Diversity of Cellular Life

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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 CO2, O2, H2O 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:– Muscle Epithelial– Nervous Connective

• 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