Cells and Tissues

1. Key Terms Cells: The basic building blocks of all living things. Everything alive is made of cells. Eukaryotes: Cells that have a nucleus (where DNA is stored) and other special parts. Humans, animals, and plants have eukaryotic cells. Prokaryotes: Cells without a...

1. Key Terms Cells: The basic building blocks of all living things. Everything alive is made of cells. Eukaryotes: Cells that have a nucleus (where DNA is stored) and other special parts. Humans, animals, and plants have eukaryotic cells. Prokaryotes: Cells without a nucleus. Bacteria are an example of prokaryotes. DNA (Deoxyribonucleic Acid): The instructions found inside cells that tell them how to grow, live, and make new cells. Amoeba: A tiny, single-celled living thing. It moves and eats by changing its shape. Cells: Cells are the basic building blocks of all living organisms. Each cell is specialized to perform certain functions, such as muscle contraction or nerve transmission. In multicellular organisms, cells work together to form more complex structures. Tissues: Groups of similar cells that work together to perform a specific function form a tissue. For example, muscle tissue consists of muscle cells, and nervous tissue consists of neurons.  There are four primary types of tissue: epithelial, connective, muscle, and nervous tissue. Organs: Organs are structures made up of different types of tissues that work together to perform specific functions. For example, the heart is an organ composed of muscle tissue (to pump blood), connective tissue (to hold it together), and nerve tissue (to control its function). Organs are typically specialized for a particular function, such as the lungs for breathing or the liver for detoxifying chemicals. Organ Systems: Organ systems consist of multiple organs working together to carry out complex bodily functions. For example, the circulatory system includes the heart, blood vessels, and blood, all working to transport nutrients and oxygen throughout the body. Other examples include the digestive system, respiratory system, and nervous system. Organisms: An organism is a living being that consists of various organ systems working together to maintain life. For example, humans are organisms composed of multiple systems (e.g., circulatory, digestive, nervous) that interact to keep the body functioning. Organisms can be as simple as single-celled bacteria or as complex as multicellular animals like humans. Summary: Cells form tissues. Tissues form organs. Organs work together in organ systems. Organ systems make up an entire organism. Differences and Similarities Between Types of Cells: Prokaryotic vs. Eukaryotic Cells: o Prokaryotic cells are simpler, smaller, and lack a true nucleus (e.g., bacteria). They do not have membrane-bound organelles. o Eukaryotic cells are more complex, larger, and have a true nucleus that contains the DNA (e.g., animal and plant cells). They also have membrane-bound organelles. Differences: Prokaryotic cells- are smaller in size, no membrane bound nucleus Eukaryotic cells- larger in size, has membrane bound nucleus Plant Cells vs. Animal Cells: Plant cells - have a cell wall Plant cells - have a chloroplasts (for photosynthesis) Plant cells - have large vacuoles. Animal cells - do not have a cell wall Animal cells - do not have any chloroplasts Animal cells - do not have any vacuoles and if they did it would be very small. Function of Cell Parts Cell Wall: Found only in plant cells, it gives the cell a strong shape and protects it.  Cell Membrane: This is like a thin skin around the cell that controls what goes in and out. Cytoplasm: A jelly-like substance inside the cell where the cell parts float and where some cell activities happen. Nucleus: The control center of the cell that holds DNA and tells the cell what to do. Cell Organelles: Small parts of the cell that do special jobs, like: Mitochondria: They provide energy for the cell. Chloroplasts (in plant cells): They help plants make food from sunlight. Vacuole: A storage space inside cells. Plant cells have one large vacuole, while animal cells have smaller ones. Types of Microscopes: 1. Fluorescence Microscope: Uses special light to see things that are glowing or shining in the cell. 2. Light Microscope: Uses regular light to see things up close, like cells. 3. Electron Microscope: Uses electrons (tiny particles) to see really, really small things, even tinier than what a light microscope can see. Types of Microscopes: 1. Fluorescence Microscope: Uses special light to see things that are glowing or shining in the cell. 2. Light Microscope: Uses regular light to see things up close, like cells. 3. Electron Microscope: Uses electrons (tiny particles) to see really, really small things, even tinier than what a light microscope can see. Main Parts of the Microscope: Eyepiece: This is the part you look through. It helps you see the tiny things you're examining. Objective Lenses: These are the lenses near the bottom of the microscope that zoom in on the specimen. They come in different sizes for different levels of zoom (like 4x, 10x, or 40x). Nosepiece: This is the part that holds the objective lenses. You can turn it to switch between different lenses. Stage: The flat area where you place the slide (the glass piece that holds the specimen). Stage Clips: These hold the slide in place so it doesn't move around. Illuminator: This is the light source that shines light up through the slide so you can see the specimen better.  Condenser: This helps focus the light onto the slide to make the image clearer. Diaphragm: This is a small wheel or lever that controls how much light gets through to the slide. Arm: The part you hold when you carry the microscope. It connects the top and bottom parts. Base: The bottom part of the microscope that keeps it stable and steady. Coarse Focus Knob: This knob moves the stage up and down a lot so you can get closer or further from the slide quickly. Fine Focus Knob: This knob helps you make tiny adjustments to focus on the specimen more clearly. Using the Microscope Setting Up: Place the microscope on a flat, stable surface like a table or desk. Make sure there is enough light in the room or use the built-in light source. Holding the Microscope: Always hold the microscope by the arm with one hand.  Support the base with your other hand. This helps prevent it from tipping over. Placing the Slide: Carefully place your slide on the stage and use the stage clips to hold it in place. Make sure the slide is centered under the objective lens you will use. Focusing on the Specimen Start with the Lowest Magnification: Use the lowest power objective lens first (usually the shortest one). Look through the eyepiece and use the coarse focus knob to bring the specimen into view. Switch to Higher Magnifications: Once you have the specimen in focus at low power, you can switch to a higher power objective lens. Use the fine focus knob to make small adjustments for a clearer image. Caring for the Microscope Cleaning the Lenses: Use a soft, lint-free cloth or lens paper to gently clean the eyepiece and objective lenses. Avoid using your fingers on the lenses as this can leave smudges. After Use: Lower the stage to its lowest position before switching off the light. Remove the slide from the stage and properly dispose of it if it’s not reusable. Storing the Microscope: Cover the microscope with a dust cover to keep it clean.  Store it in a dry place, away from direct sunlight and moisture. Handling: Avoid touching any glass parts with your fingers. Don’t force any parts; if something isn’t moving smoothly, check for obstructions. What is a microscope? A microscope is an instrument used to magnify small objects, allowing the it to be observed in detail.