more module 3 work (split up) Flashcards
transcription launches the
production of RNAs and protein that function in the cell
RNA polymerase
-enzyme
-works in conjunction with other proteins to make an RNA version of the information encoded in a gene
why is transcription spontaneous?
b/c the substrates involved are ribonucleotide triphosphates (NTPs) which have high potential energy
template strand
the strand that is “read”
the strand transcribed by the RNA polymerase
non-template (coding) strand
the complementary strand that is not transcribed
the DNA sequence in each gene codes for an
RNA product that will be synthesized by RNA polymerase during transcription
every gene has a region of DNA called
a promoter
promoter
site where RNA polymerase makes initial contact with DNA to start transcription
the initiation of complex proteins bind to
DNA at the promoter and open it, unwinding the double helix
“upstream”
part of gene the RNA polymerase has already transcribed
“down stream”
part of gene the RNA polymerase has not read or transcribed yet
transcriptionally active gene are
-acetylated histones
-de-methylated DNA
transcriptionally inactive gene
-de-acetylated histones (w/acetate) ->C2H3O2-
-methylated DNA (w/mythanol)-> CH3OH
genetic code
the set of relationships btw the 64 possible codons in mRNA and the amino acids that are added to a newly synthesized protein
codon
a group of three bases in an mRNA that codes from an amino acid
start codon
codon that determines where translation and protein synthesis begins
-where the sequence of amino acids in protein will start
stop codon
signals where translation ends
-previous amino acid becomes the last amino acid in the protein
-usually UAA, UAG, and UGA
transcription in eukaryotes requires access to genes, which are…
stored in chromosomes inside the nucleus
three key steps transform pre-mRNA into mature RNA
1) Adding 5’ cap
2) splicing out introns
3) adding poly-A tail
adding 5’ cap
-as the 5’ end of mRNA emerges from RNA polymerase, enzymes attach a modified form of the nucleotide guanine (G) along with three phosphate groups
- helps protect mRNA from RNA-degrading enzymes and helps RNA bind to the ribosome so translation can begin
splicing out introns
-molecular machines cut the RNA strand at end of introns and removes them
-when splicing is complete, remaining exons are joined together
adding poly-A tail
on 3’ end of pre-mRNA a special RNA polymerase adds a string of nucleotide adenine (A)
-helps protect mRNA from RNA-degrading enzymes and are binding sites from proteins that interact with ribosomes and make translation likely
once a mature mRNA is produced
the amount of protein produced from that message is controlled
phsophorylated
when phosphate group is added
dephosphorylated
when phosphate group is removed
phosphorylation and dephosphorylation can
either activate or deactivate the protein involved
-like a light switch
kinase
enzyme that adds a phosphate group to other proteins
during transcription, RNA forms base-pairs with the ___ strand. The new RNA has the same polarity (with Us not Ts) as the ___ strand.
-template
-non-template (coding)
new nucleotides in DNA bond to the ___ end of the chain
3’
with Rosalind Franklins discovery of the double helix, what did researches find out?
the sugar-phosphate backbone was on the outside, the realized that the complementary base pairs would fir inside and form hydrogen bonds
higher number of G and C bonds means…
the strand will have a higher melting point because they have 3 hydrogen bonds
Which carbons (1’-5’) are bonded to a Phosphate group?
5’ and the 3’
in the subunits of DNA, the free hydroxyl group is attached to the ___ carbon
3’
you could have similar % of nucleotides in tissues, but they produce different proteins, why?
-the genetic info store is maintained in all cell types but only some of the genetic information in the DNA is used in each cell type
what are some roles for histones?
-protection of fragile sites on the DNA
-compaction of the long DNA strands
-control of what DNA info is used and what is stored
transcription occurs along a ___ template forming an mRNA in the ___ direction
1) 3’ to 5’
2) 5’ to 3’
the genes in an operon share ___ promoter
a single
constitutive expression
genes are expressed at a constant level
for alternative splicing, do you need a different gene for every protein that the cell can produce?
no, alternative splicing can lead to the synthesis of several forms of mRNA from a single gene
eukaryotic transcription
introns and exons are transcribed, but the RNA from introns does not leave the nucleus
the binding of activator proteins regulates…
the conditions under which the RNA polymerase binds to the core promoter
