1. The Making of Proteins Using the Genetic Information Stored in DNA
Protein Synthesis
The Making of Proteins
Using the Genetic Information
Stored in DNA

2. Central Dogma of Molecular Biology
Genetic information flows in one direction –
from DNA to RNA to proteins.

3. Relationship between DNA, Genes, Proteins
Genetic information passed from parent to offspring is DNA

4. Each DNA molecule has hundreds of sections known as genes
Gene - section of DNA that provides the instructions for making a protein

5. Protein molecules are polymers formed by joining amino acids

6. The type of protein made is determined by the order of amino acids.

7. 1,000’s of different protein molecules are made by the cell every minute

8. Protein Synthesis - process of using DNA’s code to make proteins.
Two-part process:
1. Transcription
2. Translation

9. Transcription - DNA code used to make RNA
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

10. Enzymes unwind DNA to expose bases in a specific gene.
How Transcription Works
Enzymes unwind DNA to expose bases in a specific gene.
start site
nucleotides
transcription complex

11. RNA polymerase moves along the DNA
Transcription
RNA polymerase attaches complementary RNA bases to the exposed DNA strand
RNA polymerase bonds the nucleotides together to form RNA .
DNA
RNA polymerase moves along the DNA

12. Transcription – rewriting DNA into RNA

13. Transcription
The newly made RNA strand detaches from the DNA after the gene is transcribed.
The small RNA strand exits the nucleus through pores in the nuclear membrane
RNA

14. Transcription – DNA code rewritten in the “Language” of RNA
DNA RNA
C G
G C
T A
A U
Uracil replaces Thymine in RNA

15. Transcription – DNA code rewritten in the “Language” of RNA
GTC ABC ATG ACT AAT GCT AC DNA
CAG UCG UAC UGA UUA CGA UG RNA
DNA RNA
C G
G C
T A
A U Uracil replaces Thymine in RNA

16. Transcription makes 3 types of RNA:
Messenger RNA (mRNA) –carries DNA’s protein making code to ribosomes
Ribosomal RNA (rRNA) –forms ribosomes, the cell’s “protein factories”
Transfer RNA (tRNA) – carries amino acids to the ribosome to make proteins.

17. Messenger RNA
Carries the message of a DNA’s gene needed to make a protein.
Each group of 3 nucelotides 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.

18. Transcription compared to replication.
Transcription and replication both involve enzymes and complementary base pairing.
The two processes have different end results.
Replication copies all the DNA; transcription copies a gene.
Replication makes one copy; transcription can make many copies.
growing RNA strands
DNA
one
gene