Protein synthesis: transcription and translation

1. Lesson # 15
Gene expression

2. Protein synthesis
• When a gene is expressed it means
that a protein is formed.
• In order for the protein to form
two steps need to take place:
1. DNA transcription
2. RNA translation
• Proteins are large biomolecules
important in giving structure and
taking part in metabolic processes.
• Proteins are made up of smaller
units called amino acids.

3. 1. DNA Transcription
• The DNA code of a specific gene (locus) is re-written or transcribed into a
new molecule called messenger RNA (mRNA).
• RNA is a molecule made up of a single strand of nucleotides.
• The nucleotides found in RNA are
• Adenine (A)-- Uracil (U).
• Guanine (G) -- Cytosine (C)
• Thymine (T) is not found in RNA.

4. 5’
5’
5’
3’
3’
3’

5. DNA Replication
• The section of DNA that needs to be
transcribed un coils and strands
separate.
• The strand 3’5’ serves as a template
for the formation of the mRNA
transcript.
• The mRNA transcript will exit the
nucleus.
• When it reaches a ribosome it will be
translated.

6. mRNA Translation
• The code is written in triplets.
• Every 3 nucleotides translates for a
specific amino acid.
• Triplets are also called codons.
• The ribosome reads the codons and
bonds the corresponding amino acid.
• In the end, there will be a chain of
amino acids forming the new protein.