zChapter 1: Exploring Life

Unifying Themes in Biology zEvolution~ biology’s core theme; differential reproductive success (sex!) zEmergent Properties~ hierarchy of life zThe Cell~ all organism’s basic structure zHeritable Information~ DNA zStructure & Function~ form and function zEnvironmental Interaction~ organisms are open systems zRegulation~ feedback mechanisms zUnity & Diversity~ universal genetic code zScientific Inquiry~ observation; testing; repeatability zScience, Technology & Society~ functions of our world

Hierarchy of Organization zMolecule zOrganelle zCells zTissues zOrgan zOrganism

Feedback Regulation: Negative zAccumulation of an end product of a process slows that process zExample: sugar breakdown generates ATP; excess ATP inhibits an enzyme near the beginning of the pathway

Feedback Regulation: Positive zAn end product speeds up its production zExample: blood clotting in response to injury

The Process of Science zThe Scientific Method zDeductive reasoning z“If….then” Logic zHypothesis vs. Theory

Properties of Living things

Early Views of life zVitalism : The insistence that there is some big, mysterious extra ingredient in all living things z Led to idea of spontaneous generation z Flies came from dead animals z Mice came from Hay

z Idea was challenged by scientist Francesco Redi in z Designed an experiment where 3 jars contained meat. The Redi Experiment

Setup 1 z One Jar contained meat and had an open top which would allow the passage of flies. y (maggots would appear on the meat)

Setup 2 z The second jar was covered with an airtight lid not allowing the passage of flies.  (no maggots would appear on the meat)

Setup 3 z The third was covered by a screen allowing passage of eggs, but not flies.  (few maggots would appear on meat)

Conclusion z Since the third setup would theoretically allow the passage of “ethers”, but no maggots appeared, it was implied that flies were the source of the maggots. y Led to the theory of Biogenesis x All life comes from preexisting life

PROPERTIES of LIFE z Be made of Cells. z The Cell is the basic unit of life y Is self contained and possesses a barrier (membrane) which separates itself from the environment. z Two types of organisms. y Unicellular - One celled organism (Uni=1) y Multicellular - Many cells (Multi=”many”)

PROPERTIES of LIFE z Living Things must Reproduce. z Must be able to create more of it’s own kind z Two types of reproduction: y Sexual - Two parent organisms combine genetic material to produce the offspring. y Asexual - When a single organism can divide or “bud” to create it’s offspring without another of it’s species.

PROPERTIES of LIFE z Living things must Have DNA. z (Universal Genetic Code?)

PROPERTIES of LIFE z Living things must Grow & Develop. z Growth refers to two processes. y Increase in the number of cells. y Increase in the size of cells. z Development refers to changes in the organism which occur through it’s life- span. y Includes cell differentiation. y Includes organ development y Includes aging & death.

PROPERTIES of LIFE z Living things obtain & use energy. z Energy is used by all living things for growth, development & reproduction. y Life processes which result in “building” the organism ia known as Anabolism. y Life process where energy is extracted by “breaking-down” substances is called Catabolism.

PROPERTIES of LIFE z Living things must Respond (or react) to their environment in some way. z Something which causes an organism to react is known as a Stimulus (stimuli). z The ability of an organism to react is called Irritability. z Most responses are geared for maintaining Homeostasis. y Homeostasis is a process where an organism maintains a stable internal environment so life can continue. y Some examples include temperature, pH, and water content of the cell.