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
• ne 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