Lesson Overview 7.4
THINK ABOUT IT The diversity of life is so great that you might have to remind yourself that all living things Are composed of cells Use same basic chemistry Contain same kinds of organelles. This does not mean that all living things are the same. Differences arise from the ways in which cells are specialized cells associate with one another to form multicellular organisms.
The Cell as an Organism How do individual cells maintain homeostasis (including unicellular organisms)? To maintain homeostasis, unicellular organisms Grow Respond to the environment Transform energy Reproduce
The Cell as an Organism A single-celled, or unicellular organism, does everything you would expect a living thing to do. Just like other living things, unicellular organisms must achieve homeostasis, relatively constant internal physical and chemical conditions. Homeostasis Review from the BBC!
The Cell as an Organism Based on numbers, unicellular organisms dominate life on Earth. Unicellular organisms include both prokaryotes and eukaryotes. Prokaryotes, especially bacteria, are remarkably adaptable and live almost everywhere in the soil, on leaves, in the ocean, in the air, and even within the human body.
Bacteria that cause infections:
The Cell as an Organism Many eukaryotes also spend their lives as single cells. Algae on Pond Some types of algae, which contain chloroplasts and are found in oceans, lakes, and streams around the world, are single celled. Yeasts, or unicellular fungi, are also widespread. Yeasts play an important role in breaking down complex nutrients, which makes them available for other organisms.
The Cell as an Organism Whether a prokaryote or a eukaryote, homeostasis is an issue for each unicellular organism. Every unicellular organism needs to Find sources of energy or food Keep water and mineral concentrations within certain levels Respond quickly to changes in environment
Multicellular Life How do the cells of multicellular organisms work together to maintain homeostasis? Cells of multicellular organisms become specialized. To maintain homeostasis: Cells have specific tasks Cells communicate with one another
Multicellular Life Cells of multicellular organisms are interdependent. Example: Like members of a successful baseball team, they work together. In baseball, players take on a particular role, such as pitcher, catcher, infielder, or outfielder. Messages and signals are sent and understood by teammates and coaches to play the game effectively.
Cell Specialization Different cell types playing different roles. Some cells are specialized to move, others to react to the environment, and still others to produce substances that the organism needs. No matter what the role, each specialized cell contributes to the overall homeostasis of the organism.
Specialized Animal Cells Particles of dust, smoke, and bacteria are part of even the cleanest air. Cilia Specialized animal cells act like street sweepers to keep the particles out of the lungs. These cells are full of mitochondria, which provide a steady supply of the ATP that powers the cilia on their upper surfaces.
Specialized Plant Cells Pollen grains are highly specialized cells that are tiny and light, with thick cell walls to protect the cell s contents. Pine pollen grains have two tiny wings that enable the slightest breeze to carry them great distances.
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 tissue 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 organ. Each type of tissue performs an essential task to help the organ function. In most cases, an organ completes a series of specialized tasks.
Levels of Organization A group of organs that work together to perform a specific function is called an organ system. 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 Cells are grouped together and work as a whole to perform special functions copyright cmassengale 19
Tissue A group of similar cells to perform a particular function Animals : epithelial tissue, muscular tissue Plants : vascular tissue, mesophyll copyright cmassengale 20
Organ Different tissues group together to carry out specialized functions Heart : consists of muscles, nervous tissue and blood vessels Leaf : consists of epidermis, mesophyll and vascular tissue copyright cmassengale 21
The Structures of a Leaf (Plant Organ) Chloroplast Palisade Mesophyll Cell Spongy Mesophyll Cell Air Space Stoma copyright cmassengale 22
The Structures of a Heart (Animal Organ) copyright cmassengale 23
System Several organs and tissues work together to carry out a particular set of functions in a co-ordinated way Human : digestive, respiratory, excretory, circulatory and reproductive systems Plant : root and shoot systems copyright cmassengale 24
Human Body Systems Examples of systems : Digestive System Respiratory System Circulatory System Nervous System Reproductive System copyright cmassengale 25
Examples of a Human Body System copyright cmassengale 26
Examples of a Human Body System The Respiratory System copyright cmassengale 27
Examples of a Human Body System Circulatory System copyright cmassengale 28
Examples of a Human Body System Nervous System copyright cmassengale 29
Organisms YOU! What other levels of organization can we add from Ch. 2? 30
Nonliving Levels Subatomic Particles (Protons, neutrons, electrons) ATOMS MOLECULES ORGANELLES (elements) (compounds like (Nucleus, ER, Golgi carbohydrates & proteins) 31
Living Levels CELLS life starts here TISSUES Similar cells working together 32
More Living Levels ORGANS ORGAN SYSTEMS ORGANISM Different tissues working together Different organs working together 33
LEVELS OF ORGANIZATION Living Levels continued: POPULATION (one species in an area) COMMUNITY (several populations in an area ECOSYSTEM (forest, prairie ) BIOME (Tundra, Tropical Rain forest ) BIOSPHERE (all living and nonliving things on Earth) 34
Cellular Communication Cells in a large organism communicate by means of chemical signals that are passed from one cell to another. Cellular signals can speed up or slow down the activities of the cells that receive them, and can cause a cell to change what it is doing. Proteins in Cell Membrane
Cellular Communication Some cells form connections, or cellular junctions, to neighboring cells. Some junctions hold cells firmly together.
Cellular Communication Junctions can allow small molecules carrying chemical messages to pass directly from one cell to the next. Cells must have a receptor to respond to the signal. Chemical signals sent by various types of cells can cause important changes in cellular activity. For example, such junctions enable the cells of the heart muscle to contract in a coordinated fashion. Proteins in Cell Membrane