Transcript Control of Gene Expression (PowerPoint) Madison 2009

The local police have recovered these three body parts from two
backyards in Madison.
Break into your groups and answer the following questions:
- How many people are dead?
- How could you find out?
- What assumptions have you made?
Hair was also found at each of the sites where body parts were found,
and the police have a male person of interest in the case. To get a
DNA sample for forensic testing from this person, the police need a
tissue sample. Which of the following should they use?
A. A cheek cell sample
B. A blood sample
C A hair sample
D. A semen sample.
E. It doesn’t matter.
The DNA testing revealed that all three organs came from the same
individual. Yet these three organs are obviously different.
In what ways are they different?
Given the following choices, which best describes a difference between them
a. DNA & RNA
b. RNA & protein
c. Only proteins
d. DNA & protein
e. None of the above
Gene Expression Teachable Unit
Title - Introductory module on control of gene expression
Context
Introductory-level biology course.
Students' Prior Knowledge
- DNA replication (& cell division)
- Central dogma
- Methods for determining DNA content of cells (restriction fragment length
polymorphisms, Southern blotting)
Learning Goals & Outcomes
1) Students will understand that all somatic cell types have identical
genomes but different proteins, and this can lead to dramatic differences
in morphology and function.
a) Students will be able to describe a method to show that the DNA content of
different cell types is identical.
b) Students will be able to explain why an individual cell can produce an entire
organism
2) Students will understand how mechanisms of transcriptional regulation
lead to differential gene expression and thus to differences in cell
function. Students will be able to:
a) describe how genes are transcribed;
b) compare & contrast the roles of promoter and other DNA regulatory
elements in control of transcription
c) predict the effects of alterations to these regulatory elements on transcription
d) explain how differences in regulatory factors interacting with these elements
leads to differing expression in different cell types or environments
e) compare & contrast the suite of trans-acting regulatory factors found in
different cell types
f) explain how variability in consensus sequences can determine the rate of
transcription;
g) explain how multi-component protein factors can be variably composed
and thus affect gene expression.
3) Students will understand that the plasticity of gene expression involves
both cell-to-cell differences and individual cell variability as a function of
environmental conditions. Students will be able to:
a) Interpret gene expression data from different cell types or environments
b) Diagram the shift in transcription that happens in different growth media
Crosscutting Themes
4) Students will be familiar with the experimental evidence for this knowledge.
5) Students will understand the conditional nature of science.
6) Students will be able to tolerate uncertainty in scientific knowledge.
Are you, or do you know someone,
who is lactose intolerant?
A = yes
B = no
C = I don’t know
Is lactose intolerance normal,
or a disease?
A = normal
B = disease
Minilecture/discussion - lactose, lactase,
physiology, persistence (ethnography?)
Group work
Now that you know something about
lactose and it’s digestion, propose as
many biological mechanisms as you can
for why lactose tolerance disappears in
some people.
The Human Lactase Gene
exons
promoter
x
Chromosome 2
Location of lactase
persistence mutations
This diagram shows where mutations resulting in lactase persistence are found.
Propose a plausible mechanism for how a mutation at this site leads to
persistence of lactose tolerance.
Summative assessment
On chromosome #9, gene Y is turned on in liver
cells. On chromosome #22, gene Z is turned
on in heart cells. In the human syndrome
Ickiosis, a segment of chromosome #22
containing gene Z is translocated onto
chromosome #9. This translocation places
the Z gene coding region, without its
promoter, directly downstream of gene Y.
Make a prediction as to where gene Z is
expressed in people with Ickiosis and explain
why.