Introduction to Biology Studying Life’s Diversity and Intricate Processes

Biological Inquiry  Bio = of living things  What Are the Characteristics of Living Things?  What are the Themes that Connect Biological Concepts?  How Do Biologists Study Living Things?

What are common characteristics of living things?  Properties of Life  order (organization)  energy processing  regulation  growth and development  reproduction  response to the environment  evolutionary adaptation

Theme: New Properties Emerge at Each Level in the Biological Hierarchy  Principle of Emergent Properties  New characteristics arise out of the arrangement and interactions of the components of a complex system (whole > sum of the parts) order

Organizational Hierarchy of Life Most Complex Least Complex sub-atomic particles atom molecule macromolecule organelle cell tissue organ organ system organism population community ecosystem biosphere protons, neutrons, electrons nitrogen nucleotide DNA nucleus neuron nervous tissue brain nervous system fish school of fish coral reef populations coral reef (living + nonliving) inhabitable regions of earth

Theme: Cells are an Organism’s Basic Units of Structure and Function.  Two types of cells  Prokaryotic  Archaea and Bacteria  few internal membranes  no membrane-bound nucleus  Eukaryotic  Protists, Fungi, Animals, Plants  extensive internal membranes  membrane-bound nucleus order

Theme: Structure and Function are Correlated at all Levels of Biological Organization.  How is red blood cell structure suited to its function of carrying oxygen? order

Theme: Organisms Interact with Their Environments, Exchanging Matter and Energy  Processes occurring in ecosystems  Cycling of nutrients, such as minerals  One-way flow of energy from sunlight to  Producers who synthesize organic (carbon-containing) molecules  Consumers who obtain organic molecules from producers or other consumers energy processing response to environment

Energy Processing  Energy = ability to do work  Energy conversion = change of one form of energy to another  Metabolism = sum of chemical reactions in an organism  Heterotrophic: other feeder  taking in organic molecules produced by other organisms  Autotrophic: self-feeder  photosynthesis = using the energy of the sun to produce organic molecules

Theme: The Continuity of Life is Based on Heritable Information in DNA.  The molecule of heredity = DNA = deoxyribonucleic acid reproduction regulation

Per 23 chromosomes Now estimated at 30,000 genes

Theme: The Continuity of Life is Based on Heritable Information in DNA. Nuclear division reducing the chromosome number, leading to sperm or eggs Nuclear division retaining the original chromosome number

Theme: The Continuity of Life is Based on Heritable Information in DNA.  Growth = increase in size  Development = change in characteristics growth and development

Theme: Feedback mechanisms regulate biological systems.

 Living things maintain homeostasis = a relatively stable internal condition regulation response to environment

Theme: Evolution Accounts for the Unity and Diversity of Life  Two components of Darwin’s Theory of Evolution  Descent with modification: current species arose from a succession of ancestors  Natural Selection: individuals with traits that provide an advantage in the current environment are more likely to survive and reproduce response to environment evolution

Theme: Evolution Accounts for the Unity and Diversity of Life  Descent with modification

Theme: Evolution Accounts for the Unity and Diversity of Life  Natural Selection leads to a change in the genetic characteristics of a population  evolution  Adaptation = characteristic that promotes survival and reproduction

The Unity and Diversity of Living Things An Evolutionary Tree of Life The Three Domains of Life Represent the Earliest Branches in Evolutionary History Contains multiple kingdoms

How Do Biologists Study Living Things?  Discovery Science  Make Observations = objective notations of a phenomenon  Inductive Reasoning  many specific observations  generalizations  eg. E. coli has DNA, plant leaves have DNA, humans have DNA  All organisms have DNA

How Do Biologists Study Living Things?  Hypothesis-based Science  Ask Questions  Formulate an Hypothesis: tentative answer to well-framed question  Deductive Reasoning  general  specific  If…then statements  If all living things maintain homeostasis and Paramecium is a living thing, then Paramecium regulates its internal fluid balance.  Make Predictions based on hypothesis  Test Predictions by Conducting Experiments

How Do Biologists Study Living Things? Biology 21 Definition An Hypothesis will haveAn Hypothesis will have –Two measurable variables –Precise relationship between them (relationship = prediction) The relationship between DNA content and length of the cell cycle is a direct proportion.

How Do Biologists Study Living Things?  A good hypothesis is  Testable  experiments can be designed to test predictions from the hypothesis  experimental results must be repeatable  Falsifiable  allows scientists to eliminate alternative hypotheses

How Do Biologists Study Living Things? Testing hypothesesTesting hypotheses –Controlled Experiment test designed to determine the effect of one factor while keeping all other factors constanttest designed to determine the effect of one factor while keeping all other factors constant experimental = sample treated to test for effect of the factor being studiedexperimental = sample treated to test for effect of the factor being studied control = sample treated like experimental in all ways EXCEPT for the factor being studiedcontrol = sample treated like experimental in all ways EXCEPT for the factor being studied

Use of a Controlled Experiment Increasing dose of almonds on subjects with hyperlipidemia. Full almond = 73 grams/day Control = whole wheat muffins (>5% saturated fat) Half almond = half dose almond + half dose muffins All supplements provided equal amounts of energy in the diet. Jenkins, et al., 2002, Circulation 106:1327

How Do Biologists Study Living Things? Supported Hypothesis Supported Hypothesis Theory = hypothesis supported by repeated testingTheory = hypothesis supported by repeated testing Principle or Law = theory that has been supported over a long period of timePrinciple or Law = theory that has been supported over a long period of time –Cell Principle –Principle of Evolution –Principle of Emergent Properties