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What are the molecules of life? • The forming and breaking of bonds is called a chemical reaction. • Organic molecules are long chains of carboncarbon bonds that form molecules including the four major classes of macromolecules. FOUR major types of macromolecules • Carbohydrates: sugars, pastas, breads, starches, etc. Lipids (fat) • Lipid: fats, wax, oils Protein • Protein: amino acids, enzymes, keratin, etc. Nucleic acid • Nucleic acids: Deoxynucleic acid (DNA), Ribonucleic acid (RNA) Carbohydrates • Carbohydrates are organic macromolecules composed of carbon, hydrogen, oxygen. • Carbohydrates are the main source of fuel for human beings. • Rice, corn, wheat, and oats provide 60% of the calories consumed by human beings. • These grains are also rich in protein, vitamins, and dietary fiber when not refined. Refined grains • Many times, the foods we eat (polysaccharides such as white bread or white rice) are refined or bleached. • This means that they have taken away the bran and the germ part of the grain kernel, leaving behind only the endosperm How does this work? • A pollen tube then grows through the style of the pistil and into the ovule, which contains the egg. • Double Fertilization occurs as one sperm fuses with an egg and the other with two nuclei. • The sperm that fuses with the two nuclei becomes a source of nutrient for the embryo. This is the endosperm. Double fertilization Implication? • We receive less nutrients, vitamins, and minerals when we eat refined foods compared to whole grain. What is the endosperm? • The endosperm is the nutritive tissue that makes up 85% of the kernel’s weight. • It is primarily composed of starch, lipids, and proteins. It is formed within ovule or embryo sac of a seed plant. • Endosperm constitutes the embryo’s main food source for several days after germination. Balanced diet requires a variety of foods • Other food plants include legumes, which are members of the pea (or bean) family, sugar cane, potatoes, vegetables, and fruits. • We require a variety of food so that we can acquire an adequate amount vitamins, minerals, and essential amino acids. Types of carbs • Monosaccharides-fructose, glucose, and galactose. Ex: Fruit sugar • Disaccharides—sucrose, which is table sugar (glucose + fructose). Also lactose or milk sugar (glucose + galactose) • Polysaccharides-(sucrose + sucrose…) starchy foods like potatoes, rice, etc. These are called complex carbohydrates. Cellulose, which makes up grass, are polysaccharides that are indigestible for human beings. Polysaccharides • Starches are found in plants and glycogen in animals. Both are polysaccharides usually used as reserved for the organism. Pasta contains lots of polysaccharides. We consume it and convert it to glycogen when not using it. Structural Polysaccharides • Cellulose, because of its Beta formation on its Carbon-1, compared to Alpha in starch, is not edible for human consumption but is excellent for producing tough walls in plants. Cows have certain bacteria in their stomachs that can digest cellulose Sugar chain formation • These polymers (cellulose, polysaccharides) are made up repeating units called monomers. In the case of sugar, monomers of monosaccharides make disaccharides, chains of disaccharides make polysaccharides. • Condensation reaction or dehydration reaction occurs whenever two monomers are linked. In this case, a water is removed whenever two monosaccharides are put together to make a disaccharide. Dehydration Synthesis (condensation reaction) • Water is removed. The 1,4 glycosidic linkage brings the two monomers together • What happens when I consume lots of carbohydrates? Disassembling of polymers to monomers require an addition of water (with the help of enzymes), or hydrolysis. Hence, it is just the reverse of dehydration synthesis. Is this a balanced diet? • On a given day, 25% of the adult American population visits a fast food restaurant – http://tuberose.com/Fast_Food.html Do Americans eat a balanced diet? But we really consume this… What is recommended • According to the USDA, food consumption in all of the five food groups is lower than the recommended daily servings. • In fact, about 30% of Americans are obese. This does NOT include the amount of Americans who are overweight. Boyles, S. Web MD, Inc. 2002 Fats • A fat molecule is made of glycerol and THREE fatty acids. (Fig 5-10 pg 65). When created, it is called triacylglycerol, or triglyceride. Phospholipids are formed from TWO fatty acids and a glycerol. They are usually the skeleton of a cell membrane Bad fat • Lipids are organic macromolecules that are not soluble in water. These include fats, steroids, & wax. • Saturated fat—Fat