Transcript Biology Today Third Edition

Eli Minkoff • Pam Baker
Biology Today
Third Edition
Chapter 12
Stem Cells, Cell Division, and Cancer
Copyright © 2004 by Garland Science
We are multicellular
(many cells)
Cells are organized into tissues
Tissues are organized into organs
Organs are organized into organ systems
We are multicellular
(many cells)
tissue
- group of cells working together
organ
- group of tissues
“
“
organ - group of organs
system
“
“
Where did these come from?
Figure 12.8b
lots of cells
Figure 12.8b
doing lots of different things…
integration
and
cooperation
homeostasis
cell number
cell division (mitosis)
closely regulated in normal cells
cell cycle
Figure 12.2
factors controlling cell division
1. room to grow
2. signals to grow
3. attachment to surface
factors controlling cell division
1. room
2. signals
3. attachment
contact inhibition
growth factors
Figure 12.14
Figure 12.3
Figure 12.14
Figure 12.4 (1)
attachment
Cancer cells show the
ability to divide without
being attached
Figure 12.4 (2)
genes control cell division
gene expression
transcription
translation
remember chapter 2?
genes control cell division
gene expression is regulated
1. promoter sequences
2. enhancers & repressors
3. repressor inhibitors
Figure 12.5
Figure 12.6
genes control cell division
gene expression is regulated
1. promoter sequences
2. enhancers & repressors
3. repressor inhibitors
limits to cell division
internal clock
telomere
(end-)
telomere
loses nucleotides each division
when enough are lost,
cell division is finished
Figure 12.7
telomere
loses nucleotides each division
bacteria
and
gametes
have telomerase
telomere
loses nucleotides each division
bacteria
have telomerase
and
gametes
and
cancer cells
There are controls on cell division
attachment, contact inhibition
genetic regulation
telomeres
A mistake in any of them could lead
to uncontrolled cell growth
eight cell stage (mammal)
each cell can become
complete organism
embryonic stem cells
Figure 12.8b
?
Are the cells losing the ability to
become “everything?”
Figure 12.9
specialized cells retain their full
set of genetic information
Stem Cells
What are they?
Fig. 12-13
1. undifferentiated
4. replace
themselves
2. can divide
3. and differentiate
Stem Cells
Embryonic …human cell lines
first made in 1998
Adult
…like bone marrow
…can be induced
to become lots of
different tissues
Cloning
What is it?
….asexual reproduction of
a group of genetically
identical organisms (cells).
Cloning
Why do it?
Cloning
Two types:
theraputic
reproductive
Cloning
theraputic
grow cells to avoid
transplantation problems
Cloning
reproductive
Dolly (the sheep)
calves, cats, mice, dogs
humans?
Cloning
Ethical questions?
When is an embryo “human”?
Who “owns” embryos?
Normal development
controlled cell division
controlled differentiation
What if these controls are lost?
CANCER
normal
cell
transformation
unregulated
cell
(changes in the DNA)
(occur during cell division)
Figure 12.14
Oncogenes
genes that cause transformation (cancer).
Proto-oncogenes
genes controlling normal cell growth
Tumor suppressor genes
p53
normal p53 represses cell division
and kills cells when they are abnormal
Figure 12.3
Figure 12.15
Places where
oncogenes may
affect cell
division
(pg. 434, BT3)
damaged genes =
mutations
source ?
DNA replication
typo’s
1/ 1,000,000 nucleotides
(1/ million)
(2 1/2 typos in our textbook)
Most “typo’s” are fixed by
“spell-checker” proteins
Figure 12.16b
Transformation
accumulation of mutations
transformed cells may
form a tumor
tumor types:
benign
contained
localized
removed
malignant
disruptive
invasive…
metastasis
“cause” of cancer
Genetics
Environment
Lifestyle
?
?
?
little change in
gene pool
Fig. 12-18
change in
lifestyle and
environment
REVIEW
Gene expression
•controls normal cell behavior
•carefully regulated
•If damaged….
...may lead to cancer
risk factors:
genetics
some colon cancers
defect in spell-checker protein
a rare eye cancer
defect in cell cycle control gene
some breast cancers
BRCA1
predisposition
(defect in tumor suppressor)
risk factors:
age
Table 12.4
Age specific probabilities of developing breast cancer
AT AGEPROBABILITY OF DEVELOPING BREAST CANCER
IN THE NEXT 10 YEARS
20
30
40
50
60
%
1 IN:
0.04
0.40
1.49
2.54
3.43
2500
250
67
39
29
risk factors:
viruses
20% of cancers worldwide caused by viuses
Kaposi’s sarcoma
liver cancer
AIDS
hepatitis
80% of liver cancers caused by viral infections
cervical cancer
HPV
80% of cancers of genitals and anus caused by PV
also sexual promiscuity
women married to men who have multiple
partners have higher risk of cervical cancer
risk factors:
carcinogens
Physical
Radiation
UV (sun)
Atom bombs
X-ray (high doses)
melanoma
Japan
M. Curie
probably not cell phones, power lines, etc.,…
risk factors:
carcinogens
Chemical
Cigarette smoke
second hand smoke = smoking
Figure 12.20a
Figure 12.20b
risk factors:
carcinogens
Chemical (see table 12.5)
Cigarette smoke
Asbestos
Benzene
Diesel exhaust
Formaldehyde
Painting materials
etc…
risk factors:
diet
ACS:
For the majority of Americans who do
not use tobacco products, dietary
choices and physical activity are the
most important modifiable determinants
of cancer risk.” BT3, pg. 446
risk factors:
diet
Fiber
Fat
good
bad
Industrialized
non-industrialized
(more pollution)
(less pollution)
Iceland
New Zealand
equatorial Africa
U.S.
high fiber/low fat
equatorial
Africa
low fiber/high fat
colon
and
rectal
cancer
U.S.
New Zealand
Iceland
risk factors:
diet
Fiber
Fat
good
bad
Alcohol
very bad
synergism
together-worse than alone
Figure 12.21
risk factors:
individual variation
immune system
weak immunity
hormones
the “pill”
stress, age, …
-more cancer
breast cancer
ovarian cancer
risk factors:
social and economic factors
maybe
treatment
surgery
must be visible to remove it
single cell left behind…recur
usually used along with…
radiation and/or chemotherapy
radiation and/or chemotherapy
cancer cells are dividing…
…if disrupt cell division…
radiation
breaks up DNA beyond repair…
…cells die
chemotherapy
block DNA synthesis,
block RNA synthesis,
block mitosis,…
radiation and/or chemotherapy
both are non-specific…
….hurt/block normal cells too
hair
red blood cells
immune cells
New treatments
chemicals (from plants)
immune system
photodynamic therapy
…
Detection
breast/testicle examine
pap-smear
prostate (PSA, exam)
genetic predisposition (BRCA)
Prevention
smoking
30%
30%
diet
avoid carcinogens
avoid radiation
get regular check-ups
Figure 12.8b