Honors Biology – Chapter 4: Cells

1. Honors Biology – Chapter 4: Cells Let’s review!

2. The Cell Theory • 1. All living things are made of cells • 2. All cells come from other cells.

3. Prokaryotic cells • Bacteria and archaea are prokaryotes. • Prokaryotes are: • Smaller and simpler than eukaryotes • Have a plasma membrane, chromosomes, and ribosomes. • Have a ‘nucleoid’ but no true organelles.

4. The surface of prokaryotes may: • Be surrounded by a chemically complex cell wall • Have a capsule surrounding the cell wall • Have short projections (fimbriae) that help attach to other cells or the substrate, OR • Have longer projections (flagella) that help propel the cell through its liquid environment.

5. Comparing Prokaryotes and Eukaryotes

6. Eukaryotic cells • Nucleus: • Contains most of the cell’s DNA (called chromatin in a non-dividing cell) • Contains the nucleolus (where ribosomal RNA is made • Is surrounded by a nuclear “envelope”, a double membrane with pores.

7. Eukaryotic nucleus

8. Ribosomes • Involved in the cell’s protein synthesis. • Some are free – suspended in the cytoplasm; used to make proteins that function in the cytoplasm itself • Some are bound – attached to the endoplasmic reticulum.

10. Endoplasmic Reticulum (ER) • Smooth ER does not have attached ribosomes and looks smooth. • Some smooth ER helps store calcium. • It also produces enzymes: • Some are important in the making of lipids, oils, phospholipids and steroids. • Some help process drugs and alcohol

13. Rough Endoplasmic Reticulum • Rough ER has ribosomesattached to it, giving it a rough or studded appearance. • It makes more membrane for itself • It makes proteins destined to leave the cell

15. Golgi apparatus • Serves as a molecular warehouse and finishing factory for products made by the ER.

17. Lysosomes • Lysosomes are membranous sacs containing digestive enzymes. • It helps digest food particles engulfed by a cell. • It also helps remove or recycle damaged parts of a cell.

19. Vesicles • Temporary membrane ‘bags’ that help move things around the cell.

20. Vesicles in action!

21. Vacuoles • Large vesicles that have a variety of functions. • Help eliminate excess water in a freshwater protist. • In plants, vacuoles may: • Have digestive functions • Contain pigments • Contain poisons that help protect the plant.

22. Contractile vacuoles in a paramecium (a freshwater protist)

23. Food vacuole

24. Mitochondria • Harvest chemical energy from food in the process of cellular respiration. • In prokaryotes, this process is carried out by the plasma membrane.

25. Mitochondrion

26. Chloroplasts • Convert light energy to chemical energy through the process of photosynthesis

27. Chloroplasts

28. Cytoskeleton • Provides a dynamic changing framework to support the cell.

30. Cell junctions – animal cells • Animal cells: • Tight junctions – prevent leakage • Anchoring junctions – fasten cells together into sheets • Gap junctions – channels that allow molecules to flow between cells

31. Tight junctions

32. Anchoring junctions

33. Gap Junctions

34. Cell junctions – Plant cells • Plant cells have plasmodesmatathat serve in communication between cells.

35. Plasmodesmata