Term
| What is described as a linear polymer of nucleotides that transfers information in cells? |
|
Definition
|
|
Term
| What are the three components of a Nucleotide? In what amounts are they present? |
|
Definition
| Nitrogenous Base, Five-Carbon Sugar, Phosphoric Acid; In Equal Amounts |
|
|
Term
| What is the term for a nitrogenous base that is a 6 membered heterocyclic aromatic ring containing two nitrogens? |
|
Definition
|
|
Term
| What is the term for a nitrogenous base that has 2 rings, one of them being an imidazole? |
|
Definition
|
|
Term
| What are the Purines? Are they found in DNA or RNA? |
|
Definition
|
|
Term
| What are the pyrimidines? Are they found in DNA or RNA? |
|
Definition
| Cytosine (Both), Thymine (DNA), Uracil (RNA) |
|
|
Term
| What sugar is found in a Ribonucleoside? Deoxyribonucleoside? |
|
Definition
| D-ribose (D-ribofuranose); 2-deoxy-D-ribose (2-deoxy-D-ribofuranose) |
|
|
Term
| What is a Nitrogenous base + a sugar? Via what type of bond is the base linked to the sugar? |
|
Definition
| Nucleoside; Glycosidc bond |
|
|
Term
| What endings do you add to purines & pyrimidines to name their nucleoside? |
|
Definition
| Purine: -osine Pyrimidine: -idine |
|
|
Term
| What is a nucleoside + a phosphate group? How is this bond formed? |
|
Definition
| Nucleotide; phosphoric acid esterified to a sugar OH group |
|
|
Term
| In what direction are polymers of nucleic acid formed & via what type of bond? In what direction are they read? |
|
Definition
| bonds form 3' to 5'; by phosphodiester bridges; read in 5' to 3' |
|
|
Term
| How many classes of Nucleic Acids are found in DNA? What are they? |
|
Definition
|
|
Term
| How many classes of Nucleic Acids are found in RNA? What are they? |
|
Definition
| 5; messenger RNA, ribosomal RNA, transfer RNA, small nuclear RNA, & small non-coding RNA |
|
|
Term
| What class of RNA serves to carry information that is encoded in DNA to the sites of protein synthesis? |
|
Definition
|
|
Term
| A single mRNA contains information for synthesis of many proteins in prokaryotes or eukaryotes? |
|
Definition
| Prokaryotes; in eukaryotes 1 mRNA codes for 1 protein |
|
|
Term
| T/F Heterogeneous nucelar RNA has introns & exons. |
|
Definition
|
|
Term
| What is defined as an intervening sequence? |
|
Definition
|
|
Term
| Which of the following is preserved in mature mRNA: introns or exons? |
|
Definition
|
|
Term
| Relative sizes of rRNA subunits are referred to as what? |
|
Definition
| Sedimentation Coefficients (S) |
|
|
Term
| T/F The bases of tRNA ae usually methylated and make up a long polynucleotide chain. |
|
Definition
| False - The bases are methylated, but the polynucleotide chain is short (73 to 94 bases) |
|
|
Term
| What is the sequence found at the 3' end of tRNA? |
|
Definition
|
|
Term
| What are the substrates of protein synthesis? |
|
Definition
|
|
Term
| What gives tRNA its characteristic secondary structure? |
|
Definition
| Intrastrand Hydrogen Bonds |
|
|
Term
| What makes RNA more susceptible to hydrolysis? |
|
Definition
| Vicinal -OH groups (2' and 3') |
|
|
Term
| Which is more stable DNA or RNA, why? |
|
Definition
| DNA because it lacks the 2' OH |
|
|
Term
| What is RNA resistant to? What are DNA and RNA hydrolyzed by? |
|
Definition
RNA is resistant to dilute acid
RNA is hydrolyzed by dilute base; DNA & RNA are hydrolyzed by nucleases |
|
|
Term
| What type of enzyme are nucleases & how do they act? |
|
Definition
| Phosphodiesterases that cleave phosphodiester bonds using H2O |
|
|
Term
| What is used to tell if a nuclease cleaves on the 3' or 5' side of the phosphorus? What does each type of cleavage yield? |
|
Definition
3' side labeled "a" - yields a 5'-phosphate
5' side labeled "b" - yields a 3'-phosphate |
|
|
Term
| Describe Snake Venom Phosphodiesterase and its product. |
|
Definition
| a-exonuclease -- 5'-AMP product |
|
|
Term
| Describe spleen phosphodiesterase and its product. |
|
Definition
| b-exonuclease -- 3'-CMP product |
|
|
Term
| Describe pancreatic RNase and its product. |
|
Definition
| b-endonuclease; specific to pyrimidines (C & U) = only cleaves at 5'-end of pyrimidines in the middle of the chain. |
|
|
Term
| Which is more abundant in the cell rRNA or mRNA? |
|
Definition
| rRNA 80-90% (mRNA only 3-5%) |
|
|
Term
| T/F Post-transcriptional regulation occurs after transcription is complete and before translation. |
|
Definition
| False; it occurs after transcription, but it does not have to be complete for post regulation to begin |
|
|
Term
| In what type of organism are transcription and translation concomitant processes? |
|
Definition
| Prokaryotes (don't have a nucleus) |
|
|
Term
| Where do transcription & translation occur in Eukaryotes? |
|
Definition
| Transcription in nucleus; Translation in cytoplasm on ribosome |
|
|
Term
