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