Organisms Communicate Timing & Communication

Review: Cells Communicate Cells detect chemistry/environmental conditions Signal Transduction Pathway

Review: Cells Communicate Cells within organ systems communicate Immune System: Contact (helper T) Nervous System: Short Distance (synapse) Endocrine System: Long Distance (hormones)

Organisms Communicate Communication needs timing and coordination Bacteria Fungi Plants Animals

Maintaining Homeostasis Feedback Loops Maintaining Homeostasis

As we move through this unit…. Negative feedback: returning the changing condition back to its target set point Ex: temperature regulation in animals Ex: plant responses to water limitations Positive feedback: amplification of a response by moving away from its set point. Ex: ripening of fruit Ex: labor in childbirth

Alteration of feedback mechanism Leads to harmful effects on individual Ex: diabetes

Physiological Events Organisms respond to changes in their environment through behavioral and physiological mechanisms

Bacteria Examples Using energy to respond to the environment to maintain homeostasis

Chemotaxis Directed movement in response to stimulus toward attractant: food away deterent: poison Structure: flagellum

Quorum Sensing Bacteria expel proteins in normal lifecycle Populations increase other functions begin

Endospores When environment lacks specific nutrients, bacterial cell develops protective cell Genome is copied Water is removed Metabolism stops Original cell lysis Endospore endures Dormant for centuries

Fungi Examples Using energy to respond to the environment to maintain homeostasis

Fruiting Body Occur as a result of internal and external signals that synchronize with environmental cycles and cues Ex: development in response to nutritional depletion

Plant Examples Using energy to respond to the environment to maintain homeostasis

Phototropism Growth in response to light Mechanism: auxin hormone (positive) toward light shoots (negative) roots down Mechanism: auxin hormone

Photoperiodism Response to timing of light Mechanism: phytochrome Determine time of day/season Mechanism: phytochrome

Ripening of Fruit Positive feedback mechanism Mechanism: Ethylene

Plasmodesmata Plants pass materials between cells

Defensive mechanisms Physical defense: Chemical defense: Thorns, trichomes Chemical defense: Glycosides Symbiotic defense: Recruitment of animals

Pollination Flower development https://vimeo.com/75555419

Water availability C4 plants

Animal Examples Using energy to respond to the environment to maintain homeostasis

Behaviors Response of a muscle or gland under control of the nervous system in response to a stimulus Innate vs. Learned

Orientated Movement Kinesis Random movement in response to stimulus Ex: Paramecium slow down and turn more often in the presence of bacteria (food)

Orientated Movement Taxis Direct movement toward/away from stimulus Ex: American Cockroach hides from light

Migration Regular long distance change in location Mechanism (in birds) Magnetite in brain to visualize magnetic field

Hibernation Lowering of metabolism to survive seasons

Communication Honeybees perform the waggle dance to communicate the location of food sources

Communication Pheromones Ex: alarm or reproductive

Courtship

Cooperation Pack behavior in animals

Habituation A loss of responsiveness to stimuli that convey little or no new information Ex: prairie dog alarm call in human presence

Associative Learning Ability to associate one environmental feature with another Ex: Mouse associates color/taste

Imprinting The process of recognizing and following the first moving object encountered during a “sensitive period” of life (learned/innate)

Imprinting Scientists often wear costumes to prevent human imprinting with endangered species

Cognition & Problem Solving The process of knowing by awareness, reasoning, recollection & judgment. Ex: primates learn how to use tools