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Key Idea #14 Cells in all multicellular organisms are specialized to take in nutrients, which they use to provide energy for the work that cells do and to make the materials that cells or organisms need. http://library.thinkquest.org/C004535/media/cell_membrane.gif Chemical Compounds in Cells Nutrients taken in by the cell provide materials to build cell organelles build specialized molecules used by the organisms, including: – – – – carbohydrates lipids (fats) proteins nucleic acids: DNA and RNA In plants, water and carbon dioxide are taken in by the plant and used to produce carbohydrates, proteins and fats (lipids). Carbohydrates are energy-rich compounds made of the elements carbon, hydrogen, and oxygen. are an important part of cell membranes and cell walls. include sugars found in fruits and some vegetables. include starches found in potatoes, corn, rice, and wheat bread which your body breaks down into glucose (a sugar). Proteins are large organic molecules made of carbon, hydrogen, oxygen, nitrogen and sulfur. are found in foods such as meats, eggs, fish, nuts and beans. form parts of cell membranes. make up many of the organelles found in cells. are used by cells in your body to build body parts such as hair and nails. ldenicola.wordpress.com publications.nigms.nih.gov Fats (Lipids) are energy-rich compounds made of carbon, hydrogen, and oxygen. include fats, oils, and waxes found in seeds. – – – – Peanuts, almonds walnuts (fat) Sunflower (fats) Olive (oil) avocado (oil) include cholesterol. – an important part of animal cell membranes – Meat, cheese, and eggs are all high in cholesterol. FYI The jojoba (Simmondsia chinensis), a native shrub of the southwestern United States produces seeds and liquid wax. The white, solid wax is produced by hydrogenation of the unsaturated liquid wax. Hydrogenation is the process that involves the addition of hydrogen to the fatty acids under heat and pressure. Nucleic Acids are very large organic molecules made of carbon, oxygen, hydrogen, nitrogen, and phosphorus. contain the instructions needed to carry out life. – DNA: • genetic material that contains the information that is passed from parent to offspring – RNA: • important for protein production • found in the cytoplasm and nucleus Plants are multicellular organisms that produce their own food. Plants use energy from light to make sugar molecules from the atoms of carbon dioxide and water. Plants use these sugars along with minerals from the soil to form fats, proteins, and carbohydrates. Fats, proteins and carbohydrates can be used immediately, incorporated into the cells of a plant as the plant grows, or stored for later use. Water helps cells keep their size and shape. is important because most chemical reactions in cells require water. botany.thismia.com Cell Membrane acts as a gatekeeper is selectively permeable and controls what substances can enter or leave the cell is permeable to oxygen, water, and carbon dioxide – (they can pass through it) is not permeable to some large molecules and salts – (they can’t pass through it) Substances that can move into and out of a cell use one of three methods: diffusion osmosis active transport Diffusion – Molecules in Motion Diffusion is the main method by which small molecules move from an area of higher concentration to an area of lower concentration. Diffusion occurs when molecules bump into each other and eventually spread out evenly throughout an area. Diffusion and Osmosis Osmosis is the diffusion of only water molecules through a selectively permeable membrane. is important to cells because they can’t function properly without adequate water. Note: Only water molecules pass through the cell membrane during osmosis. http://www.biologycorner.com/resources/osmosis.gif Active transport uses the cell’s energy (ATP) to help nutrients enter the cell that can’t pass through the cell membrane by diffusion. Active Transport Active transport examples: Engulfing Transport proteins in the cell membrane pick up molecules outside the cell and carry them inside. http://www.nicksnowden.net/images/Membranes_and_Transport/endocytosis.gif ; phschool.com.jpg