INTRODUCTION TO BIOLOGY - Scientific Method - Life’s Characteristics - Taxonomy - Scientific Tools

Science and Biology Science Biology- The study of life. A process of inquiry to investigate the world around us. Science discovers reliable knowledge about nature, due to the SCIENTIFIC METHOD. Observation-> Question-> Hypothesis-> Controlled Experiment-> Collect and Analyze Results-> Publish-> Peer Review Biology- The study of life. From Latin: Bio- “Life” -ology “The study of”

Life Characteristics Metabolism: Homeostasis: The sum of all chemical activities in an organism. Respiration, transport, excretion, nutrition, regulation. Autotrophs (a.k.a producers) synthesize their own food (chemo- or photo- synthesis) Heterotrophs (a.k.a consumers) depend on autotrophs for food Homeostasis: Maintaining a constant, stable internal environment. Ex. Body temperature, hormones, blood pH

Feedback Mechanisms Used to maintain homeostasis Positive Feedback – Reinforcement of a body process “A makes more of B which makes more of A” Ex. Birth contractions, lactation, blood clotting, fever Negative Feedback – Counteraction of a body process “When something goes too high, lower it.” “When something goes too low, raise it.” Ex. Body temperature, blood pH, blood Glucose levels

Life Characteristics, cont’d Responsiveness/Sensitivity: Response or reaction to both biotic (living) and abiotic (non-living) stimuli. STIMULUS - A change in the internal or external environment causing a response. Reproduction and Development: Ability to replicate its own kind. ASEXUAL (one cell divides into 2, into 4, etc.) SEXUAL (zygote  cell division  cell specialization  growth  maturation)

Life Characteristics, cont’d Evolution/ Adaptation: Change in frequency of alleles (genes) in a population…not individuals! Ability to change or adapt if the environment changes. Best for sexual reproducing organisms. 6. Cells The simplest unit of organization of all life. The CELL THEORY states that all living things are made of and came from living cells, and that every cell itself is a living thing.

Life Characteristics, cont’d 7. Genetic Material Living things pass on heritable information through DNA. DNA is a double helix, consisting of two long chains of nucleotides (sugar, phosphate, base) 8. Organization (Complexity): Hierarchical organization Most Simple  Most Complex Levels can vary depending on the organism

Organization Of Organisms Atom- Basic unit of matter Molecule- Atoms bonded together Organelle- Functional units of cells Cell – Basic unit of living organisms Tissue- Group of cells performing a similar function Organ- Group of tissues performing a similar function Organ system- Group of organs performing….. Organism- Any living thing (Can also be a single cell) Species – Organisms that can interbreed and produce fertile offspring. 10. Population– All members of the same species in an area. 11. Community – Groups of different populations in an area. 12. Ecosystem– Community with the non-living environment. 13. Biosphere – Anyplace life exists on Earth.

Classification of Organisms TAXONOMY The branch of biology that deals with the naming of organisms. Binomial nomenclature system (started by Carolus Linnaeus in 1753). Genus species Species Genus – closely related species. Family Order Class Phylum Kingdom (Bacteria, Archaebacteria, Protists, Fungi, Plants, Animals) Domain (Eubacteria, Archaea, Eukarya)

PROKARYOTIC EUKARYOTIC no nuclear membrane DNA enclosed in nuclear membrane DNA in a circular strand structurally simple structurally complex metabolically complex many organelles including mitochondria (most) and chloroplasts (when photosynthetic) cell fusion does not occur cell fusion does occur small size: 0.5-10 µm larger cell size 10-100 µm

Phylogeny & Terminology PHYLOGENY (Phylogenetic Tree) – Evolutionary history of a group. ROOT – The base…the lower down, the more ancient BRANCH – Shows species (or populations) through time. NODES (Forks): Ancestral group splits into two (or more) descendent groups. If there is more than 2 ancestral groups, then it shows POLYTOMY. OUTGROUP – A group known to have diverged (split off) before the rest of the groups under consideration. TIP (Terminal Node): Species alive at present day or have gone extinct. SISTER TAXA: Taxa occupying adjacent tips.

SISTER TAXA TIP POLYTOMY OUTGROUP NODE BRANCH ROOT

MONOPHYLETIC GROUP: PARAPHYLETIC GROUP: Ancestral species and all descendants on one branch. Kingdoms Fungi, Plantae, and Animalia. PARAPHYLETIC GROUP: One branch that does not include all the descendants of a common ancestor. - MUCH more diversity exhibited Kingdom Protista.

Monophyletic Group Paraphyletic Group SISTER TAXA TIP POLYTOMY OUTGROUP NODE BRANCH ROOT

Scientific Tools- Microscopes Light Microscopes Compound Microscope (transmitted light) Dissecting Microscope (reflected/transmitted light) Electron Microscope Shoots electrons through the specimen Downside? Kills specimen on contact- Cannot view movement and behavior Benefit? Gives extremely detailed images