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Macromolecules. Carbohydrate ― polyhydroxy aldehydes and ketones sugars: monosaccharides & disaccharides e.g. glucose, fructose, sucrose, lactose
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Macromolecules Carbohydrate ― polyhydroxyaldehydes and ketones sugars: monosaccharides & disaccharides e.g. glucose, fructose, sucrose, lactose polysaccharides: e.g. starch, glycogen, cellulose Lipids ― soluble in nonpolar solvents fatty acid esters ― steroids ― prostaglanidns ― leukotrienes Protein ― polymers of amino acids enzymes ― transporters ― receptors ― immunoglobulins etc. Nucleic Acid ― polymers of nucleotides DNA: determines sequence RNA RNA: determines sequence of cellular proteins regulates gene expression
Structure PROTEINS Polymers of Amino Acids DNA (gene) mRNA Protein sequence YMGCFTSSGLIVVEHY... Function
NUCLEIC ACIDS polymers of nucleotides DNA RNA encodes genetic information has both functional & informational roles in gene expression Genes code for Cell’s Proteins
NUCLEOTIDES Base: Adenine, Guanine, Thymine (Uracil), Cytosine Sugar: Ribose or deoxy-ribose Phosphates: 1-3 via phosphate ester bonds nucleoside = base + sugar
Nucleic Acid Bases Adenine CH3 Guanine Uracil Thymine Cytosine
Purine Ring N N 6 7 4 5 N 1 5 8 3 2 N 4 9 N 2 6 3 1 N Pyrimidine Ring
N2 NH3 or NO3- soil bacteria plants anabolic 1 Protein N - Cpds includes purine & pyrimidine bases Amino acids
Protein Glucose Ribose-5-P Pyruvate bases RNA AcetylCoA Nucleotides DNA NADH C6 C4 FADH2 ADP Krebs Cycle C5 C4 ATP O2 Amino Acids
4 N 5 3 C C C C 2 6 1 N O O || || H2N - C - O - P - O | O Pyrimidine Ring Aspartate carbamoyl phosphate
N 6 7 N 5 1 8 C C C C C 2 4 9 3 N N Purine Ring Glycine CO2 Aspartate Glutamine tetrahydrofolate
Uracil H2N N N N CH3 O O O N N N Cytosine O O H H Thymine Pyrimidines
N N H2N N N N N Guanine N N Adenine O H H2N Purines
OH HO 5 O 1 4 3 2 HO OH ribose - RNA Nucleotide Sugars 2-deoxyribose - DNA
Cytidine: a nucleoside H2N O N O O - P - O O O - P - O HO O N dCDP HO OH deoxycytidine dCMP
This structure is …. a) a purine b) a nucleoside c) a nucleotide d) DNA Base Phosphate ↓ 5´ 1´ 4´ This nucleotide is…. a) adenine monophosphate b) guanine monophosphate c) guanosine monophosphate d) AMP 3´ 2´ Sugar This structure contains …. a) ribose b) 2´ deoxyribose c) 3´ deoxyribose d) a hemiacetal functional group Phosphate ester bonds are also found in a) phosphoglycerides b) activated phosphorylase c) both d) neither This bond indicated by the ↓ is … a) covalent b) phosphate ester c) both d) neither
Nucleic Acid Bases Adenine CH3 H Guanine Uracil Thymine Cytosine
Structure Nucleotides & DNA DNA (gene) mRNA Protein sequence YMGCFTSSGLIVVEHY... Function
O || -O - P - | O_ O || O - P - | O_ O || O - P - | O_ A | O O 3 3 hydroxyl OH 5 phosphate O- | -O - P - || O O- | O - P - || O O-(H+) | O - P - || O C | O 5 O OH Phosphodiester bond formation
O || -O - P - | O_ O || O - P - | O_ O || O - P - | O_ A | O O C | O O || -O - P - | O_ O || O - P - O- | O_ O O 3-5 phosphodiester bond OH Phosphodiester bond formation dinucleotide 5’ end | _ O - P - | O_ 3’ end
P-P-P C S P G S P A S P T S P T S OH 5 3
1950 ―Erwin Chargaff In DNA isolated from any species # A = # T & # G = # C A-T : G-C ratio varies 1953 ― Franklin and Wilkins ― Watson & Crick DNA has double helix structure Bases paired in center A=T & GC Complementary strands progress in opposite directions. 5’- C G A T T C AG C - 3’ 3’- G C T A AG T C G - 5’
G S P 3 5 C S P P-P-P C S P T S P G S P A S P A S P P-P-P A S P T S P T S P 5 3
N H2N N N N N CH3 CH3 CH3 N N O O O N N N O O O H H H Thymine Thymine Thymine A
N H2N N N CH3 N N O N O H A T
N NH2 H2N N N X N N O N X A C
N N NH2 N N N N O O H H2N G C
Can’t have 2 pyrimidines paired : too far apart for H-bonds o 11 A C T 2 purines don’t fit inside helix
DNA double helix B Form minor groove major groove
N N N N CH3 N N O N O H A H H T
N N N N N N N O O H N H H G H H C
Gene Expression DNA (gene) ↓ mRNA ↓ Polypeptide chain ↓ Folded polypeptide ↓ Functional protein
1 N N CH3 HO CH3 O O N N O enol 10,000 or 104 H keto Thymine has an equilibrium between keto & enol forms
OH H3C N H2N N N X N N O N X A T (enol)
OH H3C N N N N N O N O H H2N G T (enol)
G S P 3 5 C S P P-P-PC S P T S P T G S P A S P G S P P-P-PA S P G T S P T S P 5 3 DNA Pol has proof reading capability There is a DNA repair system in place in cells to repair DNA structural anomalies that Arise due to replication errors or DNA damage If a cell cannot keep up with DNA repair – apoptosis (programmed cell death) pathways should prevent cell growth and division.
DG = DH - TDS dsDNA ↔ ssDNA Which form is favored at elevated temperatures? Why? a) dsDNA b) ssDNA c) the equilibrium will not change with T
ssDNA A=T rich GC rich dsDNA dsDNA ↔ ssDNA Lower A260 higher A260 A260 40 50 60 70 80 T (ºC)
DNA double helix B Form minor groove major groove
DNA forms supercoils Example shown is bacterial plasmid DNA Supercoiling compacts DNA to take up less space The structural form of DNA influences expression DNA forms supercoils Example shown is bacterial plasmid DNA Supercoiling compacts DNA to take up less space The structural form of DNA influences expression
NucleosomesDNA wrapped around a histone core structure Eukaryotic DNA forms chromosome structures These contain DNA binding protein called histones