Integrated SequencePhysics Chemistry Organic Biology

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Special points of emphasis

Functional Groups in Organic Chemistry

Acids and Bases

Reactions of Organic Phosphorus Compounds

Carbohydrates

Nucleic Acids

Gene Expression

The Molecular Biology Laboratory

Here is some important nomenclature for the MCAT. Nucleosides are glycosides of ribose or deoxyrobose with replacement of the anomeric hydroxyl group by a purine or pyrimidine. (The anomeric hydroxyl group is the hydroxyl group remaining from the carbonyl in a sugar's straight chain form after hemi-acetal formation). Nucleotides are phosphate esters of nucleosides.

DNA and RNA are polymers of nucleotides. DNA holds the genetic code, and the several forms of RNA (mRNA, tRNA, and rRNA) together enable the translation of the genetic code into the sequence of proteins.

The phosphate group(s) of a nucleotide are acidic. The two protons of the phosphate group of AMP are governed by pK+'s of 3.8 and 6.2, respectively, so at neutral pH, the dianion of AMP predominates. The negatively charged phosphate groups present in DNA and RNA give the molecules an overall negative charge which enables electrophoretic separation in the laboratory.




Work, Energy, and Power

Electricity

The Chemical Bond

Thermochemistry

Chemical Thermodynamics and the Equilibrium State

Conjugated π Systems and Aromaticity

Reactions of Organic Phosphorus Compounds

Nucleic Acids

Bioenergetics and Cellular Respiration

ATP is a nucleotide, which stores the energy liberated during conversion of carbohydrates to carbon dioxide and water in metabolism. The energy is stored by means of the phosphate ester linkages (many enzyme processes are coupled with phosphate ester hydrolysis). Hydrolysis of the terminal phosphate linkage of ATP is accompanied by an internal energy decrease for two main reasons. ATP is highly negatively charged with four negative charges present on the phosphate groups (two on the terminal phosphate and one each on the two others). Hydrolysis enables the separation of these negative charges from each other. Secondly, there is greater resonance stabilization in ADP than in ATP.



Nucleic Acids

The Endocrine System

Cyclic AMP is the second messenger triggered by arrival at the cell surface of glucagon or epinephrine to stimulate glycogen breakdown. These hormones activate adenylate cyclase, an enzyme associated with the plasma membrane, which catalyzes the conversion of ATP into Cyclic AMP.







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