What Does It Mean To Be Alive? The Characteristics of Life

What Do These Organisms Have In Common? Organism means “living thing”  so what do these “living things” have in common; what makes them “living” Reach and grab dna – all have dna: genetic material , reproduce , composed of cells , adapt/evolve , growth (flower bloomed), etc.

Characteristics of life Life is based on organic chemistry Composed of cells- smallest living unit Use energy Form and size range Growth (and development) Life span Response to environment Reproduction Adapt/evolve over time Definite form and size range / grow within means (ex: size between us and grasshoppers – there’s a huge difference!) Limited life span * non-living objects may exhibit a few of these chara, but never show all (ex: virus – reproduce)

LIFE PROCESSES Homeostasis

Homeostasis Not a Life Process, but a reason for them Condition of a constant internal environment  balance Life processes are needed to maintain a fairly constant environment within an organism in spite of its constantly changing external environment. Examples of homeostasis in action: Body Temp --Heart Rate Blood pressure --Water levels/pressure pH levels --Gas exchange (CO2 and O2) Glucose (sugar) levels

Nutrition Take materials (nutrients, energy) from external environment and change them into forms they can use. Ingestion (taken in) Digestion (broken down) Heterotroph vs. Autotroph

Transport Process by which substances enter & leave cells and become distributed within the cells. (small organisms)-materials exchanged directly with external environment (large organisms)-circulatory system moves materials to and wastes from the cells of an organism Fluid/blood in circulatory system is kept in motion, distributing materials among all the cells within the organism – in plants, transport structures aid in root to leave transportation

Respiration Process which releases chemical energy stored in food. Respiration is NOT BREATHING! Aerobic Respiration Anaerobic Respiration All life processes require a constant supply of energy – obtain their energy by releasing chemical energy stores in nutrients **ORGANISMS THAT BREATHE DO SO TO EXCHANGE GASES NEEDED FOR RESPIRATION – RESPIRATION HAS TO DO WITH ENERGY RELEASED WITHIN CELLS AND MAY/MAY NOT INVOLVE BREATHING** Respiration involves a complex series of rxns – aerobic respiration (sugar/food molecules broken down to produce water and CO2 – require O2 , so call aerobic Anaerobic – breaks down food without using oxygen

Synthesis Synthesis-combine simple substances (products of digestion) chemically to form more complex substances. Assimilation-incorporation of materials into an organism’s body. Synthesis – “ making or constructing “ something – photosynthesis- making food with light (photo) energy Then, glucose that is synthesized by a plant is assimilated in form of starch

Growth Process by which organisms increase in size (unicellular) Increase in cell size (multicellular) Increase in BOTH number and the size of the cell (accompanied by cellular specialization) Due to the assimilation of nutrients! Cellular specialization – cells become specialized for different fxns (blood cells, liver cells, etc.)

Excretion Removal of wastes from the organism. Wastes are products of chemical reactions that occur within cells. All organisms produce waste substances (can no longer be used, may be harmful to body if accumulation occurs)

Regulation All activities that help maintain an organism’s homeostasis. Examples: nervous & endocrine system N.S. – carries messages ; endocrine – release chemicals/hormones into bloodstream (chemical messengers) * both bring about changes in the organism due to response to changes in either internal or external environment

Reproduction Process by which living things produce new organisms of their own kind. NOT necessary for survival of an individual! Asexual Reproduction- Sexual Reproduction- Not necessary for survival or individual, but it is for the survival of that type of organism! Asexual – single individual produces offspring identical to parent Sexual – two parents produce offspring that are not identical to parent(s)

Metabolism All of the chemical reactions occurring within the cells of an organism. Continuous release & use of energy Catabolism + Anabolism = Metabolism MOST important life process! Metabolism = (anabolism) builds complex substances from simpler ones AND (+) breaks down complex substances into simpler ones (catabolism)

Metabolism Anabolism = putting together simple substances to make complex substances ex: photosynthesis where plant uses CO2 & O2 to make energy for plant Catabolism = breaking down complex substances in order to use material for other substances ex: food digested in humans used to make energy and materials for body Metabolism = (anabolism) builds complex substances from simpler ones AND (+) breaks down complex substances into simpler ones (catabolism)