Reverse Transcription Flashcards
RNA forms a complementary strand (aka cDNA) to make a double helix structure
REVERSE TRANSCRIPTION
DNA forms mRNA to synthesize protein
Central dogma
“Dogma” means ____
true
Utilizes RNA to form complementary strand to become complementary DNA to synthesize protein
RNA Viruses / retrovirus
Examples of RNA virus/retrovirus
HIV
COVID-19
A polymer of nucleotides similar to DNA.
RNA
Sugar in RNA
RIbose
Nitrogen base in RNA
Uracil
Synthesized as a single strand
RNA
T/F: RNA becomes double stranded when there are bent
TRUE
T/F: RNA has complementary partner strands
FALSE; No complementary partner strands
○ Present in the base sequence of the RNA
○ Forms hoops or folds
Internal Hemologies
T/F: RNA can also pair with complementary single strands of DNA or another RNA to form a double helix
TRUE
Enumerate the types of RNA
- Ribosomal RNA (rRNA)
- Messenger RNA (mRNA)
- Transfer RNA (tRNA)
- Small Nuclear RNAs
rRNA is what percent of total RNA
80% to 90%
rRNA is an important structural components to _______
ribosomes
T/F: rRNA is a specific site of protein synthesis during translation
FALSE: Non-specific sites
Connection between the information stored in DNA; nucleus (transcription)
Messenger RNA (mRNA)
Messenger RNA (mRNA) is a ______
Translation apparatus
Produces the protein products responsible for the phenotype
Translation apparatus (mRNA)
Nucleic acid to protein requires reading of the mRNA
Transfer RNA (tRNA)
T/F: tRNA are relatively long, single -stranded polynucleotides
FALSE: relatively SHORT
How many baes are in tRNA?
73-93 bases
tRNA
At least ___ tRNA for each amino acid
one
Proteins are formed when:
○ _________ and _______ strand binds
○ Complement strands have amino acids and is connected by the _______
Complement, template
Peptide bonds
Copying of one strand of DNA into RNA
TRANSCRIPTION
Transcription is catalyzed by which enzyme?
RNA polymerase
Transcription occurs during which cell division phase?
Interphase
Steps in the transcription initiation:
(1) formation of a closed promoter complex
■ To an open promoter complex
(2) conversion of the closed promoter complex to an open promoter complex
(3) polymerizing the first few nucleotides (usually up to 10)
■ Polymerize = hybridize
(4) promoter clearance (long enough to form a stable hybrid with a template strand)
Directs the sequential binding of ribonucleotides
Elongation
Elongation
Directs the sequential binding of ribonucleotides happens in
5’ end to 3’ end
RNA polymerase and transcription bubble move along the template DNA
Elongation
Elongation
RNA polymerase and transcription bubble move along the template DNA
3’end to 5’end
T/F: in elongation, the melted region exposes the bases of the template DNA by pair
FALSE: One by one
________ / ___________ can signal the termination of transcription
Terminator / termination sites
Specific sequences downstream of the actual gene for the RNA to be transcribed.
