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• Zygote: fertilized cell
created by the union of
the egg and sperm
• Embryonic stem cells
– Created during earliest
divisions
– Potential to become
any type of cell
• Average human:
– 100 trillion cells
– Over 200 types of
human cells
Determination
• Determination
– Stem cell genes
program the
cell to be a
specific type
– Few weeks into
development
– Irreversible
Differentiation
• Differentiation
– Cells acquire the
structures &
functions of a
specialized cell
– Specific genes
activated
Quick Questions
• Do your muscle cells have the same DNA as your skin
cells?
Yes
• Do your skin cells have the same DNA as your brain cells?
Yes
• Do your brain cells have the same DNA as your liver cells?
Yes
• So if all your cells have the same DNA, how do they know
to do different jobs?
Stay tuned for the answer
Stem cell programmed to become a muscle cell
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G
How
the the
top same
cell know
to become
a muscle
cell…and
If theywill
have
genes…how
does
one become
a the
bottom
become
a nerve
cell if they have identical genes?
muscle to
and
the other
a nerve?
Stem cell programmed to become a nerve cell
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G
Stem cell programmed to become a muscle cell
Gene A
ON
ON
Gene B
Gene C
ON
Gene D
Gene E
Gene F
Gene G
Remember that genes tell cells to create proteins. Muscle
During
“differentiation”,
genes
are on the
cells create
different proteins certain
from nerve
cells based
activated
in some
genes that are
active. cells, but deactivated in others.
Stem cell programmed to become a nerve cell
ON
ON
Gene A
Gene B
Gene C
ON
Gene D
Gene E
Gene F
Gene G
Programmed
cell death
(apoptosis)
between the
fingers
Webbed Toes
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
• Organ: Groups of
tissue
– Ex: lung contains
each tissue
• Organ System: Group
of organs working
together
– Digestive System
• Organism: all organ
systems working
together
Epithelial
Tissue
Nerve
Tissue
Muscle
Connective
TissueTissue
•Transmit
protection
sheetsignals
of cells
•
electric
• Contracting
• Support the
cells
body
•Brain
skin, &
stomach
lining
•
Spinal
Cord
• Skeletal,
• Bone, fat,
cardiac
tendons
cells
YouTube Review Video for help
Click here if the video
above does not work.
1)
2)
3)
4)
What is a zygote?
What is the specific function of a stem cell?
How does “determination” differ from “differentiation”?
Cells are programmed to die during a process called
______.
5) From smallest to largest, name the 5 levels of organization.
6) Name the four types of tissues.
7) Which tissue is able to stretch and contract?
8) Which tissue transmits electric signals?
9) Which tissue covers and protects the body?
10) Which tissue connects the body?