8.3 Study Guide Flashcards
Define transcription. What is the central dogma of molecular biology?
The central dogma of molecular biology is that DNA is used to produce RNA, which is used to produce proteins (which then build the body and make it function). Transcription is the process by which proteins produce mRNA sequences using DNA as a template from which to copy.
What are the four RNA bases? How do they pair with each other? How do they differ from the DNA bases?
The four RNA bases are Guanine, Cytosine, Adenine, and Uracil. Guanine and Cytosine pair with each other only, while Adenine and Uracil pair with each other only in RNA. They differ from DNA bases only in that, in DNA, Threonine is used in place of Uracil, however, the pairings are still the same.
Eukaryotic genes generally consist of four section types: Promoters, Enhancers, Exons, and Introns. What is the role/purpose of each section type?
Promoters: Section of a DNA strand where transcription is set to begin and where the Transcription Factor Complex is built out of several proteins, allowing RNA Polymerase to bond to the strand and begin transcription.
Enhancers: Section of a DNA strand found somewhere behind the Promoter where specific proteins bond and make contact with the Transcription Factor Complex to catalyze the Initiation of the transcription process.
Exons: Sections of a DNA strand that are ‘read’ and copied to build an RNA strand by RNA Polymerase.
Introns: Sections of a DNA strand that are, instead of being read and copied, spliced and removed from the constructed RNA strand during transcription to produce an RNA strand ideal for translation to a specific protein.
Describe Initiation. What is the purpose of transcription factors in this process?
Initiation is the beginning of the transcription process and occurs when enhancer proteins catalyze a reaction within the Transcription Factor Complex that sends RNA Polymerase moving along a DNA strand and constructing RNA. The purpose of transcription factors in this process is to bind together at the promoter section of the DNA strand and act as a medium for RNA Polymerase to bind to the strand. This brings RNA Polymerase to a position where it can be sent along the DNA strand to construct RNA.
Describe Elongation. What is the name of the process by which proteins remove introns from the copied gene sequence?
Elongation is the process by which RNA is actually built by RNA Polymerase as it moves along a DNA strand during transcription. Exons are specific sections of the DNA strand that are copied and kept in the final RNA molecule, while introns are specific sections of the DNA strand that are removed from the final molecule. The name of the process by which proteins remove introns from the copied RNA molecule is ‘Splicing’ or ‘Gene Splicing’.
Describe Termination. What is added to the created mRNA sequence after termination is triggered?
Termination is the process by which transcription is ended or ‘terminated’ at what is known as a polyadenylation site. After termination is triggered, a polyA (polyadenylation) ‘tail’ is added to the 3’ end of the constructed RNA molecule to complete its construction and provide stability.
What is the purpose of gene splicing? How is it done?
The purpose of gene splicing is to edit the DNA code copied to make RNA to produce an RNA molecule that will code for a very specific protein that may not have been intended by the original code. This allows the body to produce proteins as required instead of producing a specific set based on exactly copied genes. Gene splicing is done by proteins that fix themselves around introns, sections of RNA marked for removal, unbind them from the RNA strand, and then rebind the remaining sections back together before the molecule of RNA is finalized.
What is the purpose of alternative gene splicing? What makes it different from regular gene splicing?
Alternative gene splicing is the process by which the same gene, or DNA strand, is spliced in different ways when copied multiple times, leading to different types of proteins being produced from the same gene. The purpose of alternative gene splicing is to introduce variability and flexibility in protein production through this effect, as the body can tailor its genes to fit the wide range of proteins that may be required by cells.
