Protein ins Proteins Proteins are energy-yielding nutrients - PowerPoint PPT Presentation

Protein ins

Proteins • Proteins are energy-yielding nutrients composed of carbon , hydrogen , oxygen , nitrogen , and sometimes sulfur atoms • Differ from carbohydrates and lipids because of the presence of nitrogen • The human body has at least 30,000 types of proteins , each with a different biological function

Monomers and Polymers of f Proteins • The monomer of a protein is an amino acid • Polymers of proteins include dipeptides (two amino acids) and polypeptides (many amino acids)

Amino Acids • There are 20 amino acids that are bonded together in different combinations to form thousands of different proteins • DNA provides the instructions for how the amino acids will be bonded to form the proteins in your body

Structure of f an Amino Acid • Each amino acid as a variable group of atoms – this is called the R group • The R group is what makes each of the 20 amino acids different from one another • Draw a label an amino acid in your notes:

Examples of Amino Acids

Examples of Amino Acids

Essential versus Nonessential Amino Acids • Nonessential amino acids can be manufactured by the body • Essential amino acids must be obtained through the foods you eat (diet) • Foods that are high in protein include: lean meats, fish, legumes (beans), soybeans, egg whites, nuts

Peptide Bond Formation • Two or more amino acids may be joined together by dehydration synthesis • The chemical bond that holds two or more amino acids together is known as a peptide bond

Protein Shape Determines Function • A sequence of amino acids, or polypeptide, must be folded into a specific 3-dimensional shape in order to carry out its function

Protein Denaturation • The 3-dimensional structure of a protein can be altered and changed – this is called denaturation • Denatured proteins lose their biological function • Factors that cause denaturation include: • Heat • Changes in pH • Alcohol • Salt

Biological Function of Proteins • How are proteins used by living organisms? • Build and maintain body tissues • Regulate body processes • Coordinate movement • Fight infection • Transport molecules • Control cell reactions

Body Tissues • Proteins provide structure, support and covering of body • Tissues, such as bone, muscle, tendons, ligaments, skin, hair and nails are all composed of protein • Examples include collagen and keratin

Regulate Body Processes • Proteins regulate body processes by acting as hormones to control metabolism • Examples include insulin , growth hormone , and melatonin

Coordinate Movement • Proteins can interact with one another and cause movement • Examples include actin and myosin – two proteins that compose muscle tissue

Fight In Infection • Antibodies are specialized proteins that fight off microbes and protect from infection • Examples include gamma globulin and immunoglobulin

Transport Molecules • Proteins can transport molecules into and out of cells across the plasma membrane and also around the body • Examples include hemoglobin (transports oxygen) and transferrin (transports iron)

Control Cell Reactions • Proteins act as catalysts (organic enzymes ) to control the rate of chemical reactions within cells • Examples of enzymes include lactase and lipase

Protein Hydrolysis • Proteins are broken down into amino acids when consumed in foods • The body can then use the free amino acids to assemble new proteins that it needs