2. DNA replication is accomplished by employing a mechanism.
3. allows the flawless repair of DNA double-strand breaks.
A) Homologous recombination
B) Nonhomologous end-joining
4. In a double stranded DNA helix, .
A) adenine always base pairs with guanine
B) purines base pair with pyrimidines
5. During the chain elongation process of translating an mRNA into protein, the growing polypeptide chain attached to a tRNA is bound to the -site of the ribosome.
A) P B) A
6. Proteins that link the distantly bound transcription regulators to RNA polymerase and the general transcription factors include the large complex of proteins called the .
7. molecules are important in the splicing of RNA transcripts.
A) rRNA B) snRNA
8. Transcription is similar to DNA replication in that .
A) nucleotide polymerization occurs only in the 5′-to-3′ direction
B) an RNA transcript is synthesized discontinuously and the pieces are then joined together
9. RNA in cells differs from DNA in that .
A) it is single-stranded and cannot form base pairs
B) it is single-stranded and can fold up into a variety of structures
10. The subunit of a ribosome is the first to interact with new mRNAs.
1 (Version 1) Introduction to Cell Biology Name: December 02, 2010 Student ID:
11. The segments of primary RNA that are cleaved off by spliceosomes are called .
12. The human genome encodes about 24,000 genes. The typical differentiated human cell expresses at any one time?
A) between 21,500 and 24,000—at least 90% of the genes
B) between 5000 and 15,000 genes
13. Many bacterial promoters contain a region known as an , to which a specific transcription regulator binds.
14. During transcription in cells, transcriptional regulators that bind to DNA thousands of nucleotides away from a gene’s promoter can affect a gene’s transcription.
15. In principle, different cell types can an organism having three different types of transcription regulator and thousands of genes create?
A) up to 4
B) up to 8
16. Combinatorial control of gene expression .
A) involves only the use of gene activators used together to regulate genes appropriately
B) involves groups of transcriptional regulators working together to determine the expression of a gene
17. MicroRNAs .
A) are produced from a precursor miRNA transcript
B) can degrade RNAs by using their intrinsic catalytic activity
18. is not involved in post-transcriptional control?
19. The drug colchicine .
A) prevents microtubule formation. B) stabilizes microtubules.
20. Cytoskeleton is particularly important in cells.
2 (Version 1) Introduction to Cell Biology Name: December 02, 2010 Student ID:
21. The is directly responsible for segregation of chromosomes into daughter cell during cell division.
B) actin filaments
22. are intermediate filaments?
B) Nuclear lamins
23. Cilia and flagella use motors to create movement?
24. The nature of a myosin thick filament is essential for muscle contraction.
25. Kinesins and dyneins .
A) have tails that bind to the filaments
B) often move in opposite directions to each other
Section 2: Multiple Choice. Identify the single BEST answer for each question (3 points each).
26. DNA polymerases are processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the…