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Transcription and Translation
From DNA to RNA to protein
The Central Dogma of Biology
DNA RNA Protein
Overview• Genes in DNA contain
information to make proteins.
• The cell makes mRNA copies of genes that are needed.
• The mRNA is read at the ribosomes outside of the nucleus.
• Protein is produced.
Some Key Players• RNA polymerase, the enzyme
that makes RNA copies of DNA• mRNA carries the information
from a gene in DNA.• Ribosomes, made of rRNA,
consist of subunits and carry out an enzyme-like role.
• tRNA carries specific amino acids to the ribosome.
• codon- coding triplet of mRNA bases that code for 1 amino acid
RNADNA
RNApolymerase
TranscriptionAdenine (DNA and RNA)
Cystosine (DNA and RNA)Guanine(DNA and RNA)
Thymine (DNA only)Uracil (RNA only)
Transcription
RNA polymerase is the enzyme responsible for making mRNA copies of genes. DNA unzips at the
site of the gene that is needed.
Transcription
RNA polymerase matches bases of one DNA strand with RNA bases, building a strand of mRNA that
carries the information encoded in the DNA.
Transcription
Encoded in DNA is a signal telling RNA polymerase where to stop. Transcription ends at that point.
Transcription
The completed mRNA molecule then exits the nucleus for translation.
Translation• Translation begins
with a tRNA bearing methionine binding to its matching codon
• The codon for methionine is a universal �start�codon for �reading�the mRNA strand.
Translation• The second codon in
mRNA matches the anticodon of a tRNAcarrying the amino acid.
• A catalytic site on the ribosome binds the two amino acids together forming a peptide bond between them.
Translation• The mRNA shift down in
the ribosome
• Process continues with more amino acids being brought by tRNAs and peptide bonds being formed
• The process continues until the ribosome finds a �stop� codon.
Transcription vs. Translation Review
Transcription
• Process by which genetic information encoded in DNA is copied onto messenger RNA
• Occurs in the nucleus
DNA mRNA
Translation
• Process by which information encoded in mRNA is used to assemble a protein at a ribosome
• Occurs on a Ribosome
mRNA protein
Which process converts DNA information into RNA information?
A) TranscriptionB) TranslationC) BothD) Neither
Which process requires ribosomes?
A) TranscriptionB) TranslationC) BothD) Neither
Which process involves mRNA ?
A) TranscriptionB) TranslationC) BothD) Neither
In which process is the final product a protein?
A) TranscriptionB) TranslationC) BothD) Neither
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