《现代分子生物学》章节试读

《现代分子生物学》的笔记-第22页 - chapter 2

nucleotide and nucleoside
38000 genes -- human
原核细胞的增殖方式：裂殖或者出芽；真核：有丝分裂和减数分裂
原核细胞的氧化还原酶系：质膜上；真核细胞：线粒体中
原核细胞没有细胞骨架，没有细胞间的运动
光镜下只能看到染色体，不能看到染色质；电镜下可以看到染色质
Polycistronic mRNA is a mRNA that encodes several proteins and is characteristic of many bacterial and chloroplast mRNAs. Polycistronic mRNAs consist of a leader sequence which precedes the first gene. The gene is followed by an intercistronic region and then another gene. A trailer sequence follows the last gene in the mRNA. Examples of a polycistronic transcripts are found in the chloroplast. One region that exhibits a group of different polycistronic messages from the same region is the psbb/psbH/petB/petD region. The following table lists the genes, their products and the complex of which the product is a part.
Monocistronic mRNA is a mRNA that encodes only one protein and all eukaryotic mRNAs are monocistronic. The development of the mature monocistronic eukaryotic transcript involves several different processing steps. These steps are:
1. 5' capping
2. 3' polyadenylation
3. splicing together of exons if introns are present