1 / 14

Chapter 4

Chapter 4. Biochemistry: The Role of Functional Groups. OH. CH 3. Estradiol. HO. Female lion. OH. CH 3. CH 3. O. Testosterone. Male lion. Figure 4.9. Functional groups. Are the chemically reactive groups of atoms within an organic molecule

westkenneth
Télécharger la présentation

Chapter 4

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 4 Biochemistry: The Role of Functional Groups

  2. OH CH3 Estradiol HO Female lion OH CH3 CH3 O Testosterone Male lion Figure 4.9 Functional groups • Are the chemically reactive groups of atoms within an organic molecule • Give organic molecules distinctive chemical properties

  3. Important Functional Groups • Six functional groups are important in the chemistry of life • Hydroxyl • Carbonyl • Carboxyl • Amino • Sulfhydryl • Phosphate

  4. FUNCTIONAL GROUP HYDROXYL O O OH C C OH (may be written HO ) STRUCTURE In a hydroxyl group (—OH), a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Do not confuse this functional group with the hydroxide ion, OH–.) Figure 4.10 Hydroxyl group • Polar, thus water-soluble; forms hydrogen bonds Is polar as a result of the electronegative oxygen atom drawing electrons toward itself.  Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3).

  5. FUNCTIONAL GROUP HYDROXYL CARBONYL CARBOXYL O O OH C C OH (may be written HO ) The carbonyl group consists of a carbon atom joined to an oxygen atom by a double bond. STRUCTURE Figure 4.10 Carbonyl  C=O

  6. Carbonyl group A ketone and an aldehyde may be structural isomers with different properties, as is the case with many monosaccharides.

  7. FUNCTIONAL GROUP HYDROXYL CARBONYL CARBOXYL O O OH C C OH (may be written HO ) STRUCTURE When an oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group, the entire assembly of atoms is called a carboxyl group (—COOH). Figure 4.10 Carboxyl • Weak acid (hydrogen donor); when it loses a hydrogen, it becomes negatively charged (polar)

  8. The covalent bond between oxygen and hydrogen is so polar that hydrogen ions (H+) tend to dissociate reversibly; for example, H H O O + H+ H C H C C C OH O H H  In cells, found in the ionic form, which is called a carboxylate group. Figure 4.10 Carboxyl  Has acidic properties because it is a source of hydrogen ions.

  9. Ketones if the carbonyl group is within a carbon skeleton Aldehydes if the carbonyl group is at the end of the carbon skeleton NAME OF COMPOUNDS Alcohols (their specific names usually end in -ol) Carboxylic acids, or organic acids EXAMPLE H H H H O O C C H OH C C H C H C H OH H H H H C Ethanol, the alcohol present in alcoholic beverages H H Acetic acid, which gives vinegar its sour tatste Acetone, the simplest ketone H H O H C C C H H H Propanal, an aldehyde Figure 4.10 Examples: • Some important functional groups of organic compounds

  10. AMINO SULFHYDRYL PHOSPHATE O H SH N P OH O (may be written HS ) H OH The amino group (—NH2) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton. Figure 4.10 Some important functional groups of organic compounds • AMINO group • Weak base (hydrogen acceptor); when it accepts a hydrogen, it becomes positively charged

  11.  Acts as a base; can pick up a proton from the surrounding solution: H H N +N H H H (nonionized) (ionized)  Ionized, with a charge of 1+, under cellular conditions. Figure 4.10 Amino • Some important functional groups of organic compounds H+ glycine

  12. AMINO SULFHYDRYL PHOSPHATE O H SH N P OH O (may be written HS- ) H OH The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape. Figure 4.10 Sulfhydryl group • Ability to form disulfide “bridges”; important in stabilizing protein structure (cysteine) Disulfide “bridge” between amino acids (cysteine) often hold proteins in their specific 3D shapes

  13. Figure 4.10 AMINO SULFHYDRYL PHOSPHATE O H SH N P OH O (may be written HS ) H OH In a phosphate group, a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges; abbreviated P . The phosphate group (—OPO32–) is an ionized form of a phosphoric acid group (—OPO3H2; note the two hydrogens). Phosphate group • Acid (hydrogen donor) in solution; usually negatively charged (anionic) • Useful in transferring energy between organic molecules (ATP) • Present in the backbone of DNA and RNA

  14. OH O OH H H H H H O H C C C O P O N C C SH H C C HO H H H H O H H H Ethanethiol Glycine Glycerol phosphate Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. Figure 4.10 Some important functional groups of organic compounds

More Related