Cellular Diversity Life Science: Molecular

Diversity of Cellular Life Unicellular Organism Bacteria Archaea Multicellular Organism Cell Specialization Levels of Organization –cells –tissues –organs –organ systems

Three Domains There two categories of cells prokaryotes and eukaryotes. The domains are the three major divisions of life, Bacteria, Archaea, and Eukarya. ProkaryotesEukaryotes BacteriaArchaeaEukarya

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Prokaryotes A unicellular organism is an organism that is made up of only one cell. All prokaryotes are unicellular organisms. Leptospira (bacteria)E. coli (bacteria)

Prokaryotes Bacteria are single-celled prokaryotes. Archaea are prokaryotes that thrive in extremely harsh conditions (extremophiles).

Bacteria We can’t live without bacteria. Our bodies have millions of bacteria on our skin and in our nose, mouth, and gut. Bacteria help us digest our food, make vitamins, and fight off harmful bacteria.

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Bacterial Cell Bacteria and archaea are prokaryotes. They are simple cells, with no internal organization.

Eukaryotes Volvox (algae) Yeast (fungi) Eukaryotes can be multicellular or unicellular organisms.

Animal Cell Animal cells are eukaryotes. Like all eukaryotes, they have a nucleus and membrane bound organelles.

Plant Cell Plant cells are eukaryotes. They have a nucleus, membrane bound organelles, as well as some features animal cells don’t.

Multicellular Organisms Multicellular organisms contain many different kinds of cells that work together. Cell specialization means cells are specialized for the type of work they do.

Levels of Organization The levels of organization in a multicellular organism are: CellsTissuesOrgansOrgan Systems

Cells Work is divided up among the different types of cells so that they can all survive together.

Tissues In multicellular organisms, cells are organized in specialized groups called tissues. A tissue is a group of similar cells that perform a particular function. Four Main Tissue Types: Epithelial Tissue Connective Tissue Muscle Tissue Nerve Tissue

Organs Many tasks within the body are too complicated to be carried out by just one type of tissue. An organ is many groups of tissues working together to perform a function.

Organ Systems In most cases, organs must complete a series of specialized tasks. An organ system is a group of organs that work together to perform a specific function. There are 11 major organ systems in the human body, including the muscular, skeletal, circulatory, and nervous systems.