Get a learning target sheet from up front 3/9
• I can describe how growth and development are related to cell division, growth, and signaling
• I can describe how cells become specialized for specific functions
Agenda
• Ch 13 Notes 1 • Short Video & Practice activity• Finish Notes 1• Short video & Practice activity
CH 13 Notes #1 Growth & Development
• Multicellular organisms are formed bycell growth, division, and differentiation
Sexual reproduction
• Fertilization: sperm and egg coming together
• When sperm and egg come together they form a zygote
• After fertilization, cell division starts
• Embryo: organism once its made of more than one cell
Cell cycle
• Interphase (90% of the time): cell is not dividingG1 (cell gets bigger)S (DNA replication)G2 (More organelles made, getting ready to
divide)
• Mitosis: cell division
New CellCell division(mitosis)
Cell grows
DNA replication
Cell gets ready to divide
• The cells keep dividing until they make a hollow ball called a blastula
• Gastrulation: cells on the outside start to push in
• Gastrula: hollow ball of cells when cells on the outside start to push inward
• The outside cells start to form the nervous system (brain, nerves, spinal cord)
• After the nervous system starts to form we call it a neurula
Gastrulation Animation
• http://www.youtube.com/watch?v=8v6cXkzlEQA
Foldable
• Label the organism in each of the stages we’ve talked about– Zygote– Embryo– Blastula– Gastrula– Neurula
Developmental stages quiz!
How do cells become specialized (get a specific job)?
• Differentiation: cells becoming specialized (ready to perform a specific job)
• Differentiation happens when cells send chemical signals to each other
• If you move a cell it will become the same type of cell as its new “neighbors” because of these chemical signals
Becomes a nerve cell
Becomes a stomach cell
Becomes a skin cell
Stem Cells
• Stem cells: cells that have not become specialized yet
• Scientists are interested in stem cells because they can be turned into many types of other cells
Uses of stem cells
1. Healing damagedtissues
2. Gene therapy3. Drug research
Stem cell controversy
• One method of researching embryonic stem cells will kill the embryo
• BUT researchers are working to change this
A special case of development
• Metamorphosis: When an organism dramatically changes after birth
Video: Metamorphosis Examples
• Metamorphosis• http://www.teachersdomain.org/asset/tdc02_
vid_metamorph/