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 CarbohydratesSugars Lipids Fatty acids Proteins Amino acids Nucleic Acids Nucleotides

Organic Macromolecules Contain Carbon Each carbon atom can make four covalent bonds with other types of atoms or additional carbons.  Question:  Question: How many electrons does carbon need to fill its outer energy level?  Answer:  Answer: Four

Synthesis and Breakdown of Macromolecules Dehydration Synthesis Removal of water to add monomer units Hydrolysis 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 unitsHOH CH 2 OH H HO H OH H HO HH O O HOCH 2 H CH 2 OH HHO HHO O H HO H OH H HO H OH H O Glucose O HOCH 2 H CH 2 OH HHO HO HHO Fructose 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 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? 1. Monosaccharide 2. Polysaccharide 3. Disacharide

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

HH C H C H OH C H C O C C C H H H H H H H C C H H H H H H H C C O C O C C C H H H H H H H Triglyceride Triglyceride Formation C OH C C C O H H H H H H H Add 3 Fatty Acids Glycerol HOH 3 Waters C OH C C C O H H H H H H H C C C C O H H H H H H H O C H C H C H OO HH Remove These Waters C O C C C H H H H H H H C C H H H H H H H C C O C O C C C H H H H H H H

Which Is a Source of Unsaturated Fatty Acids? Linseed Oil Beef Fat

Lipids: Structure Polar Head Glycerol Fatty Acid Tails HydrophobicHydrophilic Phospholipid— component of cell membranesPhospholipid— component of cell membranes

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 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? 1. Polyunsaturated fatty acid 2. Cholesterol 3. Monounsaturated fatty acid 4. Saturated fatty acid

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 Amino Group Amino Group The “R” Group Differs for Each Amino Acid Carboxylic Acid Group “Alpha” Carbon R

Amino Acids: Phenylalanine Structure Amino Group Amino Group Carboxylic Acid Group “Alpha” Carbon Phenylalanine “R” Group

Amino Acids: Leucine Structure Leucine “R” Group Amino Group Amino Group Carboxylic Acid Group

Proteins: Structure Forming the Protein Chain Dehydration Synthesis between COOH & NH 2 Phenylalanine Leucine

Proteins: Structure Forming the Protein Chain WaterWater The Peptide Bond Phenylalanine-Leucine Dipeptide

Four Levels of Protein Structure Primary (Sequence) Secondary (Coiling by Hydrogen Bonding) Tertiary (Folding by R-group interactions) Quaternary (Two or more chains associating)

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 C O N H C O N H C O N H C O N H 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||S|S| |S|S||S|S||S|S||S|S| |S|S||S|S||S|S||S|S| |S|S||S|S||S|S||S|S| |S|S||S|S||S|S||S|S| Straight Hair |S|S||S|S||S|S||S|S| |S|S||S|S||S|S||S|S| |S|S||S|S||S|S||S|S| |S|S||S|S||S|S||S|S| |S|S||S|S||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 eg. Hemoglobin is composed of 4 protein chains 2 are called alpha hemoglobin 2 are called alpha hemoglobin 2 are called beta 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

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 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? 1. Primary 2. Secondary 3. Tertiary 4. Quaternary

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 Synthesis of mRNA mRNA DNA NUCLEUS CYTOPLASM 1

Figure Synthesis of mRNA mRNA DNA NUCLEUS CYTOPLASM mRNA Movement of mRNA into cytoplasm 12

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 5C5C 3C3C 5C5C 3C3C 3 end (a) Polynucleotide, or nucleic acid (b) Nucleotide Phosphate group Sugar (pentose) Nucleoside Nitrogenous base 5C5C 3C3C 1C1C

Figure 5.26c Nitrogenous bases Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Adenine (A) Guanine (G) Sugars Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components Pyrimidines Purines

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 six- membered 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

Sugar-phosphate backbones Hydrogen bonds Base pair joined by hydrogen bonding (b) Transfer RNA (a) DNA

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