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T H E C E L L

Explore the history, theory, and components of cells, including the nucleus, cell membrane, mitochondria, ribosomes, and endoplasmic reticulum.

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T H E C E L L

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  1. THECELL • 1665- the first cells were seen by Robert Hooke The Cell theory- The idea took 200 years to develop 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

  2. 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

  3. THE CELL THEORY All organisms are made of cells The cell is the basic structure and function in organisms All cells are produced from pre-existing cells.

  4. The Organelles -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

  5. Nucleus • The “brain” of the cell • Controls all of the cellular activities • DNA is inside the nucleus

  6. Nucleus are found inside the nucleus CHROMOSOMES- carry the information that determines what traits a living thing will have Chromosomes –

  7. NUCLEAR MEMBRANE • The “picky gate keeper”- lets some things in but not others.

  8. NUCLEOLUS • The dark area in the nucleus • Makes ribosomal subunits.

  9. CELL MEMBRANE- Phospho-Lipid 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 cell- the “gate keeper” Example: like a tea bag with tiny holes in it

  10. 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

  11. Cell Membrane: PHOSPHOLIPIDS • Each phospholipids has a HYDROPHOBIC and HYDROPHILIC end • HYDRO = means water • PHOBIC = means afraid • PHILIC = means loving

  12. 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!!!!!

  13. Cell Membrane

  14. 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.

  15. Cell wall

  16. 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 more mitochondria

  17. 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 can create

  18. 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)

  19. 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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

  26. Smooth ER vs. Rough ER

  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. GOLGI APPARATUS 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 • Next…smaller molecules are released which are absorbed by the mitochondria and used to make energy (ATP) • The enzymes in the lysosome bond to food & digest it (acidic interior)

  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. CYTOSKELETON

  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 contamination

  39. 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) • Then it is instantaneously changed into ELECTRICAL energy • Then packaged as CHEMICAL energy Chloroplast

  44. Chloroplast • photosynthesis takes place inside the chloroplast the process in which plant use water, carbon dioxide, and energy form the sun to make food Photosynthesis-

  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. Centrioles

  47. Exercize your brain w/ Review Questions

  48. 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 _________ B. If something is hydrophilic it is __________

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