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Transcription and
Translation:
From DNA to Proteins
 How
can DNA code for how I look?
 How does this code give me black
hair & brown eyes?
 How can this code make me tall or
short?
Recall: Chromosomes, Genes, and
DNA
•DNA makes up
GENES, which are
found on
CHROMOSOMES.
•Gene— a segment
of DNA that provides
information for
making a specific
protein.
DNA is expressed as
PROTEINS—determines your
traits!
DNA  RNA  Proteins
(Transcription)
(Translation)
THE CENTRAL DOGMA!
Replication
DNA can’t
fit through
nuclear membrane, so it
needs to send a
“messenger” RNA (mRNA)
to the ribosomes to make
proteins.
DNA is very important
and must be kept
protected!
DNA
Transcription
RNA
Nucleus
Translation
Protein
Cytoplasm
Transcription (DNA  mRNA)
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Transcription occurs in the NUCLEUS
RNA = Ribonucleic Acid (a nucleic acid)
DNA is template for RNA
mRNA is made of same bases, except uses
URACIL instead of thymine.
 A pairs


with U
G pairs with C
Every 3 letters of mRNA are called a CODON.
Transcription
The new mRNA molecule is formed by incorporating
nucleotides that are complementary to the template
strand.
DNA coding strand
5
’
3’
DNA
GT CA TT CGG
3’
G UC AUUCG G
3’
C AG T AAGCC
5’
DNA template strand
5
’
RNA
DNA vs. RNA
RNA
DNA
1. Single-stranded
1. Double-stranded
2. A pairs with Uracil (U)
2. A pairs with Thymine (T)
3.
Sugar = Ribose
3. Sugar = Deoxyribose
4.
Location = Nucleus
and Ribosomes
4.
Location = Nucleus
There are 3 Types of RNA



mRNA
Messenger
Job is to
carry the
message
from the
nucleus to
the
ribosome

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
tRNA
Transfer
Job is to
transfer the
amino acids
to the
ribosome
Only in
cytoplasm
•rRNA
•Ribosomal
•Composes the
ribosome itself
•Only in
cytoplasm
Three types of RNA
Translation (mRNA  Protein)



Takes place in RIBOSOMES
mRNA is template for tRNA
Transfer RNA (tRNA)

tRNA translates the message, picks up
corresponding amino acid, and puts it
together into a protein chain.
 Every 3 letters of tRNA are called an
ANTICODON.
Translation
DNA  mRNA  tRNA
DNA
mRNA
tRNA
ATC CTA GTG CAT
UAG GAU CAC GUA
AUC CUA GUG CAU
Amino Acids—make up proteins

"Why do we need mRNA if DNA holds all the
genetic instructions for the proteins the cell
needs to produce?"

DNA must be protected at all costs AND it
is too big to leave the nucleus.
Vocabulary to Know….
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DNA
Nucleus
Ribosomes
Transcription
Translation
RNA
Protein
mRNA
tRNA
Amino acid
Quiz yourself!!!!!!