2. Proteins from Amino Acids
What
Figure 2.20  Translation produces a polymer of amino acids to form a protein. A, A peptide bond (shown as a red line) forms when two amino acids are covalently connected with water as a waste product. Colors are for illustration purposes; R1 and R2 represent additional atoms. B, In vitro translation with each column a different experiment with + indicating presence of an ingredient. Blank boxes show which ingredient was omitted. Below the table are protein gel electrophoresis results from the seven inputs above.
Talking Point: The bonds are called peptide bonds because they build proteins, also called polypeptides. This covalent bond is not different than other C-N covalent bonds.
Fig. 2.20
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

3. Proteins from Amino Acids
What
Researchers’ Big Question:
What cellular components are needed to make protein?
Figure 2.20  Translation produces a polymer of amino acids to form a protein. A, A peptide bond (shown as a red line) forms when two amino acids are covalently connected with water as a waste product. Colors are for illustration purposes; R1 and R2 represent additional atoms. B, In vitro translation with each column a different experiment with + indicating presence of an ingredient. Blank boxes show which ingredient was omitted. Below the table are protein gel electrophoresis results from the seven inputs above.
Talking Point: In vitro experiment and the experimental setup.
Fig. 2.20
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

4. Proteins from Amino Acids
What
ingredients: DNA
energy
tRNA
ribosomes
mRNA
amino acids
Researchers’ Big Question:
What cellular components are needed to make protein?
Figure 2.20  Translation produces a polymer of amino acids to form a protein. A, A peptide bond (shown as a red line) forms when two amino acids are covalently connected with water as a waste product. Colors are for illustration purposes; R1 and R2 represent additional atoms. B, In vitro translation with each column a different experiment with + indicating presence of an ingredient. Blank boxes show which ingredient was omitted. Below the table are protein gel electrophoresis results from the seven inputs above.
Talking Point: In vitro experiment and the experimental setup.
Fig. 2.20
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

5. Proteins from Amino Acids
What
method: gel electrophoresis
stain all proteins dark
Figure 2.20  Translation produces a polymer of amino acids to form a protein. A, A peptide bond (shown as a red line) forms when two amino acids are covalently connected with water as a waste product. Colors are for illustration purposes; R1 and R2 represent additional atoms. B, In vitro translation with each column a different experiment with + indicating presence of an ingredient. Blank boxes show which ingredient was omitted. Below the table are protein gel electrophoresis results from the seven inputs above.
Talking Point: Investigators used normal protein gels and dyed all the proteins a dark color so they could be visualized.
Fig. 2.20
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

6. Proteins from Amino Acids
Which ingredient is not necessary for translation?
chromosomes
tRNA
ribosomes
mRNAs
Figure 2.20  Translation produces a polymer of amino acids to form a protein. A, A peptide bond (shown as a red line) forms when two amino acids are covalently connected with water as a waste product. Colors are for illustration purposes; R1 and R2 represent additional atoms. B, In vitro translation with each column a different experiment with + indicating presence of an ingredient. Blank boxes show which ingredient was omitted. Below the table are protein gel electrophoresis results from the seven inputs above.
Talking Point: In addition to defining what was needed for translation, the investigators invented a good method that was used to deduce the genetic code.
Fig. 2.20
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

7. Decoding the First Codon
What
What
modern genetic code table
with all possible codons
no one knew about codons
or which amino acids were
coded by particular sequences
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: Setting up the experimental question.
Fig. 2.21
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

8. Decoding the First Codon
ingredients:
energy
tRNA
ribosomes
mRNA
amino acids
What
instead they added UUUUUUUU…..
as the only type of mRNA
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: First codon tested was UUU which ensured the code would not be read from DNA.
…then they asked: what kind of protein is made?
Fig. 2.21
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

9. Decoding the First Codon
What
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: The first codon had been deciphered and the race was on to determine all 64.
Fig. 2.21
modified from Nirenberg and Leder. 1964

10. Decoding the First Codon
measure polymerization over time
What
What
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: Investigators measured polypeptide formation over time in different temperatures.
Fig. 2.21
modified from Nirenberg and Leder. 1964

11. Decoding the First Codon
measure polymerization over time
What
…UUUU... 0° C
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: Polymerization of poly-phenylalanine at 0 C is steady.
Fig. 2.21
modified from Nirenberg and Leder. 1964

12. Decoding the First Codon
measure polymerization over time
…UUUU... 24° C
What
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: The translation of poly-U mRNA is faster at 24 C.
Fig. 2.21
modified from Nirenberg and Leder. 1964

13. Decoding the First Codon
measure polymerization over time
What do you conclude about the effect of temperature on protein synthesis?
higher temperatures cause faster protein synthesis
lower temperatures cause faster protein synthesis
temperature has no effect on the rate of protein synthesis
we cannot tell from the data
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: In vitro translation is very fast at 37 C (less than 5 minutes to completion). After the protein is produced, it begins to degrade at this warmer temperature.
Fig. 2.21
modified from Nirenberg and Leder. 1964

