2.4 Proteins

Guidance- The detailed structure of 6 proteins selected to illustrate the functions of proteins is not needed- Egg white or albumin solutions can be used in denaturation experiments.- Students should know that most organisms use the same 20 amino acids in the same genetic code , although there are some exceptions. Specific examples could be used for illustration.

UNDERSTANDINGS Amino acids are linked together by condensation to form polypeptides.

There are 20 different amino acids in polypeptides synthesized on ribosomes.

Amino acids can be linked together in any sequence, giving a huge range of possible polypeptides.

The amino acid sequence of polypeptides is coded for by genes.

Living organisms synthesize many different proteins with a wide range of functions.

Every individual has a unique proteome.

APPLICATIONS/SKILLS A: Rubisco, insulin, immunoglobulins, rhodopsin, collagen, and spider silk as examples of a range of protein functions.

A: Denaturation of proteins by heat or by deviation of pH from the optimum.

S: Drawing molecular diagrams to show the formation of a peptide bond.

Formation of polypeptides Polypeptide sequence controlled by genes

Composed of amino acids Sequence determines shape which determines function

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In an Aqueous Solution

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Denaturing proteins: temperature Increase in molecular motion puts stress on bonds Protein loses its shape which causes it to lose its function Could return to normal shape if returned to optimal temperature

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Denaturing proteins: pH Presence of extra charges interferes with hydrogen bonding

Prevents protein from taking on functional shape

HomeworkVOCAB OTHER

Challenge yourself #7Exercises 9-11

genepolypeptideR-groupn-terminal endc-terminal endprimary protein structuresecondary protein structure

tertiary protein structurequaternary protein structureproteinpolypeptidegenomeproteome