I. Chapter 5 Summary
A. Simple Sugars (CH2O)n: 1. One C contains a carbonyl (C=O) rest contain -OH 2. Classification by functional group: aldoses & ketoses 3. Classification by number of C's: trioses, pentoses, hexoses 4. Stereochemistry: all sugars have D conformation 5. Cyclic structure: -OH bonds to carbonyl carbon ==> 5- or 6-member ring B. Disaccharides: 2 simple sugars joined by "glycosidic" bond between - OH of one and carbonyl of another 1. Table sugar 2 . M a l t o s e 3. Lactose C. Polysaccharides 1. Food Storage: starch and glycogen are polymers of glucose 2. Structural: cellulose is polymer of glucose 3. Differ in conformation of carbonyl C where sugars are joined II. Nucleotides & Nucleic Acids A. Nucleotides: Base-sugar-phosphate B. Nucleic Acids 1. Nucleotide polymer connected by phosphodiester bonds 2. RNA (RiboNucleic Acid)-nucleotides contain ribose sugar 3. DNA (DeoxyriboNucleic Acid)-nucleotides contain 2!-deoxy-ribose sugar III. Lipids A. Glycerides 1. Triglycerides: 3 fatty acids bonded to 3 -OH's of glycerol by ester bonds 2. Phospholipids: Diglycerides and Amphipathic (have polar and nonpolar groups) 3. Phospholipid bilayer B. Cholesterol-sterol lipid
Fig. 4.2: In 1953 Stanley Miller simulated what were thought to be
Figure 4-02 environmental conditions in the prebiotic earth.
1 Chapter 5: Biological Building Block Molecules (Monomers) and Macromolecules
Complex Polymer Monomer Simple Polymer (Macromolecule) Monosaccharide Polysaccharide Oligosaccharide (Simple Sugar) (Complex Carbohydrate) Nucleotide Oligonucleotide Nucleic Acid Polypeptide Amino Acid Peptide Protein
What do Macromolecules Do?
Carbohydrates & Lipids: Important Functions fuel molecules for energy structural roles Nucleic Acids: Store, Transmit, and Decode Hereditary Information (also some structural roles) Proteins: Perform an incredible number of functions! structural proteins transport proteins enzymes hormones & signaling molecules storage proteins receptor proteins contractile & motor proteins defense proteins
2 Fig. 5.2: Common Features of Macromolecules 1. Proteins, carbohydrates and nucleic acids are complex polymer molecules created by joining together building blocks called monomers
5 6 7
Monomers are linked by a condensation reaction (a dehydration reaction that produces H2O)
Fig. 5.2 Common Features of Macromolecules 2. Protein, carbohydrate and nucleic acid polymer molecules are broken down into monomers by hydrolysis of the bonds between monomers
Hydrolysis adds a water molecule, breaking a bond
3 Common Features of Macromolecules 3. Protein, carbohydrate and nucleic acid polymer molecules can fold into complex 3-dimensional shapes (specific shape depends on sequence of monomers)
Ionic bonds, Hydrogen bonds and Van der Waal’s interactions are important in specifying and maintaining shape
Common Features of Macromolecules 4. Protein, carbohydrate, lipids and nucleic acids can associate with each other and with other types of molecules via specific intermolecular interactions
Molecular shape, Ionic bonds, Hydrogen bonds and Van der Waal’s interactions are important to determine strength and specificity of interactions
4 Fig. 2.17: Important Concept The function of a macromolecule is determined by its Molecular Shape (conformation) & Composition Macromolecules such as proteins work by interacting with other molecules. These interactions depend on the molecules having complementary shapes that fit together (like a lock and key)
Chapter 5: Biological Building Block Molecules (Monomers) and Macromolecules
Complex Polymer Monomer Simple Polymer (Macromolecule) Monosaccharide Polysaccharide Oligosaccharide (Simple Sugar) (Complex Carbohydrate ) Nucleotide Oligonucleotide Nucleic Acid Polypeptide Amino Acid Peptide Protein
5 Carbohydrates: Contain Carbon, Hydrogen and Oxygen in the ratio CH2O Monomers: The simplest Carbohydrates are the Simple Sugars, these are classified by: O Type of Carbonyl group Ketone Ketose R-C-R O Aldehyde Aldose or by R-C-H Number of Carbon atoms: 3 C’s Triose 4 C’s Tetrose 5 C’s Pentose 6 C’s Hexose
Note: suffix …ose indicates a sugar
Trioses Aldose Ketose
All sugars, except Di-hydroxy acetone, can have D or L optical isomers, although only the D isomers exist naturally.
