PROTEINS

Compare the structure and functions of lipids, proteins. Objective: Compare the structure and functions of lipids, proteins. Warm Up: What foods do you eat that contain lipids (fats) or proteins? List two sources of lipids and two sources of proteins.

Today’s Plan Warm up Real world reading Review lipids Review protein notes Create a Model Draw the Macromolecules Closing

Lipids Lipids are a large and varied group of biological molecules. Lipids are made mostly from carbon and hydrogen atoms and are generally not soluble in water. The common categories of lipids are fats, oils, and waxes. Lipids can be used to store energy. Some lipids are important parts of biological membranes and waterproof coverings. Steroids synthesized by the body are lipids as well. Many steroids, such as hormones, serve as chemical messengers.

Lipids Many lipids are formed when a glycerol molecule combines with compounds called fatty acids.

Lipids If each carbon atom in a lipid’s fatty acid chains is joined to another carbon atom by a single bond, the lipid is said to be saturated. If there is at least one carbon-carbon double bond in a fatty acid, the fatty acid is said to be unsaturated. Lipids whose fatty acids contain more than one double bond are said to be polyunsaturated.

Lipids Lipids that contain unsaturated fatty acids, such as olive oil, tend to be liquid at room temperature. The data in the table illustrate how melting point decreases as the degree of unsaturation (number of double bonds) increases.

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.

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

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

A protein consists of one or more polypeptide chains.

Protein Proteins are macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen. Proteins are polymers of molecules called amino acids. Proteins perform many varied functions, such as controlling the rate of reactions and regulating cell processes, forming cellular structures, transporting substances into or out of cells, and helping to fight disease.

Protein Amino acids are compounds with an amino group (–NH2) on one end and a carboxyl group (–COOH) on the other end. Covalent bonds called peptide bonds link amino acids together to form a polypeptide. A protein is a functional molecule built from one or more polypeptides.

Structure and Function All amino acids are identical in the amino and carboxyl groups. Any amino acid can be joined to any other amino acid by a peptide bond formed between these amino and carboxyl groups.

Structure and Function Amino acids differ from each other in a side chain called the R-group, which have a range of different properties. More than 20 different amino acids are found in nature. This variety results in proteins being among the most diverse macromolecules.

Levels of Organization Proteins have four levels of structure. A protein’s primary structure is the sequence of its amino acids. Secondary structure is the folding or coiling of the polypeptide chain.

Levels of Organization Tertiary structure is the complete, three- dimensional arrangement of a polypeptide chain. Proteins with more than one chain have a fourth level of structure, which describes the way in which the different polypeptide chains are arranged with respect to each other. For example, the protein shown, hemoglobin, consists of four subunits.

Objective: Compare the structure and functions of lipids, proteins and carbohydrates. Closing: Summarize the difference between carbs, proteins and lipids or answer the following: A scientist removed the cell membranes from bacteria cells in a culture. She analyzed the cell membranes for specific molecules. Which of these was probably the most common type of molecule present in the bacteria cell membranes? lipid amino acid nucleic acid carbohydrate