6. Which process mediates protein degradation?
(A) Translation
(B) Transcription
(C)Replication
(D) Ubiquitination
(E) Photosynthesis

2. What description about micro RNAs (miRNAs) is incorrect? (A) Most miRNAs are transcribed by RNA Pol II. (B) One type of miRNAs can target to many mRNAs. (C) The mature miRNAs are about 21-22 nucleotide, which hybridize perfectly with their target mRNAs.(D)They associate with Ago protein to form RISC (RNA-induced silencing complex) complex. (E) They can induce mRNA degradation or inhibit mRNA translation.

3. The exons of nuclear pre-mRNA have to be removed for mature mRNA synthesis. Which is incorrect? (A) One transesterification reaction results in splicing of exons in pro-mRNA. (B) The spliceosome is a snRNAs complex to catalyze the exon removals without ATP. (C) The splicing is preformed after thtranscription termination. (D) Only 1% of human genes undergo alternative splicing to yield different mRNAs that encode distinct proteins. (E) SR proteins contribute to exon definition.

4.Which part of the ribosome is responsible for peptidy1 transfer? (A) LSU (B) SSU (C)mRNA (D)tRNA (E) SiRNA

5.Transporting macromolecules to the nucleus through nuclear pores from the cytosol typically requires which one's help? (A) Epinephrine (B) Exportin (C) Importin (D) AMPK (E) mTOR

7.The sodium-potassium pump establishes concentration gradients (A) of higher sodium concentrations inside the cell and higher potassium concentrations outside the cell. (B) of sodium and potassium but the area of their concentrations depends on the needs of the cell. (C) of higher potassium concentrations inside the cell and higher sodium concentrations outside the cell. (D) of ATP inside the cell where it is needed. (E) by pumping sodium outside the cell and potassium is cotransported out as well.

8.Which of the following component(s) is NOT required for those proteins to be internalized during endocytosis? (A) cargo adaptor (B) coat protein (C) GTPase (D) translocon (E) All of above are used in the secretory pathway

9. Which of the following pathway(s) is NOT the correct description for secretory proteins during protein transport? (A) Secretory proteins move to the plasma membrane for protein expression. (B) Trans-Golgi network is thought to be the sorting hub for secretory proteins. (C) Secretory proteins can be recycled back to ER using the tyrosine-based sorting motif. (D) Secretory proteins move to ER by cotranslational transport machinery in mammalian cells. (E) All of above are correct.

10. Polymerization of collagen into large collagen fibers occurs (A) in the endoplasmic reticulum. (B) in the Golgi complex. (C) in secretory vesicles. (D) extracellularly. (E) none of the above.

11.Signaling at synapses is usually terminated by (A) calcium influx. (B) potassium influx. (C) inhibitory neurotransmitters. (D) degradation or reuptake of neurotransmitters. (E) none of the above.

12. Which repair is considered as an error-free mechanism? (A) Homologous recombination (B) Non-homologous end-joining (C) Microhomology-mediated end-joining (D) Single strand annealing (E) Transcription-coupled DNA repair