(From a gene to a protein)
Stated Clearly - What is a Gene?

• DNA is the genetic material
• DNA codes for different genes
– Genes are sections of DNA that code for a specific protein which determines different traits

Which contain: - a phosphate group
- a sugar (deoxyribose)
- a nitrogenous base

The first step in decoding a genetic message from DNA is to copy it into RNA. Called Transcription.

The second step in protein synthesis, is to decode RNA into a chain of amino acids which forms a protein. Called
Translation.

DNA  (transcription)  RNA  (translation)  Proteins

• Proteins are made by joining amino acids into long chains
(polypeptides)

• Structural
– muscle, hair
• Chemical / Functional
– antibodies, hormones, enzymes

• Involved in protein synthesis
• Made up of nucleotides:
• A phosphate group
• A sugar (ribose)
• Nitrogenous bases
• (RNA only has A, U, C, G there is no T!)
• There are three types of RNA

• mRNA – (Messenger RNA) copy of DNA containing instructions for assembling proteins. Created in the nucleus.

• Ribosomes are made of rRNA.
Attaches individual amino acids together.

• tRNA - brings amino acids to the ribosome.

• Flow of info: DNA  mRNA
• Location: Nucleus
• mRNA is produced by copying a section/gene of the DNA (RNA Polymerase)
• Where does the mRNA go?
– Cytoplasm/Ribosomes
Transcription Animation

• Flow of info: mRNA  Proteins
• Location: Cytoplasm/Ribosomes
• Decoding mRNA into a chain of amino acids (protein)

• A ribosome (rRNA) attaches to the mRNA
• The mRNA code is read 3 letters/bases at a time (codon)
• The start codon (AUG) tells the rRNA to begin adding amino acids.

•The tRNA (with amino acid) that pairs with the codon will come to the ribosome and bind to the mRNA.
•The ribosome adds new tRNA molecules and amino acids as it moves along the mRNA.

• As each new tRNA enters the ribosome, one leaves.
• Before tRNA can leave the ribosome, the amino acids will bond together to make a polypeptide (protein) chain

• The process continues until the ribosome reaches a stop codon.
Translation Animation

Full Process Animation
(Transcription & Translation)

Amoeba Sisters - Protein Synthesis
Gene Expression / Protein Synthesis