| Do Eukaryotes have polycistronic or monocistronic mRNA? What does that mean? |
|
Definition
| Monocistronic; 1 RNA encodes for 1 protein, also has a 3' poly-A tail & a 5' G-cap |
|
|
Term
| Which is larger exons or introns? |
|
Definition
|
|
Term
| Where does mRNA splicing occur? |
|
Definition
|
|
Term
| Which are more highly conserved introns or exons? |
|
Definition
|
|
Term
| What are the three steps of post-translational regulation in the nucleus? |
|
Definition
| 1. Capping & Methylation 2. Polyadenylylation 3. Splicing |
|
|
Term
| What are the enzyme and substrate of capping a pre-mRNA? |
|
Definition
| Enzyme = guanylyl transferase, Substrate = GTP |
|
|
Term
| At what positions on the 5'-end is the pre-mRNA methylated? |
|
Definition
| N7, C2'-O of next two residues, and 6-amino of first Adenine |
|
|
Term
| What are the reasons for capping mRNA? |
|
Definition
1. cap is recognized by cap-binding proteins
2. cap distinguishes mRNA from other RNA
3. for export from the nucleus
4. necessary for translation
5. stabilizes mRNA in the cytoplasm |
|
|
Term
| What signals the termination of transcription? |
|
Definition
| When the RNA polymerase transcribes the AAUAAA (poly-A) sequence |
|
|
Term
| What happens after termination of transcription? |
|
Definition
| 10-30 nucleotides after poly A signal the string is cleaved & 200 adenine residues are added = poly A tail |
|
|
Term
| What is the function of the poly A tail & what is it bound to? |
|
Definition
| Stimulates translation & governs stability of mRNA; bound by PABP |
|
|
Term
| What signals the end of the transcriptional unit? |
|
Definition
|
|
Term
| What binds to the 3'-end of the transcript by interacting with the G/U-rich sequence further downstream? |
|
Definition
| CPSF (Cleavage and Polyadenylylation Specificity Factor) |
|
|
Term
| T/F The polyadenylated tail requires a DNA template. |
|
Definition
| False, the poly A tail is not encoded in the genome. |
|
|
Term
| What maintains the pre-mRNA untangled and accessible? |
|
Definition
| pre-mRNA association with proteins = Ribonucleoprotein |
|
|
Term
| What defines the exon/intron junctions in eukaryotic mRNA precursors? |
|
Definition
|
|
Term
| What is the substrate for splicing? |
|
Definition
| RNP complex - capped polyadenylated RNA |
|
|
Term
| What do introns start and end with? Where is the intron branch site? |
|
Definition
| 5'-end has GU and 3'-end has AG; branch site is upstream from the 3'-splice site (always have an A in the middle) |
|
|
Term
| Describe the lariat structure. |
|
Definition
| unstable covalently closed loop or RNA that forms a 2' to 5' phosphodiester bond |
|
|
Term
| What does a snRNP consist of? |
|
Definition
| RNA and up to 10 different proteins |
|
|
Term
| Where are snRNPs found? What do each of the snRNP do? |
|
Definition
| in Spliceosomes; U1 - 5' splice; U2 - branch; U4,5,6 - recruits branch point to 5'-splice site |
|
|
Term
| Does spliceosome assembly require ATP? |
|
Definition
|
|
Term
| What reaction joins exons? |
|
Definition
|
|
Term
| What is the first event of splicing? |
|
Definition
| U1 recognizes the 5' splice site |
|
|
Term
| What is meant by the fact that processing is coupled to transcription? |
|
Definition
| As soon as transcription begin, post-translational regulation begins just after it - they can occur simultaneously |
|
|
Term
| In which type of splicing is every intron removed & every exon incorporated into mature RNA producing a single form of mature mRNA? |
|
Definition
|
|
Term
| What are the three ways a Eukaryotic gene can give rise to multiple forms of mature RNA? |
|
Definition
1. use of different promoters
2. Selection of different polyadenylylation sites
3. Alternative splicing of primary transcript |
|
|
Term
| Which type of splicing produces protein isoforms and expands the coding potential of the genome? |
|
Definition
|
|
Term
| What are the fates of mRNAs in the cytoplasm? |
|
Definition
| Translation, Degradation, Localization -> translation |
|
|
Term
| How are mRNAs directed to the ER and what type of proteins do these code for? |
|
Definition
| by a signal at the amino terminus; secreted or membrane-bound proteins |
|
|
Term
| What are the typical base deaminations? |
|
Definition
|
|
Term
| What are the three ways RNA editing can increase protein diversity? |
|
Definition
1. Altering AA coding possibilities
2. Introducin premature stop codon
3. changing splic site in transcript |
|
|
Term
| What enzyme carries out the A to I exchange in RNA editing? |
|
Definition
| ADAR (Adenosine Deaminase Acting on RNA) |
|
|
Term
| Is mRNA editing tissue dependent? |
|
Definition
|
|
Term
| What is the basis for the unified theory of gene expression? |
|
Definition
| Transcription, processing, mRNA export, and translation do not occur one after another but in a sort of continuous assembly line system |
|
|
