Transcript LB145-lecture16

So... why are you here?
Announcements
•
REU: Summer research in Malibu with pay $
•
Prof Peter Smith on Thursday, I’m traveling to
a CF research conference.
•
Exam II available for 7 days so far (since
Tuesday) and due in 20 days, Nov 21st
•
SALG feedback expires tonight, ec 2 points.
•
Textbook Reading: today you were to read 7
pages on Translation, take notes, study them
Our goals are not achieved by only reading or
listening to a lecturer—you must actively do
things in order to learn (Bio or Kung Fu)
QuickTime™ and a
decompressor
are needed to see this picture.
last night’s homework
(why do we have homework?)
1. Why does your textbook keeping saying "ribosome
structure reflects its function"? What does that mean? Give
examples.
2. Which pages of today's reading are predominately
"review" of what we've discussed already weeks ago in
class (and that you drew on the poster in your room)? [list
page numbers]
3. What is *one* example of something in this reading that
sounded really new to you, that you don't recall us
discussing/learning about previously in LB145?
7
last night’s homework
(why do we have homework?)
1. Why does your textbook keeping saying "ribosome
structure reflects its function"? What does that mean? Give
examples.
2. Which pages of today's reading are predominately
"review" of what we've discussed already weeks ago in
class (and that you drew on the poster in your room)? [list
page numbers]
3. What is *one* example of something in this reading that
sounded really new to you, that you don't recall us
discussing/learning about previously in LB145?
8
last night’s homework
(why do we have homework?)
1. Why does your textbook keeping saying "ribosome
structure reflects its function"? What does that mean? Give
examples.
2. Which pages of today's reading are predominately
"review" of what we've discussed already weeks ago in
class (and that you drew on the poster in your room)? [list
page numbers]
3. What is *one* example of something in this reading that
sounded really new to you, that you don't recall us
discussing/learning about previously in LB145?
9
Ribosome
mRNA
Signal
peptide
Signal
peptide
removed
Signalrecognition
particle (SRP)
CYTOSOL
ER LUMEN
SRP
receptor
protein
Translocation
complex
ER
membrane
Protein
last night’s homework
(why do we have homework?)
1. Why does your textbook keeping saying "ribosome
structure reflects its function"? What does that mean? Give
examples.
2. Which pages of today's reading are predominately
"review" of what we've discussed already weeks ago in
class (and that you drew on the poster in your room)? [list
page numbers]
3. What is *one* example of something in this reading that
sounded really new to you, that you don't recall us
discussing/learning about previously in LB145?
12
last night’s homework
(why do we have homework?)
1. Why does your textbook keeping saying "ribosome
structure reflects its function"? What does that mean? Give
examples.
2. Which pages of today's reading are predominately
"review" of what we've discussed already weeks ago in
class (and that you drew on the poster in your room)? [list
page numbers]
3. What is *one* example of something in this reading that
sounded really new to you, that you don't recall us
discussing/learning about previously in LB145?
13
DNA
TRANSCRIPTION
3
5 RNA
transcript
RNA PROCESSING
RNA
polymerase
Exon
RNA transcript
(pre-mRNA)
Intron
Aminoacyl-tRNA
synthetase
NUCLEUS
Amino
acid
CYTOPLASM
AMINO ACID ACTIVATION
tRNA
mRNA
Growing
polypeptide
3
A
Activated
amino acid
P
E
Ribosomal
subunits
5
TRANSLATION
E
A
Codon
Ribosome
Anticodon
Why should I care?
• What real use is such a detailed
understanding of how the process of
Transcription or Translation works?
1.
siRNAs
(small interfering,
silencing)
miRNAs
(micro)
RNA interference (RNAi)
2. Design and testing of antibiotics
Azithromycin
Zyvox (MRSA)
methicillin-resistant Staphylococcus aureus (MRSA)
vancomycin-resistant Enterococcus faecium (VRE)
Test your knowledge
• Identify the best
answer
Which of the following is NOT true of a codon?
A. It consists of three nucleotides.
B. It may code for the same amino acid as
another codon.
C. It never codes for more than one amino acid.
D. It extends from one end of a tRNA molecule.
E. It is the basic unit of the genetic code.
Which of the mutations would be most likely to
have a harmful effect on an organism?
A. a base-pair substitution
B. a deletion of three nucleotides near the middle
of a gene
C. a single nucleotide deletion in middle of intron
D. a single nucleotide deletion near the end of the
coding sequence
E. a single nucleotide insertion downstream of, and
close to, the start of the coding sequence
Translation: 3 parts
•
•
•
Language (AUG!)
Translators (tRNA & synth)
Factory (Ribosome
subunits)
Language (AUG!)
What words are hidden in this sentence?
UUAAG
I AUG I GGG I UAU I AAG I UCA I ACC I UU
UUAAGAUGGGGUAUAAGUCAACCUUGA
What additional information do you need?
?????????? I THE I RED I DOG I ATE I THE I CAT I STOP
Frameshift mutation (delete E in RED)
?????????? I THE I RDD I OGA I TET I HEC I ATS I TOP
Translators (tRNA & synth)
•
•
tRNA is a translator/transfers amino
acids (Multiple types of RNA)
Aminoacyl-tRNA Synthetase (Charging
enzyme loads aas on tRNAs)
Charging Enzymes (aminoacyl tRNA synthetases)
QuickTime™ and a
Animation decompressor
are needed to see this picture.
Factory (Ribosome subunits)
•
•
•
Small and large subunits (mix of
protein & rRNA)
Large subunit contains different
chambers (P-peptide, A-amino acid, Eexit)
Phases: Initiation, Elongation (3
steps), and Termination
Initiation
3U A C 5
5A U G 3
Initiator
tRNA
Large
ribosomal
subunit
P site
GTP GDP
E
mRNA
5
Start codon
mRNA binding site
3
Small
ribosomal
subunit
5
A
3
Translation initiation complex
Amino end
of polypeptide
E
3
mRNA
5
P
A
site site
Elongation
1. Codon recognition
Amino end
of polypeptide
E
5
1. Codon recognition
3
mRNA
P A
site site
GTP
GDP
Elongation
E
P A
2. Bond formation
Fig. 17-18-3
Amino end
of polypeptide
E
5
1. Codon recognition
3
mRNA
P A
site site
GTP
GDP
Elongation
E
P A
E
2. Bond formation
P A
Fig. 17-18-4
Amino end
of polypeptide
E
Ribosome ready for
next aminoacyl tRNA
5
1. Codon recognition
3
mRNA
P A
site site
GTP
GDP
Elongation
E
P A
E
P A
GDP
GTP
3. Translocation
E
2. Bond formation
P A
Termination
Release
factor
3
5
Stop codon
(UAG, UAA, or UGA)
Termination
Release
factor
Free
polypeptide
3
5
5
Stop codon
(UAG, UAA, or UGA)
3
2 GTP
2 GDP
Termination
Release
factor
Free
polypeptide
5
3
5
5
Stop codon
(UAG, UAA, or UGA)
3
2 GTP
2 GDP
3
Translation steps