PROTEINS

Characteristics of Proteins Contain carbon, hydrogen, oxygen, nitrogen, and sulfur Serve as structural components of animals Serve as control molecules (enzymes) Serve as transport and messenger molecules Basic building block is the amino acid

Proteins Function: many, many functions hormones movement signals from one body system to another insulin movement muscle immune system protect against germs enzymes help chemical reactions

Amino Acid Amine group acts like a base, tends to be positive. Carboxyl group acts like an acid, tends to be negative. “R” group is variable, from 1 atom to 20. Two amino acids join together to form a dipeptide. Adjacent carboxyl and amino groups bond together.

Amino acid chains Each amino acid is different Proteins amino acids chained into a polymer amino acid Each amino acid is different some “like” water & dissolve in it some “fear” water & separate from it

Some Amino Acids

Some More Amino Acids

Still More Amino Acids

Formation of a Dipeptide Dehydration synthesis

Amino Acid + Amino Acid --> Dipeptide Amino Acid + Dipeptide --> Tripeptide A.A. + A.A. + …..+ Tripeptide --> Polypeptide

Water-fearing amino acids Hydrophobic “water fearing” amino acids try to get away from water in cell the protein folds

Water-loving amino acids Hydrophillic “water loving” amino acids try to stay in water in cell the protein folds

A protein consists of one or more polypeptide chains.

For proteins: SHAPE matters! Proteins fold & twist into 3-D shape that’s what happens in the cell! Different shapes = different jobs growth hormone hemoglobin pepsin collagen

It’s SHAPE that matters! Proteins do their jobs, because of their shape Unfolding a protein destroys its shape wrong shape = can’t do its job unfolding proteins = “denature” temperature pH (acidity) unfolded “denatured” In Biology, it’s not the size, it’s the SHAPE that matters! folded