Macromoleculas

8/23/2010

M ACROMOLÉCULAS

BIOLOGIA MOLECULAR 436

I NTRODUCCIÓN
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I NTRODUCCIÓN
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Las células están constituidas de un 70–95% de agua, y el resto consiste mayormente de compuestos basados de carbono El carbono es inigualable en su habilidad de formar moléculas grandes, complejas y diversas

Moléculas que contienen carbono son llamadas en general MOLECULAS ORGÁNICAS La QUÍMICAORGÁNICA estudia los compuestos que contienen carbono

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I NTRODUCCIÓN
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M OLÉCULAS
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ORGÁNICAS

Algunas moléculas formadas por compuestos de carbono son: Proteínas Ácidos nucleícos

Las propiedades distintivas de las moléculas orgánicas dependen no solo del esqueleto de carbono que las forman sino también de los grupos funcionales pegados aellas Varios grupos característicos están a menudo pegados a los esqueletos de las moléculas orgánicas
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Carbohidratos
Lípidos
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G RUPOS
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FUNCIONALES

G RUPOS

FUNCIONALES

Son los componentes de las moléculas orgánicas que están envueltos frecuentemente en las reacciones químicas El número y arreglo de los grupos funcionales le da propiedades únicas a cada moléculaEstradiol

Testosterona

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G RUPOS

FUNCIONALES

Los 7 grupos funcionales más importantes son:
 Grupo hidroxilo  Grupo carbonilo  Grupo sulfhidrilo  Grupo fosfato

 Grupo carboxilo
 Grupo amino

 Grupo metilo

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CHEMICAL GROUP

Amino

Sulfhydryl

Phosphate

Methyl

STRUCTURE

(may be written HS—)

Carboxyl
In a phosphategroup, a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges. The phosphate group (—OPO32–, abbreviated P ) is an ionized form of a phosphoric acid group (—OPO3H2; note the two hydrogens). Organic phosphates A methyl group consists of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or toa different atom.

The amino group (—NH2) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton.

The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape.

STRUCTURE

Carboxylic acids, or organic acids

NAME OF COMPOUND

NAME OF COMPOUND

Amines

Thiols

Methylated compounds

EXAMPLEEXAMPLE Glycine Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. Cysteine Cysteine is an important sulfur-containing amino acid. Glycerol phosphate In addition to taking part in many important chemical reactions in cells, glycerol phosphate provides the backbone for phospholipids, the most prevalent molecules incell membranes. Contributes negative charge to the molecule of which it is a part (2– when at the end of a molecule; 1– when located internally in a chain of phosphates). Has the potential to react with water, releasing energy. 5-Methyl cytidine 5-Methyl cytidine is a component of DNA that has been modified by addition of the methyl group. Addition of a methyl group to DNA, or to molecules bound toDNA, affects expression of genes. Arrangement of methyl groups in male and female sex hormones affects their shape and function.

Has acidic properties because the covalent bond between oxygen and hydrogen is so polar; for example, Acetic acid, which gives vinegar its sour taste

FUNCTIONAL PROPERTIES

FUNCTIONAL PROPERTIES

Acts as a base; can pick up an H+ from the surrounding solution(water, in living organisms).

Two sulfhydryl groups can react, forming a covalent bond. This ―cross-linking‖ helps stabilize protein structure. Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be ―permanently‖ curled by shaping it around curlers, then breaking and re-forming the cross-linking bonds.

Acetic acid

Acetate ion...