Cell Structure and Function

1. Hail University Faculty of Sciences Department of Biology Practical Biology Biol 101Lab 3 Cell Structure and Function

2. The cell is the structural and functional unit of all living organisms. • Researches had formulated the cell theory that has three principles: • Robert hookewas the first scientist who look at cells under a microscope by viewing and describing the box – like structures of cork. • All organisms are composed of one or more cells. • The cell is the basic functional unit of living organisms. • All cells arise by division of pre-existing cells

3. All cells share four structural features: • Plasma membrane • Delineate the border of the cell • Function in regulate the passage of materials into and out of the cell. • Deoxyribonucleic acid (DNA) • Function as the genetic instructions for the cell. Plasma membrane Genetic material DNA

4. Plasma membrane • Ribosomes • Function as a site of protein synthesis • Cytoplasm • Components enclosed by the plasma membrane by which the rest of organelles are floating. Ribosome Cytoplasm Genetic material DNA

5. Cells vary in: • Size • Function • Organization With respect to internal organization there are two major types of cells according to the presence of nucleus. Nucleus is the spherical organelle within the cytoplasm, which contain the genetic materials (DNA) and controls cell metabolism and division.

6. Prokaryotic (before the nucleus) • Eukaryotic (true nucleus)

8. Basic shapes of bacterial cells • Spheres (cocci)

9. Rods (bacilli)

10. Spirals

11. Humancheekepithelialcells The cells that line the inner check (inside the mouth) called epithelial cells, easily removed by: • With a clean toothpick, gently scrape the inside of your cheek several times. • Roll the scraping into a drop of water on a clean microscope slide. • Add a small drop of methylene blue. • Cover with coverslip gently. • Discard the used toothpick. • Examine under microscope and notice:

12. The cell appear as pentagons • The cells are flat • The nucleus will beblue • The cytoplasm will stain light blue • The cell membrane

13. Onion epidermal cells Prepare a wet mount of onion epidermal tissue according to the steps Cut an onion bulb into quarters. Remove one of the fleshy scale leaves

14. Fold the leaf backward to produce a ragged piece of epidermis. Peel back a small piece of epidermis.

15. Spread the epidermis in a drop of water on a slide Add a small drop of Lugol’s solution, gently cover it by cover slip to avoid air bubbles Observe under microscope and notice

16. The shape of onion cells • The nucleus • The cell wall • Cytoplasm

17. Plant cell Cell wall Cell membrane Golgi apparatus Ribosome Chloroplast Smooth ER Nucleus Rough ER Large central vacuole Mitochondrion Cytoplasm

18. Animal cell Mitochondrion Lysosome Golgi apparatus Rough ER Nucleus Smooth ER Cell membrane Cytoplasm Ribosome

19. Animal cells compared with plant cells

20. Thank You