Week 6_Gene expression Flashcards
what is the central dogma of info flow in biological systems?
DNA
–> transcription by RNA polymerases
–> RNA
–> translation by ribosomes
–> protein
what does the DNA do?
stores information
what does RNA do?
carries that information into the cytoplasm
what do ribosomes do?
translate the information into proteins
describe the updated central dogma with retroviruses
retroviruses (use RNA as their genetic material)
–> viral infection of a cell (viral enzyme: reverse transcriptase)
–> viral DNA genes
–> cellular enzymes: transcribe and translate
–> viral proteins: new virus is produced (ex. HIV virus)
describe the updated central dogma without retroviruses
RNA
–> reverse transcription
–> DNA
–> transcription
–> RNA
–> translation
–> protein
reverse transcriptase is very ___
error prone
reverse transcriptase is very error prone:
causes retroviruses to…
can quickly become…
causes retroviruses to mutate a lot
can quickly become drug resistant (hard to treat)
does every gene code for a protein?
no;
some are protein coding genes (PCG)
some are non-protein coding genes (nPCG)
how does a PCG code for proteins?
PCG is transcribed into a messenger RNA (mRNA)
mRNAs are translated into proteins
how does an nPCG not code for any proteins?
nPCG is transcribed into a non-coding RNA which is not translated into a protein (but still has a function)
what are examples of non-coding RNA that nPCGs become?
transferRNAs
ribosomal RNAs
microRNAs
describe the anatomy of a gene
promoter region
coding region
termination sequence
what is the promoter region?
site where RNA polymerase binds
what is the coding region?
contains the DNA sequence that will be transcribed by RNA polymerase
what is the termination sequence?
where transcription ends
which two regions in a DNA sequence is not transcribed?
promoter and termination regions
what is the difference between RNA and DNA?
RNA is single stranded
DNA is double stranded
the 4 RNA nucleotides are…
C, G, A, U
the 4 DNA nucleotides are…
C, G, A, T
what are the complementary base pairing rules for RNA nucleotides?
G = C
A = U
what are the complementary base pairing rules for DNA nucleotides?
G = C
A = T
in transcription, RNA polymerases synthesize an RNA strand (transcript) that is ___ to a DNA strand
complementary
describe how the template strand produces the coding strand:
(1) RNA polymerase binds to the gene, unwinds the DNA strands
(2) RNA polymerase reads the template strand of the gene
(3) the RNA sequence is complementary to template strand sequence
what are the phases of transcription?
initiation
elongation
termination
what is initiation?
RNA polymerase attaches to the promoter region of the gene
separates the coding and template strands
what is elongation?
RNA polymerase transcribes (reads) the template strand to generate the RNA transcript
what is termination?
RNA polymerase reaches the termination sequence
- detaches from the DNA
- releases the RNA transcript
describe what is different about transcription in prokaryotes vs in eukaryotes
different RNA polymerase enzymes
different details of process
different events immediately after transcription
