Diversity of Cellular Life 7-4

Unicellular Organisms Cells are the basic units of all organisms, but sometimes a single cell is the organism A.k.a unicellular organisms Do everything you would expect a living thing to do Dominate life on earth

Multicellular Organisms Made up of more than one cell Multicellular organisms depend on communication and cooperation among specialized cells Through a process known as cell specialization, cells inside an organism have developed to perform specific tasks for the organism

Specialized Animal Cells Animal cells are specialized in many ways: –Red blood cells are specialized to transport oxygen –Cells in the pancreas are specialized to produce proteins Packed with ribosomes, rough ER, Golgi app., and clusters of vacuoles filled with enzymes

Movement is made possible by specialized structures in muscle cells –Cells generate force by overdeveloped cytoskeletons –Packed with actin microfilaments and the protein myosin –When muscles contract, chemical energy is used to pull fibers past each other, generating a force

Specialized Plant Cells Plants can rapidly exchange CO 2, O 2, H 2 O vapor, and other gases through tiny openings on the undersides of leaves –Openings called stomata –Guard cells regulate exchange by monitoring plant’s internal conditions

Levels of Organization The levels of organization in a multicellular organism are –Cells –Tissues –Organs –Organ systems

Tissues Cells are the first level of organization Similar cells that are grouped together and perform a similar function make up tissues 4 main types of tissues: –MuscleEpithelial –NervousConnective

There are 3 types of muscle tissue Skeletal – muscles attached to bones Smooth - makes up the walls of organs like your stomach and veins Cardiac - muscle that makes up the heart

Nervous tissue transmits and receives impulses Connective tissue holds organs in place Epithelial tissue covers the body and lines organs

The 3rd largest level is organ An organ is a group of similar tissues that perform a particular function. Each muscle in your body is an individual organ

The largest level of organization is organ system An organ system is a group of organs that work together to perform a specific function Your body has 11 different organ systems