1. Cells and Tissues

2. Cells and Tissues
Carry out all chemical activities needed to sustain life
Cells are the building blocks of all living things
Tissues are groups of cells that are similar in structure and function

3. Anatomy of the Cell Cells are not all the same
All cells share general structures
All cells have three main regions
Nucleus
Cytoplasm
Plasma membrane
Figure 3.1a

4. The Nucleus Control center of the cell Contains genetic material (DNA)
Three regions
Nuclear envelope (membrane)
Nucleolus
Chromatin

5. The Nucleus
Figure 3.1b

6. The Nucleus Nuclear envelope (membrane) Barrier of the nucleus
Consists of a double membrane
Contains nuclear pores (relatively large) that allow for exchange of material with the rest of the cell
Nucleoplasm – jellylike fluid in which the nucleoli and chromatin are suspended.

7. The Nucleus Nucleoli Nucleus contains one or more nucleoli
Sites of ribosome assembly
Ribosomes migrate into the cytoplasm through nuclear pores
Serve as the actual sites of protein synthesis

8. The Nucleus Chromatin Composed of DNA and protein
Present when the cell is not dividing
Scattered throughout the nucleus
Condenses to form chromosomes when the cell divides

9. Plasma Membrane Barrier for cell contents Double phospholipid layer
Hydrophilic heads
Hydrophobic tails
Also contains:
proteins
cholesterol
glycoproteins

10. Plasma Membrane Proteins Scattered through out lipid bilayer.
Responsible for most specialized functions
Enzymes
Receptors, or bindings sites, for hormones
Chemical messengers
Most are involved in transport functions

11. Plasma Membrane Cholesterol Located in the plasma membrane
Helps to stabilize membrane
Helps keep membrane fluid

12. Plasma Membrane Glycoproteins
Branching sugar groups attached to most proteins.
Found on the extracellular side
Gives the cell a fuzzy, sticky, sugar-rich surface
Determine your blood type
Act as receptors for bacteria, viruses or toxins

13. Plasma Membrane
Figure 3.2

14. Plasma Membrane Specializations
Microvilli
Finger-like projections that increase surface area for absorption

15. Plasma Membrane Specializations
Membrane junctions
Tight junctions
Impermeable junctions
Bind cells together into leakproof sheets
Small intestines – prevent digestive enzymes from seeping into bloodstream.

16. Plasma Membrane Specializations
Membrane junctions
Desmosomes
Anchoring junctions that prevent cells from being pulled apart
Buttonlike
Connected by fine protein filaments

17. Plasma Membrane Specializations
Membrane junctions
Gap junctions
Allow communication between cells
Common with heart and embryonic cells.
Cells are connected by hollow cylinder composed of proteins - connexons

18. Plasma Membrane Specializations
Figure 3.3