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Cells Mr. Mincer/Mrs. Scully Living Environment Life is Cellular! • All life is made of either a single cell, or a collection of cells • Discovered in the mid 1600’s, because that’s when microscopes were invented. • Cells can be very small and simple, or large and complex Cell Theory • Cell theory has three main ideas: – All living things are composed of cells – Cells are the basic unit of structure and function in living things – New cells are produced only from existing cells Cells • All cells have a few things in common: – All contain genetic material (DNA) – All have a cell membrane which will selectively let certain materials through – All need a microscope to be seen Types of Cells • There are two types of cells – Prokaryote-smaller, not as well organized – Eukaryote -Bigger, most multi-cellular organisms are made of eukaryotic cells Prokaryotes • No Nucleus – The nucleus is the place in some cells where the DNA is stored • No organelles (or very few) – An organelle is a structure within a cell that has a specific function, like an organ • Example: Bacteria Eukaryotes • Contain a nucleus and organelles • Usually larger than prokaryotic cells • Thought to have evolved from a symbiotic relationship between two prokaryotic cells • All multi-cellular organisms are made up of eukaryotic cells Cells Are Factories • In a factory, many different raw materials are brought in and assembled into finished products • In a cell, the same thing happens – Raw materials, or molecules, are brought in and different organelles rearrange and assemble them into the things the cell needs – Each organelle has a different job, just like different workers in a factory – The nucleus tells the other organelles when and how much of the products they produce Organelles • Nucleus-Stores DNA, which is the blueprint for almost everything that happens in the cell (The foreman) • Ribosomes- Create proteins (worker) • Endoplasmic Reticulum- Assembles lipids and proteins (worker) • Golgi Apparatus- Modifies, sorts and packages proteins (shipping department) Organelles Cont’d • Lysosomes- Dissolve old or broken organelles (Janitorial Staff) • Vacuoles- Storage spaces for the cell, can store water, food, toxins, etc. (Warehouse) • Mitochondria- Convert molecules into energy (Generators) • Chloroplasts- Converts sunlight, CO2, and H2O into food (Cafeteria) Cytoskeleton • Eukaryotic cells have a skeleton, just like you! • There skeleton is made of protein fiber, or filament, which helps support the cell, but also helps with transportation Cell Membrane and Walls • Cell Wall-Plants, Fungi, and some Prokaryotes have cell walls. Mostly made from carbohydrates, they provide support and protection. • The cell membrane (which both prokaryotic and eukaryotic cells have) is called the lipid bilayer – Lipids are fats, and bi means 2. So, the lipid bilayer means 2 layers of fat molecules Cell Organelles Passive vs. Active Transport • Active Transport- The cell has to use Energy to move something • Passive Transport-The cell doesn’t use any ENERGY to move something – Diffusion – Osmosis – Facilitated Diffusion Diffusion • The process by which a fluid flows from where it is to where it isn’t – Or, from areas of high concentration to areas of low concentration – E.g. Sugar molecules will move from an area of high concentration to an area of low concentration Osmosis • Same thing as diffusion, except: It’s Only Water Molecules!! Facilitated Diffusion • Same thing as diffusion, but the cell membrane helps the process out by using specific structures to help the molecules make it through the membrane. Effects of Osmosis on Cells • Isotonic- Same amount of water in as out • Hypertonic- Less water outside the cell, so the cell shrinks from water loss • Hypotonic- Less water inside the cell, so the cell swells from inflow of water Active Transport • Endocytosis- Folding the cell membrane around something. • Pinocytosis-Folding the cell membrane around a small amount of liquid to take into the cell • Exocytosis-Merging the membrane of a vacuole with the cell membrane to expell something from the cell • Phagocytosis- Large extensions of cytoplasm surround another cell, or food particle. Endocytosis Pinocytosis Droplets of fluid Exocytosis Phagocytosis Cellular Respiration • Cells need ENERGY! • Cells get their energy from breaking down chemical bonds. • This process is called: Cellular Respiration. Cellular Respiration • It ALWAYS starts in the cytoplasm with a process called: GLYCOLYSIS! • Glycolysis: Glucose is broken down into two pyruvic acids and the cell gains 2 ATP. • ATP is ENERGY! It’s the molecule that your cells use to store energy. After Glycolysis… • Then, if there is oxygen AND mitochondria… – The process moves into the mitochondria into the Krebs Cycle for 2 more ATP – Then onto the Electron Transport Chain for 32 ATP! – This is called: • Aerobic Cellular Respiration 2 2 32 Electron Transport Chain • Yields a TON of ATP (32 per glucose molecule!) Cellular Respiration • C6H12O6 + O2 CO2 + H2O + ENERGY! + + + After Glycolysis if no O2 • Alcoholic Fermentation – 2 pyruvic acids are turned into 2 more ATP and alcohol • Lactic Acid Fermentation – 2 pyruvic acids are turned into 2 more ATP and lactic acids Mitosis! • Mitosis is the process by which cells divide and end up with the same exact amount and type of DNA as the parent cell. Four Phases… • 1. Prophase-To begin mitosis, the nuclear membrane breaks down, while the chromosomes shorten and thicken (a chromosome is two chromatids, bound at a point called the centromere, making an "X" shape). The other structures important for mitosis also form (i.e. the centrioles). • 2. Metaphase- Spindle fibers align the chromosomes along the middle of the cell nucleus. This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive only one copy of each chromosome, for a complete set. Last Two… • 3. Anaphase-The paired chromosomes separate at the centromere and move to opposite sides of the cell. Motion results from a combination of centromere movement along the spindle microtubules and through the physical interaction of polar microtubules. • 4. Telophase-Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the light microscope. The spindle fibers disperse, and cytokinesis or the partitioning of the cell may also begin during this stage. Cytokinesis • The process by which the cell finishes dividing. – Animal cells- The cell membrane pinches closed into two daughter cells – Plant cells- A cell plate forms, which becomes the new cell wall for the daughter cells, then the new cell membrane forms. Cancer • Cancer is just the unregulated division, by mitosis, of a cell. • Your immune system catches most cancerous cells, but the ones that it doesn’t can become life-threatening.