DNA Replication and PCR
Which direction does DNA Pol III synthesize?
5' to 3' direction
What is DNA transcribed into?
RNA/mRNA/pre-mRNA
Region before a coding sequence of DNA that TFs bind to; the TFs recruit and activate RNA Pol II to start transcription.
What are ribosomes made out of?
rRNA and proteins
What molecule does tRNA bind at the 3' OH site?
Why do origins of replication have A-T consensus sequences?
A and T has only 2 H bonds, so they are easier to break than C and G, since they have 3 H bonds.
What is the central dogma of molecular cell biology?
The flow of genetic information goes from DNA -> RNA -> Proteins
What is euchromatin?
Euchromatin: Loosely packed chromatin
Heterochromatin: Tightly packed chromatin
What do we call the region on tRNA that binds to mRNA?
The anticodon
What do posttranslational modifications do?
They chemically alter amino acids to influence folding
Why is Taq polymerase used in PCR, and not DNA Pol III?
DNA Pol III denatures at the temperature used to separate DNA's strands, but Taq polymerase can withstand these temperatures.
What are tRNAs?
RNA molecules that bind to specific amino acids and add them to the polypeptide chain.
Why must mRNA be protected with a 5' cap and a Poly(A) tail?
Free floating RNA in our cells will be attacked by our immune system
What mutation results in a different amino acid being created due to an altered DNA sequence?
Where does cotranslational and postranslational imports occur?
Cotranslational import: Endoplasmic reticulum (ER)
Postranslational import: Cytosol
What role do dNTPs play in DNA replication?
dNTPs are the molecules used to grow the DNA strand; the triphosphate is high-energy and unstable, breaking the 2nd and 3rd phosphate off is provides the energy to attach the nucleotide to the stand.
What is the difference between the coding and template strand?
The coding strand, therefore, looks identical to the mRNA strand, but has thymines instead of uracils.
Why is alternative splicing important?
It allows the generation of many different protein products from one strand of mRNA
How does the "wobble" position accommodate the degenerate triplet code?
The wobble position allows tRNA to bind to multiple triplet codes, explaining why multiple triplet codes make the same amino acid on the codon table
Avoids misfolding; if the polypeptide chain is completed before modifications, it may spontaneously fold and prevent needed deletions, rearrangements, or chemical modifications
Explain the "Leading strand" and "Lagging strand"
The leading strand can be synthesized continuously by DNA Pol III since it is naturally in the 5' to 3' direction.
The lagging strand is naturally in the 3' to 5' direction, so DNA Pol III must synthesize it backward in short segments (Okazaki fragments).
Why are transcriptionally active chromosomes usually uncondensed?
If chromosomes are condensed, the DNA is too tightly packed to be read and used. Loosely packed DNA can be read and transcribed.
What two processes need to happen in order for pre-mRNA to become mRNA?
1. It needs to be protected: 5' Cap and Poly(A) tail
2. It needs to be spliced: Introns and Exons
Give the polypeptide that would be created from this mRNA sequence:
3' - CUUAGAAUGGCCUAUUGA - 5'
Met-Ala-Tyr
In the context of the carboxyl and amine ends, what is the different between Type I and II transmembrane proteins?
Type I: Amine side is in the ER, carboxyl end is in cytosol
Type II: Carboxyl is in ER, amine side is in cytosol