1. DNA, RNA and Protein Synthesis
How Proteins Are Made and How Are Your Traits Determined through Gene Expression?

2. Organic compounds contain C, H, O, N
What are Proteins?
Organic compounds contain C, H, O, N
Made of small units called amino acids-
building blocks of proteins

3. What are Proteins continued?
Proteins are made at the ribosomes
Ribosomes read the DNA message
on the mRNA and join amino acids
to make proteins
Your body can make 12 of the 20 amino
acids, but the other 8 essential amino acids must come from your diet
Name food items that are good source of these essential amino acids? (Hint: must come from protein source).

4. Functions of Proteins of chemical reactions (lower amount of energy
Enzymes-catalyst proteins used to control the rate
of chemical reactions (lower amount of energy
needed to start a reaction)
Structural component of body: skin, hair, muscles, bone
Marcia S. Brose, M.D., Ph.D., Assistant Professor, Hematology/Oncology, The University of Pennsylvania Cancer Center, Philadelphia, PA. Review provided

5. Functions of Proteins continued
Some proteins are hormones and carry chemical messages; for example insulin, regulates blood sugar
Transport substances such as hemoglobin in RBC that
carries O2
Protect body against disease; antibodies of immune system

6. SO…how does a cell make proteins anyway
SO…how does a cell make proteins anyway? And what does this have to do with DNA and RNA?

7. DNA RNA vs. Let’s Review… Contains ribose sugar Is single stranded
Contains deoxyribose sugar
Is double stranded
Bonds A-T and C-G
Never leaves the nucleus
Contains ribose sugar
Is single stranded
Bonds A-U and C-G
Can leave the nucleus

8. Remember there are three types of RNA
mRNA
mRNA: messenger RNA; carries DNA message to ribosomes
tRNA: transfer RNA; transfers amino acids to ribosomes
tRNA
towing
Amino acid
Remind students that there are three different RNA molecules that are involved with protein synthesis and briefly go over their function.
mRNA: messenger RNA. It carries the DNA message from the nucleus to the ribosomes. tRNA: transfer RNA. It carries amino acids from the cytoplasm to the ribosomes.
rRNA: ribosomal RNA. It is found at the ribosomes.
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Protein
factory
rRNA: ribosomal RNA; makes up ribosome-protein factories of the cell

9. Role of RNA A C G T
While DNA contains the instructions for making proteins in the form of genes…
RNA is the molecule that actually does all the work of putting the protein together

10. Overall Process of Protein Synthesis (Gene Expression)
Transcription
Translation
DNA
mRNA
Transcription
Information in DNA is “transcribed” (rewritten) as a molecule of mRNA
Protein
Translation
DNA information on mRNA is “translated” into protein language

11. Enzymes There are two different enzymes necessary in making a protein.
Helicase – breaks hydrogen bonds between nitrogen bases
Polymerase – brings new nucleotides and bonds them to existing strands
What organic compound group do enzymes belong to?

12. TRANSCRIPTION- First Process of Protein Synthesis
Occurs in the nucleus
Uses RNA Polymerase
Makes mRNA from DNA template
60 nucleotides are copied per second
Initiator (start) Codon: AUG

13. TRANSCRIPTION Steps A T C G
Helicase breaks the hydrogen bonds between the nitrogen bases

14. TRANSCRIPTION A T
Helicase breaks the hydrogen bonds between the nitrogen bases A T G C G C A T G C

15. TRANSCRIPTION A T
Helicase breaks the hydrogen bonds between the nitrogen bases A T G C G C A T G C

16. TRANSCRIPTION A T
Helicase breaks the hydrogen bonds between the nitrogen bases A T G C G C A T G C

17. TRANSCRIPTION A T
Helicase breaks the hydrogen bonds between the nitrogen bases A T G C G C A T G C

18. TRANSCRIPTION A T
Helicase breaks the hydrogen bonds between the nitrogen bases A T G C G C A T G C

19. TRANSCRIPTION A T
Helicase breaks the hydrogen bonds between the nitrogen bases A T G C G C A T G C

20. TRANSCRIPTION A T
2. The DNA strands break apart A T G C G C A T G C

21. TRANSCRIPTION A T C G T A G C A G

22. TRANSCRIPTION A T C G T A G C A G

23. TRANSCRIPTION A T C G T A G C A G

24. TRANSCRIPTION A T C G T A G C A G

25. TRANSCRIPTION A T C G T A G C A G

26. TRANSCRIPTION A T C G T A
3. RNA Polymerase brings in mRNA nucleotides and matches them with their DNA complement. G C A G

27. A T C G T A G C A G G

28. A T C G T A G C A A G G

29. A T C G T A G C C A A G G

30. T A T C G A G G C C A A G G

31. T A T C G A A G G C C A A G G

32. U T A T C G A A G G C C A A G G

33. A T C G U T A G
mRNA
DNA C A G

34. G A C U T
4. mRNA breaks away from the DNA strand and goes to the ribosome A T C G A G C A G

35. G A C U T A T C G A G C A G

36. G A C U T A T C G A G C A G

37. G A C U T A T C G A G C A G

38. G A C U T A T C G A G C A G
To Ribosome

39. 5. The DNA strand is put back together

40. A T G C A T C G

41. A T G C A T C G

42. A T G C A T C G

43. A T G C A T C G

44. A T G C A T C G

45. A T G C

46. SUMMARY Transcription Translation DNA mRNA tRNA Protein Amino Acid A UG G A C U A U
Amino Acid
DNA
mRNA
tRNA
Protein

47. Some additional notes about making mRNA…
DNA contains many non-coding regions, also known as “junk DNA”
RNA is not made from the junk DNA
Only 1 of the 2 DNA strands is used to make the
mRNA; this strand is called the DNA template
DNA code on the mRNA is read three bases at once, and these three letter base combinations on the mRNA are called codons
Codons determine your genetic code and the traits expressed from protein synthesis
DNA contains many regions that do not code for anything. These non-coding regions, also known as “junk DNA,” are unique to each organism within a species.
mRNA is not made from the junk DNA. mRNA simply skips over these non-coding regions when it copies DNA.