14. Decoding the First Codon
measure polymerization over time
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: In vitro translation is very fast at 37 C (less than 5 minutes to completion). After the protein is produced, it begins to degrade at this warmer temperature.
Fig. 2.21
modified from Nirenberg and Leder. 1964

15. Decoding the First Codon
measure polymerization over time
ingredients:
energy
tRNA
ribosomes
mRNA
amino acids
instead they added UUUUUUUU…..
as the only type of mRNA
What question are the researchers asking with these samples?
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: Negative controls show no polymerization regardless of the temperature.
Fig. 2.21
modified from Nirenberg and Leder. 1964

16. Decoding the First Codon
measure polymerization over time A B
Which sample is a control? C D
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: Negative controls show no polymerization regardless of the temperature.
Fig. 2.21
modified from Nirenberg and Leder. 1964

17. Decoding the First Codon
UUU encodes phenylalanine (phe = F)
Figure 2.21 Deciphering the first codon. A, Polymers of uracil (poly-U) mRNA were added to in vitro translation mixture conducted at three temperatures. Negative controls lacked the poly-U mRNA. B, The first codon decoded was for the amino acid phenylalanine (phe or F).
Talking Point: The first codon had been deciphered and the race was on to determine all 64.
Fig. 2.21
modified from Nirenberg and Leder. 1964

18. Decoding the Two More Codons
test …AAAA…
Which sample is a control? A B
Figure 2.22 Deciphering AAA and CCC codons. A, Poly-A and poly-C mRNAs were tested at two different temperatures. B, Genetic code determined for two additional codons at noted in table.
Talking Point: Poly-A mRNA produced poly-lysine protein in vitro.
Fig. 2.22
modified from Nirenberg and Leder. 1964

19. Decoding the Two More Codons
test …AAAA…
Figure 2.22 Deciphering AAA and CCC codons. A, Poly-A and poly-C mRNAs were tested at two different temperatures. B, Genetic code determined for two additional codons at noted in table.
Talking Point: Poly-A mRNA produced poly-lysine protein in vitro.
lysine polymers
(lys = K)
Fig. 2.22
modified from Nirenberg and Leder. 1964

20. Decoding the Two More Codons
test …CCCC…
Figure 2.22 Deciphering AAA and CCC codons. A, Poly-A and poly-C mRNAs were tested at two different temperatures. B, Genetic code determined for two additional codons at noted in table.
Talking Point: Poly-C mRNA produced polypeptide composed of all proline.
lysine polymers
(lys = K)
Fig. 2.22
modified from Nirenberg and Leder. 1964

21. The Genetic Code first 3 codons deciphered Fig. 2.23
Figure 2.23 Full genetic code used by plants, animals, bacteria and archaea. Detailed descriptions of each amino acid are available at this interactive web page (
Talking Point: The first three deduced codons.
Fig. 2.23
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

22. Stop and Start Codons 3 “stop codons” 1 “start codon” Fig. 2.23
Figure 2.23 Full genetic code used by plants, animals, bacteria and archaea. Detailed descriptions of each amino acid are available at this interactive web page (
Talking Point: 1 “start” codon and 3 stop codon (no amino acids). Start codon often is the first codon to be translated in a protein.
1 “start codon”
Fig. 2.23
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

23. Amino Acids with Six Codons
Figure 2.23 Full genetic code used by plants, animals, bacteria and archaea. Detailed descriptions of each amino acid are available at this interactive web page (
Talking Point: Several Integrating Questions ask you to explore this table more fully.
Fig. 2.23
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

24. Amino Acids with One Codon
Figure 2.23 Full genetic code used by plants, animals, bacteria and archaea. Detailed descriptions of each amino acid are available at this interactive web page (
Talking Point: Several Integrating Questions ask you to explore this table more fully.
Fig. 2.23
Copyright © 2015 by AM Campbell, LJ Heyer, CJ Paradise. All rights reserved. 

26. Huntington’s Disease
Caused by mutations in the HTT gene, which encodes the protein huntingtin.
Gene is big! 9,429 basepairs (protein is 3142 a.a.)
Normal individuals have 6-31 CAG repeats
Diseased individuals have CAG repeats
Every person who inherits the expanded HD gene will develop the disease
Symptoms usually appear between ages 30 to 50; worsen over years
There is no cure

27. Huntington’s Disease
Would you want to know if you have the expanded HD gene?
If you found out that you had it, would you live your life differently? If so, how?

28. Who owns your DNA? Who should have access to your genetic information?
your parents?
your siblings?
your romantic partner?
your employer?
your health insurance company?
If you or your partner get pregnant, do you want the fetus to be tested for genetic diseases? Why or why not?
What sources of DNA do you leave in the environment around you?
Should there be laws about who can sequence your DNA without your consent?

29. lily flowers cross-pollinate
stamen (makes pollen)
pistil (makes eggs)

30. pea flowers self-pollinate
stamen (makes pollen)
& pistil (makes eggs)
inside there