L-Glyceraldehyde D-Glyceraldehyde
6 Common Simple Sugars
Trioses
Pentoses
Hexoses
Fig. 5.4a: Linear and ring forms of glucose Pentoses and Hexoses form ring structures in water when one of the –OH groups forms a bond to the carbonyl group
Linear and 2 forms, β and α ring forms
7 Figure 5.5a: Disaccharides
1–4 glycosidic linkage
Glucose Glucose Maltose
Disaccharides contain two simple sugars joined by a Glycosidic Bond Common Disaccharides
Malt Sugar Milk Sugar Table Sugar Glucose-Glucose Galactose-Glucose Glucose-Fructose
Polysaccharides (Glycans):
Starch and Glycogen: Fuel storage polysaccharides
α (14) Glycosidic Bond
Cellulose: Structural polysaccharide
β (14) Glycosidic Bond
8 FLEig 5-6. 5.6: Food Storage Polysaccharides - Starch and Glycogen
Chloroplast Starch Mitochondria Glycogen granules
0.5 µm
1 µm
Amylose Amylopectin Glycogen
Starch: a plant polysaccharide Glycogen: an animal polysaccharide
LE 5-8 Fig. 5.8: Structural Polysaccharides - Cellulose
Cellulose microfibrils in a plant cell wall Cell walls Microfibril
0.5 µm
Plant cells
Cellulose molecules
β Glucose monomer
9 Structural Polysaccharides - Chitin
β (14) Glycosidic Bond Chitin forms the hard exterior exoskeleton of insects It is also used to make biodegradable surgical threads
Nucleotides / Nucleic Acids
Complex Polymer Monomer Simple Polymer (Macromolecule) Monosaccharide Polysaccharide Oligosaccharide (Simple Sugar) (Complex Carbohydrate) Nucleotide Oligonucleotide Nucleic Acid Polypeptide Amino Acid Peptid e Protein
10 Nucleotides: Adenine consists of three components: •Nitrogenous base, Adenine in this example Phosphate •A sugar: ribose or 2’-deoxyribose •Phosphate
N-Glycosidic Bond
Adenosine 5’-monophosphate (AMP) Phosphoester Bond
RNA DNA
Fig. 5.26a: The components of Nucleic Acids 5′ end
Nucleoside Nitrogenous base Phosphodiester Bond
Phosphate group Pentose sugar
Nucleotide
3′ end Polynucleotide, or Nucleic Acid
11 Fig. 5.26b: Nucleoside Components
Nitrogenous bases Pyrimidines
Cytosine Thymine (in DNA) Uracil (in RNA) C T U
Purines
Adenine Guanine A G
Pentose sugars
Deoxyribose (in DNA) Ribose (in RNA)
Nucleoside components
Fig. 5.27: The DNA double helix and its replication.
5′ end 3′ end
Sugar-phosphate backbone
Base pair (joined by hydrogen bonding)
Old strands
Nucleotide about to be added to a new strand
5′ end
New strands
3′ end 5′ end
5′ end 3′ end
12 Lipids
Lipids are a diverse group of molecules which are primarily water-insoluble and include:
Fats triglycerides Oils Waxes Phospholipids Biological Steroids Membranes Carotenoids
Fatty acids are the building blocks of lipids
Fatty Acids
Saturated fatty acids: Unsaturated fatty acids: No double bonds between One or more double bonds adjacent carbon atoms between adjacent carbon atoms
Acyl chain (16 – 18 carbons)
Straight Bent (kinked) conformation conformation
13 Fig 5.11 & 5.12: Triglycerides
Triglycerides consist of 3 fatty acids bonded to the three hydroxyl (-O-H) groups of a molecule of glycerol (ester bonds) Fats = triglycerides from animals with mostly saturated fatty acids
(condensation reaction)
Oils = triglycerides from Acyl chains can be saturated plants with mostly unsaturated or unsaturated fatty acids
Fig 5.13: Phospholipids
Hydrophilic head
2 Hydrophobic tails
Phospholipds are amphipathic molecules (contain both hydrophilic and hydrophobic parts)
14 Fig 5.14 / 7.2: Phospholipids Assemble to Form Membrane Bilayers
Fig 7.2
Phospholipid bilayers form impermeable membranes that enclose and compartmentalize cells
Steroids are lipid molecules (water insoluble) based on a hydrocarbon structure with four fused rings
Cholesterol is the most common steroid and is found in membranes
Cortisol, Estrogen and Testosterone are steroid The Polar -OH group makes hormones this molecule amphipathic
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