Biology Biology: Exploring Life Biology is the scientific study of life.

Biology

Biology: Exploring LifeBiology is the scientific study of

life

http://www.ux1.eiu.edu/~cfruf/images/bio3002/els_le2.jpg

Biological Hierarchy of Organization:

Life can exist here

Hierarchy of Life; Organization levels

Molecules are atoms held together by chemical bonds (ex: DNA, protein)

Organelles are membrane-bound structures with specific functions for & w/in some cells

Cells are the smallest unit of life; separates the environment with a membrane

Tissues are layers of cells to perform a specific function

Organs are groups of tissues working together to perform a specific function

Hierarchy of Life; Organization levels, cont’d

Organ Systems are organs grouped together to perform a function

Organism is a living thing within a population

Population: the same species living within a specific area

Community: many groups of different species within an ecosystem

Ecosystem: contains biotic (living) factors & abiotic (nonliving) factors within a specified area/community

Biosphere: all ecosystems of the Earth

Hierarchy of Life; Organization levels, cont’d

• From most specific to general:

Atoms Molecules Organelles Cells Tissues Organs Organ Systems Organism Population Community Ecosystem Biosphere

*Blue color denotes living/biotic

Cycle of Nutrients and Energy:

http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/ecosystem/zebra2.gif

Organism Interaction, Matter, and Energy

• An Ecosystem contains 3 categories of organisms:– Producers (autotrophic organisms like plants,

algae, and some bacteria): perform photosynthesis (absorb H2O, CO2 & sunlight & convert these to sugar and O2)

– Consumers (heterotrophic organisms like animals): organisms that eat plants and other animals. These take in O2 and release CO2, while releasing waste into the environment.

– Decomposers (heterotrophic organisms like bacteria and fungi) that break down wastes and dead/decomposing organisms, while recycling matter into the environment (which the producers use).

Organism Interaction, Matter, and Energy, Cont’d

• Ecosystems have 2 major processes: Recycling chemical nutrients and energy flow.

• Recycling chemical nutrients: O2, CO2, H2O, etc. go from the air and soil to producers to consumers to decomposers and then back to the air and soil. These are recycled!

• Energy Flow: solar energy is absorbed by producers & converted to chemical energy thru photosynthesis.

– Chemical energy is passed thru many organisms (consumers: primary to secondary, etc) and then finally to decomposers.

– At every pass, some energy is LOST as heat.

– Energy flows THROUGH the ecosystem (enters as light; exits as heat).

Cells, the structural & functional unit of life

• The cell is the basic unit of life, the lowest level of structure at which the properties of life emerge. These correlate structure = function!

• The cell:– Regulates its internal environment (homeostasis)

– Takes in & uses energy

– Responds to its environment

– Develops & maintains a complex organism

– Reproduces (give rise to new cells)

Cells, the structural & functional unit of life, Cont’d

Characteristics of a Cell:• Enclosed in a membrane (which regulates the

flow/regulation of materials in and out of the cell)• Contains DNA (genetic material), cytoplasm,

ribosomes

2 types of cells:• Prokaryotic Cell (Kingdoms Archaebacteria and

Eubacteria): bacteria; small and simple cells

• Eukaryotic Cell (All other Kingdoms): plants, animals, protists, and fungi.

– Have organelles (functional compartments with specific functions)

– Have a nucleus that contains DNA

Prokaryote:

http://www.ichristianschool.com/biology/images/prokaryote.jpg

Eukaryote:

http://faculty.uca.edu/~johnc/eukaryote.jpg

Unity of Life• The continuity of life is based

on ALL living things have DNA (genetic material).

• Genes (inheritable material) are made up of DNA sequences

– DNA is 2 chains coiled together to form a double helix (structure)

– Nucleotides= building blocks; these contain nitrogenous bases attached: adenine (A), thymine (T), guanine (G), or cytosine (C).

• All forms of life contain the same genetic code; the sequences (order) is different. This results in different genes.

http://www.scq.ubc.ca/wp-content/dna.gif

Unity of Life, Cont’d – CHARACTERISTICS OF LIFE:

In addition to Genes, all organisms have:• Order (level of organization)• Metabolism (all chemical reactions)• Regulation (a.k.a. homeostasis, or control of the

internal environment to sustain life)• Growth (increase in size)

• Development (change in form)

• Energy processing (ability to use & transform, or transduce, energy)

• Response to Environment (both internal & external stimuli)

• Reproduction (make more like themselves)

• Evolutionary Adaptation (traits that are best suited to the environment that are passed on to the offspring; ie. camouflage, spots, etc)

Diversity of Life – Classification of organisms• A species is the smallest category of

organisms (most specific)– share the most common characteristics – can reproduce with each other.

• Taxonomy is the branch of Bio which names & classifies organisms according to characteristics and similarities – molecular, genetic, biochemical, morphological,

evolutionary phylogenies/histories, etc.

