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Transcript
THE CELL • 1665- the first cells were seen by Robert Hooke He saw empty cubicles In cork from the bark of a tree. He called them cells. Cells he saw were dead with only the cell wall left 1 THE CELL Scientists learned that the cell was filled with fluid and that it contained a nucleus. (Brown) 1838- Schleiden- studied plant cells and he concluded that all plants are made of cells. 1839- Schwann- said the same thing about animal cells. 1858- Virchow- stated that all cells come from pre-existing cells 2 THE CELL THEORY • All organisms are made of cells • The cell is the basic structure and function in organisms • All cells are produced from preexisting cells. 3 -nucleus -cytoplasm -nucleolus -cytoskeleton -cell membrane -vacuole -mitochondria -chloroplast -golgi Apparatus -centrioles -lysosomes -ribosomes -endoplasmic reticulum(ER) Rough ER & Smooth ER - nuclear membrane - cell wall -chromosomes - large central vacuole 4 Nucleus The “brain” of the cell Controls all of the cellular activities DNA is inside the nucleus 5 Nucleus CHROMOSOMES- are found inside the nucleus carry the information that Chromosomes – determines what traits a living thing will have 6 NUCLEAR MEMBRANE The “picky gate keeper”- lets some things in but not others. 7 NUCLEOLUS The dark area in the nucleus Makes ribosomal subunits. 8 CELL MEMBRANE- PhosphoLipid Bilayer holds the cell together keeps all of the pieces (like the organelles and the cytoplasm) inside the cell controls what goes in and out of the cellthe “gate keeper” Example: like a tea bag with tiny holes in it 9 How does the cell membrane work? Has 2 layers of MOLECULES = BILAYER Bi means two The layers are made up of molecules called phospholipids **THINK OF a sandwich with two pieces of bread and some stuffing on the inside 10 Cell Membrane: PHOSPHOLIPIDS Each phospholipids has a HYDROPHOBIC and HYDROPHILIC end •HYDRO = means water •PHOBIC = means afraid •PHILIC = means loving 11 Cell Membrane: PHOSPHOLIPIDS The fatty acid tails of the molecule are “afraid” of the water and phosphate end “loves” being in the water. Proteins are stuck inside the membrane Proteins are across the bilayer and make the channels that let ions and molecules in and out of the cell Lipid bilayer with embedded proteins!!!!! 12 13 Cell Wall The cell wall is found in plant cells, fungi, some protists and in bacteria, but NOT in animal cells! The cell wall is made of different things in different types of organisms. Plant cell walls are made of cellulose, a structural polysaccharide. 14 Cell wall 15 Mitochondria Mito = Mighty / Power The Power-House of the cell Aerobic cell respiration happens here They break down food molecules so the cell has the energy (ATP)to live If a cell needs a lot of energy…it will have 16 more mitochondria The Mitochondria structure has three main parts: OUTER MEMBRANE: covers the mitochondria INNER MEMBRANE: folds many times to increase the surface area because chemical reactions (glycolysis) occur here So…the more space it has the more energy it 17 can create MATRIX: a fluid that has water and proteins all mixed together (like a solution) •The proteins take the food molecules in and combine them with Oxygen to release the energy (ATP) 18 Ribosomes •small dot-like structures in cells •they are often associated with forming rough ER •Ribosomes are the site of protein synthesis in cells •they are made by the nucleolus of the cell •A ribosome can make the average protein in about one minute 19 Ribosome Structure •Ribosomes are made up of proteins and ribonucleic acid(RNA) •These molecules are arranged into two subunits •These subunits are attached to each other and together form the entire ribosome •When viewed through a light microscope the ribosomes appear as dots 20 Types of Ribosomes •There are two kinds of ribosomes 1) Attached to the rough ER-Attached ribosomes make proteins that are part of membranes or are secreted out of the cell 2) Floating in the cell cytoplasm-Free ribosomes make proteins that are used in the cytoplasm 21 Endoplasmic Reticulum also known as the “ER” it is an organelle inside the cell that is made up of membranes in the CYTOPLASM of the cell, sort of like a vessel system. There are two different Smooth ER Rough ER 22 Smooth ER Main function is to transport things Breaks down poisons in our body Creates steroids- make sex hormones Stores Ions for the cell to keep nutrients balanced 23 Rough ER It has bumps all over it giving it a “rough” appearance Bumps are called RIBOSOMES ER collects the proteins (built by the ribosomes) and creates a bubble around them The proteins may remain embedded in the ER membrane. VESICLE- is formed when the ER pinches off a part of its membrane 