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The chemical elements present in amino acids

C, H, O and N (C, H, O are the main 3 in all)

Four groups of amino acids

Nonpolar, polar, acidic, and basic

The type of reaction which occurs when amino acids join together to form polypeptides


The four levels of protein structure

Primary, secondary, tertiary, quaternary

Primary structure of a protein and chemical bond

Has a unique sequence of amino acids and is just one strand. All amino acids have the alpha carbon bonded to a hydrogen atom, carboxyl group, and amino group

Proteins are composed of (monomers)

Amino acids

Amino acids are linked together by

Peptide bonds to form chains

Secondary structure of a protein

1. å helix: a delicate coil held together by hydrogen bonding between every fourth amino acid.
2. ß pleated sheet: two or more regions of the polypeptide chain connected by hydrogen bonds between the backbones.
Type of bonding: Hydrogen

Tertiary structure of a protein

Refers to the comprehensive 3-D structure of the polypeptide chain of a protein. Hydrophobic interactions, hydrogen bonding, ionic bonding, and disulfide bridge.

Quaternary structure of a protein

Refers to the structure of a protein macromolecule formed by interactions between multiple polypeptide chains. Each polypeptide chain is referred to as a subunit. Proteins with quaternary structure may consist of more than one of the same type of protein subunit. They may also be composed of different subunits. Hemoglobin is an example of a protein with quaternary structure. Hemoglobin, found in the blood, is an iron containing protein that binds oxygen molecules. It contains four subunits: two alpha subunits and two beta subunits.

Secretion of proteins

Many of the proteins produced by a cell will be secreted to be used outside of the cell

The site of protein synthesis


Packages proteins for export

Golgi apparatus

Salivary gland cell

Secretes Amylase

Pancreatic cell

Secretes insulin

Stomach wall cell

Secretes pepsin

Pituitary gland cell

Secretes ADH


Secretes antibodies

How many different monomer units are found in proteins

20 amino acids

Conjugated protein

A complex protein, such as hemoglobin, consisting of amino acids combined with other substances

Structural protein

Part of the structure of hair, Keratin.
Part of structure of spindle fibers, Tubulin.

Hormonal (Messenger) protein

Coordination of an organism's activities, ADH

Defensive (Messenger) protein

Binds to antigens and sends signals to lymphocytes, Antibody

Contractile and Motor (Structural) proteins

Movement structure of muscles, Myosin and Actin

Carrier proteins

Transports oxygen to tissues, Hemaglobin

Enzymatic proteins

Joins together nucleotides to form DNA, DNA polymerase
Induced by the presence of lactose in the lac operon system in E.coli

Soluble or insoluble protein

Fibrous: Insoluble
Globular: Soluble

Structural or molecular recognition protein

Fibrous: Structural
Globular: Molecular recognition

Parallel strands or spherical shape

Fibrous: Parallel
Globular: Spherical

The significance of polar and non-polar amino acids

Controlling the position of proteins in membranes,
Creating hydrophilic channels through membranes,
Specificity of active site in enzymes

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