This is completed from broadest category to most specific:

Domain Kingdom Phylum Class Order Family Genus Species

http://upload.wikimedia.org/wikipedia/commons/9/96/Scientific_classification.png

http://www.lesley-smitheringale-fine-art.com/wp-content/uploads/2008/05/atlas-moth-scientific-classification.jpg

There are 3 Domains: Domain Bacteria or Eubacteria, Domain Archaea, Domain Eukarya

• Domain Bacteria or Eubacteria (have peptidoglycan in their cell walls)

• Domain Archaea (live in extreme environments, like hot or salty places, or anaerobic environments)

– BOTH Bacteria and Archaea are prokaryotic, are bacteria, are unicellular & microscopic, and are found in Kingdoms Archaebacteria and Eubacteria.

• Domain Eukarya

– Include all eukaryotic organisms (have organelles & a nucleus).

– Include protists (Kingdom Protista). These are uni or multicellular. Ex. Include algae and protozoans

– Include plants (Kingdom Plantae), which have a rigid cell wall and perform photosynthesis.

– Include animals (Kingdom Animalia) which lack a cell wall and must consume food

– Include fungi (Kingdom Fungi) which are yeast, mushrooms and molds that decompose dead organisms.

– Protista, Plantae, and Fungi are generally separated by their modes of nutrition.

Domain Bacteria: Electron Micrograph of

E. Coli

http://www.foxnews.com/images/250204/0_61_bacteria_e_coli.jpg

Domain Arachaea: Image of

Methanococcus jannaschii

http://www.biology.iupui.edu/biocourses/n100/images/dmethanopyrus.jpg

http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/Evolution,%20Speciation,%20Taxonomy/specia12.gif

A Micrograph of Euglena (Protist):

http://www.biologyreference.com/images/biol_04_img0381.jpg

Plant: Palm Tree

http://www.untiredwithloving.org/palm_tree_2.jpg

Fungi: Death Cap, Death Angel Mushroom

http://www.gencat.cat/especial/bolets/img/toxics/farinera_borda1.gif

Animal: Bull Shark

http://animals.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/animals/images/primary/bull-shark.jpg

Evolution Explains the Unity & Diversity of Life• Darwin wrote On the Origin

of Species by Means of Natural Selection which supported the idea of evolution = species alive today are descendants of ancestral species (a.k.a. ‘descent with modification’).

• This means descent from a common ancestor. This supports the unity of life.

• Darwin’s idea supported the diversity of life (modification as species diverged). http://www.goodschist.com/wp-content/gallery/charles-

darwin/Darwin_age29.JPG

Darwin recognized that variations existed within organisms. –These enhance their ability to survive AND reproduce (this is the essence of evolution by means of natural selection).

• These successful adaptations are the result of evolution, the process of change over time which has transformed life on Earth.

Evolution Explains the Unity & Diversity of Life, Cont’d

• Darwin proposed that evolution occurred through Natural Selection (NS):

– Recognized (observed) that w/in a population, variations exist AND in many cases more organisms were produced than could survive (to produce their own offspring); this was an overproduction of offspring.

– From these observations, he suggested that the individuals who were likely to survive AND reproduce were best suited to the environment; they inherited the best traits and would pass these traits on to their offspring.

– Overtime, the best suited (or favorable) traits would accumulate within a population. This could eventually lead to a new species.

Evolution Explains the Unity & Diversity of Life, Cont’d

• The environment ‘selects’ for individuals w/certain traits meaning there is an unequal reproductive success. This is Natural Selection (NS).

• The product of NS = evolutionary adaptation, or the accumulation of favorable traits in a population over time.

• NS is an editing process that works on heritable variations which are exposed to environmental factors that favor reproductive success.

• Major alteration of a species could occur from many small changes w/in a population. Darwin proposed that a new species could arise due to these gradual changes over long periods of time.

Scientific Method – terms that have different meanings in Science versus mainstream use:

• Science means “to know.”

“Science can neither prove nor disprove the existence of a God or supernatural power- for such questions are outside the bounds of science.”

• A hypothesis is a possible (plausible) explanation based on observation (that can be tested). Mainstream use : an “educated guess”

Theories in science:• A theory is a hypothesis that has been tested

repeatedly and is generally regarded as true. Examples: Theory of Evolution, Theory of Relativity, Atomic Theory, Cell Theory.

Mainstream use: just an “idea”

The Evolution Connection

Evolution is the CORE theme in biology.

• There are many differences (and similarities) in DNA among individuals, populations, and species; this reflects evolutionary change.

• Through the Human Genome Project (HGP), scientists have been able to ID & construct the DNA base sequences of many species.

– allows comparative & functional genomics (the ability to identify common genes, search for new medical treatments, and more using DNA technology).

• DNA differences in humans is used in forensics: this is DNA fingerprinting or DNA profiling and is used to convict or exonerate, determine paternity, or identify remains.

Evolutionary knowledge can help scientists in the understanding:•Vaccinations•HIV drugs •virus evolution•the development of antibiotic-resistant bacteria & pesticide-resistant crops•how to help endangered species