Molecular Genetics (PP #4)

5’ capping, polyadenylation, splicing

What are the 3 stages of post-transcriptional processing?

5’ capping

____ ________ - adding a complex of proteins to the 5’ end of the RNA strand; it acts as the ticket out of the nucleus

the RNA can’t leave the nucleus

What happens if there is no 5’ cap?

5’ nucleases

What does the 5’ cap protect against?

5’ nucleases

___ ________ - enzymes that degrade RNA; they come along and chew up the RNA from the 5’ end

polyadenylation

_____________ - adding adenines to the end before RNA leaves the nucleus

3’ nucleases

What does polyadenylation protect against?

translation

What can polyadenylation regulate?

mRNA

What do the 3 parts of the post-transcriptional process leave you with?

splicing

__________ - a biological process that removes non-coding regions of genes and joins coding regions together

splice site sequences

between the exons there are sequences called _______ ______ ________

splice site sequences

_________ _____ __________ - help tell the spliceosomes the exact sequences that need to be cut

spliceosomes

__________ - large complexes of RNA and proteins that remove introns from pre-mRNA and join exons together

gene

______ - nucleotide sequence that codes for one or more functional products

coding region

_______ ______ - sequence of nucleotides that specifies the amino acid sequence in the protein gene product

promoter

________ - sequence in the DNA that acts as a binding site for RNA polymerase (not transcribed or translated)

RNA polymerase

______ ________ - enzyme that performs transcription or will take the DNA and transcribe it into an mRNA

5’ untranslated region

____ __________ _______ - leader sequence that comes after the promoter and before the coding region; this sequence is transcribed/made into RNA but never translated

5’ untranslated region

____ ___________ ______ - allows recognition of mRNA during translation and allows the ribosome a place to bind

3’ untranslated region

____ ___________ ________ - trailer sequence that comes immediately after a stop codon in the coding region of the gene; prepares the enzyme that does transcription; is never translated

terminator

_________ - sequence in DNA that signals RNA polymerase to stop transcription (not transcribed or translated)

terminator

_________ - opposite of the promoter region; allows RNA polymerase to unbind instead of bind

exons

_______ - sequences that will end up in the mRNA

protein

exons will be translated into _______ once the exit the nucleus

introns

_______ - sequences that are removed from mRNA before translation

nucleus

introns stay inside the ________

Dscam

______ - a protein expressed in neurons that keeps the dendrites from sticking together

transcription

________- copying DNA into RNA with the help of RNA polymerase

promoter

________ - DNA sequences at the beginning of genes that provide a landing pad for RNA polymerase and a bunch of other proteins

TATA box

a good amount of promoters contain the ______ _____

TATA box

_____ ____ - a sequence characterized by alternating adenines and thymines; recognized by a protein that plays a role in stabilizing RNA polymerase and encouraging activity

enhancers

_______ - short sequences that recruit activator proteins and help RNA polymerase work more efficiently

enhancers

________ are often located far away, so DNA must loop around to allow ________ (same blank) to get close to the promoter

23

the nucleus contains the genome, which is split into ______ pairs of chromosomes

histones

each chromosome contains a long strand of DNA tightly packed around proteins called ________

RNA polymerase

when a gene switches on, the enzyme _____ ________ attaches to it

mRNA

the RNA polymerase moves along the DNA making a strand of _____ out of free bases in the nucleus

DNA code

the _____ _____ determines the order in which the free bases are added to the mRNA

processed

before the mRNA can be used as a template for the production of proteins, it needs to be _________

cytoplasm

Where does the mRNA go when it leaves the nucleus?

ribosomes

protein factories in the cytoplasm called ________ bind to the mRNA

ribosome, amino acids

once the mRNA enters the cytoplasm, a _______ reads the code in the mRNA to produce a chain of ______ ______

tRNA

_______ molecules carry the amino acids to the ribosome

3

mRNA is read ____ base at a time

tRNA

as each triplet is read, a _____ delivers the corresponding amino acid, which is adding to the growing chain

protein

once the last amino acid has been added the chain folds into a complex 3D shape that forms the _______

transcription factors

________ _______ help control which genes are expressed in which cells, helping cells perform specialized functions

transcription factors

________ ________ - proteins that scan along the DNA, looking for specific DNA sequences to bind to

interact, recruit

once transcription factors bind to the specific DNA target they change shape, and can _______ with or _______ other proteins

transcription factors

through binding and interaction with other proteins, _______ _______ can increase (turn on) or decrease (turn off) the expression of specific genes

microRNA

_______ - a type of small, noncoding RNA

introns

the sequences that code for microRNA are found in _______

regulate

the purpose of introns is to _______ the production of proteins

microRNA

________ regulates gene expression through RNA interference/gene silencing

polyA tail

microRNA can influence digestion of the _______ _____

microRNA

_______ can cut the polypeptide as it’s being produced by the ribosomes

microRNA

as a group, _______ block translation by messing up the translation process

the ribosome looks for the kozak sequence

How does the cell know which AUG to use to start the translation process?

consensus sequence

the Kozak sequence is a type of ________ _________

reading frame

the Kozak sequence helps set up the ______ _______

reading frame

when the ________ ______ isn’t set up properly, sequences won’t have the same meaning

redundant

______ - used when talking about multiple codons that code for the same amino acid

3rd, 1st

most of the time redundancy in codons is due to the ___ letter, but in some cases the ___ letter may be redundant

shape, hydrogen bonding

_____ is the reason for redundancy; in the 3rd letter position the amino acid is coming at an angle, which throws off the ________ _______

free ribosome

a ribosome made in the cytosol is a ______ ________ and is not needed for export

chaperonins

_________ - proteins involved in folding

single nucleotide polymorphism

What does SNP stand for?

SNP

______ - a single nucleotide that differs dramatically across people

fine association mapping

_____ _________ _______ - looking at sequences and comparing them across several individuals

sequence alignment

________ _______ - taking all the sequences that you have and lining them up in a way that the letters match up

conserved sequences

________ _________ - sequences that are similar across species

allele

______ - variation of a gene; the variation comes in the sequence of letters

constitutive expression

________ _________ means always being transcribed

95%

up to _____% of human multi-exon genes undergo alternative splicing to encode proteins with different functions

intron

spliceosomes look for sequences in the _______; in the case of alterations in splicing, if the sequence has been changed in that ______ (same blank) sequence then it can’t be detected, so the spliceosome skips

inclusion

if an alteration in splicing causes ________, it means a splice site will show up where it shouldn’t be

splicing

a lot of diseases can be tied to poor _________

the introns in his body were never fully spliced out, so the protein became nonfunctional, causing muscle heterotrophy due to constant cell division

What occurred for his muscles to grow this much?

kozak sequence

________ ________ - sequence the ribosomes recognize that contains the start codon

homolog

________ - a gene that acts the same in another organism because it has the same evolutionary origin

differential splicing

________ ________ - allows us to make different mRNAs in different cells from the same original piece of RNA that came from a particular gene

endoplasmic reticulum

bound ribosomes are associated with the _________ _________

bound ribosomes

_________ _________ do a lot with post-translational processing