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