Download Developmental Gene Expression Part II

Warm-Up (1/7)
On the piece of white paper from the back, answer
the following question.
Describe using representations
(model, illustration, diagram, et
cetera) three different
mechanisms cells use to
regulate gene expression.
Name
Date
Period
2E.1b: Induction of transcription factors during development results in
sequential gene expression.
2E.1b.1: Homeotic genes are involved in developmental patterns and
sequences.
2E.1b.2: Embryonic induction in development results in the correct timing of
events.
3B.2b: Signal transmission within and between cells mediates cell function.
Illustrative example: morphogens stimulate cell differentiation and
development.
Gene Regulation During Development
“Waddington’s
Landscape”
Timing and
coordination of TFs
determine embryonic
development
Gene Regulation During Development
For A to
become B ,
blue TF has
to be high
and green TF
has to be low
TF
concentration
time
A
cell type
B
Gene Regulation During Development
For A cells
to become C
cells, red TF
other A cells
must be high,
and green TF
and blue TF
must be low.
TF
concentration
some A cells
time
A
A
cell type
B
C
2E.1b: Induction of transcription factors during development results in
sequential gene expression.
2E.1b.1: Homeotic genes are involved in developmental patterns and
sequences.
2E.1b.2: Embryonic induction in development results in the correct timing of
events.
3B.2b: Signal transmission within and between cells mediates cell function.
Illustrative example: morphogens stimulate cell differentiation and
development.
Development of Insects and Mammals
Mammals
Insects
Different TFs activate
different homeotic genes.
Development of Insects and Mammals
Mammals
Homeotic genes promote
formation of different
body parts.
Insects
How?
Development of Insects and Mammals
Morphogens stimulate different amounts of gene expression.
amount of
morphogen
required
gene A
gene B
morphogen
P 2nd
messenger
gene C
gene D
Development of Insects and Mammals
Morphogens stimulate different amounts of gene expression.
amount of ligand
Gene
expressed
What if this was activated in
the head?
Development of Insects and Mammals
Morphogens stimulate different amounts of gene expression.
Fly with this much
ligand
in the
head.
amount of ligand
Gene
expressed
Fly with this much
ligand
in the
head.
Critical Thinking Question #1
Discuss this question with your partner and write or
represent it. I will call on three people to share their
partners’ answers.
Explain how timing and coordination of gene
expression during development is regulated by cell
signaling.
Critical Thinking Question #2
The development of the
Drosphila (fruit fly) embryo
involves the coordinated
expression of many genes.
The gene bicoid is a
transcriptional repressor of a
second gene, giant, and is
expressed early at the
anterior end of the embryo
during development (see
diagram below). Explain
why it is necessary for bicoid
to be expressed early and
predict the expression
pattern of giant if bicoid
expression was prevented in
an experiment.
Closure
On the piece of white paper from the
back, answer the following question:
How do morphogens affect the
spatial (physical) distribution of
body parts during development?
Name
Date
Period
Scale
1 – 10