Cell Structure Section 3 From Cell to Organism

Cell Structure Section 3: From Cell to Organism Preview • • • Bellringer Key Ideas Diversity in Cells Levels of Organization Body Types Summary

Cell Structure Section 3 Bellringer What type of society would you prefer to live in: one in which you must do everything for yourself, including growing and gathering food, building shelter, etc. , or one in which each person does the job that they do best? What are some advantages to having each person do a specialized job? What are some advantages to doing everything yourself?

Cell Structure Section 3 Key Ideas • What makes cells and organisms different? • How are cells organized in a complex multicellular organism? • What makes an organism truly multicellular?

Cell Structure Section 3 Diversity in Cells • Both prokaryotic and eukaryotic cells can have a variety of shapes and structures. • The function of a cell is determined by its shape and the organelles found in the cell. • The different organelles and features of cells enable organisms to function in unique ways in different environments.

Cell Structure Section 3 Diversity in Cells, continued Diversity in Prokaryotes • Prokaryotes can vary in shape, the way they obtain and use energy, and their ability to move. • Many prokaryotes have a flagellum, a long, hair-like structure that grows out of the cell and enables the cell to move through its environment. • Prokaryotes may also have pili, short outgrowths that allow the cell to attach to surfaces or other cells.

Cell Structure Section 3 Flagella On Prokaryotic Cells B Click to animate the image. C D A E F

Cell Structure Section 3 Diversity in Cells, continued Eukaryotic Cell Specialization • Eukaryotic cells can vary in shape and external features. • Depending on their function, eukaryotic cells can also vary in their internal organelles. For example, muscle cells, which use large amounts of energy, contain many mitochondria. • Animal and plant cells are two types of eukaryotic cells. Both have many of the same organelles, but plant cells also have chloroplasts, a large central vacuole, and a cell wall.

Cell Structure Section 3 Eukaryotic Cells Click to animate the image. I J C D A B M L J E A G E F H G D C B F I H K

Cell Structure Section 3 Levels of Organization • Plants and animals have many highly specialized cells that are arranged into tissues, organs, and organ systems. • A tissue is a distinct group of similar cells that perform a common function. • An organ is a collection of tissues that work together to form a structure which performs a specific function. • An organ system is composed of a group of organs that work together to perform major body functions.

Cell Structure Section 3 Organization in Multicellular Organisms Click to animate the image.

Cell Structure Section 3 Body Types • Unicellular organisms can thrive independently or live together in groups. • Cells that are permanently associated but do not work together or integrate cell activities are called colonial organisms. • A multicellular organism is composed of many individual, permanently associated cells that coordinate their activities with each other. True multicellularity occurs only in eukaryotes.

Cell Structure Section 3 Visual Concept: Comparing Organisms that are Unicellular and Multicellular

Cell Structure Section 3 Body Types, continued • In a multicellular body, cells are interdependent. Distinct types of cells have specialized functions to help the organism survive. • The individual cells in a multicellular organism cannot survive alone and are dependent on the other cells of the organism. • Must multicellular organisms begin as a single cell, which divides to form more cells. These cells then grow and become specialized in a process called differentiation.

Cell Structure Section 3 Visual Concept: Differentiation

Cell Structure Section 3 Summary • The different organelles and features of cells enable organisms to function in unique ways in different environments. • Plants and animals have many highly specialized cells that are arranged into tissues, organs, and organ systems. • A multicellular organism is composed of many individual, permanently associated cells that coordinate their activities with each other.