BIO 100 Chapter 3 Notes
BIO 100 Chapter 3 Notes BIO 100
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This 5 page Class Notes was uploaded by Lauren Tebbe on Wednesday September 28, 2016. The Class Notes belongs to BIO 100 at Eastern Kentucky University taught by Kenneth Blank in Fall 2016. Since its upload, it has received 7 views.
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Date Created: 09/28/16
Chapter 3 BIO Notes 1 Organic Molecules o Distinguish between organic and inorganic molecules o Recognize the importance of functional groups in determining the chemical properties of an organic molecule o Chemistry is divided into organic and inorganic and the difference is that organic studies organic molecules that contain atoms of carbon and hydrogen and makes up portions of cells, tissues, and organs. Inorganic molecules contain water and table salt. o This chapter focuses on organic molecules, also known as biological molecules. 2 The Carbon Atom o Remember that carbon with a total of 6 electrons has four electrons in the outer shell and in order for it to acquire four electrons to complete its shell, it shares electrons with elements such as hydrogen, nitrogen, and oxygen. o Carbon can bond with as many as four other elements. o Hydrocarbon can branch whereas carbon to carbon is just long o Carbon can form double bonds with itself and other atoms. o The versatile nature of carbon means that it can form a variety of molecules with the same chemical formula but different structures. o Molecules with the same combinations of atoms but different structures are called isomers. 3 The Carbon Skeleton and Functional Groups o The carbon chain of an organic molecule is called its skeleton or backbone. o The reactivity of an organic molecule is largely dependent on the attached functional groups. o A functional group is a specific combination of bonded atoms that always has the same chemical properties and therefore always reacts in the same way, regardless of the particular carbon skeleton to which it is attached. o Functional group determines chemical properties. o Although hydrocarbons are nonpolar and hydrophobic (not soluble in water) glucose with several -OH groups is actually hydrophilic (soluble in water). o Functional groups identify the types of reactions that the molecule will undergo. 4 The biological Molecules of Cells o Summarize the categories of carbohydrates and provide examples of their diverse biological functions. o Summarize the categories of lipids and provide examples of their diverse biological functions. o Summarize the variety of protein types and provide examples of their diverse biological functions. o Summarize the two categories of nucleic acids and describe their biological functions. o Despite their great diversity, biological molecules are groups into only 4 categories: carbohydrates, lipids, proteins, and nucleic acids. o Food contains nucleic acids, the type of biological molecule that forms the genetic material of all living organisms. o Certain biological molecules in cells are composed of a large number of the same type of subunits called monomers. When many monomers join, the result is a polymer. o A cell uses dehydration synthesis reaction to synthesize any type of biological molecule because the equivalent of a water molecule is removed as the reaction occurs. o To break down a biological molecule a cell will use an opposite type of reaction, hydrolysis reaction, because water attaches to one monomer and -H to the other monomer. (basically water is used to break down monomer bounds) 5 Carbohydrates o Carbohydrates are almost universally used as an immediate source of energy. o They exist either as saccharide monomers or polymers of saccharides. o Carbohydrate can refer to single sugar (monosaccharide) 2 sugar (disaccharide) or many sugar (polysaccharide) o A simple sugar like monosaccharides can be the backbone of carbon consisting of 3-7 carbons. o Glucose has 2 important isomers called fructose and galactose. o Plants manufacture glucose from the sun, universally the immediate source of energy. o Ribose and deoxyribose has 5 carbon atoms and are significant because they are found in nucleic acids RNA and DNA o A disaccharide contains 2 monosaccharides linked together by dehydration synthesis reaction (maltose, sucrose, lactose). o Maltose is composed of 2 glucose monomers. o Our bodies digest sucrose into 2 monomers, glucose and fructose. Later this fructose is changed to glucose, our usual source of energy. If not needed, glucose can metabolize to fat. o Fat is the body's primary energy storage form. o Lactose contains a glucose molecule combined with galactose molecule. o Plants store glucose as a starch. Animals store glucose as glycogen which is more highly branched. o Branching subjects a polysaccharide to more attacks by hydrolytic enzymes therefore branching makes a polysaccharide easier to break down. o Cellulose is the most abundant of all the carbohydrates which in turn are the most abundant of all organic molecules on earth. o Long glucose chains are held parallel to each other by hydrogen bonding to form strong microfibrils and then fibers. o In humans, cellulose have the benefit of dietary fiber. o Chitin is a polymer of glucose molecule, however each glucose subunit has an amino group attached to it making it chemically very different even though structurally it looks the same. o Chitin is found in a variety of organisms including animals and fungi. Not digestible by humans but used in medicine as wound dressing and suture material for its antibacterial and antiviral properties. 