Chapter 1 intro to life on earthPresentation Transcript
Chapter 1An Introduction to Life on Earth
What is Biology?--- The science of living organisms and life processes.
So what exactly is life?
Life: An evanescent phenomenon dependent for its continued existence, andperpetuation, on cyclic enzymatic reactions in an environment consistingprincipally of protein and water. Student Dictionary of Biology.(1972) Van Nostrand Reinhold Company, New York.Life: the property by which living organisms are distinguished from deadOrganisms or inanimate matter. Websters II New Riverside Dictionary. These definitions suck terribly. Neither of the Biology texts (for majors or non-majors) that we use include the term “life” in their glossaries.
The characteristics of life:1. Complex, organized structure2. Response to stimuli - a change outside (or inside) leads to another change3. Homeostasis - the ability to maintain the structure and regulate the internal environment.4. Ability to acquire material and energy -The material and energy are often transformed5. Growth6. Reproduction - either sexual or asexual DNA is genetic information, the “blueprint” for the offspring7. Ability to evolve - to change to fit the environment
Complex, organized structure The complexity of life is built in levels. Fig. 1-8
Each level has ingredients or componentswhich interact to make something greater than the sum of the parts. Emergent PropertiesExample: NaCl (Sodium Chloride)Sodium = solid metalChlorine = poisonous gasPut them together = table salt
That part of Earth inhabitedBiosphere by living organisms; includes both the living and nonliving components Earths surface A community together with itsEcosystem nonliving surroundings snake, antelope, hawk, bushes, grass, rocks, stream Two or more populations of differentCommunity species living and interacting in the same area snake, antelope, hawk, bushes, grass Very similar, potentially interbreedingSpecies organisms Members of one species inhabitingPopulation the same area herd of pronghorn antelope Fig. 1-1
Multicellular An individual living thing composedOrganism of many cells pronghorn antelopeOrgan Two or more organs working together in the execution ofSystem a specific bodily function the nervous system A structure usuallyOrgan composed of several tissue types that form a functional unit the brain A group of similar cells that performTissue a specific function nervous tissueCell The smallest unit of life nerve cell Fig. 1-1
A structure within a cell thatOrganelle performs a specific function mitochondrion chloroplast nucleusMolecule A combination of atoms water glucose DNA The smallest particle of an elementAtom that retains the properties of that element hydrogen carbon nitrogen oxygenSubatomic Particles that make up an atomParticle proton neutron electron Fig. 1-1
If you put a plant in your window, the stem will lean in the direction of the sun. This is an example of which characteristic of life?• Living things are organized.• Living things respond to stimuli.• Living things maintain homeostasis.• Living things need energy.
Response to stimuli Organisms react to external and internal stimuli.Some reactions are slow and can’t be seen.
Our body works to keep our temperature atabout 98.6ºF. This is an example of which characteristic of living things?• Living things are organized.• Living things respond to stimuli.• Living things maintain homeostasis.• Living things need energy.
Homeostasis-the ability to maintain the structure and regulate the internal environment. In order to stay alive and function, organisms must keep the conditions within their bodies fairly constant.
Ability to acquire material and energy The material and energy are often transformed . Energy is used to maintain a high level of complexity and organization, to grow, and to reproduce.
Organisms can take in nutrients (food) forraw materials and energy (heterotrophs) Or they can use sunlight for energy (photosynthesis) to produce energy- rich sugar molecules (autotrophs)
The word heterotroph means “other-feeder” or:• Able to photosynthesize.• Able to make its own food.• Must rely on other organisms for energy.• Make its own energy.
Metabolism changes the raw material and energy into the forms which are needed for maintenance, growth, reproduction, etc .Metabolism is basically the sum total ofall of the chemical reactions that occur within an organism.
GrowthAll organisms grow during their life
ReproductionIndividuals reproduce their own kind.
The genetic information for “How to build anoffspring” is stored in the DNA of the parent(s) and that information is passed on to the offspring. Fig. 1.6
Evolution If the environment changes, then thepopulation of organisms must change to fit the environment or face the possibility of extinction.This process of survival of the fittest is natural selection
The evolutionary changes are usually slow,taking several generations and occur by the accumulation of DNA changes known as mutations.
All life forms have these characteristics in common, yet there is an amazingdiversity in the forms of life on the planet.
All living organisms are organized into groups. Each of the major organizational groups are called domains
There are two prokaryotic domains;Bacteria and Archaea and a eukaryotic domain; Eukarya. Fig. 1.11
In the figure, which organism ismost closely related to humans?• Bacterium• Protist• Archaean• Tree Figure 1-11
Within the domains are at least 6 groups known as kingdoms Each kingdom has different attributes which define them. (See table 1-1)
The first difference is cell type PROKARYOTES EUKARYOTESNo nucleus or nuclear Nucleus with a nuclear envelope envelopeGenetic material in a Genetic material within “nucleoid region” the nucleus No organelles or Contains cytosol with internal membranes membrane-bound organelles
The third attribute in the classification of organisms at the kingdom levels is how the organism obtains nutrients/energyThree basic methods Make food using sunlight - photosynthesis Uptake of nutrients by absorption Uptake by eating or ingestion