Cell and Molecular Biology

Transcription

1 Cell and Molecular Biology ( ): academic year 2013 Content & Objective :Cell Chemistry and Biosynthesis 3 rd Edition, 1994, pp th Edition, 2002, pp th Edition, 2008, pp Exam: 10 marks/2 h lecture MEQ: 4-6 questions Professor Dr. Jerapan Krungkrai (jerapan.k@chula.ac.th)

2 1994, 2002, Gerald Karp: Cell & Mol Biol; 4 th edition, th edition 2008

3 Cytoplasm of cell is crowded. Proteins=Red, Ribosome=Green, RNAs=Blue Size= 100 nm (1 ribosome has a molecular mass of 2,700 kda; 1 bacterial cell contains ~ 20,000 ribosomes 1 human cell =??) Human cell: Types: ~ 220; number: ~ cells

4 In an atom, electron = proton = atomic number, (H atom has no neuton), If neutron + proton = atomic weight

5 hydrophobic

6 I. Chemical components of a cell In In human body: chemical elements (number of atoms in % of total) (number of atoms in % of total atoms) H= 64%, C= 8%, O= 25%, N= 2%, Ca+Mg+Na+K= 1%, others=1-2%. H = 64%, C= 8%, O = 25%, N= 2%, Ca+Mg+Na+K= 1%, others =1-2%. (Ref: Alberts et al, 2008) In human body: chemical elements (% of total dry weight) H = 10%, C= 50%, O = 20%, N= 8.5%, Ca+Mg+Na+K= 7%, others = 4.5%. (Ref: Biochemistry Textbook)

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9 1.1Water and acid-base Lattice

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11 1.2 Nearly all of the molecules in cell are carbon compounds.

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13 1.3.1 Sugars 1.3 Cells use four basic types of small molecules.

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15 1.3.2 Fatty acids

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17 1.3.3 Amino acids

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19 1.3.4 Nucleotides

20 coenzyme

21 Noncovalent bonds specify both the precise shape of a macromolecule and its binding to other molecules.

22 2. Biological order and energy 2.1 Biological order is made possible by the release of energy from cells Entropy, S disorder energy order Laws of Thermodynamics: 1. Energy conservation 2. Universe constantly changes so as to become more disordered (increase entropy, S) Gibbs free energy, G,

23 2.2 Photosynthetic organisms use sunlight to synthesize organic compounds

24 2.3 Chemical energy passes from plants to animals, as carbon cycle Respiration by microorganisms

25 2.4 Cells obtain energy by the oxidation of biological molecules Reduced Oxidized atom Reduced atom energy Oxidized Each of these steps is energetically favorable inside a cell.

26 2.5 The breakdown of an organic molecule takes place in a sequence of enzyme-catalyzed reactions Principle of activation energy Enzyme catalysis; a) jiggling-box model b) energy distribution of the identical molecules

27 Enzyme catalysis

28 Coupling reactions

29 2.6 Parts of energy released in oxidation reactions is coupled to the ATP formation. Catabolism Anabolism 2.7 ATP hydrolysis generates order in cells.

30 3. Food and the derivation of cellular energy 3.1 Food molecules are broken down in three stages to give ATP. Catabolism from food ATP waste products (CO 2, H 2 O, NH 3 )

31 3.2 Glycolysis

32 3.3 NADH is a central intermediate NADH=Nicotinamide adenine dinucleotide Pyruvate dehydrogenase Acetyl CoA

33 3.4 Krebs cycle (tricarboxylic acid, TCA cycle or citric acid cycle) 3.5 Electron transport chain forms a proton gradient and generate ATP 1 Glucose ATP ATP

34 4. Biosynthesis and the creation of order 4.1 Free-energy change for a reaction determines whether it can occur. delta G. 4.2 Biosynthetic reactions are often directly coupled to ATP hydrolysis. ATP hydrolysis e.g. high-energy intermediates driven by ATP hydrolysis

35 High-energy intermediates driven by ATP hydrolysis and generate polymer from its monomer 4.3 The structure of some coenzymes, involving in transfer of specific chemical groups, suggests that they may have originated in an RNA world, e.g., ATP, NADH, acetyl CoA (contains adenine and ribose moiety)

36 4.4 Biological polymers are synthesized by repetition of elementary dehydration reactions Monomers or subunits Polymers

37 5. The coordination of catabolism and biosynthesis (anabolism) Metabolism

38 Coordination of catabolism and anabolism Metabolism Metabolism is organized and regulated, through the change of enzyme activity, Metabolic maps of 500 reactions e.g.,1) allosteric control 2) covalent modification 3) multienzyme complex 4) compartmentation Cholesterol metabolic pathway

39 Feedback inhibition Glycolysis and Gluconeogenesis (enzymes 1,3, 9 for glucose pyruvate) Phosphofructokinase Example, bacterial amino acids pathway energy

40 Multienzyme complex Increase enzyme efficiency

41 Compartmentation: 1) Within cells 2) Within organisms Cori s cycle: Nobel 1947

42 Cell and Molecular Biology ( ) Content & Objective Cell Chemistry and Biosynthesis 3 rd Edition, 1994, pp th Edition, 2002, pp th Edition, 2008, pp Exam: 10 marks/ 2h lecture MEQ: 4-6questions