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MCAT Bio: Molec Gene
| Question | Answer |
|---|---|
| phosphate | nucleosides are like nucleotides except they lack ___________ groups |
| OH | RNA has ____ on the 2' C whereas DNA just has an H |
| DNA synthesis | _____ _________ always occurs 5' --> 3' end |
| phosphodiester | nucleotides are connected by a _______________ bond |
| pyrimidines | cytosine, thymine, and uracil are all _____________ |
| purines | adenine and guanine are both _______________ |
| negatively | DNA is __________ charged |
| negatively | at physiological pH, both GTP and ATP are ____________ charged |
| 2 | A - T connected by ____ hydrogen bonds |
| 3 | G - C connected by ____ hydrogen bonds |
| methylation | this process protects prokaryotic DNA from restriction enzymes from chopping it up --> restriction enzymes are only supposed to chop up viral DNA to restrict growth |
| supercoiling | when DNA unwinds, it twists in on itself in a process called _____________ ; less subject to damage from shear force and it carried out by DNA gyrase |
| 8 | eukaryotic DNA is wrapped around a set of ____ histones, which makes up a nucleosome |
| chromatin | nucleosomes coil together to form __________ |
| heterochromatin | the type of chromatin that is inactive; tightly wound; dark-staining |
| euchromatin | the type of chromatin that is active; unwound; light staining; more easy to access by enzymes |
| centromere | part of the chromosome where spindle fibers attach; where sister chromatids are held together; the number of these determine the ploidy of a cells |
| telomeres | the ends of eukaryotic, linear chromosomes made up of short sequence repeats which allow the ends to loop around |
| degradation | telomeres stabilize the ends of chromosomes and prevent __________ of them |
| transcription | DNA is converted into RNA via this process |
| translation | RNA is converted into proteins via this process |
| replication | DNA is used to make more DNA via this process |
| start | Met: AUG = _________ codon |
| stop | UAA, UGA, UAG = __________ codon |
| polymerase | point mutations, small deletions/insertions, and small repeats are all examples of ____________ errors in which a mistake is made when nucleotides are being added to a strand |
| transposons | aka. jumping genes --> cause large insertions/deletions, insertions, and duplications; can be inverting, complex, or composite |
| missense | a mutation in which a codon for an aa becomes a new codon for a new aa --> changes aa |
| nonsense | a mutation in which a codon for an aa becomes a stop codon --> smaller protein made |
| silent | a mutation in which a codon for an aa becomes a new codon but still codes for the same aa --> no change |
| framshift | ____________ mutations include insertions/deletions in which the reading frame changes; more severe than point changes because they affect the rest of the aa sequence |
| transposase | the "cut-and-paste" enzyme; coded by transposons --> cuts it out and pastes it somewhere else |
| mismatch, methylated | __________ repair pathway - occurs during/shortly after replication - parent strand is ____________ to distinguish wrong nucleotides and denotes the daughter strand in which the pathway will repair |
| base excision | _________ (nucleotide) ___________ repair pathway - can happen at any time in the cell cycle (ideally before replication) - removes bad bases and replaces it with good bases |
| homology-directed | _________-________ repair - occurs in broken chromosomes when there is physical damage or damage caused by X-rays - must happen after replication (when sister chromatid is present) - use the identical sister chromatid as template |
| end | non-homologous _______ joining repair - occurs in broken chromosomes when there's physical damage/X-ray damage - can happen anytime during cell cycle - ligate broken ends together - can be mutagenic because of lost bases or result in translocation |
| 5,3 | DNA replication occurs in the ___' --> ___' direction |
| helicase | this enzyme unwinds the DNA for replication |
| topoisomerase | this enzyme cuts DNA to relax supercoiling |
| primase | this enzyme makes the RNA primer needed to DNA replication |
| DNA polymerase | this enzyme uses DNA as a template to create more DNA during replication |
| RNA polymerase | this enzyme uses DNA as a template to create RNA during transcription |
| ligase | this enzyme links Okazaki fragments |
| eukaryotes, prokaryotes | in ____________ there are multiple origins of replication whereas in ___________ there is only a single origin of replication |
| I | in prokaryotes, DNA polymerase __ - lower processivity - adds nucleotides at RNA primer - aso have 5' - 3' exonuclease which removes the RNA primer |
| III | in prokaryotes, DNA polymerase __ - high processivity - adds bps ~400 bps downstream from the origin - main replicating enzyme |
| replication | (replication/transcription) - no stop site - primer needed - editing |
| transcription | (replication/transcription) - has stop site --> poly A tail - no primer needed - no editing |
| promoter, high, low | - this part of the DNA comes before the operator - can be strong (_____ affinity to RNA pol) --> alot of RNA transcribes - can be weak (_____ affinity to RNA pol) --> less RNA transcribes |
| operator | - this part of the DNA is sandwiched in between the promoter and the start site |
| prokaryotes | for ___________ - transcription and translation occur at the same time in the cytosol - no post-transcriptional modifications of mRNA - polycistronic = many difference proteins from single mRNA - 1 RNA pol |
| eukaryotes | for ___________ - transcription and translation occur at different time and different places - post-transcriptional modifications of mRNA - monocistronic = one mRNA - one protein - 3 RNA pols (I, II, III) |
| 5'-cap | one type of post-transcriptional modification to mRNA which involves the addition of a ______-______; stabilizes and protects mRNA as it travels through the cytosol |
| splicing | the post-transcriptional process in which introns are removed from mRNA and exons are pieced back together |
| poly-A tail | the post-transcriptional modification of mRNA in which a sequence of adenosines are added to the 3' end; protects end from enzymatic degradation in the cytocol |
| 70 | the total subunit (___ S) for prokaryotic ribosomes |
| 80 | the total subunit (___ S) for eukaryotic ribosomes |
| 2 | ____ ATP are required to load tRNA |
| wobble | the ____________ hypothesis states that the first 2 codon-anticodon pairs bind normally but the third codon-anticodon pair is more flexible; A on tRNA can get converted to inosine allowing for even more flexibility |
| p | in translation, the __-site of the ribosome is where growing protein is held |
| a | in translation, the __-site of the ribosome is where the new AA is added |
| protein folding | - a type of post-translational modification to proteins - aided by chaperonins |
| covalent | _________ modifications: - post-translational modification - disulfide bridges, glycosylation, phosphorylation, etc. |
| philic, phobic | the outer region of DNA is hydro__________ due to the OH groups on the phosphate-ribose backbone; the inner region of DNA is hydro_____________ due to nitrogenous bases with lots of CH groups |
Created by:
coletty218
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