1、基因指导蛋白质的合成1. mRNA(信使信使RNA） Messenger RNAs-are the nucleic acids that record information from DNA in the cell nucleus and carry it to the ribosomes and are known as messenger RNAs (mRNA). （功能：作为编码蛋白质中氨基酸的模板功能：作为编码蛋白质中氨基酸的模板）2.rRNA (核糖体核糖体RNA）Ribosomal RNAs-exist outside the nucleus in the cytoplasm o
2、f a cell in structures called ribosomes Ribosomes are small, granular structures where protein synthesis takes place. Each ribosome is a complex consisting of about 60% ribosomal RNA (rRNA) and 40% protein. (功能：功能：核糖体的核糖体的 组成结构的一部分）组成结构的一部分）3. tRNA (转运转运RNA）Transfer RNAs-The function of transfer RNA
3、s (tRNA) is to deliver amino acids one by one to protein chains growing at ribosomes. （功能：功能：转运氨基酸）转运氨基酸）Translation is the process by which the genetic messages carried by mRNA are decoded and used to build proteins in the cytoplasm1.Station cytoplasm2.Templet mRNA3.Material amino acids4.Products p
4、roteinsA set of three nucleotide bases on an mRNA molecule is called a codon.(翻译是在细胞质中进行的。它是指以信使RNA为模板，合成具有一定氨基酸顺序的蛋白质的过程。）(场所；细胞质)( 模板：信使RNA)(原料：氨基酸)( 产物：蛋白质)(信使RNA上决定一个氨基酸的三个相邻的碱基叫一个密码子）UCAUG A UUAmRNACODONCODONCODON 1. Each codon specifies a single amino acid .For example,CGC encodes arg.(一个密码子编码
5、一个氨基酸，例如CGC编码精氨酸） 2.大多数氨基酸有多个密码子，例如，GUU，GUA都编码缬氨酸3.AUG（编码甲硫氨酸）为起始密码子，翻译从此密码子开始，少数起始密码子为GUG4.UAA,UAG,UGA（终止密码子，不编码任何氨基酸），翻译到次终止1.Initiation AUG,GUG（起始密码子）2.Stop UAA,UAG,UGA（终止密码子）3.One codon decides one amino acid一个密码子决定一个氨基酸4. one amino acid may have many codons一个氨基酸可有多个密码子UCAUG A UUAA U CMetUU AT P
6、rotein synthesis occurs in three stages: Initiation, Elongation and Termination.(蛋白质的合成包括三个步骤：起始，延长，终止) 1. Initiation(起始) mRNA attaches to the ribosome.(mRNA与核糖体结合）与核糖体结合）A set of three nucleotide bases on a tRNA molecule is called an anticodon(反密码）A A ULDNA bases=RNA base =3 amino acidQuestions1.Fo
7、r the DNA strand 5-TACGATCATAT-3 the correct complementary DNA strand is: A.3-TACGATCATAT-5 B.3-ATGCTAGTATA-5C. 3-AUGCUAGUAUA-5 D. 3-GCATATACGCG-5E. 3-TATACTAGCAT-52.In the Meselson-Stahl DNA replication experiment, if the cells were first grown for many generations in N-15 containing media, and the
8、n switched to N-14 containing media, what percent of the DNA had 1 light strand and 1 heavy strand after 2 generations of growth in N-14 growth media? A.0 B.25 C.50 D.75 E.100BC3.Three types of RNA involved in comprising the structural and functional core for protein synthesis, serving as a template
9、(模板) for translation, and transporting amino acid, respectively, are: A A mRNA, tRNA, rRNA B B rRNA, tRNA, mRNA C C tRNA, mRNA, rRNA D D tRNA, rRNA, mRNA E rRNA, mRNA ,tRNA4.A messenger RNA is 336 nucleic acids, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is: A A 999 B B 630 C C 330 D D 111 E E 110ED 5.With what mRNA codon would the tRNA in the diagram be able to form a codon-anticodon base pairing interaction? A. 3-AUG-5 B. 3-GUA-5 C. 3-CAU-5 D. 3-UAC-5 E. 3-UAG-5A
