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Transcript
Chapter 1 Sec. 1 Discovering Cells I. Cells are the basic unit of structure and function in all living things. II. First sightings of cells a. Was not possible until the discovery of the microscope (around 1590). i. Microscopes make small things look larger by focusing light through lenses. If more than one lens, called a compound microscope. ii. They changed everyone’s understanding of living things. b. Robert Hooke i. Looked at cork slices and described the millions of cells. c. Anton van Leeuwenhoek i. First to see many one celled animals, including bacteria. III. The cell theory a. A theory is not an educated guess. It is a well-tested statement that explains a wide range of observations. b. Cell theory says i. All living things are made of cells ii. Cell are the most basic structure of living things iii. All cells are produced from other cells IV. How a light microscope works a. Magnification i. The ability to make things look larger ii. The convex lenses bend the light iii. The second lens gets a magnified image and magnifies it further. iv. The power of a microscope is the power of the lenses multiplied. b. Resolution i. Ability to clearly distinguish the parts of the image. Means same as sharpness. V. Electron microscopes a. Use electrons (a part of atoms) to create image, instead of light, so have much better resolution than ordinary microscopes. Chapter 1 Sec. 2 Looking inside cells I. Cell wall a. A rigid layer of non-living material surrounding plant cells only b. Made of cellulose (wood is mostly cellulose) II. Cell membrane a. All cells, plants and animals, have a membrane b. It has openings (pores) that control what goes in or out of the cell III. Nucleus a. The “brain” or control center of the cell which controls everything that happens b. Nuclear membrane i. Works just like the cell membrane c. Chromatin i. Strands that contain all of the genetic material, which has instructions for everything the cell does d. Nucleolus i. A small body where ribosomes are made. IV. Organelles in the cytoplasm a. The cytoplasm is a clear, thick, gel-like fluid that makes up most of the cell. The organelles do most of the work in the cell. b. Mitochondria i. Rod shapes bodies that produce the energy cells need to function. Muscles have many mitochondria. c. Endoplasmic reticulum i. Passageways that move stuff from one part of the cell to another. d. Ribosomes i. Where proteins are made. ii. Proteins control most of what and who we are e. Golgi bodies i. Help the endoplasmic reticulum to move materials throughout the cell f. Chloroplasts i. Green bodies in plants only ii. Turn sunlight into food for the cell g. Vacuoles i. Water-filled sacs that also hold food and other stuff needed by the cell ii. When plants look limp, it’s because their vacuoles are empty h. Lysosomes i. A chemical factory that breaks down food and old, unused cell parts. V. Bacterial cells a. Much smaller and much simpler than plant or animal cells b. Human skin cell 10X as big as a bacteria c. Have cell wall/membrane and ribosomes d. Genetic material is loose in the cell. e. None of the other organelles VI. Specialized cells a. Ranging from very long nerve cells, muscles, bone, to small round blood cells. Chapter 1 Sec. 3 Chemical compounds in cells I. Elements and Compounds a. Element is a substance that cannot be broken down into smaller substances. b. Atom is the smallest unit of an element c. Compounds are two or more elements chemically combined i. Properties are different from the elements that make them up d. Molecules are the smallest unit of a compound II. Organic & inorganic a. Living things are based on (and made up of) carbon-based compounds. Nearly everything with carbon in it is organic i. Exceptions include coal, diamonds, and carbon dioxide. b. Other compounds are called inorganic. c. Carbohydrates, proteins, lipids, and nucleic acids are all organic. III. Carbohydrates a. Made of carbon, oxygen, and hydrogen. b. Sugars and starches are common examples c. Fruits and many vegetables are made of sugars. d. Starches are complex sugars that store better i. Like potatoes , wheat, & rice ii. Your body breaks them down into sugar (glucose) that you can burn IV. Proteins a. Large organic molecules b. Protein structure i. Made from amino acids. There are only 20 amino acids, but can be combined thousands of ways ii. Cannot make proteins w/o amino acids c. Enzymes i. A protein that speeds up (or lowers the temperature) of chemical reactions in living things ii. Life would not be possible w/o enzymes V. Lipids a. Fats, oils, & waxes are all lipids b. Another energy rich source c. A more efficient way to store energy than in carbohydrates d. Cholesterol is a lipid. You need some, but too much builds up in blood vessels and causes heart attacks. VI. Nucleic acids a. Carry the instructions necessary for life b. Have you heard of DNA? That stands for dioxy (2 oxygens) ribo nucleic acid VII. Water & living things a. Water is 2/3 of your body b. Most chemical reactions in your body only take place if compounds are dissolved in water c. Maintains cell size and shape d. Helps maintain a constant temperature Chapter 1 Sec. 4 Cell in its environment I. Cell membrane as a gatekeeper a. Selectively permeable which means it lets some things through and keeps others out b. 3 ways are diffusion, osmosis & active transport II. Diffusion – molecules in motion a. Is the main mechanism used by cells b. It is the process of moving from high concentration to lower concentration i. Concentration is the amount of something in a given volume c. Think about how perfume spreads d. What causes it? i. The higher the concentration, the closer molecules are to each other. ii. Closer means more collisions, which push them apart iii. The molecules keep spreading out until they are evenly distributed e. Diffusion in cells i. If there is a higher concentration outside the cell of something that the membrane will let through, it will diffuse into the cell ii. Like oxygen in water III. Osmosis – the diffusion of water a. A special kind of diffusion, only for water IV. Active transport a. Diffusion/osmosis are passive transport, which means doesn’t require any energy b. Sometimes cells need to move something inside, even though the concentration inside is already higher than outside. This requires energy and is called active transport c. Transport proteins i. Protein picks up molecule and moves it through the cell membrane (in or out) d. Transport by engulfing i. Surrounds something, then pinches off that part of the membrane to form a vacuole V. Why are cells small? a. The bigger it is, the further some of the cytoplasm is from the membrane. It would take too long to move stuff into or out of cytoplasm far away.