1. Protein Synthesis
Transcription

2. Transcription
Producing an mRNA (messenger RNA) molecule from DNA template
Occurs in nucleus
There are 3 steps to transcription:

3. 1) Unzipping of DNA
DNA helicase breaks the hydrogen bonds between the bases of specific section

4. 2. Complimentary base pairing (cbp)
RNA nucleotides bind with DNA nucleotides by cbp on ONE of the DNA strands
RNA polymerase catalyzes this rxn

5. 3) Joining of adjacent nucleotides
Hydrogen Bonds
The sugar from one nucleotide bonds with the phosphate of the next, making a single stranded mRNA chain
Done by enzyme RNA ligase

6. Before mRNA leaves the nucleus
When the mRNA molecule is created, there are 2 sections of the molecule, INTRONS and EXONS.
Exons = the code that is useful for transcripting into proteins
Introns = are not useful
An enzyme splices the introns, puts together the useful sections (exons)

7. Splicing of mRNA

8. Coding on mRNA
Genetic code is read by the order of the bases on the mRNA
These bases are read in groups of 3 and are called CODONS
Each codon codes for a specific amino acid

9. There are 43 ( = 64) codons possible --> therefore there are easily enough codons to code for all the necessary amino acids.
The same amino acid is often specified by more than one codon. However, the reverse is never true.
that is, any one codon only specifies ONE amino acid
Do not need to write!!

10. Example of codons and aa’s
Codon CCU codes for the amino acid =
Proline
There is a special start codon
AUG (with aa methionine)
There are special stop codons
UAA, UAG, UGA (do not have aa’s)
This code is read and translated into polypeptide/protein at the ribosome (rRNA) with the help of a third type of RNA, transfer RNA (tRNA)

11. Done 1st half of protein synthesis! Now review!
YAY!!!

13. Which of the following occurs during complementary base pairing?
A. Bonds form between uracil and thymine.
B. Bonds form between cytosine and guanine.
C. Bonds break between phosphates and sugars.
D. Bonds break between amino acids and phosphates.

14. Which of the following is produced as a result of replication?
A. DNA
B. protein
C. mRNA
D. ribosomes

15. In which of the following are both helicase and DNA polymerase active
In which of the following are both helicase and DNA polymerase active? A. X only B. Y only C. Z only D. X and Z

16. The sequence of bases in one strand of a DNA molecule is C C G T A C
The sequence of bases in one strand of a DNA molecule is C C G T A C. Which of the following represents the sequence of bases that attach to this strand during replication?
A. G G C A T G
B. G G C U T G
C. C C G T AC
D. G G C A U G

17. One structural difference between DNA and tRNA is that
A. DNA has uracil and tRNA does not.
B. tRNA contains more bases than DNA.
C. DNA contains deoxyribose and tRNA does not.
D. tRNA contains more hydrogen bonds than DNA.

18. Which of the following bonds have formed during this process?
A. W and Y
B. W and Z
C. Y only
D. Z only

19. Woot woot! Now worksheet!