1. From Gene to Protein
Chapter 17

2. What you need to know:
The key terms: gene expression, transcription, and translation.
The major events of transcription.
How eukaryotic cells modify RNA after transcription.
The steps to translation.
How point mutations can change the amino acid sequence of a protein.

3. Concept 17.1: Genes specify proteins via transcription and translation

4. _____________________: process by which DNA directs the synthesis of proteins (or RNAs)
Old idea: one ________ - one ____________ hypothesis
Proposed by Beadle & Tatum – mutant mold experiments
Function of a gene = dictate production of specific enzyme
Newer idea: one gene - one ______________ hypothesis
Most accurate: one gene - one ______ molecule (which can be translated into a polypeptide)

5. Flow of genetic information
CENTRAL DOGMA: DNA  RNA  protein
__________________: DNA  RNA
_________________: RNA  protein
____________ = site of translation

6. Flow of Genetic Information in Prokaryotes vs. Eukaryotes

7. one gene = one RNA molecule
DNA
RNA
Nucleic acid composed of nucleotides
___________ -stranded
___________ = sugar
___________
Many different roles!
Nucleic acid composed of nucleotides
___________ -stranded
_____________ = sugar
_____________
Template for individual

8. ________ plays many roles in the cell
_________________=precursor to mRNA, newly transcribed and ____________________
mRNA= the edited version; ______________ the code from DNA that specifies amino acids
tRNA= carries a specific __________________to ribosome based on its ______________ to mRNA codon
rRNA= makes up 60% of the ____________________; site of protein synthesis
snRNA= ___________________RNA; part of a ________________. Has structural and ___________ roles
srpRNA=a signal recognition particle that binds to signal peptides
RNAi= ________________ RNA; a ____________ molecule
ribozyme= RNA molecule that functions as an ___________

9. The Genetic Code
For each gene, one DNA strand is the ___________ strand
mRNA (5’  3’) _____________ to template
mRNA triplets (__________) code for amino acids in polypeptide chain

10. The Genetic Code
64 different codon combinations
_______________: 1+ codons code for each of 20 AAs
Reading frame: groups of ___must be read in correct groupings
This code is universal: __________________
__________________.

11. Concept 17.2: Transcription is the DNA-directed synthesis of RNA

12. Transcription
Transcription unit: stretch of _______ that codes for a ______________ or ________ (eg. tRNA, rRNA)
_______________________________:
Separates _____ strands and _____________ mRNA
mRNA elongates in ___  ___ direction
Uracil (U) replaces thymine (T) when pairing to adenine (A)
Attaches to __________________ (start of gene) and stops at ____________________ (end of gene)

13. 1. Initiation
Bacteria: RNA polymerase binds ___________ to promoter in DNA

14. 1. Initiation Eukaryotes:
___________= DNA sequence (TATAAAA) _____________ from promoter
_______________ _____________ must recognize TATA box before RNA polymerase can bind to DNA promoter

15. 2. Elongation
__________________adds RNA nucleotides to the ____ end of the growing chain (A-U, G-C)

16. 2. Elongation
As RNA polymerase moves, it untwists DNA, then rewinds it after mRNA is made

17. 3. Termination
RNA polymerase transcribes a _________________ sequence in DNA, then mRNA and polymerase detach.
It is now called __________________ for eukaryotes.
__________________ = mRNA ready for use

18. Flow of Genetic Information in Prokaryotes vs. Eukaryotes

19. Concept 17.3: Eukaryotic cells modify RNA after transcription

20. Additions to pre-mRNA:
____________ (modified guanine) and 3’ _____________( A’s) are added
Help __________from nucleus, protect from enzyme ____________, attach to _____________

21. RNA Splicing
Pre-mRNA has introns (____________ sequences) and _________________ (codes for amino acids)
______________ = __________ cut out, exons joined together

22. Ribozyme = ______ acts as ___________________
RNA Splicing
small nuclear ribonucleoproteins = snRNPs
snRNP = snRNA + protein
Pronounced “snurps”
Recognize splice sites
snRNPs join with other proteins to form a ________________
Spliceosomes catalyze the process of removing introns and joining exons
Ribozyme = ______ acts as ___________________

23. Why have introns? Some regulate _____ activity
Alternative RNA Splicing: produce different combinations of exons
One gene can make more than one polypeptide!
20,000 genes  100,000 polypeptides

24. Concept 17.4: Translation is the RNA-directed synthesis of a polypeptide

25. Components of Translation
mRNA = _______________
tRNA = ________________
Ribosome = ____ of translation

26. tRNA Transcribed in _____________ __________ to each amino acid
___________ AA to ribosomes
Anticodon: pairs with complementary mRNA _______
Base-pairing rules between 3rd base of codon & anticodon are not as strict. This is called __________________.