TERMINATION
Characterized by two inverted repeats spaced
Intrinsic Termination
Involves an inverted repeat (internal holologies making hairpin loop but no strings of uracil)
rho (ρ)—dependent termination
internal homologies making hairpin loop but no
strings of ______
uracil
Binds to the RNA during transcription and stops the RNA polymerase to stop the elongation
rho (ρ)
Enzyme: reverse transcriptase (reported first by ___________)
Dr. Howard Temin
Conversion of the RNA template into its complementary DNA strand (cDNA)
Reverse Transcription of RNA
Essential in analysis of gene transcripts
Complementary DNA strand (cDNA)
Complementary DNA strand (cDNA)
Can be ______, _______, _______ to estimate the copy of specific genes in order to characterize and validate gene expression
sequenced
cloned
applied
_____________ are RNA dependent DNA polymerases
Reverse Trancriptases
Bind to the RNA template and convert to complementary DNA strand with the presence of dNTP
Reverse Transcriptases
What is dNTP
Deoxynucleotide triphosphates
RNA must be converted to double stranded DNA first (done by the __________)
Reverse transcription
T/F: Double stranded DNA is a better template for amplification than single stranded
TRUE
RNA dependent DNA polymerase is derived from _____________
reverse transcribing viruses
enumerate examples of reverse transcribing viruses
○ Mooloney Murine Leukemia Virus
○ Avian Myeblastoma Virus (AMV)
Developed to amplify RNA targets (RNA viruses such as HIV, HCV, and influenza are key examples)
Reverse Transcriptase PCR
The method entails an initial step of transcribing a portion of the RNA genome into complementary DNA (cDNA) which is then amplified through PCR
Reverse Transcriptase PCR
_________ / ________ to prime the synthesis of the initial DNA strand
oligodT primers
Random hexamers
Enumerate the three kinds of primers
a. Oligo dTs
b. Gene specific primers
c. Random hexamers
Highly specific for the target of interest
Oligo dTs
Poly “T” sequences: ______ bases long that will prime complementary DNA synthesis only from RNA with _____________
18
poly A tails
End part of RNa with multiple adenine bases
poly A tails
End part of RNA with multiple thymine bases
Poly T tails
Synthetic DNA strands which can be represented as a sequence of ‘T’ nucleotides
Oligo dTs
Can be designed to anneal to a specific gene
Gene specific primers
T/F: Gene specific primers has a specific base pair
TRUE
Random hexamers aka ______
Decamers
6-10 long base with random bases
Random hexamers/decamers
Match and hybridize the random site of target RNA to prime DNA synthesis
Random hexamers/decamers
Random hexamers consist of how many bases which anneal ______ to RNA molecules?
10 bases
randomly
Enumerate enzymes employed for reverse transcriptase
Reverse Transcriptase
Rnase H
DNA Polymerase I (Klenow Fragment)
ENZYME
○ cDNA strand
○ Still has errors
Reverse Transcriptase
An enzyme that hydrolyzes RNA from a complementary DNA strand
Rnase H
polymerase activity; If without the small fragment: klenow fragment used in laboratories
Long fragment
Exonuclease activity
Small fragment
Enumerate the steps/process of RT-PCR
STEP 1: ANNEALING OF THE PRIMER
STEP 2: REVERSE TRANSCRIPTION
STEP 3: REMOVAL OF MISMATCHES BY RNASE H
STEP 4: REPAIR OF STRAND BY DNA POLYMERASE I KF
STEP 1: ANNEALING OF THE PRIMER
RNA tends to form secondary structures via ____________________________ (AT/U & CC)
Watson-Crick base pairing
STEP 1: ANNEALING OF THE PRIMER
In order to remove the secondary structure
Denaturation
Samples are heated with the gene specific primer
Then, cooling at room temperature
STEP 1: ANNEALING OF THE PRIMER
STEP 1: ANNEALING OF THE PRIMER
Cooling at room temperature facilitates __________
annealing
Reverse transcriptase commences transcription at the primer binding site
STEP 2: REVERSE TRANSCRIPTION
Usual errors are the uracils (it should be thymine as it is a cDNA)
STEP 3: REMOVAL OF MISMATCHES BY RNASE H
STEP 3: REMOVAL OF MISMATCHES BY RNASE H
Usual errors are the _________
Uracils
Errors are filled by the DNA polymerase or the Klenow Fragment
STEP 4: REPAIR OF STRAND BY DNA POLYMERASE I KF
Errors are filled by the DNA polymerase or the Klenow Fragment
STEP 4: REPAIR OF STRAND BY DNA POLYMERASE I KF
The resulting DNA strand can be subjected to DNA sequencing in order to determine the identity of the transcript
DOWNSTREAMING PROCESS
Can also be amplifying: multiplication of the strands
DOWNSTREAMING PROCESS
Simplicity and convenience and can minimize chance of contamination
One step RT PCR:
Cannot be used for detecting multiple products
One step RT PCR
Two step RT PCR steps:
○ 1st step: RT reaction (product: cDNA)
○ 2nd step: PCR amplification