Chemical Signals 1

BIOL 1407

Chemical Signals

• Cells use chemicals to communicate with other cells

• http://www.livevideo.com/video/9DF33CE7B1014B55BEF2322395D72133/neutrophil-chemotaxis.aspx

• Photo Credit of Neutrophil engulfing anthrax bacteria: Tim Vickers, 2007, Wikimedia Commons

Chemical Signaling: Direct Contact

Chemical Signaling: Short-Distance

Chemical Signaling:

Long-Distance

Chemical Signaling Between Individuals

• Pheromones• Video of Orchid Wasp

Mimic: http://www.youtube.com/watch?v=-h8I3cqpgnA

• Photo credit for Spined Soldier Bug eating Mexican Bean Beetle larvae: USDA, 2006, Wikimedia Commons

• Article on Spined Soldier Bug and his pheromones: http://www.nytimes.com/1992/03/01/news/cuttings-the-enemy-s-enemy-is-the-soldier-bug.html?partner=rssnyt&emc=rss&pagewanted=all

Signal Transduction Pathways

Receptors

Target Cells: Have

Receptors for Signal

Target Cells and Specificity

Types of Hormones

Transport and

Receptor Location

Water-Soluble

Hormones

G Proteins

Second Messengers

• cAMP• cGMP

• IP3 and DAG• Calcium• Calmodulin

Lipid-Soluble

Hormones

Steroid Hormones

• Brassinosteroids in plants

• Steroid hormones in animals– Synthesized from Cholesterol– Testosterone, Progesterone, Estrogens– Cortisol and Aldosterone from adrenal cortex

Seed Dormancy and Germination

• ABA – High levels inhibit

germination = promotes dormancy

• Gibberellins– High levels promote

seed germination

Al-your-own skew-Tell-um

Trigger for Desert Seed Germination: Rain

Photo Credit for Storm Over Western Ghats: PlaneMad, 2006, Wikimedia Commons

Desert Seed Germination

• Attenborough Video:– http://www.you

tube.com/watch?v=z1IBnHIOFxs

– Photo Credit for South Africa Desert in Bloom: Winfried Bruenicen, 2001, Wikimedia Commons

Volatile Chemicals

• Jasmonic Acid and Plant Volatiles

• Dodder plant seeks close relationship with tomato plant– http://imagearchive.ps

u.edu/displayimage.php?pos=-19895

• Photo Credit for Dodder in Bloom: Michael Becker, 2005, Wikimedia Commons

Photo Credit for Dodder on Acacia: Khalid Mahmood, 2007, Wikimedia Commons

Photo Credit for Parasitoid Wasp on Plant Bug Nymph: Scott Bauer, USDA, 2003, Wikimedia Commons

The End

Unless otherwise specified, all images in this presentation came from:

Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.