Math for Life BIOLOGICAL MACROMOLECULES. LIPIDS: Fatty acids Triglycerides Phospholipids Steroids

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1 REFERENE TABLES BILIAL MARMLEULES LIIDS: Fatty acids Triglycerides hospholipids Steroids ARBYDRATES: Mono and Disaccharides olysaccharides Derivative carbohydrates RTEINS: Amino acids roteins NULEI AIDS: RNA subunits DNA subunits RNA and DNA strands T

2 REFERENE TABLES LIIDS: Fatty Acids Text Figure 3.20 (a) Key oints Long nonpolar hydrocarbon tails, polar carboxyl group. ome in saturated and unsaturated forms; unsaturated fatty acids have kinks that prevent them from packing closely together. omponent of triglycerides and phospholipids almitic acid All bonds between carbon atoms are single, making a saturated fatty acid. The straight chain allows this molecule to pack tightly among other similar molecules. (b) A double bond between two carbons makes an unsaturated fatty acid. 2 The kinks prevent close packing Linoleic acid BAK T

3 REFERENE TABLES LIIDS: Triglycerides Text Figure 3.9 Triglyceride lycerol (an alcohol) Ester linkage Fatty acid molecules The synthesis of an ester is a condensation reaction. Nonpolar hydrocarbon chains are hydrophobic. Each junction in this lipid tail represents a carbon with hydrogens to fill available covalent bonds: or Key oints Three fatty acid tails plus a glycerol. Those that are solid at room temperature (because the fatty acids are largely saturated thus allowing the molecules to pack closely together) are fats; those that are liquid at room temperature (because unsaturated fatty acid tails prevent the molecules from packing closely together) are called oils. Both fats and oils store energy. BAK T

4 REFERENE TABLES LIIDS: hospholipids Text Figure 3.2 Key oints Two fatty acid tails (nonpolar) attached to a glycerol that is attached to a phosphate containing compound (polar). Biological membranes are largely made up of phospholipid bilayers. (a) hosphatidyl choline The hydrophilic head is attracted to water, which is polar. hosphate holine 3 3 N lycerol 2 2 The hydrophobic tails are not attracted to water. (b) Membrane phospholipid LIIDS: Steroids Text Figure 3.2 ydrophilic head ydrophobic tails Throughout this book, phospholipids in membranes are shown with this symbol holesterol is a constituent of membranes and is the source of steroid hormones. Vitamin D 2 can be produced in the skin by the action of light on a cholesterol derivative. ortisol is a hormone secreted by the adrenal glands. Testosterone is a male sex hormone. Key oints ompounds whose multiple rings share carbons. Steroids function in membranes (e.g. cholesterol) and as signaling molecules (e.g. hormones). BAK T

5 REFERENE TABLES ARBYDRATES: Mono and Disaccharides (Sugars) Text Figure 3., 3.2, & 3.3 Aldehyde group Straight-chain form Intermediate form α-lucose or β-lucose The straight-chain form of glucose has an aldehyde group at carbon. A reaction between this aldehyde group and the hydroxyl group at carbon gives rise to a ring form. Depending on the orientation of the aldehyde group when the ring closes, either of two rapidly and spontaneously interconverting molecules α-glucose and β-glucose forms. Key oints Energy source. Distinguished by the number of carbons. Trioses (3) include glyceraldehyde, a component of A. entoses () include compounds found in plant cell walls; ribose and deoxyribose, the sugars found in nucleotides (see below), are both pentoses. exoses (6) all have the formula 6 2 6, but the atoms are arranged differently. lucose, a hexose, is in all living cells; its energy is released in the process of glycolysis. Disaccharides are made up of two monosaccharides joined by glycosidic linkages. ligosaccharides are made up of a few monosaccharides joined by glycosidic linkages. Some oligosaccharides have additional functional groups attached; for example, some are attached to cell surface lipids that face the outside of the cell. These oligosaccharides act as cell recognition signals; the collection of all of those cell surface oligosaccharides is sometimes called the glycocalyx. BAK T

