The Central Dogma of Biology describes the process of protein synthesis from DNA to RNA to protein. DNA is transcribed into messenger RNA (mRNA) in the cell nucleus. The mRNA then exits the nucleus and the process of translation occurs in the cytoplasm. During translation, ribosomes use the mRNA to assemble amino acids into a protein chain based on the mRNA codon sequence. Transfer RNA (tRNA) molecules match their anticodons to the mRNA codons and add the corresponding amino acids to the growing protein chain. Eventually a whole protein is produced based on the DNA code provided in the gene.

1. The Central Dogma of Biology
DNA RNA Protein

2. The Central Dogma of Biology
Protein synthesis begins with a section of DNA
called a gene which contains the information
for the production of a single protein.

3. The Central Dogma of Biology
DNA

RNA

Protein
Transcription
Translation

5. There are three important differences between the
structure of DNA and the structure of RNA.
1. The pentose sugar found
in RNA is ribose instead of
deoxyribose.
2. The nucleotide thymine
found in DNA is replaced
with uracil in RNA.
3. DNA is a double-helix,
and RNA is a single strand.

6. Transcription
RNA Polymerase breaks the hydrogen bonds
between the two strands of DNA.

7. Transcription
One of the DNA strands serves as a template
for the construction of a new messenger RNA.

8. Transcription
Complementary nucleotides align themselves
along the exposed nitrogen bases of the DNA.

9. Transcription
The newly constructed mRNA molecule is
released into the nucleus and the DNA
reforms.
mRNA
DNA
RNA Polymerase

10. Transcription
The transcription phase of protein synthesis is
over when mRNA exits the nucleus through a
nuclear pore and enters the cytoplasm.
http://www.youtube.com/watch?v=41_Ne5mS2ls

11. Protein Synthesis: Part Two
Translation
Translation takes place in the cellular cytoplasm. The
process is mediated by large molecular machines called
Ribosomes.

12. Vocabulary:
Ribosomes: the molecular structure responsible for
translating mRNA into protein.

13. Translation
Most ribosomes are found on the outside membrane
of the rough endoplasmic reticulum.

14. Rough Endoplasmic Reticulum: A membranous structure in
the cytoplasm of a cell where proteins destined for export are
assembled.
Vocabulary:

15. Translation starts when a ribosome attaches to a
messenger RNA molecule and begins to assemble
amino acids based on the sequence of codons in the
mRNA molecule.
Translation

16. DNA and RNA use only four
bases to create a code that
determines the sequence of
20 different amino acids in
the final protein.
In order to do this nucleic
acids use three letter
“words” called codons to
indicate each of the amino
acids in the sequence.
What are codons?

17. Codons

18. The Genetic Code

19. A third form of RNA called transfer RNA, tRNA, is found in
the cytoplasm.
Translation

20. Translation
The tRNA molecule has a sequence of three nucleotides called
an “anticodon” at one end and a corresponding amino acid at
its opposite end.
Anticodon
Amino Acid
Transfer RNA

21. Translation
During translation the anticodon on the tRNA aligns with the
codon on the mRNA

22. The ribosome provides a site where tRNA molecules
align with the codons on the mRNA molecule.
Translation

23. Translation
The amino acid on the tRNA is then “transferred” to the
growing protein chain and the tRNA is released back into
the cytoplasm to pick up another amino acid.
http://highered.mcgraw-
hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120077/
micro06.swf::Protein%20Synthesis

24. Eventually the ribosome reaches the end of the mRNA and
protein sequence is complete.
Translation
http://www.youtube.com/watch?v=41_Ne5mS2ls
http://www.youtube.com/watch?v=Jml8CFBWcDs&feature=related

26. “This is too hard.”

27. What happens when DNA makes a typo?

29. Myostatin is a protein which inhibits the growth of
muscle tissue.
Defect in myostatin gene results in extraordinary
muscle growth

30. Albinism is a genetic defect of an enzyme involved in the production of melanin.