Transcript Levels of Organization

• Zygote: fertilized cell
created by the union of
the egg and sperm
• Zygote divides into
Embryonic stem cells
23
chromosomes
– Potential to become
any type of cell
Egg Cell
• Average human:
– 100 trillion cells
– Over 200 types of
human cells
23
chromosomes
Embryonic Stem cells
zygote
Stem cell controversy
• Stem cells are being used in research to help treat various diseases… so
why is this controversial?
If someone has brain damage… stem cells can be grown into new brain cells to
help the person recover.
Stem cell controversy
• Stem cells are being used in research to help treat various diseases… so
why is this controversial?
If someone has muscle damage… stem cells can be grown into new
muscle cells to help the person recover.
Stem cell controversy
• Stem cells are being used in research to help treat various diseases… so
why is this controversial?
If someone is blind… stem cells can be grown into new eye cells to help the
person recover.
Stem cell controversy
• Stem cells are being used in research to help treat various diseases… so
why is this controversial?
• Where do stem cells come from?
– When couples seek help to create a child, many eggs and sperm are
collected and mixed together to create many embryos
– Embryos are implanted into the woman, where hopefully they will grow
into a baby
– Stem cells are obtained from left over 4-5 day embryos
• Why controversial?
– Reason: Embryo is destroyed in the process of obtaining the stem cells
– Argument: Some claim this kills a human life
– Counter Argument: These leftover embryos will soon be discarded as
medical waste
• The Myth:
– When a woman gets an abortion, she can donate the dead embryo to
stem cell research.
Determination
• Determination
– Few weeks into
development
– Genes program
the stem cell to
become a
specific cell
– Irreversible
Lump of stem cells
Differentiation
• Differentiation
– Cells acquire the
structures &
functions of a
specialized cell
– Specific genes
activated
Some stem cells become…
Differentiation
• Differentiation
– Cells acquire the
structures &
functions of a
specialized cell
– Specific genes
activated
Other stem cells become…
Differentiation
• Differentiation
– Cells acquire the
structures &
functions of a
specialized cell
– Specific genes
activated
And other stem cells
become…
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 (soon to be muscle cell)
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G
These
If
theselight
cellsswitches
have theare
same
symbolic
DNA, of
how
thewill
genes
the top
inside
celleach
know
to become
stem
cell. a muscle cell?
Stem cell (soon to be nerve cell)
Gene A
Gene B
Gene C
Gene D
Gene E
Gene F
Gene G
Stem cell (soon to be muscle cell)
Gene A
ON
ON
Gene B
Gene C
ON
Gene D
Gene E
Gene F
Gene G
The proteins created in the top cell will cause the stem cell to become a
muscle cell….
During “differentiation”, certain genes are activated in
What do genes direct cells to create?
some
cells,created
but deactivated
in others.
The
proteins
in the bottom cell
will cause the stem cell to
become a nerve cell.
Stem cell (soon to be nerve cell)
ON
ON
Gene A
Gene B
Gene C
ON
Gene D
Gene E
Gene F
Gene G
Differentiation
Brain cells
• Differentiation
– Cells acquire the
structures &
functions of a
specialized cell
– Specific genes
activated
Muscle
cells
Pancreas cells
Skin cells
Programmed cell death (apoptosis)
between the fingers & toes
Incomplete Apoptosis
(Webbed Toes)
• Cell: Basic unit
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
Muscle Tissue
• Contracting cells
• Skeletal, cardiac cells
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
Connective Tissue
• Support the body
• Bone, fat, tendons
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
Ligaments connect
your femur (thigh
bone)…
to your tibia (shin
bone)
Connective Tissue
• Support the body
• Bone, fat, tendons
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
Connective Tissue
• Support the body
• Bone, fat, tendons
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
Epithelial Tissue
• protective sheet of cells
• skin, stomach lining
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
Nerve Tissue
• Transmit electric signals
• Brain & Spinal Cord
• Cell: Basic unit
• Tissue: Group of cells
– 4 types
• Organ: Groups of
tissue
– Ex: lung contains
each tissue
• 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
– Respiratory System
• 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
– Respiratory System
• 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
– Respiratory System
• 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
– Respiratory System
• Organism: all organ
systems working
together
YouTube Review: Levels of Organization
Review
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?