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Characteristics and Needs of Living Things Six characteristics of all living things (organisms) Four basic needs of all living things Need for energy Need for water 1. Cellular organization All organisms made of cells – basic unit of structure and function in an organism Unicellular – single celled Multicellular – multi celled 2. Cellular composition Water - Most abundant chemical in cells. It is needed for metabolism. carbohydrates (energy source) proteins and lipids (building materials) nucleic acids (genetic material that directs cell’s activities). 3. Energy use Cells use energy to perform work All living things require energy Primary source of energy is the sun Food + Oxygen = ATP (energy) 4. Growth and development Growth – becoming larger Development – change that occurs during cell’s life to become more complex 5. Response to surroundings Cells react to changes in their surroundings called a stimulus. Ex: light, temp, sound. This action or change in behavior is called a response. 6. Reproduce Cells produce offspring that are similar to the parents 1. energy 2. water 3. living space (competition) 4. stable internal conditions (homeostasis) Cells must have food as their energy source. Autotrophs-organisms that make their own food (selffeeder) ex: plants Heterotrophs-organisms that cannot make their own food (other-feeder) ex: animals, mushrooms, slime molds Most organisms can only live a few days without water. Organisms need water to: Obtain chemicals from their surroundings Break down food Grow Move substances within their bodies Reproduce (Water can dissolve more chemicals than any other substance on earth.) Need for living space Need for stable internal conditions All organisms need place to live, get food and water, find shelter. Limited space causes competition. Plants compete for space for leaves, roots. Animals move and compete for space Organisms must be able to keep conditions inside body constant even when surroundings change. Homeostasis – maintenance of stable internal conditions despite changes in the surroundings. Discovering Cells and Microscopes Invention of microscope Robert Hooke Anton van Leeuwenhoek Matthias Schleiden Theodor Schwann Rudolf Virchow Cell theory Microscope Electron microscope Made it possible to discover and learn about cells. Uses lenses and light to magnify objects. Compound microscope has more than one lens Using thin slices of cork was one of first people to observe cells. Looked like tiny rooms so he called them cells. Looked at pond water and saw one-celled organisms which he called animalcules (little animals). Looked at teeth scrapings and was first person to observe bacteria. Concluded that plants were made of cells. Concluded that all animals are made of cells. Proposed that new cells were formed from existing cells all living things are composed of cells cells are the basic unit of structure and function in living things all cells are produced from other cells Magnification – ability to make things look larger by use of lenses and light. Resolution – ability to clearly distinguish individual parts of an object Uses beam of electrons instead of light to examine a specimen. Much higher resolution. Cell Structures Organelles Cell wall Cell membrane Nucleus Cytoplasm Organelles in the nucleus Organelles in the cytoplasm Small structures within cells - carry out specific functions Rigid outer layer made of cellulose - surrounds plant cells. Helps protect and support. Found in both plant and animal cells. Controls what moves in and out of cell. Maintains homeostasis. Large, oval structure. Brain or control center of the cell directing all activities. Clear thick jelly-like fluid between the cell membrane and the nucleus. Nuclear membrane - Surrounds the nucleus and protects it. Chromatin - Thin strands floating in nucleus. Contain genetic material and direct functions of the cell. Nucleolus - Small object in nucleus which is where ribosomes are made. Ribosomes produce proteins. Mitochondria – rod shaped structures. Powerhouse of the cell - produce most of the energy. Endoplasmic reticulum – passageways which carry proteins and other materials. Ribosomes – grainlike bodies attached to endoplasmic reticulum. Produce proteins and pass them to the er. Golgi bodies – flattened sacs that receive proteins and other materials from ER, package them, and distribute them to other parts of the cell. Also release materials outside the cell. Chloroplasts – Large green structures in plant cells. Capture energy from sunlight and use it to produce food. Give plants their green color Vacuoles – round, water-filled storage sac. Store food, materials and waste products. When full of water make the plant firm. Plants have one large – animals usually do not have. Lysosomes – small structures that contain chemicals that break down large food particles into smaller ones. Also break down old cell parts – cleanup crew. Bacterial cells Specialized cells Levels of organization Differences between plant, animal and bacterial cells Different from plant and animal cells - eukaryotes usually smaller does not have a nucleus – prokaryotes genetic material found in cytoplasm only contain ribosomes – none of the other organelles Vary greatly in size and structure. Each carries out a different specific function. Structures are suited to function. cells tissues organs organ systems organism 1. Plant cells have cell walls, chloroplasts, and one large vacuole. 2. Plant cells have a somewhat rectangular shape. 3. Animal cells do not have cell walls or chloroplasts 4. Animal cells have several small vacuoles. 5. Animal cells have a somewhat spherical shape. 6. Bacterial cells have no nucleus– the genetic material is in the cytoplasm. 7. Bacterial cells have a cell wall and a cell membrane. 8. Bacterial cells are much smaller than plant and animal cells. They lack most of the organelles found in plant and animal cells.