diversity of cellular life 7-4. unicellular organisms cells are the basic units of all organisms,...
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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 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