皮皮学,免费搜题
登录
搜题
【多选题】
How do retroviruses proliferate in host cells?
A.
Like retrotransposons, retroviruses use the enzyme reverse transcriptase to convert RNA into DN The enzyme is encoded by the retroviral genome, and a few molecules of the enzyme are packaged along with the RNA genome in each virus particle. When the single-stranded RNA genome of the retrovirus enters a cell, the reverse transcriptase brought in with it makes a complementary DNA strand to form a DNA/RNA hybrid double helix.
B.
The RNA strand is removed, and the reverse transcriptase (which can use either DNA or RNA as a template) now synthesizes a complementary DNA strand to produce a DNA double helix. This DNA is then inserted, or integrated, into a randomly selected site in the host genome by a virally encoded integrase enzyme. In this integrated state, the virus is latent: each time the host cell divides, it passes on a copy of the integrated viral genome, which is known as a provirus, to its progeny cells.
C.
The next step in the replication of a retrovirus—which can take place long after its integration into the host genome—is the copying of the integrated viral DNA into RNA by a host-cell RNA polymerase, which produces large numbers of single-stranded RNAs identical to the original infecting genome.
D.
These viral RNAs are then translated by the host-cell ribosomes to produce the viral shell proteins, the envelope proteins, and reverse transcriptase—all of which are assembled with the RNA genome into new virus particles.
拍照语音搜题,微信中搜索"皮皮学"使用
参考答案:
参考解析:
知识点:
.
..
皮皮学刷刷变学霸
举一反三
【多选题】人力资源的特点有哪些?
A.
能动性
B.
实效性
C.
智力性
D.
资本性
E.
个体差异性
F.
动力性
【判断题】在环境温度低于()摄氏度时可以对后视镜加热,以保证其可视性。
A.
正确
B.
错误
【简答题】什么是人力资源?人力资源的特点有哪些?
【单选题】在航空货运中GB代表( )。
A.
中国
B.
美国
C.
英国
D.
日本
【简答题】人力资源的特点有哪些
【多选题】. 动机冲突的情境有以下几类?( )
A.
、 双趋冲突
B.
、双避冲突
C.
、趋避冲突
D.
、双重趋避冲突
【单选题】在环境温度低于()摄氏度时可以对后视镜加热,以保证其可视性。
A.
20
B.
30
C.
10
D.
25
【判断题】色谱柱使用的下限温度取决于固定液呈现液态的最低温度。
A.
正确
B.
错误
【单选题】缺氧时呼吸系统代偿()
A.
在PaO2 低于正常时就刺激外周化学感受器引起
B.
是急性低张性缺氧最重要的代偿反应
C.
长期缺氧时通气增加反应仍非常敏感
D.
急性缺氧早期虽引起低碳酸血症, 但对呼吸代偿无影响
E.
休克、右心衰等循环性缺氧时呼吸代偿也很明显
【单选题】航空货运中GB代表( )
A.
中国
B.
美国
C.
英国
D.
日本
相关题目: