2A: overview of central dogma Flashcards
what is the central dogma?
universal information flow from DNA to RNA to protein (process of conversion of genotype into phenotype)
what is transcription? (general)
process by which information encoded in DNA is made into a complementary RNA copy
what is translation? (general)
the use of information encoded in RNA to assemble amino acids into polypeptides (proteins)
what is the template strand?
the strand that is used to make complementary RNA in transcription (the strand read by RNA polymerase)
what is the coding strand?
the coding strand is opposite of the template strand and has the exact same sequence of bases as the RNA formed in transcription (except has T instead of U)
which strand of DNA is shown on chromosomal maps?
the coding strand
how do we find out which strand is entirely coding and which is entirely template?
we don’t. each strand of DNA has sections where it is coding and where it is template
what is the process of transcription?
RNA polymerase creates RNA sequence (called mRNA) complementary to template DNA. follows same basic rules as DNA replication
where is reverse transcriptase found?
in viruses with RNA genomes (such as HIV/AIDs)
what is the process of infection by an RNA virus?
① virus’s genome (RNA) enters host cell along with reverse transcriptase (enzyme)
② reverse transcriptase generates ssDNA from virus’s RNA genome
③ second strand of DNA is synthesized, using first strand as template (so its now dsDNA)
④ dsDNA integrated into host DNA as a provirus (which is like a prophage)
⑤ the DNA is transcribed into mRNA, and then translation occurs
what makes RNA viruses impossible to make a vaccine for?
their use of reverse transcripase. reverse transcriptase is extremely bad at proofreading, which results in a high rate of mutation
did RNA or DNA evolve first? reasoning?
RNA because besides being able to store genetic information, it can also catalyze reactions, like an enzyme.
what are ribozymes?
RNA catalysts that can catalyze reactions on the RNA molecules that lead to their own synthesis
how were the jobs of information storage and catalysis taken by DNA and catalysts (proteins) from RNA?
DNA and proteins just do a better jobs at those tasks than RNA. DNA is much more stable than RNA and proteins are more efficient at catalysis and are able to make shorter chains with more variety than RNA
why is DNA better than RNA at storing information?
it is more stable and being double stranded allows the complementary strand to be used as a template to repair the other strand if it is damaged
where does transcription and translation occur in prokaryotes?
cytoplasm (this allows transcription and translation to occur at the same time)
where does transcription and translation occur in eukaryotes?
transcription: in nucleus
translation: in cytoplasm
what did Garrod study and what did this show?
he studied the disease that makes your pee black and his work on it was the first to show a specific relationship between genes and metabolism
what was Beadle and Tatum’s experiment?
they studied 3 auxotrophic mutants of Neurospora crassa that did not grow in medium without arginine supplements. they put all 3 mutants into mediums with no supplements, mediums with ornithine supplement, mediums with citrulline supplement, and mediums with arginine supplement, and kept track of growth.
what did Beadle and Tatum conclude from their experiment?
they concluded that the biosynthesis of arginine occurs in a series of steps, and each step is controlled by a gene that codes for the enzyme for the step.
what are the two types of RNA genes encode for?
➞ coding RNA
➞ noncoding RNA
what does coding RNA do? what RNA is coding RNA?
codes for proteins/polypeptides.
mRNA is coding RNA
what does noncoding RNA do? what RNA is noncoding RNA?
noncoding RNA does not code for a protein.
tRNA, rRNA, snRNA, and microRNA are all noncoding RNA
how many nucleotides are required to code for 20 different amino acids?
3
