1. Essential knowledge 3.D.2:
Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling.

2. Stages of cell signaling (3 steps)

3. Cells communicate by cell-to-cell contact
Immune cells interact by cell-cell contact, antigen-presenting cells (APCs), helper T-cells and killer T-cells.

4. Cell to cell communication:
Plasmodesmata between plant cells that allow material to be transported from cell to cell.

5. Cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting cell.
Examples:
• Neurotransmitters
• Plant immune response
Ubiquitination is a central role in cell signaling that regulates several processes including protein degradation and immunological response.[19] Much of the defense in plants relies on the destruction of defective or invaded materials within the cell, increasing the importance of functional proteasomes and protein targeting.

6. Other examples of short distance communication
Quorum sensing in bacteria
r_on_how_bacteria_communicate.html

7. Other examples of short distance communication
• Morphogens in embryonic development - Morphogens are soluble molecules that can diffuse and carry signals that control cell differentiation decisions in a concentration-dependent fashion. Morphogens typically act through binding to specific protein receptors.

8. Quorum sensing in bacteria
Quorum sensing is a system of stimulus and response correlated to population density.
Used to coordinate gene expression according to the density of their local population.
Bacteria use it to coordinate certain behaviors based on the local density of the bacterial population.

10. Signals released by one cell type can travel long distances to target cells of another cell type.
Endocrine signals are produced by endocrine cells that release signaling molecules, which are specific and can travel long distances through the blood to reach all parts of the body.
Example 1: Insulin

11. Signals released by one cell type can travel long distances to target cells of another cell type.
Example 2: Human growth hormone
HGH, produced by the pituitary gland, spurs growth in children and adolescents.
Example 3: Thyroid Hormone

12. Goiter
If there is a deficiency of dietary iodine, the thyroid will not be able to make thyroid hormone. The lack of thyroid hormone will lead to decreased negative feedback on the pituitary, leading to increased production of thyroid-stimulating hormone, which causes the thyroid to enlarge (the resulting medical condition is called endemic colloid goiter

13. Jokes

16. The manliest pic you will see all day.

18. Dream the impossible dream!

19. HANG ON A SEC
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