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Biology 12

Biology 12. Introduction to the Cell. Cells. Recall from grade 11: All living things....plants, animals, fungi, bacteria and protists ...share a number of characteristics They move, take in nutrients, excrete wastes, respire, reproduce, grow, respond to stimuli

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Biology 12

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  1. Biology 12 Introduction to the Cell

  2. Cells Recall from grade 11: • All living things....plants, animals, fungi, bacteria and protists...share a number of characteristics • They move, take in nutrients, excrete wastes, respire, reproduce, grow, respond to stimuli • They are all made of 1 or more cells, containing DNA

  3. The Cell Theory • All living organisms are made up of 1 or more cells • The cell is the basic unit of life • All cells come from the division of pre-existing cells

  4. Cell Trivia • Average size of a cell? 0.001 cm = 0.1 mm = 10 um • Smallest cell? 0.3 um = a mycoplasm • Largest cell? Some algae are 2-3 cm; egg of a chicken is 1 cell

  5. Draw an ‘O’ on your page.... • 40,000 red blood cells (rbc) in that circle • Make 2.5 million new rbc’s/second • Draw a 1 cm square on your arm... • 150,000 skin cells in that square • How many cells are in your body? • 50-100 trillion cells

  6. Prokaryote vs. Eukaryote • Bacteria cells • No nucleus (DNA loose in cytoplasm) • No membrane-bound organelles (have ribosomes) • Outer covering is chemically different • Animal, plant, fungus & protist cells • DNA always in the nucleus • Many membrane-bound organelles (nucleus, chloroplast, ER, Golgi apparatus, etc..) • Outer covering is chemically different

  7. The big idea for this unit • The cell is the basic unit of life • Living cells are composed of elements that form large, complex molecules • These molecules are arranged into the functional units of the cell called ORGANELLES • We can see how the cell operates by understanding how each organelle functions and how they work together.

  8. Let’s see what you remember from good old grade 9….. • Find a group of 3 or 4 • Draw a cell (plant or animal) and label as many organelles as you can remember. • Describe the functions of the organelles you have drawn • Trade with another group and add to theirs if needed

  9. Cell Structures (note: the letters beside the structure names refer to the cell diagrams.)

  10. Cell Structures For each of the cell structures, you need to know their… • Basic structure • Function(s) • How functions relate to other structures • Picture • Electro micrograph picture

  11. Cytoplasm(x) • Semifluid medium that contains all the organelles. • The “filler” of the cell.

  12. Cell Membrane (a) • Phospholipid bilayer • has proteins embedded in it • (More on this next week)

  13. Cell Membrane (a) • Regulates materials that enter and leave cell • Recognition of foreign cells and materials • Allows cells to adhere (stick) to each other • Carries messages and info to other cells • Provides the cell with support, structure, shape, and strength • Responds to the environment (ex. touch)

  14. Cell Wall (b) • Only in plant cells • Made of cellulose • Makes a strong “box” around outside of cell which provides structure and supports the cell shape

  15. Nucleus (c) • The nucleus is a complex structure. • It is full of important structures, such as nucleoplasm, chromatin and the nucleolus

  16. Chromatin (ch) • Threads of DNA that are suspended in the nucleoplasm (a semi-fluid just like the cytoplasm). • When chromatin coils up it will form chromosomes.

  17. Nucleus (c) • 2 main functions • Contains DNA: DNA carries genetic information from one generation to the next • Control center of cell (it contains the “blueprints” for making proteins & dictates which proteins are produced in the cell – therefore controlling the chemical reactions of the cell and body)

  18. Nucleolus (d) Nucleolus (nucleoli—plural) • Located in the nucleus (may be one or more) • rRNA (ribosomal RNA) is made in the nucleolus • Then rRNA joins with proteins to make RIBOSOMES (g) • Thus, it is the site of ribosome synthesis

  19. Nuclear Membrane (e) • Surrounds the nucleus • Double membrane = 2 phospholipid bilayers • Nuclear Pores (f): openings that allow materials in and out

  20. Nuclear Membrane (e) • It controls what materials enter and leave the nucleus

  21. Ribosomes (g) • Made of 2 components • Protein & rRNA (ribosomal RNA) • They are the site of protein synthesis (where proteins are made) • Exist as either free in cytoplasm or bound to ER

  22. Ribosome (g) • Bound ribosomes are attached to the ER (rough ER) & normally make proteins used in cell membrane or transported out of cell • Free ribosomes are suspended in the cytoplasm and usually make proteins used within the cell • In both cases, ribosomes are not usually loose but in clumps called polysomes

  23. Endoplasmic Reticulum “ER” (h,i) • The phospholipid bilayers are in the shape of flattened membranous tubes or tunnels and extend throughout the cell • Rough ER (h) has ribosomes attached, smooth ER (i) does not • Rough ER is basically an extension of the nuclear membrane

  24. Endoplasmic Reticulum • 3 main functions: • Makes/ manufactures materials (proteins, lipids, carbohydrates etc.) • RER makes proteins (h) • SER makes lipids/ involved in carb metab. (i) • Begins to modify proteins • Ex. Adding a sugar chain to it (now called glycoprotein) • Transportation—moves materials from 1 part of the cell to another (ex. takes materials like proteins to Golgi Apparatus)

  25. Golgi Apparatus (j) • Series of phospholipid bilayer (membranes) that appear to be stacked on top of each other (like pancakes)

  26. Golgi Apparatus (j) • Cis Face (side facing ER): • Processing = modifying materials such as those received from ER • Ex. joins things to the protein or lipid, changing them to their final form • Packaging = puts final product into a vesicle for export • Trans Face (side facing away from ER): • Ships material off to cytoplasm and cell membrane

  27. Vacuoles (k) • Phospholipid bilayer surrounding something (food, chemicals, fat, water, hormones, proteins) • Function: Stores materials and moves them from one place to another • Vesicle: a small vacuole! (L)

  28. Putting it all together

  29. Lysosomes (m) • Special type of vacuole/ vesicle that contain enzymes (break down materials) • Break down materials like food • Some enzymes break down invaders, cell debris, foreign material

  30. Peroxisomes (n) • A special type of vacuole that contains enzymes which detoxify alcohols, metabolize fatty acids and other materials, breakdown peroxides • Often found attached to smooth ER • Large number of peroxisomes (and smooth ER) found in liver and kidney to detoxify materials

  31. Mitochondria (o) • Surrounded by 2 phospholipid bilayers (double membrane) • Has its own DNA: can be independent and replicate itself Function: • Makes energy for the cell (location where cellular respiration occurs to make ATP (ATP is the cell’s energy currency)

  32. Mitochondria (o) Consists of: • An outer membrane (p) • An inner membrane (q)that is highly folded (called cristae) (r) • The matrix (the inner fluid-filled space) (s)

  33. Plastids • Only plant cells have plastids • Surrounded by a double membrane • Have their own DNA • Different types of plastids that contain different chemicals • Ex. Chloroplast (contains chlorophyll) (t) • Ex. Leucoplast, chromaplast

  34. Chloroplasts (t) (u) (v)

  35. Microtubules and Microfilaments • Long, thin rods made of protein • If protein makes a coil or thread structure = a microfilament • If protein is in a tube/ tunnel = microtubule • Give the cell shape and causes movement—can move whole cells (cilia & flagella) or things inside (centrioles & cytoskeleton)

  36. cytoskeleton

  37. Centrioles (w) • Only found in animal cells • Seen during cell division, when chromosomes pull apart. • Made of microtubules in a specific arrangement

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