参与DNA复制的几种酶的作用次序是 参与DNA复制的几种酶的作用次序是 DNA DNA解链酶 引发酶→DNA聚合酶→DNA连接酶→ 解链酶→ →DNA聚合酶→DNA连接酶 A› DNA解链酶→引发酶→DNA聚合酶→DNA连接酶→ 切除引物的酶 DNA解链酶 引发酶→DNA聚合酶→ 解链酶→ →DNA聚合酶 B› DNA解链酶→引发酶→DNA聚合酶→切除引物的酶 →DNA连接酶 →DNA连接酶 引发酶→DNA解链酶→DNA聚合酶→DNA连接酶→ →DNA解链酶→DNA聚合酶→DNA连接酶 C› 引发酶→DNA解链酶→DNA聚合酶→DNA连接酶→ 切除引物的酶 DNA解链酶 引发酶→切除引物的酶→DNA 解链酶→ →DNA连接酶 D› DNA解链酶→引发酶→切除引物的酶→DNA连接酶 →DNA聚合酶 →DNA聚合酶
19. DNA polymerase catalyzes the formation of a phosphodiester bond between a A› 5’phosphate and a 5’hydroxyl group. B› 3’phosphate and a 5’hydroxyl group. C› 5’phosphate and a 3’hydroxyl group. D› 3’phosphate and a 3’hydroxyl group. 20. The sequence of nucleotides in one strand of DNA is 5’-C C A C T G G-3’, What is the sequence of the complimentary strand of DNA? A› 5’-C C A C T G G-3’ B› 3’-C C A C T G G-5’ C› 5’-G G T C A C C -3’ D› 3’-G G T G A C C-5’
17. In eukaryotes, DNA replication occurs during which phase of the cell cycle? A› S B› G1 C› G2 D› M 18. Which of the following is not required for DNA synthesis reactions? A› dCTPs B› template DNA C› DNA polymerase D› calcium ions
3. Which element is not found in a molecule of DNA? A› carbon. B› sulfur. C› nitrogen. D› oxygen. 4. The two polynucleotide chains in a molecule of DNA are held together by what type of bond? A› Phosphodiester. B› Phosphate. C› Peptide. D› hydrogen.
1. Which is the most accurate representation of the organization levels of the genetic information in cells? A› genes –nucleotide-chromosomes -genome. B› genome- genes-nucleotides-chromosomes. C› chromosomes-genes – nucleotides-genome. D› nucleotides-genes-chromosomes-genome. 2. Eukaryotic cells differ from prokaryotic cells in that only the former contain A› ribosomes. B› cytoplasm. C› DNA. D› a nucleus.
3. On the E. coli chromosome, oriC A› encodes DNA polymerase I. B› is a binding site for histone proteins. C› is the start site for replication. D› encodes an RNA primer. 4. The enzyme that unwinds the double helix to facilitate replication is A› 3 ’ 5 ’ exonuclease. B› DNA helicase. C› DNA polymerase. D› topoisomerase.
7. Viral genomes may be composed of A› RNA only. B› DNA only. C› either RNA or DNA. D› both RNA and DNA. 8. The type of DNA found most commonly in living cells is the ___ form. A› A. B› B. C› C. D› Z
5. The DNA that makes up bacterial chromosomes is A› single-stranded. B› circular and supercoiled. C› complexed with histones. D› all the above. 6. The DNA and histone proteins in a eukaryotic chromosome are compacted into structures called A› proteosomes. B› nucleosomes. C› telomeres. D› centromeres.
1. In bacteria such as E. coli, replication of the chromosome is A› semidiscontinuous and bi-directional. B› discontinuous and unidirectional. C› continuous and bi-directional. D› semidiscontinuous and unidirectional. 2. The proofreading activity of DNA polymerase removes errant nucleotides from the ___ of a DNA strand. A› 3’ end B› 5’ end C› 3’ and 5’ end D› middle
5. When the DNA double helix is replicated, the newly synthesized 5’ 3’ strand is considered the ___ strand. A› leading B› lagging C› template D› discontinuous 6.Many types of mammalian cancer cells are notable for their A› telomerase activity. B› lack of telomerase activity. C› lack of telomeres. D› increased number of telomeres.
13. At the conclusion of DNA replication, the two resulting DNA double helices each contain A› one parental and one parental or two progeny strands. C› stretches of progeny DNA interspersed with parental DNA along both strands. D› two newly synthesized strands. 14. To begin DNA replication, a short ___ primer must first be produced. A› DNA B› RNA C› polypeptide D› histone
9.Genes located in which region of a eukaryotic chromosome are most likely to be transcribed? A› centromere B› telomere C› euchromatin D› heterochromatin 10.A nucleoside consists of a A› pentose sugar and a nitrogenous base. B› phosphate group and a nitrogenous base. C› pentose sugar and a phosphate group. D› pentose sugar, a phosphate group, and a nitrogenous base
•Molecular Biology Course
Quiz 1 1. Describe the structural difference of the DNA and RNA. How these structural differences interpret their corresponding biological functions 2. How the leading strand and lagging strand at a replication fork are synthesized in E. coli? And how these two antiparellel strands are synthesized simultaneously toward the same direction as the fork movement