24 MOVEMENT of VESICLES **The vesicle can then move to the Golgi apparatus or the cell membrane 1) If the vesicle has protein molecules inside, like hormones or enzymes, then it will float from the Golgi Body to the cell membrane, the proteins are going to be sent out of the cell… (exocytosis) 2) If the vesicle is empty but has embedded proteins, it will become new cell membrane when it attaches to the old cell membrane 25 26 27 GOLGI APPARATUS •Also called the Golgi Complex • The packing and shipping yard of the cell which is made up of a stack of flattened out sacs …like a loose stack of pancake. •Makes LYSOSOMES (animal) •Makes vesicles for secretion out of the cell 28 Think about building a model of a ship (that's the molecule). Then take that model and put it in a bottle (that's the vesicle). 29 Golgi apparatus 30 LYSOSOMES (animal) •They combine with the food vacuoles formed • by the cell •The enzymes in the lysosome bond to food & digest it (acidic interior) • Next…smaller molecules are released which are absorbed by the mitochondria and used to make energy (ATP) 31 LYSOSOMES • When an organelle no longer works, the lysosome will attach itself to it and break it down like food (kind of like a cannibal) – Chemicals can then be reabsorbed or excreted • Lysosomes can also destroy the cell if it breaks open accidentally – “Suicide Sacs” – UV light damages lysosome membrane • The enzymes inside the lysosome spread throughout the cell and digest it 32 LYSOSOMES 33 Lysosome Animation 34 CYTOPLASM Cytoplasm- everything inside the cell membrane & outside of the nucleus – Jelly-like, mostly water. Keeps organelles in a homeostatic environment. Anaerobic respiration occurs here. cytoplasm 35 CYTOSKELETON • Chief functions include: – movement of material through the cell for stuff not diffusion or osmosis – maintaining the shape of the cell – keeping the cell from getting smashed 36 37 VACUOLE • Vacuoles are “bubbles” that float in the cell • Vacuoles are more important to the survival of plant cells than they are to animal cells 38 VACUOLE: STORAGE IN PLANT CELLS • The large central Vacuole in plants support structure. So, when there is no water…the vacuole shrinks and the cell wall is the only thing holding the plant together. • Vacuoles hold onto things that the cell might need…like a backpack • There are some vacuoles that hold onto waste products, similar to having a big septic tank • Storing waste products protects the cell from 39 contamination You will know that a plant's vacuoles are shrinking when you see the plant begin to droop over HOLDING UP THE WALLS 40 Turgor Pressure- force exerted by the water entering (osmosis) the vacuole, which then swells exerting internal force on the cell wall •Causes “rigidity” so the plant my increase by stacking cells 41 Chloroplast 42 Chloroplast •the site of photosynthesis in eukaryotic cells •disk-like structures •composed of a single membrane •surrounding a fluid containing stacks of membranous disks 43 •SOLAR energy radiated from the sun is captured by plants(chloroplast) Chloroplast •Then it is instantaneously changed into ELECTRICAL energy •Then packaged as CHEMICAL energy 44 Chloroplast •photosynthesis takes place inside the chloroplast the process in which plant use Photosynthesis- water, carbon dioxide, and energy form the sun to make food 45 Centrioles: •generally appear in animal cells •they look like two cylinders at right angles to one another •they help to form the fibers that move chromosomes around when the cell is dividing •as animal cells prepare for cell division these two centrioles separate and go to opposite ends of the cell. 46 47 48 49 Answer the following questions using your notes 1. Which organelle is known as the “Brain” of the cell? 2. If you look at a picture of a cell, how would you recognize the nucleolus? 3. List the 3 main jobs of the cell membrane 4. Explain why the cell membrane has tiny holes made of protein in it. 5. The term hydro means _________. A. If something is hydrophobic it is _________ 50 B. If something is hydrophilic it is __________ 6. Which organelle is known as the Power House” of the cell? 7. Explain how you could distinguish the rough ER from the smooth ER. 8. What is the main job of the smooth ER? 9. The process of H2O moving across the cell membrane is called? 51 10. What is the main function of a lysosome? 11. What happens if a lysosome breaks open? 12. Why are vacuoles important to PLANTS? 13. Which organelle is the site of photosynthesis? 14. What are the three main ingredients for photosynthesis? 52 15. Centrioles are usually found in __________ cells. 16. What is the main function of a centriole? 17. List the two places you can find a ribosome in an animal cell. 18. What do ribosomes make? 53