Introduction to Molecular Biology 3 Flashcards
Learning objectives
Define intron, exon, splice site, promoter, and enhancer: explain their functions
Describe the processes involved in transcription, defining hnRNA (preRNA) and mRNA.
Explain the principles of transcriptional regulation
Discuss the principles of alternative splicing
Describe basic differences between RNA and DNA
RNA has a hydroxide group on carbon 2 whereas on DNA the hydroxide group is missing. This makes RNA more unstable.
The base pair for adenine for RNA is uracil and for DNA, the base pair for adenine is thymine
RNA is a single stranded structure whereas DNA is a double stranded helix structure. This makes RNA able to fold into more complex structures.
In RNA transcription, what are the two strands called and what direction do they go in?
Coding strand: 5’ to 3’
Template strand: 3’ to 5’
What are the three types of RNA polymerase and what are their functions?
RNA pol l: used for generating ribsomal RNA’s or rRNA’s
RNA pol ll: main polymerase for transcribing protein coding RNA
RNA pol lll: used for generating transfer RNA’s or tRNA’s
Describe what happens before transcription of RNA begins
the TATA box binding protein binds to the TATA box and RNA pol ll binds to the TATA box binding protein to begin transcription
What is the promoter in RNA transcription and what is it’s base make up?
The promoter contains alot of T and A usually alternating called the TATA box. It is usually 25 bases from the start site.
What is a transcription factor and what is its function?
Proteins able to move within the nucleus and affect many different genes.
Their function in RNA transcription is to bind to the promoter to help RNA pol ll to start transcrition
What does RNA pol ll need to be able to start transcription
A TATA box binding protein and transcription factors are required to help RNA pol start transcription
What are enhancers and what is their function?
Enhancers are short DNA sequences that are bound away from the promoter. Their function is to help out the promoter by attracting transcription factors
What are the transcription factor domains?
DNA-binding domain (DBD), which attaches to specific sequences of DNA (enhancer or promoter.)
Trans-activating domain (TAD), which contains binding sites for other proteins such as transcription co-regulators.
How do transcription factors react to signals?
Stimuli goes through the cell as a signal and is transmitted to a transcription factor and stimulates synthesis and transcription of mRNA
Define intron and exon and explain their functions
And intron is a non coding area and exon is a coding area for transcription
Explain how mRNA is processed after transcription has started
After RNA pol ll has synthesized about 25 nucletiodes, a 5’ methyl cap is added and when transcription is finished, pre-mRNA is cleaved and a 3’ poly-A tail is added to the end. Finally, all the intons are removed through RMA splicing to created the mature mRNA
What is the purpose of the methyl cap and poly-A tail?
To prevent mRNA from degradation, help transport nRNA and it hels identify mRNA
Where does transcription occur?
In the nucleus
