Chapter 3: Biochemistry Ms. Mezzetti Lynn English High School Science Department

Warm up: Define biochemistry What does “Chemistry of Life” mean?

Objectives: Students will be able to: Distinguish between organic and inorganic compounds. Explain the importance of carbon bonding in biological molecules. Summarize how large carbon molecules are synthesized and broken down. Describe how the breaking down of ATP supplies energy to drive chemical reactions.

Carbon Bonding Organic compounds contain carbon atoms and are found in living things. Most inorganic compounds do not contain carbon atoms.

Carbon Bonding Carbon atoms can form four covalent bonds with other atoms including other carbon atoms. The carbon bonds allow the carbon atoms to form a wide variety of simple and complex organic compounds.

Condensation Reactions/Hydrolysis Condensation Reactions remove water and combine monomers to make polymers Hydrolysis break down polymers into smaller macromolecules and monomer

Energy for life Adenosine triphosphate (ATP) stores and releases energy during cell processes, enabling organisms to function.

Organic Molecules Objectives: Students will be able to: Distinguish 3 types of carbohydrates-monosaccharides, disaccharides and polysaccharides. Explain how enzymes are a type of protein ande catalyze chemical reactions. Identify the monomers and polymers carbohydrates, proteins, lipids and nucleic acids. Describe the induced fit model of enzyme action. Compare the nucleic acids DNA and RNA.

Carbohydrates Carbohydrates are organic compounds that are: composed of carbon, hydrogen, and oxygen in a ratio of about one carbon to two hydrogen atoms to one oxygen atom. CH2O end in ‘ose Carbohydrates are a source of energy and are used as structural materials in organisms.

Carbohydrates Monosaccharide's Carbohydrates are made up of monomers called monosaccharide's, simple sugars such as glucose Disaccharides -- Two monosaccharide's join to form a double sugar called a disaccharide such as sucrose (glucose + fructose) Polysaccharides --Three or more monosaccharide's join to form large macromolecules such as starches, cellulose, chitin & glycogen. These are complex carbohydrates

Proteins Proteins are organic compounds composed mainly of carbon, hydrogen, oxygen, and nitrogen. C-H-O-N Proteins have many functions including structural-muscle fiber-collagen-keratin, defensive-antibodies, and catalytic roles-enzymes. Found in

Proteins Amino Acids: Proteins are made up of monomers called amino acids. The sequence of amino acids determines a protein’s shape and function. There are 20 different types identified by their R group. Dipeptides: Two amino acids are joined by peptide bonds to form a dipeptide. Polypeptides: A long chain of amino acids is called a polypeptide.

Structure of Proteins

Proteins Enzymes Enzymes are globular proteins that speed up chemical reactions and bind to specific substrates. The binding of a substrate with an enzyme causes a change in the enzyme’s shape and reduces the activation energy of the reaction.

Enzyme Activity

Lipids Lipids are nonpolar molecules that store energy and are an important part of cell membranes. Fats are lipids They can be saturated (animal fat/solids/lard) or unsaturated (fats from plants-oils/liquid)

Lipids Fatty Acids-building blocks of lipids (monomers) Most lipids contain fatty acids, unbranched carbon molecules that have a hydrophilic end and a hydrophobic end. Triglycerides Triglycerides consist of three fatty acids and one molecule of glycerol.

Lipids Phospholipids: make up cell membranes, consist of two fatty acids and one glycerol molecule. Waxes: A wax is made of one long fatty acid chain joined to one long alcohol. Protect animal ears and plant leaves. Steroids: A steroid is a lipid composed of four fused carbon rings.

Nucleic Acids NUCLEOTIDE A nucleic acid is a large and complex organic molecule that stores and transports information. The monomers, building blocks of nucleic acids are nucleotides. DNA contains deoxyribose, nitrogenous base and a phosphate group RNA contains ribose NUCLEOTIDE

Nucleic Acids The nucleic acid deoxyribonucleic acid (DNA) contains genetic information for cell activities. Ribonucleic acid (RNA) molecules play many key roles in building of proteins and can act as enzymes.

Structure of Nucleic Acids

Multiple Choice 1. Which of the following is not a function of polysaccharides? A. energy source B. energy storage C. structural support D. storage of genetic information

Multiple Choice, continued 2. Which of the following statements is false? F. A wax is a lipid. G. Starch is a lipid. H. Saturated fats are solid at room temperature. J. Unsaturated fats are liquid at room temperature.

Multiple Choice, continued 3. Which of the following molecules stores hereditary information? A. ATP B. DNA C. protein D. carbohydrates

Multiple Choice, continued 4. What is the name of the molecule in plants that stores sugars? A. starch B. protein C. cellulose D. glycogen

Multiple Choice, continued The figure below illustrates the basic structure of a cell membrane. Use the figure to answer the questions that follow. 5. Which of the following molecules make up the basic structure of a cell membrane? A. waxes B. steroids C. fatty acids D. phospholipids

Multiple Choice, continued The figure below illustrates the basic structure of a cell membrane. Use the figure to answer the questions that follow. 6. The “tails” of the molecules in the figure orient away from water. Which of the following describes the tail’s movement away from water? F. polar G. adhesive H. hydrophilic J. hydrophobic

Multiple Choice, continued 7. simple sugars : carbohydrates :: amino acids : A. lipids B. proteins C. nucleic acids D. amino acids

Short Response, continued Proteins are affected by environmental conditions such as heat and pH. Explain why the process of cooking an egg cannot be reversed. Answer: The heat that is added to the egg changes the bonds in the proteins and other molecules that make up the egg to such a large extent that the original protein shape can no longer be distinguished.

Open Response Enzymes are essential for the functioning of all cells. Part A Explain what enzymes do that is essential for cell function. Part B Explain the induced fit model of enzyme action. Answer: Part A Enzymes catalyze chemical reactions that are involved in important cell processes. Part B Bonding of the substrates to enzymes causes a slight change in the enzyme’s shape, thereby weakening some of the bonds and lowering activation energy.

Any Questions?