6 REFERENE TABLES Three-carbon sugar 2 3 lyceraldehyde is the smallest sugar and exists only as the straight-chain form. Five-carbon sugars Ribose Deoxyribose Ribose and deoxyribose each have five carbons, but very different chemical properties and biological roles. Six-carbon sugars α-mannose α-alactose Fructose These hexoses are isomers. All have the formula 6 2 6, but each has distinct chemical properties and biological roles. 2 Maltose is produced when an α-, glycosidic linkage forms between two glucose molecules. The hydroxyl group on carbon of one glucose in the α (down) position reacts with the hydroxyl group on carbon of the other glucose. 2 2 α-, glycosidic linkage 2 2 Formation β of α linkage + α α 2 α-lucose β-lucose α-lucose β-lucose Maltose β In cellobiose, two glucoses are linked by a β-, glycosidic linkage. 2 β-lucose β + 2 β β-lucose Formation of β linkage 2 2 β-, glycosidic linkage 2 β β-lucose β-lucose ellobiose β BAK T

7 REFERENE TABLES ARBYDRATES: olysaccharides Text Figure 3. Key oints olysaccharides are giant chains of monosaccharides joined by glycosidic linkages. ellulose, the most common organic compound on the planet, is a polysaccharide. Starch and glycogen, both of which are built up from glucose, are energy storing compounds. ellulose Starch and glycogen ydrogen bonding to other cellulose molecules can occur at these points Branching occurs here. ellulose is an unbranched polymer of glucose with β-, glycosidic linkages that are chemically very stable. lycogen and starch are polymers of glucose with α-, glycosidic linkages. α-,6 glycosidic linkages produce branching at carbon 6. BAK T

8 REFERENE TABLES ARBYDRATES: Derivative carbohydrates Text Figure 3. Key oints ompounds comprising a carbohydrate covalently linked to a functional group, such as a phosphate (e.g. sugar phosphate), an amino group (the amino sugars), or an N-acetyl group (e.g. chitin). Sugar phosphates can be intermediates in energy reactions, amino sugars can be structural. (a) Sugar phosphate Fructose,6 bisphosphate is involved in the reactions that liberate energy from glucose. (The numbers in its name refer to the carbon sites of phosphate bonding; bis- indicates that two phosphates are present.) hosphate group 2 2 Fructose Fructose,6 bisphosphate (b) Amino sugars The monosaccharides glucosamine and galactosamine are amino sugars with an amino group in place of a hydroxyl group. 2 N 2 lucosamine Amino group 2 N 2 alactosamine (c) hitin hitin is a polymer of N-acetylglucosamine; N-acetyl groups provide additional sites for hydrogen bonding between the polymers. 2 N lucosamine 3 N 2 N-acetyl group 2 N 3 hitin 3 BAK T

9 REFERENE TABLES 3.2 Twenty Amino Acids Found in roteins Amino acids have both three-letter and single-letter abbreviations. A. Amino acids with electrically charged side chains ositive + Negative Arginine (Arg) (R) istidine (is) () Lysine (Lys) (K) The general structure of all Aspartic acid (Asp) (D) lutamic acid (lu) (E) amino acids is the same... 3 N + 3 N + 3 N + 3 N + 3 N N + N N N N 3... but each has a different side chain N 2 B. Amino acids with polar but uncharged side chains. Special cases Serine (Ser) (S) Threonine (Thr) (T) Asparagine (Asn) (N) lutamine (ln) (Q) Tyrosine (Tyr) (Y) ysteine (ys) () lycine (ly) () roline (ro) () 3 N + 3 N + 3 N + 3 N + 3 N + 3 N + 3 N + 2 N S 2 N 2 N D. Amino acids with hydrophobic side chains Alanine (Ala) (A) Isoleucine (Ile) (I) Leucine (Leu) (L) Methionine (Met) (M) henylalanine (he) (F) Tryptophan (Trp) (W) Valine (Val) (V) 3 N + 3 N + 3 N + 3 N + 3 N + 3 N + 3 N S N 3 BAK T

