Name:______OBJ 1.1.3
GENE REGULATION AND CELL SPECIALIZATION NOTES
READ THROUGH EVERYTHING ON THIS SHEET THEN ANSWER THE QUESTIONS THAT FOLLOW
1. Where do cells come from?
Multicellular organisms begin as undifferentiated masses of cells. These cells are known as STEM CELLS.
Two types of STEM CELLS:
1. Embryonic Stem Cells: embryonic cells which have not yet differentiated in to different cell types (form soon after the egg and sperm meet!)
2. Adult Stem Cells: stem cells found in organisms, such as in bone marrow
2. How can different cells perform different functions if all cells have the same genes and DNA?
THE ANSWER! The cells differ based on the expression of the genes in their DNA
Gene expression: An expressed gene is a gene that is ‘turned on’ to create proteins. Those cells that are not expressed remain “silent”
Think of it this way…
Every piano has the same set of keys (just like every cell has the same DNA). However, different songs sound different because of the specific keys that the player chooses to play (just like different cells are able to perform different functions based on the genes that are “chosen” to be expressed.)
3. How does an organism know whether to turn a gene on or off?
There are several ways:
1. Environmental influences -Different genes are expressed depending on the environment of the cell. (A pianist would not chose to play Broadway show tunes in a jazz club)
-Ex. E. coli bacteria in the human stomach
-E. coli feed on lactose (a sugar found in milk)
- When lactose is present in your stomach, certain genes (lac genes) are turned on, or expressed, so the bacteria can digest lactose
-when no lactose is present, those genes remain silent and no proteins are created (because the proteins are not needed)
2. Cell Specialization
-Different genes are expressed depending on the specific job of the cell (adding unnecessary notes in a song ruins the song)
-Ex.: This creates difference types of cells (muscle cells, nerve cells, sperm cells, etc.)
-Ex. Keratin
-Keratin is a protein that produces hair.
-The genes that produce keratin are expressed in skin cells but turned off (remain silent) in blood cells
TIMING IS EVERYTHING!
Just like the wrong beat can ruin a song, the production of the wrong proteins or the production of the right proteins at the wrong time can ruin your body, and even your life.
1. Injury repair: Sometimes, it is beneficial for your body to produce A TON of new proteins, such as when you break a bone or cut your skin: new proteins aid in the healing process
2. Cancer: Other times, proteins are created at the wrong time, which causes uncontrolled cell reproduction leading to tumors that may cause cancer
WHAT DO WE MEAN BY CELL SPECIALIZATION?
Soooooo cells work together. Therefore, there has to be some organization…
→ → → →
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START FROM THE SMALLEST UNIT OF LIFE
TYPES OF CELLS
Cell Type / Function / Adapted For:1. Sperm Cell
2. Red Blood
Cell
3. White Blood
Cell
4. Muscle Cell
5. Nerve Cell
6. Xylem
7. Phloem