemical processes that is essential for life, even though many species, including animals,benefit only indirectly.
ATP and NADPH, two biochemically important energy-rich compounds.
➢Thermodynamic principle also apply to biochemistry.
➢The spontaneity of a reaction depends on the overall free-energy change(ΔG),which is expressed as:
choline etc.
A topological model of the monosaccharide transporter
Biomolecules Have Characteristic ThreeDimensional Structure
IgG
➢Covalent bonds hold atoms together so that molecules are formed.
Metabolic Regulation Is Achieved by Controlling the Activity of Enzymes
➢Thousands 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.
★ Biomolecules Are Carbon Compounds. ★ Biochemical reactions involve specific chemical bonds and functional groups—ester, ether, amide, phosphate ester and phosphoanhydride linkages. ★ The major precursors for the formation of biomolecules are water, carbon dioxide, and three inorganic nitrogen compounds——— ammonium (NH4+), nitrate (NO3-), and dinitrogen (N2).
➢In contrast, weak chemical forces or noncovalent bonds are intramolecular or intermolecular attractions between atoms.
➢Weak forces maintain biological structure and determine biomolecular interactions
➢The evidence for includes the presence in all living organisms of common biochemical building blocks, the same general patterns of metabolism, and a common genetic code.
Energy Flow
Living systems are actively engaged in energy transformations
Carnivores Herbivores
Photosynthesis
Food pyramid
A prairie falcon acquires nutrients by consuming a smaller bird.
➢The same basic structural units (cells) ➢The same kinds of macromolecules (DNA, RNA, proteins) made up of the same kinds of monomeric subunits (nucleotides, amino acids). ➢They utilize the same pathways for synthesis of cellular components, share the same genetic code, and derive from the same evolutionary ancestors.
Some functional groups and linkages of biomolecules
甲基 乙基 苯基
氨基 胺基
胍基
羰基 醛
羰基 酮
羧基
咪唑 巯基 二硫键
羟基 醚 酯 酐
硫酯 磷酰基
磷酸酐 酰基磷 酸酯
Examples
（肾上腺素）
Why do Diverse living organisms share common chemical features?
a protein recognizes its specific metabolite, a strand of DNA recognizes its complementary strand, sperm recognize an egg.
1.5.3 The Energetics of Life ( Metabolism )
ΔG= ΔH-T· ΔS
➢When ΔG<0, the reaction is spontaneous;
➢When ΔG>0, the reaction requires external energy to proceed;
➢When ΔG=0, the reaction is at equilibrium.
Weak Forces
Hydrogen bonds, Van der Waals forces, Ionic interactions, Hydropinciple of structural complementarity is the very essence of biomolecular recognition. ➢Biological systems from the macromolecular level to the cellular level operate via specific molecular recognition and interactions mechanisms based on structural complementarity:
The rate of a reaction depends on the acivation energy
The rates of enzyme-catalyzed reactions can be up to 1017 times greater than the rates of the corresponding uncatalyzed reactions.
1.5.2 Many Important Biomolecules Are Polymers ( biochemistry identity )
Macromolecules (biopolymers) are composed of building blocks (monomers)
➢Proteins----amino acids ➢Nucleic acids----nucleotides ➢Polysaccharides----sugars ➢Lipids----fatty acids, glycerol and