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Chemical Compounds in Cells and The Cell in its Environment. Elements and Compounds. What is an element? An element is any substance that cannot be broken down into simpler substances The smallest unit of an element is an atom .
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Elements and Compounds • What is an element? • An element is any substance that cannot be broken down into simpler substances • The smallest unit of an element is an atom. • All living things include carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur. • What is a compound? • A compound is made up of two or more elements. • Carbon dioxide is a compound. What elements make up carbon dioxide? • Carbon and oxygen
Organic and Inorganic Compounds • Organic compounds contain carbon, inorganic compounds do not. • Carbohydrates, lipids, proteins and nucleic acids all contain carbon. • These are common compounds in the food we eat.
Organic Compounds • Carbohydrates- energy rich • Sugars are produced during the food making process in plants • Fruits and some vegetables have high sugar content • Lipids- energy rich • Fats, oils and waxes are lipids • Cell membranes are made of lipids
More Organic Compounds • What do bird’s feather, a spider’s web and your finger nail have in common? • They are all made of protein. • Proteins are made up of amino acids • There are 20 common ones that combine to form thousands of different proteins. • Much of the structure and many of the organelles of cells are made up of proteins.
Water • Most chemical reactions within cells could not take place without water. • Water helps cells keep their size and shape. • Water helps keep the temperature of the cell from changing rapidly.
The Cell in Its Environment • The cell membrane separates the cell from the outside environment. • The cell membrane is selectively permeable. • This means some substances can pass through while others cannot.
Diffusion • Diffusion is the main method by which molecules move across the cell membrane. • In diffusion, molecules ALWAYS move from an area of higher concentration to an area of lower concentration.
Osmosis • Osmosis is the diffusion of water through a semipermeable membrane. • Cells depend on osmosis because, they cannot function properly without water. • Why can’t people drink large amounts of salt water?
Active Transport • Passive transport if the movement of dissolved material through the cell membrane without using cellular energy (high to low). • Active transport requires cellular energy (low to high). This can be done in 2 ways. • Transport proteins “pick-up” method • Engulfing