Acqua (H2O). Acqua (H2O) Gliceraldeide - lo zucchero più piccolo OH H H2 (CH20)3 = Carbo - idrato (CH20)n n compreso tra 3 e 8.

Presentazione sul tema: "Acqua (H2O). Acqua (H2O) Gliceraldeide - lo zucchero più piccolo OH H H2 (CH20)3 = Carbo - idrato (CH20)n n compreso tra 3 e 8."— Transcript della presentazione:

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2 Acqua (H2O)

3 Gliceraldeide - lo zucchero più piccolo
OH H H2 (CH20)3 = Carbo - idrato (CH20)n n compreso tra 3 e 8

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5 monomeri polimeri

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13 What is a protein? A protein is a polymer of of fixed length, composition and structure made by a combination of the 20 naturally occurring amino acids.

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21 I legami che aiutano le proteine a ripiegarsi

22 cisteine:cisteine ponti disolfuro

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24 The structure of proteins can be defined in a hierachical way
Primary structure: the AA sequence (Thr-Gly-Leu-Pro-…) Secondary structure: local repetitive motifs common to most classes of protein structures Tertiary structure: the 3D arrangement of the secondary structure motifs to form a compact protein. Quaternary structure: the arrangements of several proteins units to form a functional multimeric structure. The coordinates of all the known structures of proteins can be found in the Protein Data Bank:

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26 a-helix

27 Secondary structure. The a-helix.
The a-helix is the most common secondary structure found in proteins. Low strain and intramolecular repulsion of backbone and side chains. a-helices are stabilized by a number of factors. Favorable dipolar interaction in the backbone. Very compact structure, small solvent exposed surface.

28 Beta foglietto 1998 GARLAND PUBLISHING

29 Secondary structure. The b-sheet.
The b-sheet is made by parallel or antiparallel extended strands connected by a network of hydrogen bonds. Parallel b-sheet Antiparallel b-sheet

30 Tertiary structure. a-b proteins.

31 Tertiary structure. b-barrel.
Greek key motif

32 Tertiary structure. Membrane proteins.

33 Tertiary structure. DNA-binding proteins.
Cys Cys Zn Cys Cys The zinc finger

34 Quaternary structures.
K+ channel Haemoglobin HIV-1 protease

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39 PrPc NORMAL CONFORMATION
Predominantly alpha-helical Protease sensitive Glycoside modification Sialoglycoprotein associated to cell membrane by covalent attachement to phospholipid (GPI anchor)

40 PrPc NORMAL CONFORMATION
Normally associated to cell membrane of neurons Probably involved in synaptic function

41 THE DISEASE-ASSOCIATED ISOFORM: PrPsc
Predominantly beta-sheet Relatively resistant to proteases It accumulates in brain tissue and can cause apoptosis The infectious form has the same aminoacidic sequence seen in the normal one

42 PrPc & PrPsc From alpha helical to beta-sheet:
the change of conformation is due to a distension of the protein structure

43 AMPLIFICATION OF PrPsc
PrPc PrPSc PrPSc PrPSc Amplification of PrPSc and possible depletion of PrPc The distorted protein can bind to others and induce them to change their conformation as well, producing a chain reaction

44 Alzheimer’s: Protein Folding gone Wrong….
An amyloid plaque in Alzheimer’s disease is a tangle of protein filaments The amyloid protein (42-43 residues) is derived by proteolytic cleavage of the amyloid precursor protein, a constituent of many healthy cells APP has a-helical conformation, the amyloid protein can change into b-conformation forming aggregates, and plaques

45 monomeri polimeri

46 Struttura tipo di un nucleotide

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48 A Nucleoside(-tide) Base H+ Sugar P O OH HO NH2 N - OH O CH2 H
Phosphate NH2 N Base - H+ OH O CH2 Sugar H 2’ 3’ 4’ 5’ 1’ Nucleotide Legame N- glicosilico Nucleoside Ribosio 2-Deossiribosio OH

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50 A G C U T

51 C cytosine OH NH2

52 Struttura tipo di un nucleotide

53 nucleoside nucleotide H adenosina ATP ADP AMP

54 Functions of nucleotides:
Energy cycle Cofactors for enzymes Phosphate donors Information flow

55 Nucleotides Are Very Important
Nucleotides have many other functions: • They carry chemical energy in their easily hydrolyzed phosphoanhydride bonds. Example - ATP 2. They combine with other groups to form coenzymes. Example - coenzyme A (CoA) 3. They are used as specific signaling molecules in the cell. Example - cyclic AMP (cAMP)

56 What is ATP? An organic molecule that stores and releases chemical energy for use in body cells r

57 Nucleotides and the Energy Cycle
8 Nucleotides and the Energy Cycle NTP NDP + Pi

58 ATP + Pi ADP

59 LA CELLULA PERSEGUE DUE OBIETTIVI FONDAMENTALI:
la crescita cellulare il differenziamento cellulare In un contesto cellulare sociale, quale il tessuto e/o l’organo, i meccanismi responsabili della crescita e del differenziamento cellulare devono essere tra loro integrati e finemente regolati (omeostasi cellulare). I programmi di crescita e differenziamento cellulare sono geneticamente determinati.

60 Gli Acidi Nucleici sono le macromolecole depositarie dell’informazione genetica.
Due Tipi di Acidi Nucleici DNA → polimero di desossiribonucleotidi RNA → polimero di ribonucleotidi I Nucleotidi sono le subunità degli Acidi Nucleici

61 Il DNA è un polimero di desossiribonucleotidi

62 Il RNA è un polimero di ribonucleotidi

63 Gli Acidi Nucleici sono polimeri di nucleotidi legati tra loro da
legami fosfodiesteri tra i C 5’ e 3’