Transcription and Translation

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Transcript Transcription and Translation

By
making proteins!
DNA contains the
instructions for which
proteins to make

*and complicated instructions on when to make them that we don’t
fully understand
I.e. difference in pigments (hair, eye, skin
etc.)
 I.e. difference in enzymes (make
different amounts of molecules)
 I.e. difference in antibodies (some get
sick more often or from different things)


*A lot of differences are also due to
more complicated gene expression
Makes a purple
protein in flowers
Makes a white
protein in flowers
 Code
for slightly
different versions
of the protein
 Probably arose
through mistakes
in DNA
replication
DNA-> mRNA
 Like making a copy
of the blueprint
 Kind of like DNA
replicationcomplementary
nucleotides are
added- EXCEPT U is
used instead of T

DNA
 Deoxyribose
sugar
 A,C, G and T nucleotides
 Usually double stranded
 Stores the code (like the master
blueprint)

RNA


Ribose sugar
A, C, G and U nucleotides
Usually single stranded
› But can fold on itself

Different types and functions
› mRNA, tRNA, rRNA
› Carries code, assembles proteins
Each gene has
a promoter
 Transcription
factors help
RNA
polymerase
bind to the
promoter and
begin
transcription

RNA polymerase
DNA
AGCTATAACGACG T TAGCATCA
T CGATAT TGCUGCAAUCGUAGU
GCT GCAATCGTAGT
T CGATAT T GCT GCAATCGTAGT
mRNA
DNA
is not turned into
RNA!
An RNA molecule is
made based of the DNA
code!

mRNA Protein in the ribosome

Every 3 RNA nucleotides (letters) codes
for 1 amino acid
› Called a “codon”
Example:
DNA
ATG GCA GAC
RNA
UAC CGU CUG
Protein Tyr Arg Leu

A tRNA molecule carries an amino acid
 tRNA nucleotides must be complementary to
mRNA code

Translation always begins at the Start
Codon AUG and ends when a STOP
codon is reached
 Ex. RNA GTCA AUG GCC CCA UGG
 Protein
Met – Ala - Pro

 Transcription
› DNA (gene) transcribed to make
mRNA which carries code
› In Nucleus
 Translation
› mRNA code translated into a
protein
› With help of tRNA in the ribosome