2.1 Von Molekülen zum Stoffwechsel

Kohlenstoffatome können vier kovalente Bindungen bilden. C C H O H H Figure: 3-UN7 Title: Amino acid structure

Kohlenstoff ist wichtig für alle organischen Verbindungen Organische Moleküle Kohlenhydrate Monosaccharide Glukose Ribose Fruktose Disaccharide Saccharose (Glukose + Fruktose) Maltose (Glukose + Glukose) Laktose (Glukose + Galaktose) Polysaccharide Stärke (Pflanzen) Amylose Amylopectin Glykogen (Tiere) Zellulose (Zellwand) Lipide Fettsäuren + Glycerin Gesättigte Fettsäuren Ungesättigte Fettsäuren monoungesättigt polyungesättigt cis trans z.B. Phospholipide, Steroide, Triglyceride Proteine Aminosäuren Dipeptide Polypeptide Nukleinsäuren Nukleotide DNA RNA

organisch - anorganisch Alle organischen Verbindungen haben Kohlenstoff. Aber: nicht alle Kohlenstoffverbindungen sind organisch, z.B. CO2 Carbonate

Organische Verbindungen können auch künstlich produziert werden. z. B Organische Verbindungen können auch künstlich produziert werden. z.B. Harnstoff (urea)

Stoffwechsel (Metabolismus) Anabolismus Katabolismus Synthese komplexer Moleküle aus einfacheren Molekülen, auch die Bildung von Makromolekülen aus Monomeren durch Kondensationsreaktionen. Auflösung komplexer Moleküle zu einfacheren Molekülen, auch die Hydrolyse von Makromolekülen zu Monomeren.

Kondensation kleine Moleküle (Monomere) verbinden sich mit anderen Monomeren durch eine Kondensationsreaktion. Dabei wird Wasser abgespalten.

Hydrolyse Große Moleküle (Polymere) werden in kleine Moleküle gespalten. Wasser wird angelagert.

Kondensation Aminosäuren Dipeptide, Polypeptide Hydrolyse Monosaccharide (z.B. Glukose) Kondensation Disaccharide, Polysaccharide Hydrolyse Fettsäuren und Glycerin Kondensation Lipide Hydrolyse

Aminosäure Aminosäure Kondensation H H O H H O N C C N C C H H R OH R

Aminosäure Aminosäure Kondensation H H O H H O N C C N C C H H R OH R

WASSER Peptidbindung Aminosäure Aminosäure Kondensation H OH H H O H H C C N C C OH H H R R OH WASSER Peptidbindung

Kohlenhydrate H CH2OH HO OH O Glukose C6H12O6 Monosaccharid

Kohlenhydrate Ribose HOCH2 CH2OH HO H O Monosaccharid

Kohlenhydrate Stärke Polysaccharid 100 micrometer Stärkekörner CH2OH Figure :3-3 Title: Starch is an energy-storage polysaccharide made of glucose subunits Caption: (a) Starch globules inside individual potato cells. Most plants synthesize starch, which forms water-insoluble globules consisting of many starch molecules and makes up the bulk of this potato. (b) A small portion of a single starch molecule. Starch commonly occurs as branched chains of up to half a million glucose subunits. (c) The precise structure of the blue highlighted portion of the starch molecule in (b). Note the linkage between the individual glucose subunits for comparison with cellulose (Fig. 3-4). Stärke Polysaccharid

Lipide Glycerin Fettsäuren Triglycerid C OH H C O HO CH etc. CH2 CH C Figure :3-6 Title: Synthesis of a triglyceride Caption: Dehydration synthesis links a single glycerol molecule with three fatty acids to form a triglyceride.

Lipide gesättigte Fettsäuren (ohne C=C Doppelbindungen) Figure: 3-UN5 Title: Saturated fat gesättigte Fettsäuren (ohne C=C Doppelbindungen)

Lipide trans mono- ungesättigt cis poly- ungesättigt ungesättigte Fettsäuren (mit C=C Doppelbindungen)

Lipide Cholesterin, ein Steroid CH3 HC CH3 CH2 CH2 CH2 HC CH3 CH3 CH3 Figure :3-9 Title: Steroids Caption: Steroids are synthesized from cholesterol. All steroids have almost the same molecular structure (note the colored, fused carbon rings in all). Differences in steroid function result from differences in functional groups attached to the rings. Notice the similarity between the male sex hormone testosterone and the female sex hormone estradiol (estrogen). Question Why are steroid hormones able to act by binding with molecules inside the cell nucleus, while other types of hormones (i.e., not steroids) act only by interacting with molecules on the outside of the cell membrane? CH3 Cholesterin, ein Steroid HO

Phospholipid, in allen Membranen Lipide - CH3 - CH2 - CH3 O CH2 - CH2 - CH2 H3 - CH2 C-N-CH2 -CH2 -O-P-O-CH2 O - CH2 - CH2 = CH2 CH3 O HC-O-C- CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 O H2 C-O-C- CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH2 -CH3 polarer Kopf Glycerin Fettsäuren (hydrophil) (hydrophob) Figure :3-8 Title: Phospholipids Caption: Phospholipids have only two fatty acid tails attached to the glycerol backbone. The third position is occupied by a polar head consisting of a phosphate group (–PO4–) to which a second (typically nitrogen-containing) functional group is attached. The phosphate group is negatively charged, and the nitrogen-containing group is positively charged. Phospholipid, in allen Membranen

Proteine Aminosäure R O N C H Amino gruppe variable Restgruppe Carboxyl- O C R H N Figure: 3-UN7 Title: Amino acid structure

Proteine Aminosäure Dipeptid Peptid bindung Wasser Figure :3-12 Title: Protein synthesis Caption: In protein synthesis, a dehydration synthesis joins the carbon of the carboxyl acid group of one amino acid to the nitrogen of the amino group of a second amino acid. The resulting covalent bond is called a peptide bond.

Proteine Figure :3-13 Title: The four levels of protein structure gly leu leu val val lys lys lys gly his lys ala gly lys val his lys pro ala lys val lys Figure :3-13 Title: The four levels of protein structure Caption: Levels of protein structure are represented here by hemoglobin, the oxygen-carrying protein in red blood cells (the red discs represent the iron-containing heme group that binds oxygen). All levels of protein structure are determined by the amino acid sequence of the protein, interactions among the R groups of the amino acids, and interactions between the R groups and their surroundings. Question Why do most proteins, when heated, lose their ability to function? pro