Download RNA and Protein Synthesis

RNA,
Transcription,
& Translation
• DNA carries instructions to make
proteins.
• Each protein has a specific job to do
which helps you stay alive!
• Each cell wants to keep its DNA
safe and sound inside the nucleus.
• RNA gets DNA’s instructions out of
the nucleus and turned into a protein.
DNA
RNA
Similar:
• Is a nucleic acid
• Made of nucleotides
Similar:
• Is a nucleic acid
• Made of nucleotides
Different from RNA:
• 2 strands
• Sugar is Deoxyribose
• Has Thymine
• A & T pair up
• C & G pair up
Different from DNA:
• 1 strand
• Sugar is Ribose
• Has Uracil
(*it replaces thymine)
• A & U* pair up
• C & G pair up
3 types of RNA
3 Types of RNA
1) Messenger RNA = mRNA
– Copies DNA’s instructions
– Carries the “message” out of the nucleus
– Why can’t DNA leave the nucleus?
• It’s like the original, you don’t want it
messed up!
• mRNA can act like a “disposable” photocopy
of the instructions
• And you can make a LOT of photocopies
so a LOT of proteins can be made at the
same time
3 Types of RNA
2) Ribosomal RNA = rRNA
– A ribosome is made up of rRNA !
– Ribosomes:
• read the message of mRNA and
• make the protein
3 Types of RNA
3) Transfer RNA = tRNA
– *A Protein is a chain of Amino Acids
– tRNAs match the right Amino Acid to
the right anti-codon
– rRNA uses tRNA to translate the mRNA
message into a protein
Try this:
If a strand of DNA says this:
T C G G A C T A A
A G C C U G A U U
What will the strand of mRNA say?
– Congratulations! You just did a process
called transcription !
Transcription
• When RNA molecules are produced
by copying part of the nucleotide
sequence of DNA into to a
complementary sequence of RNA
• Transcribe = to write/copy down
• When DNA’s instructions are copied
by mRNA
Enzyme Needed
• RNA polymerase (an enzyme)
– Unzips DNA and reads one strand
– Uses DNA like a template to
Create a strand of mRNA
• Promoter regions on DNA
– tell RNA polymerase where to start
– RNA polymerase will only bind to
promoters
Transcription
Translation
• mRNA message is translated into a
protein by rRNA and tRNA
• mRNA is read 3 letters (bases) at a time
• Each 3 letter “word” of mRNA is called a
Codon
• tRNA has an anti-codon on one side and
an amino acid on the other
• Start and stop codons tell ribosome
where to start and stop
TRANSLATION
Protein
(a chain of
amino acids)
tRNA
Amino acid
Anti-codon
mRNA
Ribosome
Try This:
DNA says this: A G C G T G C C A
mRNA codons say: U C G- C A C- G G U
tRNA anti-codons say: A G C- G U G- C C A
tRNA amino acids: Serine-Histidine- Glycine
Congratulations! You have just transcribed and
translated DNA into a protein!
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