Science Notes - Cell Function PDF
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These notes provide an overview of cell function, including the size of cells, cell membranes and diffusion. The text explains how cells maintain homeostasis and perform essential biological functions.
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Sci notes ---------------------------------------------------------------------- Size fonction Single-celled organisms don't get very big hey must absorb all the substances they need through their cell T membrane. Most single-celled organisms must live in nutrient-rich water u...
Sci notes ---------------------------------------------------------------------- Size fonction Single-celled organisms don't get very big hey must absorb all the substances they need through their cell T membrane. Most single-celled organisms must live in nutrient-rich water ulticellular M organisms have several advantages over unicellular organisms - They can live in various environments - They can reach very large sizes (like a whale) - They can find energy in a wide variety of foods Why are cells so small? - T o carry out their work, cells need to be constantly supplied with substances (such as oxygen) - If the cells were larger, they would need more substances and produce more waste - It would also take too much energy for the cell - Cells vary in size and shape The cell membrane The cell membrane is a natural guardian installed around the cell he cell membrane controls the passage of matter into and out of the T cell. Permeability 1. Permeable - All substances can pass/cross the membrane 2. Impermeable - Nothing passes/crosses through the membrane 3. Selective permeability - Certain substances can pass/cross the membrane he cell membrane plays an important role in preventing toxic T substances from entering the cell and removing waste products he cell membrane is made of two layers of particles where several T proteins are housed. ome of these proteins act as open channels, forming pathways through S which certain materials can enter and leave the cell. This is why they are called “channel proteins” or “carrier proteins”. Active transport hat is to say, effective transmembrane transport by proteins and T requiring energy expenditure from the cell Diffusion The movement of fluids in the cell iffusion is the particles from a region of high concentration to a D region of low concentration Think of perfume” – Perfume particles are released into the air and “ spread throughout the room iffusion plays an important role in the process that allows living D beings to capture energy and get rid of their waste he absorption of nutrients and the elimination of waste takes place T in the cells x - In your body, the small blood vessels located in your muscles E transport oxygen-rich blood cells to each muscle cell, oxygen diffuses from red blood cells (where it is in high concentration) to muscle cells (where it is less concentrated ) he diffusion process continues until the concentration of waste T oxygen is again equal on both sides of the cell membrane. smosis - a important form of O diffusion iffusion - movement of particles from a region of high concentration D to a region of low (low) concentration ater is essential to life, plants and animals (including humans) use W water to carry out vital operations ormally, water is small enough to cross the cell membrane by N diffusion his means that the water concentration is equal on both sides of the T cell membrane. The cell phone remains the same size