Download presentation
Presentation is loading. Please wait.
1
Ch. 5 The Structure and Function of Macromolecules
2
The 4 Macromolecules Carboyhydrates Lipids Proteins Nucleic acids may consist of thousands of covalently bonded atoms
3
Similarities: chainlike molecules (polymers) small units – monomers
polymer -a long molecule with similar or identical building blocks linked by covalent bonds. small units – monomers All contain C, H, O
4
How are polymers made and broken down?
hydrolysis dehydration synthesis reaction Both involve water
5
Figure 5.2 The synthesis and breakdown of polymers
(a) Dehydration reaction in the synthesis of a polymer (b) Hydrolysis of a polymer – ex. digestion HO H 1 2 3 4 H2O Short polymer Unlinked monomer Longer polymer Hydrolysis adds a water molecule, breaking a bond Dehydration removes a water molecule, forming a new bond
6
Carbohydrates Sugars Cellulose Chitin
7
Carbohydrates include sugars and their polymers.
Monosaccharides – simple sugars CH20 Sugars end in -ose Nutrient for cells (glucose) fuel Disaccharides (double sugars) - two monosaccharides join by dehydration synthesis - a condensation reaction Polysaccharides - polymers of many monosaccharides. Function as storage and building materials
8
Figure 5.3 Monosaccharides
Triose sugars (C3H6O3) Pentose sugars (C5H10O5) Hexose sugars (C6H12O6) H C OH H C OH HO C H H C OH C O HO C H H C O Aldoses Ketoses Glyceraldehyde Ribose Glucose Galactose Dihydroxyacetone Ribulose Fructose Intermediate in photosynethesis Sunless tanning product
9
Figure 5.4 Linear and ring forms of glucose
H H C OH HO C H H C O C 1 2 3 4 5 6 OH 4 C 6 CH2OH 5 C H OH 2 C 1C 3 C 2C 1 C CH2OH HO (a) Linear and ring forms. Chemical equilibrium between the linear and ring structures greatly favors the formation of rings. To form the glucose ring, carbon 1 bonds to the oxygen attached to carbon 5. Carbonyl hydroxyl (b) Abbreviated ring structure. Each corner represents a carbon The ring’s thicker edge indicates that you are looking at the ring edge-on; the components attached to the ring lie above or below the plane of the ring.
10
Figure 5.5 How are monomers added to carbs?
Dehydration reaction in the synthesis of maltose. The bonding of two glucose units forms maltose. The glycosidic link joins the number 1 carbon of one glucose to the number 4 carbon of the second glucose. Joining the glucose monomers in a different way would result in a different disaccharide. Dehydration reaction in the synthesis of sucrose. Sucrose is a disaccharide formed from glucose and fructose. Notice that fructose, though a hexose like glucose, forms a five-sided ring. (a) (b) H HO H OH OH O CH2OH H2O 1 2 4 1– 4 glycosidic linkage 1–2 glycosidic linkage Glucose Fructose Maltose Sucrose
11
What are polysaccharides used for?
Energy storage Starch – plants Glycogen – animals Structural support Cellulose Chitin
12
Figure 5.6 Storage polysaccharides of plants and animals
Mitochondria Giycogen granules Chloroplast Starch Amylose Amylopectin 1 m 0.5 m (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide Glycogen Plant storage Animal storage Both are polymers consisting entirely of glucose monomers
13
Figure 5.7 Starch and cellulose structures
(c) Cellulose: 1– 4 linkage of glucose monomers H O CH2OH OH HO 4 C 1 (a) and glucose ring structures (b) Starch: 1– 4 linkage of glucose monomers glucose glucose Differ in OH placement Whether it is above or below the plane of the ring Isomers with different “glycosidic linkages” Form helical structures Form straight structures
14
Figure 5. 8 The arrangement of cellulose in plant cell walls
Figure 5.8 The arrangement of cellulose in plant cell walls -a major component of the tough walls that enclose plant cells Most abundant organic compound on earth! Cellulose molecules Plant cells 0.5 m Cell walls Cellulose microfibrils in a plant cell wall Microfibril CH2OH OH O Glucose monomer Parallel cellulose molecules are held together by hydrogen bonds between hydroxyl groups attached to carbon atoms 3 and 6. About 80 cellulose molecules associate to form a microfibril, the main architectural unit of the plant cell wall. A cellulose molecule is an unbranched glucose polymer.
15
Figure 5.10 Chitin, a structural polysaccharide
(a) The structure of the chitin monomer. O CH2OH OH H NH C CH3 (b) Chitin forms the exoskeleton of arthropods. This cicada is molting, shedding its old exoskeleton and emerging in adult form. (c) Chitin is used to make a strong and flexible surgical thread that decomposes after the wound or incision heals. Nitrogen appendage; different from cellulose Found in the cell walls of many fungi
16
Review Questions The building blocks of carbohydrates are? Function in? A glycosidic linkage is between what? What is the polysaccharide of plants called? Of animals? How does a cellulose molecule differ from a starch? Differ from a chitin?
