RNA Synthesis & Processing
Define 'promoter.'
Nucleotide sequence, 20-200 bp long, that serves as initial binding site of RNA polymerase and transcription initiation factors
Which of the following is a laboratory method used to detect RNA molecules - Northern, Southern or Western Blot?
Northern Blot
True or false: mRNA is translated in the 3' to 5' direction.
False, mRNA is translated in the 5' to 3' direction.
True or false: the genetic code is the list of all codons and the amino acids that they encode.
True
Alpha-helix, beta-sheet and beta-turns are examples of primary, secondary, tertiary or quatenary protein structure?
Secondary structure
What happens when there's a mutation in the promoter region?
Transcription may not initiate if RNA Polymerase is unable to recognize the promoter as a result.
Which of the following is a laboratory method used to detect DNA molecules - Northern, Southern or Western Blot?
Southern Blot
True or false: the polypeptide is synthesized during translation from the amino (NH2) end toward the carboxyl (COOH) end.
True
Explain the concept of 'degeneracy' of the genetic code.
Each amino acid is specified by more than one codon.
True or false: the secondary structure of proteins is stabilized by H-bonds between amino acid side (R-) chains.
False, secondary structure is stabilized by H-bonds between amino acid backbone atoms (the rest of the molecule apart from the R-chain, ie, including the amino and carboxyl ends).
True or false: Pre-mRNA has had its introns spliced out.
False. Pre-mRNA contains both exons AND introns and is spliced (ie, introns removed) to form mRNA.
It does, however, have both a 5' cap and a 3' poly-A tail, which were added in transcription from DNA to pre-mRNA.
Which of the following is a laboratory method used to detect protein molecules - Northern, Southern or Western Blot?
Western Blot
Where in the cell does transcription occur?
In the nucleus
Is the genetic code specific to the human species?
No! In fact, the genetic code is universal - the same triplet codons specify the same amino acids in all species.
True or false: hydrogen, ionic, covalent and van der Waals forces are all operative between the side (R-) chains of amino acids within a protein.
True!
What does addition of the 5' cap and 3' poly-A tail achieve?
1) facilitated export of mRNA from nucleus
2) protection of mRNA from enzymes in cytoplasm
3) assistance with ribosomal attachment to the 5' end
What is Taq?
A heat-resistant DNA polymerase that is put in solution with "melted" (denatured) DNA, oligonucleotide primers and free nucleotides in the amplification of DNA during the polymerase chain reaction (PCR)
Where does translation occur?
What is the significance of the AUG codon?
It corresponds to amino acid methionine and sets the reading frame.
What is the name of the signal sequence that determines where a protein is routed within a cell?
N-terminal signal sequence
True or false: start and stop codons figure prominently in transcription.
False. Start and stop codons figure in translation. For transcription, think promoter and terminator.
In gel electrophoresis, why do DNA particles move from the negative to the positive end of the agarose gel?
Phosphate groups in the DNA backbone give the DNA a negative charge; when electricity is applied to the gel, the negatively-charged DNA therefore move toward the positively charged anode.
Apart from uradine substitution of thymidine, tRNA contains the same information as which DNA strand - the coding (sense) or template (antisense) strand?
Template DNA strand
Define 'frame shift mutation' and explain how it might lead to a pre-mature stop codon.
Mutation that deletes a base pair, thus shifting the reading frame; shift of reading frame may result in premature stop codon (UAG)
Should the amino acid side chains of a protein be more hydrophilic or hydrophobic to interact with the hydrocarbon tails of membrane phospholipids?
Hydrophobic