Download Operons - Haiku Learning

Prokaryotes vs
Eukaryotes
But first it’s QUIZ TIME!!
Copier is down – deal with it
1. Write the correct mRNA transcript based
on the gene sequence below:
GTA GTA GGT
2. Use your codon chart to determine the
sequence of amino acids dictated by the
gene sequence above.
mRNA
AGA
GGA
AGC
GCA
CAG
Amino Acid
arginine
glycine
serine
alanine
glutamine
3. Which mRNA would code for both amino acid sequences
shown, simply by a shift in the reading frame?
…glutamine…glutamine…glutamine
…serine… serine… serine
A. AGUAGUAGUAGU
C. GCUGCUGCUGCU
B. AGCAGCAGCAGC
D. GCAAGCGCAAGC
Use the amino acid chart from
question #3
…glycine…serine…glycine…
4. Which of the following DNA strands
would code for the amino acid sequence
shown above?
A. ACTCCTTCT
B. TCTCCGTCG
C. CCGTCGACT
D. CCTTCGCCT
#5 and #6
5. An incoming tRNA
would attach to
which site on the
ribosome?
6. If the tRNA
anticodon is UUU,
what amino acid will
it bring to the
growing peptide
chain?
#7 and #8
7. Spliceosomes cut out ______ and splice
together ________ which get expressed.
8. Modifications to the ends of the mRNA
transcript are required before leaving the
nucleus. Which end (3’ or 5’) is modified
with a Poly- A tail?
II. RNA modification
5’ cap chemically speaknig
The movie – yes there is a movie
• http://vcell.ndsu.nodak.edu/animations/mr
naprocessing/movie.htm
Why Cap and Poly- A tail?
• Protect the messenger!
• exonucleases – protect but destroy
• http://en.wikipedia.org/wiki/5'_cap
III Bacteria genetics
• Binary fission
Prokaryotic variation in genetic
make-up
• Mutations
• Genetic recombination
– Transformation
– Transduction
– Conjugation
Transformation
Transduction
Conjugation
IV. Control of metabolic pathways
A. Two ways
1. Vary the activity of the enzymes (inhibit
them or promote their ability) – feedback
inhibition pathways
2. Vary the # of enzymes present – regulate
enzyme production at the gene expression
level
B. Gene regulation in bacteria
• OPERONS!
– Need to know that an operon is a section of
DNA that contains genes for a protein
– Need to know the parts and players
Ex 1 – Lac Operon
Ex 2 Tryptophan operon
A closer look at the parts
• A) promoter – site on DNA where RNA
polymerase can bind and begin
transcription
• B) operator – the “on/off” switch, located
between promoter and structural genes
• C) structural genes – genes that code for
a protein
Important players
• Repressor – a protein that when active will
bind to the operator thus blocking
transcription
• Regulatory gene – the DNA sequence that
codes for the repressor protein
• Co-repressor – a molecule that attaches to
an inactive repressor and makes it active
• Inducer – a molecule that attaches to an
active repressor and makes it inactive
How they work together
• Negative regulation
• Positive regulation
Negative regulation
• Two examples
– Lac operon
– Tryptophan operon – best animation link ever