Chapter 7 Section 4 The Diversity of Cellular Life Objectives: Describe cell specialization. Identify the organization levels in multicellular organisms.

Vocabulary cell specialization: the process in which cells develop in different ways to perform different tasks tissue: group of similar cells that perform a particular function organ: group of tissues that work together to perform closely related functions organ system: group of organs that work together to perform a specific function

Unicellular Organisms Cells are the basic living units of all organisms, but sometimes a single cell is a little more than that. Sometimes, a cell is the organism. A single-celled organism is also called a unicellular organism. Unicellular organisms do everything that you would expect a living thing to do. They grow, respond to the environment, transform energy, and reproduce. In terms of their number, unicellular organisms dominate life on Earth.

Yeast Volvox aureus (alga cells) Leptospira interrogans

Multicellular Organisms Organisms that are made up of many cells are called multicellular. There is a great variety among multicellular organisms. However, all multicellular organisms depend on communication and cooperation among specialized cells. Cells throughout an organism can develop in different ways to perform different tasks. This process is called cell specialization.

Red Blood Cells - transport oxygen throughout the body. Muscle Cells - contract and relax to move parts of the body Pancreatic Cells - produce compounds such as insulin that the body need. Guard Cells - control the opening and closing of stomata on the undersides of leaves

Levels of Organization Biologist have identified levels of organization that make it easier to describe the cells within a multicellular organism. The levels of organization in a multicellular organism are individual cells, tissues, organs, and organ systems.

Similar cells are grouped into units called tissues 4 main types of tissue muscle epithelial nervous connective

Many groups of tissues work together as an organ Organs Many groups of tissues work together as an organ Each muscle in your body is an individual organ Includes nervous tissues and connective tissues Performs an essential task to help the organ function

Organ Systems A group of organs that work together to perform a specific function is call an organ system