Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download macromolecules-S04Biology
Document related concepts
Transcript
Macromolecules Building Complex Molecules That Comprise Living Things Comparison of Terms Molecule Two or more atoms joined by chemical bonds Macromolecule Large polymer made of repeating monomer units Four types of organic macromolecules are important in living systems. Macromolecules: Polymers Made of Repeating Monomers Macromolecule Monomer Unit Carbohydrates Sugars Lipids Proteins Fatty acids Nucleic Acids Nucleotides Amino acids Organic Macromolecules Contain Carbon Question: How many electrons does carbon need to fill its outer energy level? Answer: Four Each carbon atom can make four covalent bonds with other types of atoms or additional carbons. Synthesis and Breakdown of Macromolecules Dehydration Synthesis Hydrolysis Removal of water to add monomer units Addition of OH and H groups of water to break a bond between monomers Dehydration Synthesis / Hydrolysis Dehydration Synthesis Hydrolysis Carbohydrates: Structure • Simple – Monosaccharides= one sugar unit Glucose = blood sugar All cells use glucose for energy Carbohydrates: Structure • Simple – Disaccharides = two sugar units CH2OH HOCH2 O H O H H + H H HO OH H CH2OH HO OH HO HO H H HO Glucose + Fructose CH2OH H HOCH2 O O H H H HO H OH H O HO CH2OH H H HO HOH HO Sucrose & Water Carbohydrates: Structure • Simple – Disaccharides = two sugar units • Sucrose = glucose + fructose table sugar • Lactose = glucose + galactose milk sugar • Maltose = glucose + glucose seed sugar Carbohydrates: Structure • Complex – Polysaccharides= many sugar units • • • • Starch -- storage in plants Glycogen -- storage in animals Cellulose -- plant cell walls, indigestible Chitin -- exoskeletons of insects, fungal cell walls Chitin Carbohydrates: Functions • • • • Energy source Structural component Cell-cell communication C:H:O ratio 1:2:1 Carbohydrates: Dietary Recommendations • 58% of calories from carbohydrates • No more than 10% of calories from simple, refined sugars • Emphasize – Complex Carbohydrates • Starch • Fiber (cellulose) – Naturally-occurring simple carbohydrates • Fructose from fruit • Lactose from milk Macronutrients As Energy Sources Applying Your Knowledge 1. Monosaccharide 2. Polysaccharide 3. Disacharide A. Which molecule consists of two sugar units? B. Which choice best describes glycogen? C. Which type of molecule provides the basic energy for your cells? D. Which type of molecule is found in milk? Macromolecules: Polymers Made of Repeating Monomers Macromolecule Monomer Unit Lipids (fats, oils, waxes) Fatty acids Lipids: Structure • Triglyceride—predominant form in diet – One molecule of glycerol – Three fatty acids – C:H:O ratio- 1:2:very few Lipids: Structure • Types of Fatty Acids – Saturated – 2H per internal carbon – Unsaturated -- <2H per internal carbon one or more double bonds • Monounsaturated – one double bond • Polyunsaturated – more than one double bond Triglyceride Formation Triglyceride H Glycerol Remove These Waters Add 3 Fatty Acids HC OH OH C O HCH HCH HCH H H H C CH OH OH OH OH C O C O HCH HCH HCH HCH HCH HCH H H H H H HC O C O HCH C O HCH HCH HCH HCH H HCH H HOH C O C O HCH C O HCH HCH HCH HCH H HCH H HOH CH O C O HCH C O HCH HCH HCH HCH H HCH H HOH 3 Waters Which Is a Source of Unsaturated Fatty Acids? Linseed Oil Beef Fat Lipids: Structure •Phospholipid—component of cell membranes Polar Head Glycerol Hydrophilic Fatty Acid Tails Hydrophobic Lipids: Structure • Steroids – Linked carbon rings – Natural body components • Hormones • Cholesterol Steroids Cholesterol Estradiol Testosterone Lipids: Functions • Concentrated energy source • Structural components of cell membranes – Phospholipids – Cholesterol • Communication – Steroid Hormones • Protection from water – Waxes Cholesterol Phospholipids Lipids: Dietary Recommendations • • • • < 30% of calories from lipids < 10% of calories from saturated fats Limit cholesterol to 300 mg/day Avoid “trans” fatty acids in partially hydrogenated products • Emphasize – Unsaturated fatty acids from vegetables, fish, legumes, and nuts – Oils: mono- or polyunsaturated Macronutrients As Energy Sources Applying Your Knowledge 1. 2. 3. 4. Polyunsaturated fatty acid Cholesterol Monounsaturated fatty acid Saturated fatty acid A. Which molecule is made of a series of carbon rings? B. Which molecule has more than one double bond? C. Which molecule has 2H for each internal carbon? D. Which molecule has one double bond? Macromolecules: Polymers Made of Repeating Monomers Macromolecule Monomer Unit Protein Amino acids Proteins: Structure • Primary structure = chain of amino acids – Amino acids have common features Carboxylic Acid Group Amino Group R “Alpha” Carbon The “R” Group Differs for Each Amino Acid Amino Acids: Phenylalanine Structure Amino Group Carboxylic Acid Group “Alpha” Carbon Phenylalanine “R” Group Amino Acids: Leucine Structure Amino Group Carboxylic Acid Group Leucine “R” Group Proteins: Structure Forming the Protein Chain Phenylalanine Leucine Dehydration Synthesis between COOH & NH2 Proteins: Structure Forming the Protein Chain The Peptide Bond Water Phenylalanine-Leucine Dipeptide Four Levels of Protein Structure Primary (Sequence) Tertiary (Folding by R-group interactions) Quaternary (Two or more chains associating) Secondary (Coiling by Hydrogen Bonding) Four Levels of Protein Structure Primary Structure = sequence of amino acids in chain Four Levels of Protein Structure • Secondary