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Transcription
Or the making of a molecule
named, messenger RNA, aka
mRNA
DNA’s Central Dogma
Do you know what a dogma is? It’s a belief or
a truth, so here’s the deal from code to protein:
Replication
transcription
mRNA
translation
protein
Don’t y’all ever wonder where all this stuff comes
from to make a you?
Remember chromosomes?
The dark staining
patterns on this
cartoon version of a
chromosome are
genes.
Genes are DNA
sequences that code for
a protein or a trait
(something we can see).
All chromosomes have genetic info to make you!
Okay, so here’s Transcription
Think of DNA (hence chromosomes) as
the reference materials of a central library.
People can’t check out reference material
(like encyclopedias, dictionaries…etc.)
because it’s too important that other
people need to use it too.
If you really need this information, you can
make a copy of it for your own use, put the
reference material back on the shelf so that
others can use it too.
Can you imagine if DNA was physically lost?
That’s why chromosomes never leave the
nucleus.
more transcription
To transcribe is to make a written copy of
something. So, transcription is making a copy of
a gene sequence on the chromosome because
transcription factors say so.
Transcription factors are poorly defined
mechanisms by which your body, via chemical
messengers, tells itself I need more of something
(proteins).
This copy from DNA’s called messenger RNA,
abbreviated mRNA.
mRNA
It’s essentially replication
except we only copy the
useful, 1-side of the DNA
ladder (the gene) NOT
THE WHOLE
CHROMOSOME!
nonsense
Link.
This is called the
sense strand. The
other side’s the nonsense strand.
RNA polymerase is responsible for creating mRNA.
Structure of mRNA
Since RNA polymerase only copies one strand,
it looks like half a ladder (duh!).
The red molecule’s the mRNA molecule.
RNA doesn’t have thymine though, it’s
replaced by another nucleotide URACIL.
Bye-bye mRNA molecule!
So now you have a copy of the useful gene
your body needs, now what? Nucleus (brains of
cell, remember?
mRNA leaves nucleus to
ribosome in cytoplasm via
a nuclear pore
Link review
This mRNA molecule goes to the ribosome.
Remember the ribosome, site of protein
synthesis?
What information is on mRNA?
mRNA carries the
message to make a
protein one amino acid
at a time (monomer to
polymer theme).
This example mRNA has 7 amino acids.
Three nucleotides on the mRNA code
for an amino acid, therefore we call
the triplet base a codon.
Genetic sequence=amino acid
sequence
Can you crack the code? Personally try the
one on the right first.
Is your brain hurting yet?
We’re done