Flashcards in Molecular Biology Review Deck (32):
RNA polymerase moves in what direction?
5' → 3' (binds 3' end of template strand)
Which is more likely to have errors, replication or transcription?
Always the same 3' → 5' strand, used to generate RNA strand (RNA sequence will be same as non-coding strand)
Uracil replaces what DNA nucleotide?
Occurs in nucleus → results in mature RNA strand
5' end capped
Poly-A tail added to 3' end
Function of capping primary RNA
Ensure mRNA's stability during translation
Function of adding poly-A tail to primary RNA strand
1. Protects mRNA from degradation by exonucleases
2. Essential for transcription termination, export from nucleus and translation
Non-coding regions of gene (do not appear in mature RNA transcript → removed in nucleus)
Coding regions of a gene (can be spliced to form multiple proteins)
3 types of mature RNA
1. Binds 1 specific AA
2. Recognizes 1 or more mRNA sequence
ribosome = rRNA + protein
1. Orients mRNA & AA complex
2. Ensure accurate reading
mRNA contains information for?
mRNA turnover rate
Very high (much less stable than tRNA and rRNA) → 1/2 life is hours to days
Allows for amplification of genetic message (multiple copies)
Conversion of mRNA into protein
AA sequence is determined by?
3 sites on ribosome
A site (aminoacyl): binds newly arriving tRNA
P site (peptidyl): tRNA carrying polypeptide chain residues
E site (exit): tRNA exits from ribosome
Ribosome reads mRNA sequence 3 nucleotides at a time → 64 possible
2 posttranslational modifications and what is their function?
1. Amino acids removed (splicing)
2. Add sugars
→ makes protein active and directs protein to appropriate location
Endoplasmic reticulum mostly contains?
Glycoproteins (protein with carbohydrate grop)
How does protein attach to ER?
Protein is on ribosome → ER recognizes tag on protein
What happens to protein in ER?
Folding and further glycosylation
Channel network in ER
Directs protein to proper location in cell
Donor molecules and acceptor residues of glycosylation
Donor molecules: nucleotide sugars (ex: ADP-glucose)
1. Asparagine (N)
2. Serine (S)
3. Threonine (T)
Exponentially amplify DNA segment in vitro
Kary Mullis, 1983
3 steps of PCR
1. Denaturation (separates DNA strands)
2. Annealing (primers bind DNA)
3. Extension (new DNA synthesized)
What is glycosylation directed by?
Enzyme-directed site-specific process (glycosyltranferases)
Where does glycosylation occur?
ER and Golgi apparatus