BioChemistry

What is Biochemistry? Biochemistry is the chemistry of the living world. Plants, animals and single-celled organisms all use the same basic chemical compounds to live. Biochemistry is about the compounds that make up living things, and the cycles that create the biological compounds.

Biochemical cycles Photosynthesis – creating sugar Carbon cycle Krebs cycle (citric acid cycle) – occurs in the mitochondria – takes pyruvate and pulls energy out of it Calvin Cycle – changes carbon into amino acids in the chloroplasts of plants. (essential amino acids that humans can’t produce and must get from eating plants or animals)

Metabolism The process of chemical digestion and it’s related reactions to provide the body’s energy. Metabolism is the total of all the chemical reactions an organism needs to survive. 2 main chemical reactions for metabolism – Glycolysis – breakdown of sugars Photosynthesis – builds sugars

Photosynthesis Light (energy) + CO2 + H2O  C6H12O6 + O2 This reaction occurs only in plants and algae to create glucose. Occurs in the chloroplast.

Glycolysis – breakdown of sugar Respiration is a 3 step process that includes gycolysis, the Krebs cycle, and electrons being moved into and out of mitochondria. Cells use the extra energy to power their functions. It is stored as ATP (adenosine triphosphate). The CO2 that we exhale comes from the breakdown of glucose in our mitochondria.

Carbohydrates Called carbohydrates because molecules have many carbon atoms bonded to hydroxide ions. Saccharides – different forms of sugar molecules Monosaccharides – one sugar molecule Disaccharides – two sugar molecules Polysaccharides – many sugar molecules

Monosaccharides Monosaccharides are the simplest form of carbohydrates. They consist of one sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose, galactose, and ribose. Glucose is created by plants during photosynthesis

Sweet foods such as honey and cane sugar are rich in monosaccharides, but a wide variety of other foods, such as dairy products, beans and fruit, also contain these simple sugars.

Disaccharides A disaccharide (also called a double sugar or biose) is the sugar formed when two monosaccharides (simple sugars) are joined. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose, lactose, and maltose. Table sugar is a disaccharide – made of glucose and fructose

Most of the primary disaccharides are simple sugars you're already familiar with and include table sugar (sucrose, which combines a molecule of glucose with a molecule of fructose), milk sugar (lactose, which combines a molecule of glucose with a molecule of galactose), and malt sugar (maltose, which combines two molecules of glucose)

Since these carbohydrates contain two sugars, disaccharides require some digestion to break them into two one-sugar units for absorption, and as each disaccharide is unique, each has its own digestive enzyme. For example, the enzyme sucrase can cut sucrose into its two individual sugar units while the enzyme lactase cuts lactose into its two sugars.

Polysaccharides Polysaccharides are long chains of monosaccharides linked by glycosidic bonds. Three important polysaccharides, starch, glycogen, and cellulose, are composed of glucose. Starch and glycogen serve as short-term energy stores in plants and animals, respectively. The glucose monomers are linked by α glycosidic bonds.

Cellulose Cellulose is the most abundant organic molecule on earth, since it is the main component of plant cell walls. Wood, paper, and cotton are the most common forms of cellulose. The glucose units in cellulose are linked by glycosidic bonds that are different than the glycosidic bonds found in glycogen and starch. Cellulose has more hydrogen bonds between adjacent glucose units, both within a chain and between adjacent chains, making it a tougher fiber than glycogen or starch. This is why wood is so tough.

Polysaccharides One example of a polysaccharide found in foods is starch. Starch food sources often are referred to as “starchy carbohydrates” and include foods like corn, potatoes and rice. Other examples include bread, cereal and pasta. Cellulose is another polysaccharide commonly found in foods. Cellulose provides a protective covering and/or structure to fruits and vegetables and their seeds. It gives foods a crunchy texture and is undigestible in the body. Many fruits and vegetables contain some aspect of cellulose, including in the skins of apples and pears, in the covering of whole grains like wheat bran and in plant leaves like spinach. Seeds and nuts also contain cellulose.

Lipids Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others.

Fats Fats consists of glycerol and 3 fatty acids Fats Fats consists of glycerol and 3 fatty acids. Fats are created via 3 reactions creating ester linkages that link the fatty acid carboxyl groups to the hydroxyl groups in glycerol. There are two different types of fatty acids, saturated and unsaturated.

Saturated fats In a saturated fatty acid, it has the maximum number of hydrogen atoms possible, thus there are no double bonds. There are only single bonds. Since saturated fatty acids are only single bonds, it can pack more tightly together at room temperature and this makes it a solid at room temperature.

Saturated fats Saturated fats occur naturally in many foods. The majority come mainly from animal sources, including meat and dairy products. Examples are: fatty beef, lamb, pork, poultry with skin, beef fat (tallow), lard and cream, butter, cheese and other dairy products made from whole or reduced-fat (2 percent) milk.  In addition, many baked goods and fried foods can contain high levels of saturated fats. Some plant-based oils, such as palm oil, palm kernel oil and coconut oil, also contain primarily saturated fats, but do not contain cholesterol.

Saturated Fats

Unsaturated fats An unsaturated fatty acid has one more double bonds. These double bonds create a kink in the hydrocarbon tail, which in return results in looser packing. At room temperature, it is a liquid. An example of this is oil. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.

Unsaturated Fats

Unsaturated fats Foods containing unsaturated fats include avocados, nuts, and vegetable oils such as canola and olive oils. Meat products generally contain both saturated and unsaturated fats.