Cellular Diversity Life Science: Molecular
Cellular Diversity
Life Science: Molecular
Diversity of Cellular Life Unicellular Organism
Bacteria Archaea Multicellular OrganismCell SpecializationLevels of Organization –cells –tissues –organs –organ systems
Cells are the basic unit of structure and function in living things.
Three Domains There two categories of cells prokaryotes and
eukaryotes. The domains are the three major divisions of life, Bacteria, Archaea, and Eukarya.
Prokaryotes Eukaryotes
Bacteria Archaea Eukarya
Three Domains
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ProkaryotesA unicellular organism is an organism that is made up of only one cell. All prokaryotes are unicellular organisms.
Leptospira (bacteria) E. coli (bacteria)
ProkaryotesBacteria are single-celled prokaryotes. Archaea are prokaryotes that thrive in extremely harsh conditions (extremophiles).
Bacterial Cell Bacteria and archaea are prokaryotes. They are
simple cells, with no internal organization.
BacteriaWe 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.
Eukaryotes are organisms with a nucleus and specialized structures called organelles.
Eukaryotes
Volvox (algae)
Yeast (fungi)
Unicellular Multicellular
Animal Cell Animal cells are eukaryotes. Animal cells also
contain centrioles and lysosomes.
Plant Cell Plant cells are eukaryotes. Plant cells also contain
chloroplasts and a cell wall.
Origin of Eukaryotic Cells• The endosymbiotic theory states that about 2
million years ago eukaryotic cells formed from a symbiosis with several different prokaryotes.
Aerobic bacteria
Ancient Prokaryotes
Ancient Anaerobic Prokaryote
Primitive Aerobic Eukaryote
Primitive Photosynthetic Eukaryote
Chloroplast
Photosynthetic bacteria
Nuclear envelope evolving Mitochondrion
Plants and plantlike protists
Animals, fungi, and non-plantlike protists
Multicellular Organisms• Multicellular organisms contain many different
kinds of cells that work together. • In multicellular organisms cells are specialized for
the type of work they do.
Levels of Organization• The levels of organization in a multicellular
organism are:
Cells
Tissues
Organs
Organ Systems
Cells• Specialized cells perform particular tasks in an
organism. Work is divided up among the different types of cells.
Tissues• A tissue is a group of similar cells that perform a
particular function.
Four Main Tissue Types: Epithelial TissueConnective TissueMuscle TissueNerve Tissue
Organs • An organ is many groups of tissues working
together to perform a function.
Organ Systems• 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.