Transcription

1
Transcription

• Or the making of a molecule named, messenger
  RNA, aka
• mRNA

2
DNAs Central Dogma
Do you know what a dogma is? Its a belief or a
truth, so heres the deal from code to protein
transcription
translation
Replication
mRNA
protein
Dont yall ever wonder where all this stuff
comes from to make a you?
3
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!
4
Okay, so heres Transcription
Think of DNA (hence chromosomes) as the reference
materials of a central library. People cant
check out reference material (like encyclopedias,
dictionariesetc.) because its 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?
Thats why chromosomes never leave the nucleus.
5
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 DNAs called messenger RNA,
abbreviated mRNA.
6
mRNA
Its essentially replication except we only copy
the useful, 1-side of the DNA ladder (the gene)
NOT THE WHOLE CHROMOSOME!
This is called the sense strand. The other
sides the non-sense strand.
nonsense
RNA polymerase is responsible for creating mRNA.
Link.
7
Structure of mRNA
Since RNA polymerase only copies one strand, it
looks like half a ladder (duh!).
The red molecules the mRNA molecule.
RNA doesnt have thymine though, its replaced by
another nucleotide URACIL.
8
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?

9
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.
10
Genetic sequenceamino acid sequence
Can you crack the code? Personally try the one
on the right first.
11
Is your brain hurting yet?
Were done