General Botany (BIO 241), 2 Feb 2015
Review and Finish Ch. 2 topics:
Review Carbohydrates and Lipids - energy-storage and structural functions- Starches and Cellulose
Organic Molecules: Proteins, Nucleic Acids
Secondary MetabolitesDNA, Genes, and Genomes (order by descent)
Carbohydrates• Monomers = simple sugars, monosaccharides- C, H, and O in 1:2:1 ratio (eg. C6H12O6)
- (CH2O)n , n= 3-7 (5, 6 most common)- C-skeleton with -OH (hydroxyl) groups 1 –C=O (carbonyl) group
Hydrophilic or Hydrophobic?
Yes: Hydrophilic
MonosaccharidesChain and Ring forms
~
- In solution, monosaccharides exist mainly in ring form (99%)- reaction between the –(C=O)H group (C1) and the hydroxyl (-OH) at C4 or C5- Carbonyl group hydroxyl- Equilibrium of 2 isomers, A and B, depending on orientation of OH relative to C6
Disaccharides• Dehydration synthesis reaction between monosaccharides. ) - requires E input of 5.5. kcal/mole)
• Sucrose is the primary form in Which sugars are transported in plants (phloem sap).
Polysaccharides: polymers of monosaccharides
• Formed by dehydration synthesis reactions (occurs in amyloplasts)
• Energy Storage – must be hydrolyzed before being transported or used as energy source (input to respiration)
Plants: -Starches - Alpha glucose subunits
Amylose - unbranched
Amylopectin - branched
-Fructans (wheat, rye, barley) – fructose subunits
Animals, fungi, prokaryotes: - glycogen (alpha glucose subunits)
Structural Polysaccharide – Cellulose (Beta-glucose subunits)
Triglycerides: glycerol with fatty acid sidechainsFats and oils: triglycerides that store energy
Phospholipids: structural lipids Self-assemble as a bilayer membrane in “solution”
Chemical characteristics: 4 interconnected hydrocarbon rings (= steroid)sterols = steroids with hydroxyl group on C-3
various side-chains (hydrocarbons, hydroxyls, hydroxyl groups) Functions:Structural (part of membranes)Hormones (signaling molecules)
Lipids: steroids and sterols
ProteinsAmino acid (protein subunit)
- amino group (NH2)- carboxyl group (COOH)- R-group (variable)
Peptide bond = Linkage N of amino group and C of carboxyl group by Dehydration Rxn.Primary structure: sequence of amino acids. Directly encoded in DNA
Protein Secondary Structure: interactions among amino acids- hydrogen
bonding - R-groups
point outward (in helix) or Up/Down (pleated sheet), giving
the protein its solubility and reactivity
characteristics.
Alpha Helix
Amino acid R-groups and protein placementR-group polarity in regions of protein 2°
structure determines placement of peripheral and transmembrane proteins.
Hydrophobic Amino Acids
Fluid Mosaic Model
Nucleic Acids-composed of
nucleotides
Nucleotide parts:- nitrogenous base
adeninecytosineguaninethymineuracil
- sugar ribose (5-C)deoxyribose (6-C)
- phosphate
DNA= deoxyribose, ACTGRNA= ribose, ACUG
DNA: Double stranded; each strand is the reverse complement of the other . Hydrogen bonding between nucleotide pairs: A ------ T/U C ------G
Nucleotides are linked into amino acids by dehydration synthesis.
ATP – adenosine (a nucleotide) triphosphateFunction: Cellular Energy Currency
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