1. Happy Tuesday! – 2/9
In this model, weak hydrogen bonds connect which of the following?
A G to C
B x to y
C y to G
D G to T

2. DNA, Protein Synthesis, and Gene Expression
Video clip -
This PowerPoint has many animated slide progressions. You may only want to print the following slides: 1-11; 33-47; 62; 64-65

3. Two Types of Nucleic Acids
1. DNA
2. RNA
a. mRNA (messenger)
b. tRNA (transfer)

4. Where are proteins made?
Ribosomes

5. Compare DNA & RNA DNA: deoxyribonucleic acid DNA is double stranded.
Contains sugar deoxyribose.
DNA contains bases adenine, thymine, guanine, cytosine.
DNA never leaves the nucleus.
RNA: ribonucleic acid
RNA is single stranded.
Contains sugar ribose.
RNA contains bases adenine, URACIL, guanine, cytosine.
RNA can leave the nucleus.
This is a review of DNA and RNA.
The slide is animated; each statement comes up automatically

6. Overall process of Protein Synthesis
transcription
translation
During gene expression, the information in DNA is first transcribed in the nucleus as a molecule of mRNA and then translated in the cytoplasm and used to build a protein.
DNA
mRNA
Protein

7. DNA’s tragedy
DNA
DNA contains volumes of information about making protein.
Unfortunately, DNA is too huge to leave the nucleus.
Remind students that DNA holds the instructions for making the protein but it cannot leave the nucleus. However, the proteins are made in the ribosomes.
ribosomes
nucleus

8. How does the cell solve this problem….transcription
That’s where mRNA comes in.
mRNA helps get DNA’s message out to the ribosomes...
DNA
mRNA
A mRNA copy of DNA is transcribed (made) because mRNA can leave the nucleus and take the message to the ribosomes.

9. First, DNA unzips itself...
ATGACGATT
TACTGCTAA
DNA unzips itself, exposing free nitrogen bases.
The slide is animated; the DNA unzips automatically

10. First, DNA unzips itself...
ATGACGATT
TACTGCTAA
DNA unzips itself, exposing free nitrogen bases.
The slide is animated; the DNA unzips automatically

11. First, DNA unzips itself...
ATGACGATT
TACTGCTAA
DNA unzips itself, exposing free nitrogen bases.
The slide is animated; the DNA unzips automatically

12. First, DNA unzips itself...
ATGACGATT
TACTGCTAA
DNA unzips itself, exposing free nitrogen bases.
The slide is animated; the DNA unzips automatically

13. First, DNA unzips itself...
ATGACGATT
TACTGCTAA
DNA unzips itself, exposing free nitrogen bases.
The slide is animated; the DNA unzips automatically

14. Transcription
The process of going DNA to mRNA
Occurs in the nucleus

15. Transcription c. Steps of Transcription:
1. First DNA unzips itself along the segment of
code (gene) needed for a certain protein.
2. mRNA is made by forming complementary
bases on the unzipped portion of DNA.

16. Transcription 3. DNA’s code is copied into groups of 3 bases
at a time called a codon.
4. Each codon codes for 1 amino acid.
5. Once the mRNA strand is transcribed, it
leaves the nucleus to find a ribosome.

17. Next, mRNA is made... ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
Have students notice that the mRNA is made from ONE side of the DNA molecule
The slide is animated; the DNA unzips automatically

18. Next, mRNA is made... U ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
The slide is animated; the RNA bases automatically pair up with DNA

19. Next, mRNA is made... U ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
The slide is animated; the RNA bases automatically pair up with DNA

20. Next, mRNA is made... UA ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion UA
The slide is animated; the RNA bases automatically pair up with DNA

21. Next, mRNA is made... UA ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion UA
The slide is animated; the RNA bases automatically pair up with DNA

22. Next, mRNA is made... UAC ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UAC
The slide is animated; the RNA bases automatically pair up with DNA

23. Next, mRNA is made... UAC ATGACGATT mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UAC
The slide is animated; the RNA bases automatically pair up with DNA

24. Next, mRNA is made... UACU ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACU
The slide is animated; the RNA bases automatically pair up with DNA

25. Next, mRNA is made... UACU ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACU
The slide is animated; the RNA bases automatically pair up with DNA

26. Next, mRNA is made... UACUG ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUG
The slide is animated; the RNA bases automatically pair up with DNA

27. Next, mRNA is made... UACUG ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUG
The slide is animated; the RNA bases automatically pair up with DNA

28. Next, mRNA is made... UACUGC ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUGC
The slide is animated; the RNA bases automatically pair up with DNA

29. Next, mRNA is made... UACUGC ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUGC
The slide is animated; the RNA bases automatically pair up with DNA

30. Next, mRNA is made... UACUGCU ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUGCU
The slide is animated; the RNA bases automatically pair up with DNA

31. Next, mRNA is made... UACUGCU ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUGCU
The slide is animated; the RNA bases automatically pair up with DNA

32. Next, mRNA is made... UACUGCUA ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUGCUA
The slide is animated; the RNA bases automatically pair up with DNA

33. Next, mRNA is made... UACUGCUA ATGACGATT
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complimentary fashion
UACUGCUA
The slide is animated; the RNA bases automatically pair up with DNA

34. Next, mRNA is made... ATGACGATT UACUGCUAA
mRNA is made from the DNA template
mRNA matches with free DNA nitrogen bases in a complementary fashion
Remind students that the RNA strand has Uracil instead of Thymine and that the Uracil pairs up with Adenine.

35. Translation The process of going mRNA to proteins
Occurs in the cytoplasm
Involves tRNA
Every tRNA has one anti-codon and one amino acid.

36. Translation e. Steps of Translation:
1. Ribosome reads mRNA and brings in
matching tRNA.
2. The codon of mRNA bases pairs to anti-codon
of tRNA.
3. tRNA drops off amino acid to ribosome and
then float away.
4. Ribosome pieces together amino acids to
build proteins.

37. Regulation of Transcription and Translation
Think about your house, do you keep all the lights on ALL the time in every room??
Gene expression is a regulated process where genes can be turned on and off as needed due to environmental factors.

38. In summary… DNA contains the information needed to make proteins.
However, DNA is too large to leave the nucleus.
RNA carries instructions to ribosomes so they can make proteins.
Gene expression is a regulated process.