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17 Cards in this Set
- Front
- Back
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4 Basic Building Blocks of Life
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1. Amino Acids
2. Fatty Acids 3. Sugars 4. Nucelotides |
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Modularity
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handful of monomers are linked together to form profoundly long complicated polymers
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Types and amounts of monomers per building block?
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4 deoxynucleotides = DNA (genomes)
4 nucelotides (A,G,T,C) = RNA (messages) 20 aa = proteins 100s monosaccharides = polysaccharides |
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Electronegativity
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-more electronegative L-->R & bottom-->top of periodic table
-H&C don't care which way they bond, tend to be more electropositive -high electroneg. = more willing to take 2 electrons than lose 6. -ex: Oxygen: pick up 2 electrons, makes 2 bonds |
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What is:
Nucleophile Electrophile |
N: nucleus lover, negative - pair of electrons
E: loves electrons, positive - |
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Nucleophilic attack in nucelic acid elongation, identify:
1) nucleophile 2) electrophile 3) future oxyanion 4) future leaving group 5) what type of bond formed? |
1) OH group off the 3' carbon
2) positive charged P atom of triphosphate group 3) lone pir of e- on oxyanion resonate back to reform double bond & kick off leaving group 4) pyrophosphate 5) phosphodiester bond |
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Nucleic Acid Base Pairing
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Adenine-Thymine
Guanine-Cystine |
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DNA --> RNA
RNA --> Protein |
Trancription
Translation |
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How are proteins linked?
What type of rxn involved? Which group is nucleophile? Which group is electrophile? |
peptide bonds - form protein
nucleophilic attack N off amino group side of aa O off carboxyl group side of aa (double bond) |
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What is first step in nucleophilic attack on an amino acid?
What is different about the intermediate group? |
amine group must become deprotonated
-the resulting lone pair of e- on N then attacks the carbonyl carbon -2 oxyanions form on the carbonyl group -very unstable so negative charge attracks protons (from sol'n ex: water) |
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In the body how is nucleophilic attack to amino acids different?
What is the bond? |
-body: aa activated by attachments to tRNA (hold in place to make sure rxn occurs)
-ribosome deprotonates the amine end (making it available for rxn) -tRNA linked to aa via an ester bond |
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Why are amines & carboxylic acids common in biomolecules & drugs?
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Most amines are protonated & positively charged
Most carboxylic acids are deprotonated & negatively charged |
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Why carboxylic acids are deprotonated?
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-resonance stabilization
-wants to give up H+, free pair of e- to resonate through large region thus spread out negative charge -unlikely for protonation bc equal on both O2 (doesn't know which to bind - only way to make stick is to increase acidity [H+] |
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Why amines protonated?
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e- on N readily available to pull a proton off of H2O
-electronegative N has increased e- density bc inductively pulls e- away from 3 bound Hydrogen |
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What do double bonds do to a structure?
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-flatten adjacent atoms
-conjugated double bonds flatten more adjacent atoms into a plane -yield flattened aromatic groups |
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Amino Acids to recognize
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Lysine
Arginine Glutamate Aspartate Histidine |
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At physiological pH (7.4), which aa side chains are protonated? (positive or negative charge?)
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protonated (positive):
1. lysine 2. arginine deprotonated: 1. glutamate 2. aspartate 1/2 protonated/deprotonated: histidine |
