Gene and How
They Work
Chapter 15
Topics you are not responsible for:
SRP-RNA
Detailed structure of bacterial and
eukaryotic RNA polymerases, and
tRNAs, ribosomes, and spliceosomes
specific promoter sequences
Alternative splicing
End of Chapter questions:
Understand: all
Apply: all
Synthesize: 1 - 3
Do all mQuiz questions
Gene Structure and Function
1
How is genetic information used?
“Transcription”
of code from DNA to RNA
“Translation”
of code from RNA into A.A. sequence
Gene Structure and Function
2
How are genes arranged on DNA?
Template strand vs complementary strand
What are the functional regions of a gene?
Gene Structure and Function
3
How does RNA transcription occur?
How does RNA polymerase ‘know’ where to begin?
Promoters
-- RNA polymerase binding site
… and gene regulation
How does RNA polymerase ‘know’ where to end?
Gene Structure and Function
4
How does transcription
proceed?
Binding to promoter
Opening of helix
Complementary base-pairing
Concurrent transcription
Transcription
Transcription - 2
Gene Structure and Function
5
What are the functions of RNA?
mRNA
Review Differences
in RNA and DNA
Structures
(Chapter 3)
tRNA
rRNA
(other types, e.g. snRNA, iRNA)
In eukaryotes,
How is mRNA modified before existing the nucleus?
Stabilizing the transcript
5’ capping
3’ poly-A tail
Removal of introns
Gene Structure and Function
6
How are introns
removed?
“RNA processing”
Introns & Exons
“snRNPs” & spliceosomes
Can be many introns
Gene Structure and Function
7
Where does translation occur?
Export to the cytosol
What is the Genetic code?
Codons specify AAs
How many codons?
How many AAs?
-- Redundancy
Starting position
Ending position
Gene Structure and Function
8
Where is translation initiated and terminated?
Start Codons & Stop Codons
What is the
“Reading Frame”?
Gene Structure and Function
9
What is the structure
of ribosomes?
Large and small subunits
rRNA and protein constituents
tRNA binding sites
Model
Gene Structure and Function
10
What is the structure of tRNA?
Anticodons
‘Charging’ of tRNAs
-- aminoacyl tRNA synthestases
Model
Translation video
Gene Structure and Function
11
What are the 3 stages of translation?
Initiation
-- formyl methionine
-- ‘fMet’
Initiation
Elongation
-- elongation factors
Termination
-- release factor
Virtual cell animation
Gene Structure and Function
12
How does the peptide pass between tRNAs
during translation?
New t-RNA enters
at the A-site
Peptide chain on
tRNA in P-site is
passed new t-RNA
Gene Structure and Function
Ribosome translocates
1 codon, and t-RNA
exists from E-site
13
What happens during
translation termination
stage?
Termination
Gene Structure and Function
14
What are effects of different types of mutations on gene
function - I?
What is a “Missense” mutation?
What is a “Nonsense” mutation?
Gene Structure and Function
15
What are effects of different types of mutations on gene
function – II ?
What causes a “Frameshift” mutation?
What is a “Silent” mutation?
Gene Structure and Function
16