View
259
Download
6
Category
Tags:
Preview:
Citation preview
Chapter 4
Transcription and Translation
The Central Dogma
Overview of transcription
Figure 4-10
Overview of transcription
Figure 4-10
Types of RNAs transcribed
Transcription of a bacterial gene
Starting and stopping transcription of a bacterial gene
Overview of RNA processing in eukaryotes
Figure 4-13/14
Intron Splicing
Different proteins are produced from the same gene by alternative RNA splicing
Figure 4-15
Figure 4-12
Repressors and Activators
Transcription in Eukaryotes
Gene regulatory proteins can bind to distant gene regulatory sequences and regulate transcription.
The three roles of RNA in protein synthesis
Three types of RNA molecules perform different but complementary roles in protein synthesis (translation)
Messenger RNA (mRNA) carries information copied from DNA in the form of a series of three base “words” termed codons
Transfer RNA (tRNA) deciphers the code and delivers the specified amino acid
Ribosomal RNA (rRNA) associates with a set of proteins to form ribosomes, structures that function as protein-synthesizing machines
The roles of RNA in protein synthesis
Figure 4-19
The genetic code is a triplet code
The genetic code can be read in different frames
Figure 4-20
Translation is a two-step decoding process
Figure 4-21
The structure of tRNA specifies its decoding function
Figure 4-22
Nonstandard base pairing often occurs between codons and anticodons
Figure 4-23
Ribosome structure in prokaryotes & eukaryotes
Figure 4-24
Image reconstruction of an E. coli ribosome
Figure 4-27
Stepwise formation of proteins on ribosomes
Translation occurs in three stages: initiation, elongation, and termination
Initiation
Figure 4-25
Initiation continued
Figure 4-25
During elongation each incoming aminoacyl-tRNA moves through three ribosomal sites
Figure 4-26
During elongation each incoming aminoacyl-tRNA moves through three ribosomal sites
Figure 4-26
Protein synthesis is terminated by release factors when a stop codon is reached
Figure 4-29
Simultaneous translation by multiple ribosomes and their rapid recycling increases the efficiency of protein synthesis
Figure 4-31
Recommended