1. Protein Synthesis

2. RNA carries DNA’s instructions.
Information flows in one direction from to to .

3. Protein Synthesis involves 2 processes:
replication
transcription
translation
RNA is a link between DNA and proteins.

4. 3.5.1 – Compare the structure of RNA and DNA.
RNA differs from DNA in three major ways.
Sugar:
RNA has a
DNA has a
Bases:
RNA has instead of
Number of strands:
RNA is
DNA is

5. Three types of RNA messenger RNA (mRNA) –
mRNA nucleotides are read in groups of three called
each codon codes for a

6. mRNA

7. Three types of RNA
transfer RNA (tRNA) –
Each tRNA carries a specific type of amino acid
Each tRNA can (sequence of three bases that associates with the codon by base pairing)

8. If the mRNA codon was AUG, what would the anticodon be?
tRNA
If the mRNA codon was AUG, what would the anticodon be?

9. Three types of RNA
ribosomal RNA (rRNA) –

10. Overview of Protein Synthesis
During transcription, one DNA strand, (template strand), provides a template for making an mRNA molecule.
Complementary mRNA molecule is made using base-pairing rules, except uracil pairs with adenine.
If the DNA template was ATG, which mRNA bases would pair with it?

11. Overview of Protein Synthesis
During translation, blocks of three nucleotides (codons) are decoded into a sequence of amino acids.

12. Transcription is catalyzed by
3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase
Transcription
Takes place in the
Copies
Transcription is catalyzed by
start site
nucleotides
RNA polymerase

13. RNA polymerase moves along the DNA
3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase
Nucleotides pair with one strand of the DNA.
RNA polymerase
The DNA helix winds again as the gene is transcribed.
DNA
RNA polymerase moves along the DNA

14. Ex. mRNA is a complementary copy of DNA – travels out of nucleus to
3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase
mRNA is a complementary copy of DNA – travels out of nucleus to
Ex.
DNA A T C C G G A A T C G G T A A A T T
mRNA

15. The mRNA strand detaches from the DNA once the gene is transcribed
3.5.2 – Outline DNA transcription in terms of the formation of an RNA strand complementary to the DNA strand by RNA polymerase
The mRNA strand detaches from the DNA once the gene is transcribed
RNA

16. 3.5.4 – Explain the process of translation leading to polypeptide formation
Transfer RNA (tRNA) transfers amino acids from the cytoplasm’s pool to a ribosome.
The ribosome

18. Amino acids are coded by Translation
3.5.3 – Describe the genetic code in terms of codons composed of triplets of bases.
Amino acids are coded by
Translation
A is a sequence of three nucleotides on mRNA that codes for a particular amino acid
codon for
methionine (Met)
leucine (Leu)

19. Regardless of the organism,
3.5.4 – Explain the process of translation leading to polypeptide formation
Amino acids are put in a specific order to – the order of the amino acids is determined by the
Regardless of the organism,

20. Ribosomes consist of two subunits.
3.5.4 – Explain the process of translation leading to polypeptide formation
Ribosomes consist of two subunits.
The large subunit has
The small subunit

21. How does the ribosome “read” and translate the mRNA?
3.5.4 – Explain the process of translation leading to polypeptide formation
How does the ribosome “read” and translate the mRNA?
Step1:
A special initiator tRNA attaches to the
The large subunit of the ribosome closes over the tRNA
In all organisms, protein synthesis begins with the codon (codes for )

22. Step 2:
The polypeptide chain grows as new tRNA molecules move into position by complementary base pairing of their anticodon with the next codon on the mRNA

23. Ribosome links amino acids together by
Translation continues until ribosome reaches a
Codons that do not code for an amino acid
Indicates that

24. The genetic code matches each codon to its amino acid
The genetic code is (redundant)
More than one codon codes for
CODON AMINO ACID
AGU
AGC
GGU

26. Exceptions…are all protein made of one polypeptide???
3.5.5 – Discuss the relationship between one gene and one polypeptide
The genetic code – the sequence of nucleotides in DNA – is ultimately translated into the sequence of amino acids in proteins – gene expression
In general, (can be structural or enzymatic) – one-gene, one-protein hypothesis
Exceptions…are all protein made of one polypeptide???