Download Module 6 Lesson 2 Notes

Transcribing mRNA from DNA
Remember that DNA contains the code
for proteins being made in the cell.
DNA is transcribed into mRNA in the
nucleus.
This process is called transcription.
DNA unwinds and mRNA nucleotides
combine to the appropriate DNA
nucleotides.
Transcription
DNA strand:
TACGACTCCAGC
mRNA complimentary strand:
AUGCUGAGGUCG
Notice that Uracil (U) replaces Thymine
(T) and combines with Adenine (A)
Making proteins
 You have already seen how we use
DNA to make RNA now we are going to
turn that RNA into Proteins
The basics
DNA

Nucleus 
RNA 
Protein
(the sequence)
Nucleus 
Ribosome
(the locations)
What we know…
 Proteins are made out of amino acids
Fun Facts you should know!
 The genetic code is in DNA
 There are 20 different amino acids
• The come from 4 different types of bases




Adenine A
Uracil U
Cytosine C
Guanine G
 Each set of three nitrogen bases represents an
amino acid is known as a codon
 Codons code for amino acids
 There are 64 possible combinations of codons. 61
code for amino acids. The three left are stop
codons.
You should know how to read this. If you can not pick up
the phone and call me so I can walk you through it!
Translation
From RNA to Protein
 Translation- occurs in the ribosome
(organelle)
 Process of reading codons, laying amino
acids in chains, making proteins
 tRNA- Brings amino acids to the
ribosome's so they can assemble into
proteins
Making proteins
1. All you have to do it make sure that
your DNA strand is transcribed into
mRNA. Like this
Original DNA Strand
ACC TAC GCG GGG CAT ATT CCG
Transcribed mRNA Strand
UGG AUG CGC CCC GUA UAA GGC
Now you have your mRNA
 mRNA UGG AUG CGC CCC GUA UAA GGC
2. Look for the start codon. Remember
this is AUG
UGG AUG CGC CCC GUA UAA GGC
(ignore the stuff before AUG we do not care about it)
You now know where to start
3. Now that you know where to start
move down the mRNA strand and read
the next codon
UGG AUG CGC CCC GUA UAA GGC
CGC codes for arginine, so add the amino acid
arginine to your growing amino acid chain
Your chain looks like this now
Start  Arginine
Move down the chain to your
next codon
 UGG AUG CGC CCC GUA UAA GGC
 CCC codes for proline
 Add proline to your chain
Start  Arginine  proline
Move down the chain to your
next codon
 UGG AUG CGC CCC GUA UAA GGC
 GUA codes for Valine
 Add valine to your chain
Start  Arginine  proline  Valine
Move down the chain to your
next codon
 UGG AUG CGC CCC GUA UAA GGC
 UAA codes for STOP
 Add STOP to your chain
Start  Arginine  proline  ValineStop
The last codon you coded
 told you to stop so you are done coding
until you see another start in the
codons.
Protein Use in Organisms
Proteins can be found in:
muscles, ligaments, bones,
tendons, hair, skin, nails, cell
membranes.
These things give organisms structure,
support and protection.
Antibodies, hormones and enzymes are
types of proteins.
Antibodies are part of an organism’s
immune system.
Hormones are secreted by glands and
allow systems to function properly.
Enzymes speed up chemical reactions in
the organism.