Carbon and the Molecular Diversity of Life

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PROPERTIES

Sulfhydryl

(may be written HS—)

Cysteine

Cysteine is an important sulfur-containing amino acid.

Thiols

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.

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Fig. 4-10f

STRUCTURE

EXAMPLE

NAME OF

COMPOUND

FUNCTIONAL

PROPERTIES

Phosphate

In addition to taking part in many important chemical reactions in cells, glycerol phosphate provides the backbone for phospholipids, the most prevalent molecules in cell membranes.

Glycerol phosphate

Organic phosphates

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.

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Fig. 4-10g

STRUCTURE

EXAMPLE

NAME OF

COMPOUND

FUNCTIONAL

PROPERTIES

Methyl

5-Methyl cytidine is a component of DNA that has been modified by addition of the methyl group.

5-Methyl cytidine

Methylated compounds

Addition of a methyl group to DNA, or to molecules bound to DNA, affects expression of genes.

Arrangement of methyl groups in male and female sex hormones affects

their shape and function.

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ATP: An Important Source of Energy for Cellular Processes

One phosphate molecule, adenosine triphosphate (ATP), is the primary energy-transferring molecule in the cell

ATP consists of an organic molecule called adenosine attached to a string of three phosphate groups

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Fig. 4-UN2

Slide 41

The Chemical Elements of Life: A Review

The versatility of carbon makes possible the great diversity of organic molecules

Variation at the molecular level lies at the foundation of all biological diversity

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Fig. 4-UN3

Adenosine

Slide 43

Fig. 4-UN4

P

P

P

P i

P

P

Adenosine

Adenosine

Energy

ADP

ATP

Inorganic phosphate

Reacts with H2O

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