17
Smallest unit – fatty acid + glycerol
Lipids Fats Oils Waxes Phospholipids Steroids Smallest unit – fatty acid + glycerol
18
Lipids do not form polymers. little or no affinity for water.
mostly of hydrocarbons form nonpolar covalent bonds. major function - energy storage .
19
Figure 5.11 The synthesis and structure of a fat, or triacylglycerol
Describe the structure of a glycerol, a fatty acid (b) Fat molecule (triacylglycerol) H O H C OH Glycerol Fatty acid (palmitic acid) HO O (a) Dehydration reaction in the synthesis of a fat Ester linkage 3 fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride.
20
Figure 5.12 Examples of saturated and unsaturated fats and fatty acids
(a) Saturated fat and fatty acid Stearic acid (b) Unsaturated fat and fatty acid cis double bond - causes bending Oleic acid Animal fats Plant/fish fats -limits the ability of fatty acids to be closely packed
21
Lipid Structure Glycerol - a three-carbon alcohol with a hydroxyl group attached to each carbon. A fatty acid - a carboxyl group attached to a long carbon skeleton, often 16 to 18 carbons long. Hydrophobic due to many nonpolar C—H bonds in the long hydrocarbon skeleton
22
Figure 5.13 The structure of a phospholipid
Hydrophilic head CH2 N(CH3)3 O P CH C Choline Phosphate Glycerol (a) Structural formula (b) Space-filling model Fatty acids (c) Phospholipid symbol Hydrophobic tails Hydrophilic head Hydrophobic tails + – polar Similar to a fat- Exception: 3rd hydroxyl group of glycerol is joined to a phosphate (neg. charge) – electronegative & hydrophilic nonpolar
23
Figure 5.14 Bilayer structure formed by self-assembly of phospholipids in an aqueous environment
Hydrophilic head WATER Hydrophobic tail
24
Figure 5.15 Cholesterol, a steroid
H3C Carbon skeleton with 4 fused rings* Common in animal cell membranes Precursor from which all other steroids are synthesized – many of which are hormones Saturated fats and trans fats exert their negative impact on health by affecting cholesterol levels
25
Questions - Lipids Common names for lipids? Smallest units?
How are they different from the other 3 macromolecules? (bonding pattern, affinity for water, carbon chain, etc.) An ester linkage is between?
26
Proteins 50% of the dry mass of most cells
Protein enzymes function as catalysts Polymers of proteins – polypeptides Smallest units – amino acids C, H, O, N, sometimes S
27
Table 5.1 An Overview of Protein Functions
28
Amino Acid Monomers Make Proteins
H N C R O OH Amino group Carboxyl carbon 5 parts: R group determines kind of a.a. thus determines properties
29
Figure 5.16 The catalytic cycle of an enzyme
Substrate (sucrose) Enzyme (sucrase) Glucose OH H O H2O Fructose 1 Active site is available for a molecule of substrate, the reactant on which the enzyme acts. 2 Substrate binds to enzyme. 4 Products are released. 3 Substrate is converted to products.
30
Figure 5. 17 The 20 amino acids of proteins
Figure 5.17 The 20 amino acids of proteins *all having carboxyl and amino groups S According to the R group O O– H H3N+ C CH3 CH CH2 NH H2C H2N Nonpolar- hydrophobic Glycine (Gly) Alanine (Ala) Valine (Val) Leucine (Leu) Isoleucine (Ile) Methionine (Met) Phenylalanine (Phe) Tryptophan (Trp) Proline (Pro) H3C O O–
31
Acidic – negative charge Basic – positive charge
OH CH2 C H H3N+ O CH3 CH SH NH2 Polar- hydrophilic Electrically Charged- Ionized Refers only to R groups –O NH3+ NH2+ NH+ NH Serine (Ser) Threonine (Thr) Cysteine (Cys) Tyrosine (Tyr) Asparagine (Asn) Glutamine (Gln) Acidic – negative charge Basic – positive charge Aspartic acid (Asp) Glutamic acid (Glu) Lysine (Lys) Arginine (Arg) Histidine (His)
32
Figure 5.18 Making a polypeptide chain
Type of reaction? Dehydration synthesis Type of bond? Peptide DESMOSOMES OH CH2 C N H O Peptide bond SH Side chains H2O Amino end (N-terminus) Backbone (a) Carboxyl end (C-terminus) (b)
33
4 Levels of protein structure
Primary Secondary tertiary quaternary N C H O R Gly Thr Glu Seu Lya Cya Pro Leu Met Val Asp Ala Arg Ser Amino acid subunits pleated sheet a helix +H3N Amino end 1 5 10 15 20 25
34
Figure 5.20 Exploring Levels of Protein Structure: Primary structure
– Amino acid subunits +H3N Amino end o Carboxyl end c Gly Pro Thr Glu Seu Lys Cys Leu Met Val Asp Ala Arg Ser lle Phe His Asn Tyr Trp Lle Polypeptide chain- *a free amino end (the N-terminus), *a free carboxyl end (C-terminus) A slight change in the primary structure can affect the proteins ability to function Ex. Sickle cell anemia (substitution of valine a.a for the normal glutamic acid a.a)