10 REFERENE TABLES RTEINS: The Universal enetic ode Text Table 2. Key oints enetic information is encoded in mrna in three-letter units codons made up of the bases uracil (U), cytosine (), adenine (A), and guanine (). To decode a codon, find its first letter in the left column, then read across the top to its second letter, then read down the right column to its third letter. The amino acid the codon specifies is given in the corresponding row. For example, AU codes for methionine, and UA codes for valine. First letter U A UUU UU UUA UU UU U UA U AUU AU AUA AU UU U UA U Second letter U A henylalanine Leucine Leucine Isoleucine Methionine; start codon Valine UU U UA U Serine U A roline AU A AA Threonine A U A Alanine UAU UA UAA UA AU A Tyrosine Stop codon Stop codon istidine AA A lutamine AAU AA Asparagine AAA AA Lysine AU A Aspartic acid AA lutamic A acid UU U UA U U A AU A AA A ysteine Stop codon Tryptophan Arginine Serine Arginine U A lycine U A U A U A U A Third letter BAK T

11 REFERENE TABLES RTEINS: roteins Text Figure 3. Key oints ne or more polypeptides, that is, polymers of amino acids linked together by peptide linkages. The order of amino acids of a protein is determined by the sequence of nucleotides in the gene encoding that polypeptide. rimary structure Amino acid monomers are joined by a backbone of peptide linkages, forming polypeptide chains. N R N eptide linkage (a) R Secondary structure olypeptide chains may form α helices or β pleated sheets. (b) α elix (c) β leated sheet Tertiary structure olypeptides fold, forming specific shapes. Folds are stabilized by bonds, including hydrogen and disulfide bonds. Quaternary structure Two or more polypeptides assemble to form larger protein molecules. The hypothetical molecule here is a tetramer, made up of four polypeptide subunits. Subunit Subunit 2 ydrogen bond Disulfide bond (d) (e) Subunit 3 Subunit BAK T

12 REFERENE TABLES NULEI AIDS: RNA & DNA strands Text Figure Ribose sugar...and phosphate groups. The numbering of ribose carbons is the basis for identification of and 3 ends of DNA and RNA strands. The backbones of both RNA and DNA contain a series of pentoses... RNA (single-stranded) yrimidine base U A hosphodiester linkage end N N N N N N N 3 end end DNA (double-stranded) ydrogen bond urine base T A N N A N N N N N N N N T hosphate group N N N N end ydrogen bonds between purines and pyrimidines hold the two strands of DNA together. 3 end In RNA, the bases are attached to the ribose. The bases in RNA are the purines adenine (A) and guanine () and the pyrimidines cytosine () and uracil (U). In DNA, the bases are attached to deoxyribose, and the base thymine (T) is found instead of uracil. Key oints DNA is the genetic material. That is, the genetic instructions for all of the proteins in the organism are encoded in its DNA. DNA is transcribed into RNA by proteins called polymerases; RNA can be transcribed into DNA by a protein called a reverse transcriptase. Messenger RNA (mrna) is translated into protein with the help of ribosomes; ribosomal RNAs (rrnas) are not translated, they are part of the ribosome; transfer RNAs (trnas) are not translated, they participate in translation by bringing amino acids to the ribosome. BAK T

13 REFERENE TABLES NULEI AIDS: RNA subunits Key oints Ribonucleotides are made up of a base plus a ribose plus, 2, or 3 phosphates. The bases are either purines or pyrimidines. A base plus a ribose makes a nucleoside; a nucleoside plus, 2, or 3 phosphates makes a nucleotide. The ribonucleotides are the components of RNA. In addition to being one of the nucleotides found in RNA, the ribonucleotide AT is very important for energy storage in cells. The ribonucleotide T is also an important source of energy for various cell processes. BAK T

14 REFERENE TABLES NULEI AIDS: DNA subunits Key oints Deoxyribonucleotides are made up of a base plus a deoxyribose plus, 2, or 3 phosphates. The bases are either purines or pyrimidines. A base plus a deoxyribose makes a nucleoside; a nucleoside plus, 2, or 3 phosphates makes a nucleotide. The deoxyribonucleotides are the components of DNA. BAK T