Structure Folded structure due to hydrogen bonds between the amino and acid groups of amino acids N C H O O C N C H O H O H N C N or Found in most proteins Found in silk Four Levels of Protein Structure • Tertiary Structure: Three dimensional folded structure due to attractions and repulsions between R groups Can involve covalent bonding hydrogen bonding ionic interactions hydrophilic and hydrophobic interactions Hair Curling S | S | | | S | S | S | | S Straight Hair | S | S S | S | | | | Naturally Curly Hair Four Levels of Protein Structure • Quaternary Structure: Association of two or more protein chains eg. Hemoglobin is composed of 4 protein chains 2 are called alpha hemoglobin 2 are called beta hemoglobin Proteins: Functions • • • • Structural Component of Cells Control of Metabolic Reactions: enzymes Growth and Repair Communication – Protein Hormones – Cell Receptors • Energy source • C:H:O ratio –no reliable ratio • For proteins Protein Protein Proteins: Dietary Recommendations • 12% of calories from proteins • 8 essential amino acids obtained from –Lean sources of animal protein –Complementary plant proteins • Beans + Grains • Beans + Seeds Applying Your Knowledge 1. 2. 3. 4. Primary Secondary Tertiary Quaternary A. Which structure results from hydrogen bonding? B. Which structure involves an association of two or more protein chains? C. Which structure describes the linear sequence of amino acids? D. Which structure depends upon interactions between the R groups of the amino acids? Nucleic Acids • Nucleic acids store, transmit, and help express hereditary information • The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene • Genes are made of DNA, a nucleic acid made of monomers called nucleotides 47 Two Types of Nucleic Acids • There are two types of nucleic acids – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) • DNA provides directions for its own replication • DNA directs synthesis of messenger RNA (mRNA) and, through mRNA, controls protein synthesis • Protein synthesis occurs on ribosomes 48 Figure 5.25-1 DNA 1 Synthesis of mRNA mRNA NUCLEUS CYTOPLASM Figure 5.25-2 DNA 1 Synthesis of mRNA mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm The Components of Nucleic Acids • Each nucleic acid is made of monomers called nucleotides • Each nucleotide consists of a nitrogenous base, a pentose sugar, and one or more phosphate groups • C:H:O ratio: No reliable ratio for nucleic acids 51 Figure 5.26ab Sugar-phosphate backbone 5 end 5C 3C Nucleoside Nitrogenous base 5C 1C 5C 3C 3 end (a) Polynucleotide, or nucleic acid Phosphate group (b) Nucleotide 3C Sugar (pentose) Figure 5.26c Nitrogenous bases Pyrimidines Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Sugars Purines Adenine (A) Guanine (G) (c) Nucleoside components Deoxyribose (in DNA) Ribose (in RNA) The Devil is in the Details • There are two families of nitrogenous bases – Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring – Purines (adenine and guanine) have a sixmembered ring fused to a five-membered ring • In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose 55 The Devil is in the Details • Adjacent nucleotides are joined by covalent bonds that form between the —OH group on the 3 carbon of one nucleotide and the phosphate on the 5 carbon on the next • These links create a backbone of sugar-phosphate units with nitrogenous bases as appendages • The sequence of bases along a DNA or mRNA polymer is unique for each gene 56 The Devil is in the Details • RNA molecules usually exist as single polypeptide chains • DNA molecules have two polynucleotides spiraling around an imaginary axis, forming a double helix • In the DNA double helix, the two backbones run in opposite 5→ 3 directions from each other, an arrangement referred to as antiparallel • One DNA molecule includes many genes 57 The Devil is in the Details • The nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C) • Called complementary base pairing • Complementary pairing can also occur between two RNA molecules or between parts of the same molecule • In RNA, thymine is replaced by uracil (U) so A and U pair 58 5 3 Sugar-phosphate backbones Hydrogen bonds Base pair joined by hydrogen bonding 3 5 (a) DNA Base pair joined by hydrogen bonding (b) Transfer RNA Link to Evolution • The linear sequences of nucleotides in DNA molecules are passed from parents to offspring • Two closely related species are more similar in DNA than are more distantly related species • Molecular biology can be used to assess evolutionary kinship 60 Could Prove Useful 61 Functional Groups • Functional Groups can modify the properties of organic molecules. • List of Functional Groups: • -OH • -CH2 • -COOH • -NH2 • -SH • -PO4 -OH Group Characteristics • • • • Polar Hydrophilic Found in some R groups Found in fatty acids -CH2 Group Characteristics • • • • Nonpolar Hydrophobic Found in protein side groups Found in many lipids -COOH Group Characteristics • Polar • Hydrophilic • Found in all proteins -NH2 Group Characteristics • Polar • Hydrophilic • Found in all proteins -SH Group Characteristics • Polar • Hydrophilic • Found in cysteine -PO4 Group Characteristics • Polar • Hydrophilic • Found in phospholipids Polar Bond • In a polar covalent bond, the electrons shared by the atoms spend a greater amount of time, on the average, closer to the Oxygen nucleus than the Hydrogen nucleus. Non Polar Bonds • Nonpolar covalent bonds are a type of chemical bond where two atoms share a pair of electrons with each other
