Gene Transcription & RNA modification 2 Flashcards
Gene
A segment of DNA that is used to make a functional product either RNA molecules (rare) or proteins (common)
Transcription
Process of synthesizing RNA from a DNA sequence
Structural genes
Encode the amino acid sequence of a polypeptide
When a _________ is transcribed the product it makes is mRNA (messenger RNA)
Structural genes
Translation
The sequence of nucleotides within mRNA determines the sequence of amino acid in a polypeptide to make proteins & those proteins determine our traits & phenotype
__________ states the usual flow of genetic material information is from DNA to mRNA to proteins
Central dogma
Gene expression
Overall process to turn a gene on to produce a functional product such as proteins
_________ genes goes through transcription & translation
Structural genes
__________ require base sequences that perform functional roles
Gene expression
What are the different sequences in DNA?
- Regulatory sequence
- Promoter
- Terminator
- Coding region
Regulatory sequence
Site for the binding of regulatory proteins, the role of regulatory proteins is to influence the rate of transcription
Promoter
Site for RNA polymerase signals the beginning of transcription
Terminator
Signals the end of transcription
What are the different sequences in mRNA?
- Ribosome bind site
- Start codon
- Codons
- Stop codon
Ribosome binding site
Site for ribosome binding, translation begins near this site
Start codon
Is ATG & it specifies the 1st amino acid in a polypeptide sequence
What is the 1st amino acid produced in bacteria?
Formylmethionine
What is the 1st amino acid produce in eukaryotes?
Methionine
Codons
3 - nucleotides sequences within the mRNA that specifies a particular amino acid
Stop codon
Specifies the end of polypeptide synthesis
What are the 3 different stop codons?
TAA, TAG, or TGA
_________ mRNA may be polycistronic
Bacterial mRNA
Polycistronic
It encodes two or more polypeptides
What are the 3 stages of transcription?
- Initiation
- Elongation
- Termination
Initiation
Starts when RNA polymerase binds to promoter
Elongation
Synthesis of mRNA
Termination
RNA polymerase stops transcription
Describe the process in transcription
- In initiation the promoter functions as a recognition site for transcription factors, where those transcription factors allow RNA polymerase to bind to the promoter & DNA is unwinded by DNA helicase to form a bubble known as a open complex
- Elongation begins when RNA polymerase slides along the DNA in an open complex to synthesize mRNA
- Termination occurs when a terminator is reached that causes RNA polymerase & mRNA to fall off the DNA
________ genes are 90% of the genes
Structural genes
Nonstructural genes
Lead to un-translated RNA
What is Non-structural genes role in translation
- Make rRNA
2. Make tRNA
What is non-structural gene role in gene expression?
- Make miRNA
What is non-structural genes role in mRNA processing?
- Make snoRNA
2. Make snRNA
A ________ is a short sequence of DNA that is necessary to start transcription in bacteria
Promoter
Transcriptional start site
Where the 1st base is used as a template for RNA transcription & is denoted as +1
_______ is where RNA polymerase binds to & its before the copy region
Promoter
What are the two sequences in the promoter region?
- -35 sequence
2. -10 sequence
What is the -35 sequence?
5’- TTGACA-3’
What is the -10 sequence?
The TATA box 5’-TATAAT-3’
_______ promoter yields better transcription because RNA polymerase binds better
Stronger
Bacterial transcription is started (initiated) when _________ binds to the promoter
RNA polymerase holoenzyme
In bacteria a core has _________
5 Subunits
When the sixth unit __________ associated with the core enzyme it creates a RNA polymerase holoenzyme
Sigma Factor
What are the two subunits in RNA polymerase holoenzyme?
- Core enzyme with 5 proteins
2. Sigma Factor
When the _____ & ______ join together it makes a complete holoenzyme
Sigma factor & core enzyme
Once the _________ is assembled it binds loosely to the DNA & slides along the DNA looking for the promoter
Holoenzyme
When the holoenzyme finds the promoter the _______ recognizes both the -35 & -10 sequences & binds tightly to them
Sigma Factor
The process of bacterial transcription is initiated when _______ in holoenzyme binds to the promoter forming a closed complex (where DNA strand is still doubled stranded)
Sigma Factor
For bacterial transcription to begin the DNA strand must unwind to form an open complex where it unwinds at the ___________ because its easier to break A-T bonds since it only has 2 hydrogen bonds
TATA box sequence
After the breaking of A-T rich region a short mRNA strand is made in the open complex then the _______ is released from the core enzyme where the release of the _____ starts the transition to elongation stage of transcription
Sigma Factor
________ made when the sigma factor is release & initiation stage ends
Nascent RNA