Notes# __________
Date ____________
From DNA to Proteins – The Process of Protein Synthesis
Central Dogma of Molecular Biology
Genetic information flows in one direction from DNA to RNA to protein .
The Relationship between DNA, Genes, and Proteins
 The genetic information passed from parent to offspring is DNA.
 Each DNA molecule has hundreds of segments known as _genes_.
 Gene - section of DNA that provides the instructions for making a _protein_
 Protein molecules are polymers formed by joining amino acids
 The type of protein made is determined by the order of amino acids.
 1,000’s of different protein molecules are made by the cell every minute
Protein Synthesis - process of using DNA’s code to make proteins.
 Two-part process:
1. Transcription
2. Translation
Part 1 Transcription - DNA code used to make RNA.
 Occurs in the cell nucleus.
 DNA is too big to leave the nucleus. So its “message” is rewritten in the
language of RNA molecules which are smaller and can leave the nucleus.
How Transcription works:
 Enzymes unwind DNA to expose bases in a specific gene.
 RNA polymerase attaches complementary RNA bases to the DNA strand
 Single strand RNA strand leaves the nucleus through membrane pores
DNA G T C A G C A T G A C T A A T G C T A C
RNA C A G U C G U A C U G A U U A C G A U G
Transcription makes 3 types of RNA
1. Messenger RNA (mRNA) – carries DNA’s protein making code to ribosomes
2. Ribosomal RNA (rRNA) - forms ribosomes, the cell’s “protein factories”
3. Transfer RNA (tRNA) – carries amino acids to ribosome to make proteins
Notes# __________
Date ____________
Messenger RNA
 Carries the message of a DNA’s gene needed to make a protein
 Each group of 3 nucleotides in mRNA is called a codon.
 Each codon specifies a particular amino acid
 A codon must be read in the right order sequence called a reading frame.
mRNA codon
Amino Acid Abbreviation
Amino Acid
Start codon - _____________________________________________________
Stop codons - _____________________________________________________
Notes# __________
Date ____________
Part 2 Translation –mRNA‘s code is used to make proteins




Site of protein synthesis – ribosomes in the cytoplasm.
Transfer RNA (tRNA) carries amino acids to the ribsome.
tRNA has a 3 nucleotide sequence called an anticodon
tRNA’s anticodon matches with mRNA’s codon to deliver the correct amino
acid needed to make the protein.
Central Dogma
Genetic information flows in one direction from DNA to RNA to protein .
DNA Dogma of Molecular BiologyRNA
PROTEIN
Central
___________________
____________________
__________________
Important jobs of Protein Molecules in Living Things:
1. Enzymes – they catalyze (speed up) and regulate chemical reactions.
2.Transport protein (channels and pumps) in cell membrane
move substances active and passive transport
3. Form cell fibers like cilia, flagella, microtubules, cytoskeleton and muscle
4. Form structural body parts like hair, nails, hooves
5. Serve in the immune system as antibodies against foreign invaders(bacteria)
Notes# __________
Date ____________