Biological Molecules (Chapter 3) part 2 of 2_Lipids__ are mostly _nonpolar hydrophobic molecules composed mainly of carbon and hydrogen -Lipids are a diverse group of organic molecules that are insoluble in water, but will dissolve in nonpolar solvents (e.g. ether, chloroform, benzene).-Important lipids are grouped into 3 types: 1) _fats, oil, and waxes__2) _phospholipids___ 3) _steroids_ Oils, Fats and WaxesCharacteristics-composed of carbon, hydrogen and oxygen-contain 1 or more fatty acids-usually no ring structure ---Fats and oils are macromolecules constructed from _fatty acids and glycerol___.---Fatty acids (FA) are hydrocarbon chains with a _carboxyl group_ at one end. The hydrocarbon chain,or tail, is hydrophobic and not water soluble. Fig. 13.12-The tail has a long carbon skeleton usually with an even number (16-18) of carbon atoms.-The carboxyl group, or head, has the properties of a carboxyl acid.---_Glycerol_ is a _three-carbon sugar__.The FA group is linked through the head to the glycerol and each hydroxyl group on the glycerol can form a linkage with a fatty acid. _Triglyceride_ is a fat composed of _acids bonded to one glycerol__ by ester linkages.Function of fats and oils:-Energy storage. One gram stores _twice as much of energy__ in its chemical bonds as a gram of polysaccharide.-Because of the higher energy per gram, energy storage is more compact with fats and oils than with carbohydrates.The main difference between fats and oils is in the fatty acids Saturated fatty acids versus unsaturated fatty acidsSaturated fatty acids are ‘saturated’ with hydrogens, there are no double bonds between carbon atoms. Fig 13.3Waxes are similar to fats and oils except _the fatty acids are linked to large, long chain alcohols__ instead of glycerol.Waxes are found in plants where waterproofing is needed and are used to build structures (i.e., beehives) Humans and most other animals can’t break them down._Phospholipid__ like an oil except 1 FA is replaced with a phosphate group and variable functional group containing N – Fig. 3.14These properties are crucial to the _structure and function of cell membranes__-Steroids- Fig. 3.15Sterols- 4 rings of carbons with various functional groups. Serve as the basis for many hormones-Cholesterol is vital to membranes of animal’s cells. It’s 2% of the human brain, insulating nerve cells. Used to make other steroids._Proteins_ are the molecular tools for most cellular functions.-Proteins are _polymers of amino acids__ arranged in a specific linear sequence and are linked by peptide bonds.-Range in length from a few monomers to more than a thousand. -Proteins-usually more than 50 AAs.-Each protein has a unique linear sequence of amino acids-Proteins are abundant, _making up 50% (or more) of some cells dry weight.Proteins have a variety of important functions. Table 3.3.1. Structural (_hair, nails, silk, scales, feathers__)2. Catalysts (_enxymes_)3. Storage of material (amino acids) or energy (albumin- source od AAs) 4. Transport (e.g., hemoglobin)5. Movement (contractile proteins)6. Hormones (_chemical messengers__)7. Defense (_antibodies, venoms_)-Amino acids are monomer building blocks of a protein. Most consist of a central carbon with four functional groups. Amino acids – R GROUPS can be hydrophilic or hydrophobic-Fig. 3.18Amino acids are joined into chains _by dehydration synthesis___ Peptide bonds are covalent bonds formed by a dehydration synthesis that links the carboxyl group of one amino acid to the amino group of another amino acid. Fig. 3.19 The molecule that is formed when two amino acids are joined is called a peptideFour levels of protein structure- Primary, secondary, tertiary, and quarternary (Fig. 3.20) Primary structure -Primary structure is the sequence of amino acids in a protein. (see fig 3-20)-Determined _by genes_-.-Different for each different protein-Determines all the remaining structuresSecondary structure in proteins: 2 main types are_Helix and pleated sheet . Stabilized by hydrogen bonding between peptide linkages in the protein backbone.Secondary structure is a regular repeating coiling and folding of a protein’s polypeptide backbone. Fig 3.20-3.21Tertiary structure ---Tertiary structure is the _irregular contortion of a protein backbone_ due to bonding or _interactions between both sides of the chain_ (R groups). -Covalent linkageDisulfide bridges -Weak interactionHydrogen bondingIonic bonds Hydrophobic interactions This third level of structure is superimposed on the primary and secondary structures.Quaternary structure ---Quaternary structure is the structure that results from the interaction among several polypeptides (subunits) in a single protein.A protein function is dependent on the correct structure at each level. __Nucleic Acids__: Information storage and transmission. The primary structure of proteins is determined by the genes that code for the proteins. Genes are the units of heredity and are made of nucleic acid (DNA).Nucleic acids are _polymers of nucleotides_ linked together by dehydration synthesis reactions. Nucleotides and are composed of a __sugar, a phosphate group, and a base_. Fig. 3.22The sugar is a 5-carbon sugar in a ring conformation.In RNA the sugar is _ribose_, whereas in DNA the sugar is a derivative of ribose called, _deoxyribose__. DNA is deoxyribonucleic acid. RNA is ribonucleic acid.The sugar and phosphate groups form a linkage which makes up the nucleic acid backbone. Variation in DNA and RNA comes from the _order of the nucleotides_ (i.e., DNA sequence). Fig. 3.24In addition to their role in DNA and RNA, nucleotides also form energy carrier molecules like adenosine triphosphate (ATP) and coenzymes. Fig. 3.23Questions: 1. Why is it important to understand functional groups? Why is Carbon so important to life?2. Name the functional groups and write their atomic makeup (ex. -OH). What are their characteristics?3. Define: monomer, polymer, dehydration synthesis, hydrolysis, disaccharide, polysaccharide, triglyceride, hydrophobic, polar.4. Name the main types of biological molecules (ex. Carbohydrates). For each of these, name theirsubtypes (ex. Monosaccharides). The subtypes of biological molecules are composed of what (ex: glucose monomer, glycerol and 3 fatty acids)? What are the main functions of each of the biological molecules and their subtypes?5. Peptides are polymers of ____________. Nucleic acids are polymers of
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