Section 2.1 Cell Structures and Types of Cells

1. Section 2.1Cell Structures andTypes of Cells

2. Cell Compartmentalization • Organelles- “tiny organs” inside the cell • have a specific job to maintain homeostasis (healthy cell) • Some are in all cells • Some are only found in either animal or plant cells

3. Structure- parts of a cell visible through a light microscope • Ultrastructure- parts of a cell visible through only an electron microscope • Plasma Membrane- “wall and gate” of the cell; 7nm wide • Selective permeability - allows some molecules to pass through while keeping others out. • Transport proteins- special tunnels or doors that only let in specific molecules Organelles of an Animal Cell

4. The Nucleus • The “brain” of the cell • Contains loosely coiled DNA (Chromatin) • Nucleolus- Compact, largely inactive DNA in chromosome form

5. Ribosomes • Ribosomes- • Factories of the Cell • Take copy of DNA’s information (mRNA) and use it as a guide to create proteins from amino acids • ER ribosomes- proteins move on to Golgi apparatus • Free ribosomes- proteins move to cytoplasm

6. Golgi Apparatus Golgi Apparatus- membrane sacs that put proteins into small packages called vesicles which are sent out or around the cell; makes lysosomes Lysosomes- sacs of hydrolytic enzymes that digest old organelles, food, and viruses/bacteria

7. The Mitochondria • power house of the cell; produces ATP (energy unit for cells) by breaking down sugars and other organic compounds • Two membranes with inner one folded many times • Matrix (inner area) produces ATP and lipids

8. Organelles for Support Cytoplasm- clear gel-like fluid inside cells; help holds organelles in place Cytoskeleton- “Bones” of the cell; crossing rods, filaments, and tubes, that hold the cells shape. Also act at a “train” system to move things around the cell

9. Cilia and Flagella • Flagella- long, wipe-like tail that pushes and rolls the cell • Move in long strokes • Cilia- short, hair-like paddles that push the cell along • Move in short fast beats all at same time

10. Organelles of a Plant Cell • The organelles already covered can also be found in plant cells • Plants have a few extra organelles • Cell wall- thick, rigid wall made of cellulose that gives the plant cell a definite shape • Plasmodesmata- small connecting points between the cells walls of neighboring plant cells; allow exchange

11. Photosynthesis Centers Chloroplasts- perform photosynthesis to make energy from sunlight in planets and some unicellular organisms Chlorophyll- chemical that absorbs wavelengths of sunlight, expect green Grana- stacks of membranes containing chlorophyll

12. Vacuoles- Both Large and Small • Vacuoles- storage compartments for food, enzymes, etc. • In plant cells- they are very large and hold lots of water and nutrients; tonoplast membrane controls exchange; also holds pigments the give flowers color • Creates turgid pressure to keep plant up right • In animal cells- very small; transport things inside the cell

13. Animal Cells Vs. Plant Cells

16. Specialization of Cells • Specialized Cells cells with physical features that allow them to do specific jobs • Ciliated cells • found in your throat and lungs • cilia on one side push material in certain direction • cilia + mucus = dust trapper • Root hair cells • found on the roots of plants • increase surface area of cell so it can absorb more water/minerals • Major theme in biology! • mitochondria, root cells, intestine, brains… all have many folds!

17. Specialization of Cells • Xylem vessels • empty waterproof tubes that allow movement of water/minerals through out the plant • Muscle cells • long, thin fibers that can shrink (contract) and expand (relax) • Allow all movement and support for skeleton • Red blood cells • contain haemoglobin; protein with Fe2+ ions that can transport O2 and some CO2 • Reason blood is red • Flat round discs allow for movement in body and exchange of gasses

18. Limits of Light • Human eye 100 μm • 1 μm= 1x 10-6 m (micron) • 1nm= 1 x10-9 m • Light microscopes show us: • Plasma membranes, cytoplasm, mitochondria, cell walls, nucleus, etc… • But we hit a limit; 0.2 μm(200nm) • Magnification number of times larger an image is to the real size of the object • Mag= size of image / real size of object • X1500 for light microscopes • Resolution ability to distinguish between two points; clarity • ½ the wavelength of radiation used • Light is 400nm – 700 nm

19. Mag and Res Practice 700nm line between VL/Infrared Resolution = ½ radiation used 0.5 * 700nm 350nm • What is the max. resolution possible for an image made using infrared? 2) Based on the image of HIV shown, what is the actual size of the virus? 3) What wavelength would be needed to take this image? 9mm 9000μm 9000 μm / 75,000 = 0.12 μm (120nm) 120nm = 0.5 x wavelength of radiation Wavelength= 240 nm (UV light)

20. Homeostasis: Happy Cells • In single-celled organisms this is not very difficult • In multi-celled, complex organisms there are many levels to organize: • Cells Single unit of life; can be specialized for a specific job (muscle cell) • Tissue Groups of the same cells working together to do a specific job (muscle tissue) • Organ Tissues grouped together to do a specific job (heart) • System Organs and extra parts working together for a specific job (Circulatory system)

21. Tissues Working Together • Plant tissue: • Upper epidermis water proof outer covering; covered with cuticle • Palisade mesophyll photosynthetic cells • Spongy mesophyll space for CO2 circulation • Phloem transport solutes • Xylem transport water and salts • Lower epidermis stomata for gas exchange

22. Homework • Read all of Unit 2 • Unit 2 Vocab is due on Sunday (Friday schedule) • Questions on p. 19 and p. 23 • Organelle Worksheet There is too much vocabulary!