that is fully bonded with hydrogen carbon atoms. They tend to be solid in room temperature. Ex: butter, animal fat Types of fats • Unsaturated fat— Fat that includes many double bonds in their carbon chains. They tend to be liquid at room temperature. Ex: vegetable oil Type of fat • Polyunsaturated fats: considered the “healthier” fats. These can be found in fish, soybean, sunflower seeds. • Omega-3 fatty acids are considered polyunsaturated. They are found in flax oil, hemp oil, pumpkin seeds, walnuts, and fishes. Omega-3 fatty acids • Omega-3 fatty acids are not generated by your body. Hence, one needs to consume it. Health benefits include prevention from coronary heart disease, reduction in hypertension, depression What are trans-fats? • Trans fatty acids are unsaturated fats which have now become saturated through hydrogenation. • It is found in foods like vegetable shortening, margarine, or fries. Research has shown that they increase LDLs (or the “bad cholesterol”), increase heart disease, and clog arteries. Why is it called trans-fat? • In 3-dimensional shape of a fat, the cis configuration is less stable than the trans. However, if we hydrogenate the oil, the cis configuration will become trans. cis trans Partially hydrogenated oils Partially hydrogenated oils Products of steroid • Steroids are lipids characterized by a carbon skeleton consisting of four rings (Fig 5:14, pg 68). They include cholesterol, which help make the plasma membrane of the cell. Recall that there are two forms of cholesterol. HDL and LDL. Which ones are better for you? Proteins • Proteins are organic molecules composed of polypeptides, or long chains of amino acids. • Proteins play structural roles in organisms, such as being a receptor in cells. Muscles and hairs are made of protein. • Proteins act as enzymes. Enzymes are very sensitive to their surrounding environment. For Ex: A change in temperature will denature the structure on an enzyme. Polypeptide synthesis • When two amino acids are to be linked together, a dehydration synthesis with the help of enzymes create a peptide bond between the two amino acids. • When this is repeated over and over again, a polypeptide is created. When various kinds of polypeptides are linked together, a basic molecule of protein is created. Levels of protein • The primary structure of a protein indicates the unique amino acid sequence. Fig 5-18, pg 71. This uniqueness attributes each type of protein. • Secondary Structure • The segments of polypeptide chain that are repeatedly coiled or folded in patterns that contribute to the protein’s overall conformation is the secondary structure of the protein. • Hydrogen bonds play an important role as they form alpha helix and beta pleated sheets found in protein secondary structures. Hydrogen bonding in Secondary Structure • • Pleated sheet Alpha helix Tertiary Structure • Irregular contortions from bonding between side chains of various amino acids due to hydrophobic interactions and disulfide bridges helps help make up the tertiary structure. • The accumulation of hydrogen bonds, ionic bonds, and van der Waals interactions on the side chains collectively strengthen the protein conformation. Tertiary Structure Quaternary Structure • When two or more polypeptide chains aggregate into a functional macromolecule, the quaternary structure of the protein is formed. EX: Collagen, hemoglobin What denatures proteins? • Heat, pH, chemicals can all change the shape of the protein or denature it. Many times, the denatured protein will go back to its original conformation when the heat or chemical is removed. However, excessive irritation may cause irreversible damage. • Chaperone proteins help in assisting the folding of proteins acting as scaffolds or temporary braces Why should a person keep cool during a fever? Nucleic Acids-informational polymers • Nucleic acid is the polymer that make up genes in DNA which help program the amino acid sequence of a polypeptide. • There are two types of nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). A nucleic acid strand is a polymer of nucleotides • Nucleic acids are polymers or monomers called nucleotides (usually made up of a five-carbon sugar, nitrogenous base, and phosphate group). Purines vs. Pyrimidines • These are the larger nucleotides that include adenine and guanine. • The smaller nucleotides are pyrimidines, which include cytosine, thymine, and uracil. • Nucleic acid polymers (polynucleotide) are joined by phosphodiester linkages between the phosphate group of one nucleotide and the sugar of the next. • Fig 5-27, pg 78. Also look at the difference between ribose and deoxyribose Phosphodiester linkages • These phosphodiester linkages or covalent bonds