35
1. pleated sheet (folded)
Figure 5.20 Exploring Levels of Protein Structure: Secondary structure – 2 forms 1. pleated sheet (folded) O C 2. Helix (coiled) O H C O H C R C O H C R C O H C R H N H H N H Amino acid subunits H R C R C H R C H C C N N N N H C O N H N H C C C O C O R C H O H R C R C H R C H R C H C O C O C O C O N H N H N H N H N H H C R H C R H C R C O N H C O N H C O N H C O C C R H R C H C N H O C N H O C N H N H O C H C R H C H C R H C R R Coils/folds caused by hydrogen bonds between the repeats N H O C N H O C O C N H O C N H C C R H R H
36
Figure 5.20 Exploring Levels of Protein Structure: Tertiary structure
Bonds: Hydrogen Disulfide covalent Ionic Van der Waals interactions Peptide CH2 O H O C OH NH3+ -O S CH CH3 H3C Hydrophobic interactions and van der Waals interactions Polypeptide backbone Hydrogen bond Ionic bond Disulfide bridge Determined by interactions among various R groups Among hydrophobic R groups Between polar and/or charged areas Strong covalent bonds between sulfydryl groups of 2 cysteine monomers Between charged R groups
37
Figure 5.20 Exploring Levels of Protein Structure: Quaternary Structure
Polypeptide chain Collagen Chains Chains Hemoglobin Iron Heme Aggregation of 2 or more polypeptide subunits Creates a 3-D shape Fibrous protein – 3 polypeptides, supercoiled, connective tissue strength (40% of human body protein) Globular protein – 4 polypeptide subunits hemoglobin Contains a nonpeptide heme + Fe atom – binds oxygen
38
Sickle-cell hemoglobin
Figure 5.21 A single amino acid substitution in a protein causes sickle-cell disease Primary structure Secondary and tertiary structures Quaternary structure Function Red blood cell shape Hemoglobin A Molecules do not associate with one another; each carries oxygen Normal cells are full of individual hemoglobin molecules, each carrying oxygen 10 m Hemoglobin S Molecules interact with one another to crystallize into a fiber, capacity to carry oxygen is greatly reduced Fibers of abnormal hemoglobin deform cell into sickle shape subunit 1 2 3 4 5 6 7 Normal hemoglobin Sickle-cell hemoglobin . . . Val His Leu Thr Pro Glu Glu Val His Leu Thr Pro Val Glu Exposed hydrophobic region
39
Figure 5.22 Denaturation and renaturation of a protein
Alterations in pH, salt concentration, temperature, exposed to an organic solvent (ether) can unravel or denature a protein (disrupts the bonding patterns) Denaturation Normal protein Denatured protein Renaturation Often can return to functional shape when the denaturing agent is removed
40
Figure 5.23 A chaperonin in action “folding a protein”
Hollow cylinder Cap Chaperonin (fully assembled) Steps of Chaperonin Action: An unfolded poly- peptide enters the cylinder from one end. The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide. The cap comes off, and the properly folded protein is released. Correctly folded protein Polypeptide 2 1 3
41
Nucleic Acids Store and transmit hereditary information
a polymer of nucleotides 2 types: DNA and RNA
42
Synthesis of mRNA in the nucleus
Figure 5.25 DNA RNA protein: a diagrammatic overview of information flow in a cell 1 2 3 Synthesis of mRNA in the nucleus Movement of mRNA into cytoplasm via nuclear pore Synthesis of protein NUCLEUS CYTOPLASM DNA mRNA Ribosome Amino acids Polypeptide
43
How does information from DNA make a protein?
DNA is copied to RNA in nucleus RNA travels to ribosome Amino acids brought to ribosome according to RNA code
44
Figure 5.26 The components of nucleic acids
CH Uracil (in RNA) U 5’ end (5th carbon w/phosphate) 5’C O 3’ end (3rd carbon –OH attachment) OH Nitrogenous base Nucleoside-2 parts O O P CH2 Phosphate group Pentose sugar (b) Nucleotide – 3 parts C N H NH2 HN CH3 Cytosine Thymine (in DNA) T HC NH Adenine A Guanine G Purines-double rings HOCH2 5’ 4 3’ 2’ 1’ 3’ 2’ Pentose sugars Deoxyribose (in DNA) Ribose (in RNA) Nitrogenous bases-rings of C,N Pyrimidines- single ring (c) Nucleoside components (a) Polynucleotide, or nucleic acid Adjacent nucleotides are joined by covalent bonds called Phosphodiester linkages (formed between the –OH group on the 3’ and the phosphate on 5”)
45
Smallest unit of a nucleic acid:
Nucleotide Sugar Phosphate group Nitrogen base Adenine Guanine Cytosine Thymine
46
Figure 5.27 The DNA double helix and its replication
3¢ end Sugar-phosphate backbone Base pair (joined by hydrogen bonding) Old strands Nucleotide about to be added to a new strand A 5¢ end New strands C G T Hydrogen bonds Hold sides together
Similar presentations
