1. The Ribosome
Is part of the cellular machinery for translation, polypeptide synthesis
Figure 17.1

2. Evidence from the Study of Metabolic Defects
In 1909, British physician Archibald Garrod
Was the first to suggest that genes dictate phenotypes through enzymes that catalyze specific chemical reactions in the cell

3. Nutritional Mutants in Neurospora: Scientific Inquiry
Beadle and Tatum causes bread mold to mutate with X-rays
Creating mutants that could not survive on minimal medium; each mutant was defective in a single gene supporting the one gene-one enzyme hypothesis

4. Overview: the roles of transcription and translation in the flow of genetic information
No mRNA
processing

5. Question:
How does RNA (ribonucleic acid) differ from DNA (deoxyribonucleic acid)?

6. RNA DNA RNA ribose sugar Nitrogenous bases: single stranded
uracil instead of thymine
U : A
C : G
single stranded
lots of RNAs
mRNA, tRNA, rRNA
transcription
DNA
RNA

7. The triplet code

8. The “Central Dogma” DNA RNA protein
flow of genetic information within a cell
transcription
translation
DNA
RNA
protein
replication

9. The dictionary of the genetic code

10. The stages of transcription: initiation, elongation, and termination

11. The initiation of transcription at a eukaryotic promoter

12. RNA processing; addition of the 5 cap and poly(A) tail

13. RNA processing; addition of the 5 cap and poly(A) tail

14. The function of the cap is:
prevent mRNA degradation by hydrolytic enzymes
helps attach to the ribosome
Function of the 3’ tail:
same functions as the 5’cap
also helps facilitate export of mRNA from nucleus

15. RNA processing: RNA splicing

16. The roles of snRNPs and spliceosomes in mRNA splicing

17. RNA Splicing Removes noncoding regions called introns
snRNPs (small nuclear ribonucleoproteins) recognize the splicing signals that are at the ends of introns
The RNA in the snRNP is called snRNA (small nuclear RNA)
spliceosomes are the larger protein assemblies formed by the joining of snRNPs

18. Correspondence between exons and protein domains

19. The structure of transfer RNA (tRNA)

20. The structure of transfer RNA (tRNA)

21. Translation: the basic concept

22. An aminoacyl-tRNA synthetase joins a specific amino acid to a tRNA

23. The anatomy of a functioning ribosome

24. The initiation of translation

25. The elongation cycle of translation

26. The termination of translation

27. Peptide Bonds Join Amino Acids

28. Polyribosomes

29. Coupled transcription and translation in bacteria

30. The signal mechanism for targeting proteins to the ER

31. The polypeptides of proteins destined for the endomembrane system are marked by a signal peptide, which targets the protein to the ER.
A signal recognition particle (SRP)
functions as an adaptor that brings
the ribosome to a receptor protein
built into the ER membrane.

32. Mutations – a change in the
genetic material; most are
neutral and have little effect on expression of genes.

33. Point Mutations – occur at
a single point in a DNA sequence
A Frameshift Mutation changes the “reading frame”
of the genetic message.

34. Categories and Consequences of Point Mutations: Base-Pair Substitution

35. The molecular basis of sickle-cell disease: a point mutation

36. The Primary Structure of a Protein

37. Categories and consequences of point mutations: Base-pair insertion or deletion

38. A summary of transcription and translation in a eukaryotic cell

39. The ___________ on tRNA
is complementary to the
___________ on mRNA.

40. Distinguish between a frameshift mutation and a point mutation.
How could a Frameshift
Mutation lead to Missense or
Nonsense codons?

41. Protein Synthesis Animations:
DNA and RNA Structure:
Processing of Gene Information (Prokaryotes vs Eukaryotes):
RNA Splicing:
How Splicesomes Process RNA:
Transcription:
Translation:
Translation Elongation:
Translation Termination:

42. What is the difference
between a mutagen and
a carcinogen?
What is the role of the
signal-recognition particle?

43. Distinguish between the roles
of each of the three sites
located within the ribosome.

44. List three major differences
between the transcription
process in prokaryotes vs.
eukaryotes.

45. Every three bases on mRNA is called a/an _______ and codes for
If a DNA sequence reads A-T-T-C-G-C what are the complementary mRNA and tRNA sequences?
RNA Polymerase attaches to the DNA strand and starts reading the bases at an area called the:
Every three bases on mRNA is called a/an _______ and codes for
a specific __________ __________.

46. Transcription
DNA mRNA
A U
T A
G C
C G
Translation
mRNA tRNA
A U
U A
G C
C G

47. Transcription takes place in
the _______ of the cell when
mRNA copies the _____
strand.
Translation takes place in the
_______ of the cell when tRNA copies the _______ strand at the __________.