Cells Cells have the same basic composition, and the same kinds of organelles, but not all living things are the same Cells are ___________________ and associate with other cells in special ways

Unicellular Organisms _________________ – relatively constant internal physical and chemical conditions Single-celled organisms are living too

Types of Unicellular Organisms __________________ Protozoa (picture on previous slide) Algae – have chloroplasts, found in water Yeast (a unicellular fungi) – break down nutrients _________________ Bacteria – highly adaptive and can live almost anywhere Both prokaryotes and eukaryotes, though unicellular, ______ __________ _______ _____________ ________________.

Multi-cellular Organisms Cells have a certain job in the body and are specialized for their task Analogy: cells work together like members of a baseball team-are interdependent Members of a baseball team have different jobs – coach, catcher, pitcher, fielders, trainers Need to communicate effectively So do cells! The cells of multicellular organisms become specialized for particular tasks and communicate with one another to maintain homeostasis.

Some specialized cells, pg 215 Fig 7-22 Human trachea epithelial cells - Fig 7-23 Pollen grains from pine tree

Levels of Organization The specialized cells of multicellular organisms are organized into tissues, then into organs, and finally into organ systems.

Levels of Organization A ______________ is a group of similar cells that performs a particular function.

Levels of Organization To perform complicated tasks, many groups of tissues work together as an _____________. Each type of tissue performs an essential task to help the organ function. In most cases, an organ completes a series of specialized tasks.

A group of organs that work together to perform a specific function is called an ________________. For example, the stomach, pancreas, and intestines work together as the digestive system. Levels of Organization

The organization of the body’s cells into tissues, organs, and organ systems creates a division of labor among those cells that allows the organism to maintain homeostasis.

Levels of Organization: review Cells make… Tissues, which make… Organs, which make… Organ systems, which make… Organisms

Cellular Communication Cells are specialized, but interdependent Cells MUST ________________ ___________________ Some cells form a connection to another cell, called cellular junctions

Signals pass through junctions, but only if they have the right _____________ (like a receiver) = specific protein that has specific shape that molds to a specific molecular messenger Ex: junctions in the heart – electrical signals pass through junctions to make heart contract and pump blood

In your Notes, answer these: 1. What is homeostasis?

2. What do unicellular organisms do to maintain homeostasis?

3. What is cellular specialization? Cellular specialization describes how, in multicellular organisms, groups of cells play different, specific roles. Ex: Cilia on trachea cells

4. What are 2 things that help cells communicate and maintain homeostasis?