6 Lipids o Although molecules classified as lipids are quite varied, they have one characteristics in common: They are all insoluble in water. This is due to the fact that lipids possess long, nonpolar hydrocarbon chains and a relative lack of hydrophilic functional groups. o Fats and oils are well-known lipids. Fats are solid at room temp, and oils are liquid at room temp. o In animals, fats are used for insulation and long-term energy storage. Plants use oils for this long-term energy storage. o Fats and oils contain 2 subunit molecules: glycerol and fatty acids. o Glycerol contains 3 -OH groups, they are polar which makes it soluble in water. o A fatty acid has a long chain of carbon atoms bonded only to hydrogen with carboxyl group at one end. o Dehydration synthesis reaction when a fat or oil form when the carboxyl portions of 3 fatty acids react with the -OH group of glycerol. o Fats and oils are called triglycerides which can pack lots of energy into one molecule because it has 3 long fatty acids attached to the glycerol molecule. o Primary long term energy source! o Most of the fatty acids in cell contain 16 to 18 carbon atoms per molecule. o Unsaturated fatty acids have double bonds in the carbon chain wherever number of hydrogens is less than 2 per carbon atom. o Saturated fatty acids have no double bonds between the carbon atoms. o Sat or unsat determine chemical and physical properties. o Trans fats contain fatty acids that have been partially hydrogenated to make them more saturated and more solid. o Phospholipids contain a phosphate functional group, constructed like a triglyceride except that in place of the third fatty acid attached to glycerol, there is a charged phosphate group. o Phosphate group is usually bonded to another polar functional group so one end is hydrophilic and water soluble (polar). Hydrocarbon chains of the fatty acids are nonpolar tails and are hydrophobic. o The bulk of the plasma membrane that surrounds cells consists of a fairly fluid phospholipid bilayer o Steroids are lipids that possess a unique carbon skeleton made of four fused rings. They do not contain fatty acids but are similar to other lipids because they are insoluble in water. o Cholesterol is a component of an animal cell's plasma membrane and it is the precursor of other steroids such as sex hormones. o Anabolic steroids (synthetic testosterone) can be used to increase muscle mass. 7 Proteins o Proteins are primary importance in the structure and function of cells: 1. Support; structural proteins 2. Metabolism; many proteins are enzymes that bring reactants together and thereby act as catalysts speeding up chemical reactions in cells. 3. Transport; channel and carrier proteins in the plasma membrane allow substances to enter and exit cells. 4. Defense; antibodies combine with disease-causing agents to prevent those agents from destroying cells and causing diseases and disorders. 5. Regulation; hormones are regulatory proteins and serve as intercellular messengers that influence the metabolism of cells. 6. Motion; contractile proteins actin and myosin allow parts of cells to move and cause muscles to contract o Amino acids identity is based on the attached R group(s) o The covalent bond that forms between an amino group of one amino acid and the carboxyl group of an adjacent amino acids is a peptide bond. o Proteins are polymers and their monomers are called amino acids that have a unique carbon skeleton in which a central carbon atom bonds to a hydrogen bond atom, two functional groups, and a side chain (R group) o 20 different amino acids and vary according to their R group. o The resulting covalent bond of two amino acids joined by dehydration synthesis between carboxyl and amino acid is called a Peptide bond. o Atoms in a peptide bond share the electrons unevenly because oxygen is more electronegative than nitrogen. o A peptide is two or more amino acids covalently bonded together and a polypeptide is a chain of many amino acids joined by peptide bonds. o Proteins are polypeptides that have been folded into a complex shape. o The amino acid sequence determines a protein's final 3D shape and its function. o Levels of proteins include primary, secondary, tertiary, and quaternary structures. 1. A protein's sequence of amino acids is called its primary structure. 2. Secondary structure occurs when portions of the amino acid chain take on a certain orientation in space, depending on the number and identity of the amino acids present in the chain. 3. Tertiary structure of protein is its overall 3D shape and results from folding and twisting of the secondary. Held in place by interactions between R groups making up helices and beta pleated sheets with polypeptide. This structure can be affected by environmental conditions. (denatured means to be broken down). 4. Hemoglobin and insulin have a quaternary structure because they contain more than one polypeptide chain. o The overall shape of proteins can be classified as fibrous or globular. Fibrous adopt rodlike structure (keratin, collagen). Globular have a rounded or irregular 3D tertiary shape (hemoglobin). 8 Nucleic acids o DNA and RNA are the nucleic acids found in cells. DNA stores genetic info that contains genes, genes specify the sequence of amino acids in proteins. RNA is the molecule that aids transcribing and translating DNA into a protein. o Nucleic acids are polymers in which the monomer is called a nucleotide that have 3 parts: phosphate, 5-carbon sugar, and nitrogen-containing base. o Each nucleotide of DNA contains one of the four bases: adenine, guanine, cytosine or thymine. o DNA is double helix. Backbone is composed of phosphates bonded to sugars and the bases. GC and AT (complementary base pairing) key to replication. o RNA uses uracil instead of thymine and RNA is single stranded. o DNA has a triplet code called codons and every 3 bases stands for one of the 20 amino acids o The shape of a protein determines its function, the structure and function of cells determined by the types of proteins they contain. 9 The covalent bond joining two amino acids is called a peptide bond.