Tutor profile: Rachel G.
Write three sentences using the verb “estudiar” in the preterit, past perfect, and the subjunctive.
Pretérito: Estudié por dos semanas para asegurarme de tener éxito. Pluscuamperfecto: Ya había estudiado para el examen antes de ir de compras con mis amigos. Subjuntivo: Dudo que él estudie mucho ya que pasa tanto tiempo jugando deportes.
Fill in the blanks in the chemical equation H2SO4(aq) + H2O(l) --> ___(aq) + ___(aq) . Name the acid and base given in the first half of the equation and their conjugate base and acid. If the acid dissociation constant (Ka) for the dissociation of sulfuric acid in water is about 2.4x106, is sulfuric acid or hydronium ion a stronger acid?
H2SO4(aq) + H2O(l) --> HSO4-(aq) + H3O+(aq) H2SO4(aq), or sulfuric acid, is the acid in the first half of the equation and HSO4-(aq), or hydrogen sulfate, is its conjugate base. Water is the base in the first half of the equation and the hydronium ion is its conjugate acid. Given that the dissociation constant of sulfuric acid is larger than 1, it is a strong acid and will dissociate completely in water. It is important to note that water is acting as a base in this situation, but because it is an amphoteric substance, it can act as either an acid or a base.
Deoxyribonucleic acid, or DNA, is a macromolecule with a double helical structure that carries the “instructions” for the development, functioning, and reproduction of organisms. Briefly outline the central dogma and the processes through which DNA is replicated and expressed.
The central dogma is the set of processes that allow for the expression of DNA through its transcription to mRNA and translation of the mRNA into protein. The double helical structure of DNA is comprised of two antiparallel and complementary strands of purine or pyrimidine bases bonded to a sugar-phosphate backbone. Replication of DNA occurs in the nucleus of the cell. It involves unwinding and separating the two parent strands, followed by the synthesis of the new complementary strand in the 5’ to 3’ direction (continuously synthesized for the leading strand and utilizing Okazaki fragments for the lagging strand). Transcription creates a copy of single-stranded, complementary messenger RNA, or mRNA. Translation of mRNA takes place in three steps–initiation, elongation, and termination– through which mRNA is decoded to synthesize a polypeptide chain by ribosome in the rough endoplasmic reticulum or cytoplasm.
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