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What is life? Compare these two pictures. Which of them shows living organisms? How do you know?

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Presentation on theme: "What is life? Compare these two pictures. Which of them shows living organisms? How do you know?"— Presentation transcript:


2 What is life? Compare these two pictures. Which of them shows living organisms? How do you know?

3 Life is typically defined as a set of properties

4 LE 1-2 Order. Evolutionary adaptation. Response to the environment. Regulation. Energy processing. Reproduction. Growth and development.

5 Life Has Hierarchial Order Life is organized from the simple to the very complex Each level of complexity is studied by a different specialty of biology

6 LE 1-3 Ecosystems The biosphere Organisms Populations Communities Cells Organelles Molecules Tissues Organs and organ systems Cell 1 µm Atoms 10 µm 50 µm

7 Energy Transformation All living organisms transfer energy from one form to another Photosynthesis-sunlight energy transformed into chemical energy (glucose) Respiration-chemical energy (glucose) converted to chemical energy (ATP)

8 LE 1-4 Sunlight Ecosystem Heat Chemical energy Consumers (including animals) Producers (plants and other photosynthetic organisms)

9 Living Organisms Regulate Their Metabolism Cellular metabolism is complex and self- regulating Cellular metabolism is regulated by enzymes Negative and positive feedback are important regulatory mechanisms

10 LE 1-11 Enzyme 1 A A B B C C D D D D D D D D D D D Enzyme 2 Enzyme 3 Negative feedback Enzyme 1

11 LE 1-12 W Enzyme 4 W X X Y Y Z Z Z Z Z Z Z Z Z Z Enzyme 5 Enzyme 6 Positive feedback Enzyme 4 Enzyme 6 Enzyme 5 Z Z Z Z Z Z Z Z Z

12 Classification Schemes To understand and study the astounding diversity of life, living organisms are grouped into taxanomic groups (taxa). Classification systems have 7or 8 taxa (depending on who you listen to): (Domain),Kingdom, Phylum, Class, Order, Family, Genus, species.

13 LE 1-14 Ursidae Ursus Carnivora Mammalia Chordata Animalia Eukarya SpeciesGenus Family Order Class Phylum KingdomDomain Ursus americanus (American black bear)

14 5 Kingdom System of Classificaton Monerans (procaryotic) Animalia (eucaryotic) Fungi (eucaryotic) Plantae (eucaryotic) Protista (eucaryotic)

15 Representative Organisms- 3 Domains

16 Scientific idea are constantly changing New information causes paradigm shifts in biology The 5 Kingdom system of classification is slowly being replaced by the 3 Domain system of classification Molecular sequencing data (the Human Genome Project) is responsible for this paradigm shift

17 3 Domain System of Classification Archae (procaryotic) (True)Bacteria (procaryotic) Eukarya (eukaryotes)-include the Kingdoms-Animalia,Plantae, Fungi, and Protista

18 LE 1-15 Bacteria 4 µm 100 µm 0.5 µm Kingdom Plantae Protists Kingdom Animalia Kingdom Fungi Archaea


20 3 Domain System of Classification- Implications Organisms that are in the same domain have a closer evolutionary relationship than organisms that are in different domains Therefore, a true bacteria and an archae bacteria are more distantly related than an amoeba and a human!

21 The Scientific Method Science attempts to provide plausible answers to observable phenomena The process by which these answers are arrived at is called the scientific method


23 LE 1-25a Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Observations Question

24 LE 1-25b Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Test prediction Test falsifies hypothesis Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test does not falsify hypothesis

25 The Study of Complex Systems Studying Complex systems to try to understand them can be accomplished by 2 different strategies: holism and reductionism. Holism-study the entire object. Problems-”Blind men and the elephant” Reductionism-tear apart and study the individual pieces. Problem-the interaction of the parts (and emergent properties) may be overlooked

26 Strategy for the Study of Cell Biology We’ll use a reductionist approach. We’ll investigate a cell by looking at atoms  molecules  the interaction of those molecules  cell organelles  the interaction of cell organelles. The interactions between molecules and organelles give rise to emergent properties (such as metabolism and reprodcution) and the sum of these emergent properties is what we call life

27 So let’s get started studying Life!

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