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Chapter 11:
• Gene regulation: very brief overview
• Stem cells
• Differentiation
• Examples in plants and animals that every cell has
the genetic potential to become an entire organism.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
BIOLOGY AND SOCIETY:
BABY’S FIRST BANK ACCOUNT
• In recent years umbilical cord and placental blood
has been collected at birth
Figure 11.1
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
FROM EGG TO ORGANISM:
HOW AND WHY GENES ARE REGULATED
• Four of the many
different types of
human cells
– They all share
the same
genome
(a) Three muscle cells (partial)
(b) A nerve cell (partial)
(c) Sperm cells
(d) Blood cells
– What makes
them different?
Figure 11.2
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Patterns of Gene Expression in Differentiated Cells
• In gene expression
– A gene is turned on and transcribed into RNA
– Information flows from genes to proteins, genotype
to phenotype
•The regulation of gene expression plays a central role in
development from a zygote to a multicellular organism
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Patterns of gene
expression in
specialized
human cells
Pancreas
cell
Eye lens cell
(in embryo)
Nerve cell
Glycolysis
enzyme
genes
Crystallin
gene
Insulin
gene
Hemoglobin
gene
Key:
Active
gene
Inactive
gene
Figure 11.3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Warmup:When your started out, you were a single
cell. Your are now made of many cells; some of
these cells function as liver cells, some as muscle
cells, some as red blood cells. What name is
given to the process that is responsible for this?
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1. regeneration 3%
2. carcinogenesis 1%
3. cellular
differentiation 94%
4. morphology
2%
DNA Microarrays: Visualizing Gene Expression
• A DNA
microarray
allows
visualization of
gene expression
1 mRNA
isolated
Reverse transcriptase and
labeled DNA nucleotides
2 cDNA made
from mRNA
3 cDNA
applied to
wells
DNA microarray
(each well contains
DNA from a
particular gene)
4 Unbound cDNA
rinsed away
Fluorescent
spot
Nonfluorescent
spot
cDNA
DNA of gene
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
DNA of gene
Figure 11.4a
• The pattern of glowing spots on a microarray
enables researchers to determine which genes are
turned on or off
Figure 11.4b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Warmup:The process by which genotype becomes
expressed as phenotype is ________________.
1%
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85%
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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recombination
transcription
phenogenesis
gene expression
ph
1.
2.
3.
4.
Warmup: Which of these techniques could tell you
how gene activity differs between individuals
with and without cystic fibrosis?
17%
amniocentesis
X ray crystallography 7%
DNA microassay
58%
Karyotyping
18%
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The Genetic Potential of Cells
• Differentiated cells
– All contain a complete set of DNA
– May act like other cells if their pattern of gene
expression is altered
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
•Differentiated plant cells have the ability to develop into a
whole new organism
Root of
carrot plant
Plantlet
Cell division
in culture
Single cell
Root cells in
growth medium
Adult plant
The somatic cells of a single plant can be placed in a growing
medium to produce clones
Figure 11.5
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Reproductive Cloning of Animals
• Nuclear transplantation
– Involves replacing nuclei of egg cells with nuclei
from differentiated cells
– Has been used to clone a variety of animals
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Scottish researchers cloned the first mammal in
1997
– Dolly, the sheep, was the product of their work
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The procedure that produced Dolly is
called reproductive cloning
Reproductive cloning
Donor
cell
Nucleus from
donor cell
Implant embryo in
surrogate mother
Clone of donor
is born
Therapeutic cloning
Remove
nucleus
from egg
cell
Add somatic
cell from
adult donor
Grow in culture
to produce an
early embryo
Figure 11.6
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Remove
embryonic stem
cells from
embryo and
grow in culture
Induce stem
cells to form
specialized cells
for therapeutic
use
• Other organisms have since been produced using
this technique, some by the pharmaceutical industry
(a) Piglets
(b) Banteng
Figure 11.7
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Can clones occur in nature in mammals?
1. Yes
2. No
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
o
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• Embryonic stem cells
– Can give rise to specific types of differentiated cells
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Liver cells
Cultured
embryonic
stem cells
Nerve cells
Heart muscle cells
Different culture
conditions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Different types of
differentiated cells
Figure 11.8
• Adult stem cells
– Generate replacements for nondividing differentiated
cells
– Are unlike ES cells, because they are partway along
the road to differentiation
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• In 2001, a biotechnology company announced that it
had cloned the first human embryo
Figure 11.9
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Which type of cell has the most potential to
differentiate into the many different cell types?
Embryonic stem cell
Adult stem cell
Somatic cell
Cloned cell
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Should we pursue cloning in all animals except
humans?
1. Yes
2. No
3. Not sure
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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Should we pursue human cloning for the purpose
of developing or performing medical
treatments?
1. Yes
2. No
3. Not sure
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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Is your clicker working?
71%
1. Yes
2. No
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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N
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29%
Which example below provides evidence that every
cell in the body has the potential to make a
whole new organism?
1. DNA microarrays
2. Differential gene
expression
3. Cloning
4. Adult stem cells
68%
32%
D
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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What is therapeutic cloning?
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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2.
Adult stem cells are induced to grow
different types of cells .
Nucleus from an adult cell is used to
make an embryo. The ES cells are
taken from that embryo and induced to
form a specific cell type.
Nucleus from an embryonic stem cell
is used to make an embryo. The ES
cells are taken from that embryo and
induced to form a specific cell type.
Adult stem cells are used to clone an
organism.
Embryonic stem cells are used to
clone an organism.
ar
e
1.
List differences between Adult stem cells and
Embryonic stem cells:
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
THE REGULATION OF GENE EXPRESSION
• How is gene expression
regulated in a cell?
Chromosome
Unpacking of DNA
DNA
Gene
– The metaphor of the
plumbing in a house is
useful
Transcription of
gene
Intron
Exon
RNA transcript
Processing of RNA
Flow of mRNA
through nuclear Cap
Tail
envelope
mRNA in nucleus
mRNA in cytoplasm
Nucleus
Cytoplasm
Translation of
mRNA
Polypeptide
Breakdown
of mRNA
Various changes
to polypeptide
Active protein
Breakdown of
protein
Broken down protein
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 11.10
If the DNA is packed tightly will the gene be expressed?
1. Yes
2. No
67%
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
o
N
Ye
s
33%
If the RNA is degraded quickly
after leaving the nucleus will
the gene be expressed?
72%
1. Yes
2. No
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
o
N
Ye
s
28%
EVOLUTION CONNECTION:
HOMEOTIC GENES
• Homeotic genes
– Are master
control genes
– Regulate many
other genes
– Help direct
embryonic
development in
many organisms
Figure 11.21
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Homeoboxes
– Are sequences of nucleotides common in many
organisms
– Can turn groups of genes on and off during
development
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Fly chromosome
Mouse chromosomes
Fruit fly embryo (10 hours)
Mouse embryo (12 days)
Adult fruit fly
Adult mouse
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 11.22
Warmup: What is the difference between
embryonic and adult stem cells?
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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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2.
The use of embryonic stem cells
raises fewer ethical issues than the
use of adult stem cells.
It is easier to induce
dedifferentiation in adult stem
cells.
Embryonic stem cells are
undifferentited; adult stem cells
are partially differentiated.
Embryonic stem cells are harder
to isolate than are adult stem cells.
Em
br
yo
1.
Warmup: The use of _________________ holds
promise for the treatment of diseases such as
Parkinson's disease.
7%
96%
69%
10%
14%
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
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1. nuclear
transplantation
2. therapeutic cloning
3. reproductive cloning
4. eugenics