27. tRNA
Aminoacyl-tRNA-synthetase: enzyme that binds tRNA to specific amino acid

28. Ribosomes Ribosome = _________ + ___________ made in _________________
__ subunits

29. Ribosomes Active sites: __ site: holds AA to be added
__ site: holds growing polypeptide chain
__ site: _____ site for tRNA

30. Translation: 1. Initiation
__________ subunit binds to start codon (AUG) on mRNA
tRNA carrying Met attaches to ___ site
__________ subunit attaches

31. 2. Elongation ________ over and over
_______ recognition: tRNA anticodon matches codon in A site
________________: tRNA in A site moves to P site; tRNA in P site moves to E site (then exits)
_________________ formation: AA in A site forms bond with peptide in P site

32. 3.Termination ___________ codon reached and translation stops
Release factor binds to stop codon; polypeptide is released
Ribosomal subunits dissociate

33. Polyribosomes
A single mRNA can be translated by ___________ ribosomes at the same time

34. Protein Folding
During synthesis, polypeptide chain coils and folds spontaneously
_________________________: protein that helps polypeptide fold correctly

35. Types of Ribosomes
________ ribosomes: synthesize proteins that ___________________________ and function there
__________ ribosomes (to ER): make proteins of _____________________ ____________ (nuclear envelope, ER, Golgi, lysosomes, vacuoles, plasma membrane) & proteins for ______________
Uses ______________ peptide to target location

36. Cellular “Zip Codes”
Signal peptide: 20 AA at leading end of polypeptide determines destination
Signal-recognition particle (SRP): brings ribosome to ER

37. Concept 17.5: Point mutations can affect protein structure and function

38. The Central Dogma ________________ happen here _________________
play out here

39. Mutations = changes in the genetic material of a cell
Large scale mutations: _________________; always cause disorders or death
_______________, _______________, inversions, duplications, large deletions
Point mutations: alter _________________of a gene
Base-pair _________________ – replace 1 with another
____________________: _________________ amino acid
____________________: ______ codon, not amino acid
________________________ – mRNA read incorrectly; _____________________ proteins
Caused by _________________ or __________________

40. Substitution = __________________

41. Substitution = _______________________

42. Substitution = _____________ (no effect)

43. Insertion = _________________ Mutation

44. ______________ = Extensive missense, premature termination

45. Pulmonary hypertension
Sickle Cell Disease
Symptoms
Anemia
Pain
Frequent infections
Delayed growth
Stroke
Pulmonary hypertension
Organ damage
Blindness
Jaundice
gallstones
Caused by a genetic defect
Carried by 5% of humans
Carried by up to 25% in some regions of Africa
Life expectancy
42 in males 48 in females

46. Sickle-Cell Disease = Point Mutation

47. Mutation occurs in the beta chain – have them look at their amino acid structures and think about why the change may be important

48. Sickle cell hemoglobin forms long, inflexible chains

50. Comparison: Prokaryotes vs. Eukaryotes

51. Prokaryote vs. Eukaryote

52. Prokaryotes vs. Eukaryotes
Transcription and translation ______ in ____________
DNA/RNA in __________
RNA polymerase binds __________ to promoter
Transcription makes ______ (not processed)
No ___________
Transcription in ________; translation in ___________
______ in nucleus, ______ travels in/out nucleus
RNA polymerase binds to _____________ & ______________ factors
Transcription makes ____- mRNA  _____________  final mRNA
Exons; introns (_________)

53. A Summary of Protein Synthesis (p. 348)
Most current definition for a gene: A region of DNA whose final product is either a polypeptide or an RNA molecule