monomeri polimeri

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.

I legami che aiutano le proteine a ripiegarsi

cisteine:cisteine ponti disolfuro

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:

 -helix

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

 1998 GARLAND PUBLISHING Beta foglietto

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

Tertiary structure.  proteins.

Tertiary structure.  -barrel. Greek key motif

Tertiary structure. Membrane proteins.

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

Quaternary structures. Haemoglobin HIV-1 protease K+ channel

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, while the amyloid protein can change into b-conformation forming aggregates, and plaques

monomeri polimeri

Struttura tipo di un nucleotide

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

A G C U T

cytosine OH C NH2

Struttura tipo di un nucleotide

nucleoside AMPADPATP nucleotide H adenosina

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

8 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)

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

NTP NDP + Pi 8

+ ATP ADP Pi

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.

Acidi Nucleici 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

Il DNA è un polimero di desossiribonucleotidi

ribonucleotidi Il RNA è un polimero di ribonucleotidi

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