PROTEINS, The Stuff of Life
PROTEINS Proteins- are one of the most diverse and complex organic molecules. Proteins control the chemistry of the cell. Genes produce proteins. There are literally thousands of different kinds of proteins. Proteins are made from building blocks called amino acids. There are 20 different types of amino acids. Proteins vary in length from 40 to 500 amino acids long.
Structure of the Amino Acid An amino acid is composed of a central carbon. Attached the central carbon are four groups.
4 Functional groups of Amino Acids: An amino acid is composed of a central carbon. Attached the central carbon are 4 groups. 1. Attached to the carbon is hydrogen.
Structure of Amino Acid cont’d 2. The second group attached to the carbon is a carboxyl group. It is the carboxyl group that makes the amino acid an acid.
Structure of Amino Acid cont’d 3. A third group that is attached to the central carbon is an amine group. This group can ionize and is a base.
Structure of Amino Acid cont’d 4. The fourth group that is attached to the central carbon is a variable group (R). There are twenty amino acids and each one has a different variable group.
What groups do these amino acids have in common What groups do these amino acids have in common? What groups are different? Above are two different amino acids. They differ in their R groups. Glycine has a H whereas alanine has a methyl group CH.
Why is it called a variable group in an amino acid? Amino acids are made of 4 groups attached to a central carbon-20 different amino acids. Hydrogen Amine group (base) NH3 Carboxyl group (acid) Variable-
20 amino acids. What group is different?
How many water molecules must be removed in order to form this polypeptide? Amino acids are put together forming a polypeptide chain. Bonds hold the amino acids together.These bonds are called peptide bonds. When a peptide bond is formed, a molecule of water is removed.
Amino acids are bonded (peptide bond) together to form polypeptide chain, removing a molecule of water between two amino acids. A peptide bond is made between the carbon and nitrogen.
Primary Structure of a protein: The sequencing of amino acids is known as its primary structure. The substituting of one amino acid for another can have serious consequences. For example sickle cell anemia results when one amino acid is substituted with another one. This is the primary structure of bovine insulin.
Secondary Structure of a protein: Very seldom does a polypeptide chain stay as a straight molecule. Usually it folds on itself forming a three dimensional structure. The proteins' structure is usually a key to its function. Hydrogen bonding between the hydrogen on the amine group and oxygen on the carboxyl group allows for secondary structure to exists. There are two main types of secondary structure, beta pleated sheets and alpha helices.
Secondary protein structure- collagen This is the protein collagen. Collagen is found in ligaments, tendons and a part of cartilage. It is demonstrating the alpha helix structure.
-Secondary structure- Hydrogen bonding between the amine groups and carboxyl group. 2 Types- -Alpha helix-collagen in tendons and legaments -Beta pleated sheet-nails This is the protein collagen. Collagen is found in ligaments, tendons and a part of cartilage. It is demonstrating the alpha helix structure.
Tertiary Structure of a protein: Seldom will polypeptide chains remain folded just once. Instead, the protein folds on itself again, forming the tertiary structure of the protein. The next slide is myoglobin, demonstrating tertiary structure. Tertiary structure is held together by R group interactions-ionic bonding, covalent bonding, bonding, hydrogen bonding and hydrophobic interactions.
-Tertiary structure- the folding of a polypeptide chain -Tertiary structure- the folding of a polypeptide chain. Held together by hydrogen bonding and interaction of the R groups. Ex. myoglobin
Quaternary Structure of a protein: Proteins can have more than one polypeptide chain in their structure. When they do, the protein demonstrates quaternary structure. Below is hemoglobin, which is composed of four polypeptide chains.
Quaternary structure can be held together by hydrogen bonding, hydrophobic interactions, and ionic bonding of the the R groups.
-Quaternary structure-Occurs when there is more than 1 polypeptide chain. Ex. Hemoglobin Caused by the interaction of the R groups. Hydrogen and ionic bonding and nonpolar interactions.
Hemoglobin is composed of 4 polypeptide chains Hemoglobin is composed of 4 polypeptide chains. Each chain has a group with iron on it.
Functions of proteins: Proteins are the "workers" in the cell. -Structural Proteins (hair, horns, etc.) -Storage Proteins (albumin, casein) -Transport Proteins (across membranes) -Hormonal Proteins (insulin) -Contractile Proteins (muscles) -Antibodies -Enzymes
DNAGENESPROTEINS DNAGENESPROTEINS Note- Unlike carbohydrates and lipids, the "blue prints" for proteins are coded for by genes or DNA. Proteins are actually made on the ribosome during a process called protein synthesis (How original). Lipids and carbohydrate synthesis are controlled by enzymes which are proteins. DNAGENESPROTEINS