Levels of Organization

Cell Specialization 23 chromosomes Zygote: fertilized cell created by the union of the egg and sperm Zygote divides into Embryonic stem cells Potential to become any type of cell Average human: 100 trillion cells Over 200 types of human cells Egg Cell 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? Do your brain cells have the same DNA as your liver cells? 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 If these cells have the same DNA, how will the top cell know to become a muscle cell? These light switches are symbolic of the genes inside each stem 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 Gene B Gene C 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…. The proteins created in the bottom cell will cause the stem cell to become a nerve cell. During “differentiation”, certain genes are activated in some cells, but deactivated in others. What do genes direct cells to create? Stem cell (soon to be nerve cell) ON ON ON Gene A Gene B Gene C Gene D Gene E Gene F Gene G

Differentiation 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)

Organization Cell: Basic unit

Organization Muscle Tissue Contracting cells Skeletal, cardiac cells Cell: Basic unit Tissue: Group of cells 4 types

Organization Connective Tissue Support the body Bone, fat, tendons Cell: Basic unit Tissue: Group of cells 4 types

Organization 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)

Organization Connective Tissue Support the body Bone, fat, tendons Cell: Basic unit Tissue: Group of cells 4 types

Organization Epithelial Tissue protective sheet of cells skin, stomach lining Cell: Basic unit Tissue: Group of cells 4 types

Organization Nerve Tissue Transmit electric signals Brain & Spinal Cord Cell: Basic unit Tissue: Group of cells 4 types

Organization Cell: Basic unit Tissue: Group of cells 4 types Organ: Groups of tissue Ex: lung contains each tissue

Organization 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

Organization 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

Organization 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

Organization 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 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 ______. From smallest to largest, name the 5 levels of organization. Name the four types of tissues. Which tissue is able to stretch and contract? Which tissue transmits electric signals? Which tissue covers and protects the body? Which tissue connects the body?