1. Cell Structure

2. Cytoplasm  All of the cellular contents between the plasma membrane and the nucleus

3. Cytosol  Fluid portion of the cytoplasm  ~55% of the cell’s volume  75%-90% water  Contains dissolved/suspended solutes:  Ions, glucose, ATP, lipids, proteins, amino acids, waste  Site of most of the chemical reactions in the cell

4. Organelles  Specialized structures inside cells that have characteristic shapes and specific functions

5. Cytoskeleton  Network of protein filaments:  Microfilaments, intermediate filaments, microtubules

6. Microfilaments  Thinnest  On the periphery of the cell  Contribute to shape and strength  Help generate movement  Support microvilli

7. Intermediate Filaments  Thicker than microfilaments, thinner than microtubules  Found in cells subject to tension  Help to hold organelles in place

8. Microtubules  Largest  Help determine shape  Function in movement of organelles  Function in movement of cilia and flagella

9. Centrosome  Near the nucleus  Pair of centrioles  Cylindrical structures composed of clusters of microtubules arranged in a circular pattern  Pericentriolar Material  Tubulins – organizing center for the growth of mitotic spindles

11. Cilia and Flagella  Motile projections on the cell surface  Cilia – numerous short hair-like projections on the cell surface.  Propel fluids across the surface of the cell  Flagella – longer than cilia, propel the entire cell.  Only example in the human is sperm cell

13. Ribosomes  Site of protein synthesis  High content of RNA  2 sub-units  Large and small  Made in the nucleolus and assembled in the cytosol  Attached to ER or free in cytosol

15. Endoplasmic Reticulum  Network of folded membranes that extends through the cytoplasm  Rough ER: extends from nuclear envelope; has ribosomes attached; processes and sorts proteins that will be incorporated into the membranes  Smooth ER: extends from rough ER; no ribosomes attached; fatty acids and steroids are synthesized.

17. Golgi Complex (Body; Apparatus)  Packages and transports materials  Cisterns – flattened membranous sacs with bulging edges that make up the Golgi Body

18. Transport of Proteins by the Golgi Body  Protein is surrounded by ER membrane and buds of to form a transport vesicle  Transport vesicle moves toward Golgi Body  Vesicle fuses with Golgi Body and proteins enter  Proteins move from one cistern to another by transfer vesicles  In last cistern proteins are sorted and packaged  Proteins leave Golgi Body in secretory vesicles, other membrane vesicles or transport vesicles

19. Lysosomes  Membrane enclosed vesicles that contain digestive enzymes  Help to recycle cellular components  Autophagy – worn out organelles are digested  Autolysis – enzymes destroy its own cell

20. Tay-Sachs Disease  An inherited condition in which one lysosomal enzyme is absent.  Normally breaks down a membrane glycolipid found in nerve cells. It is not broken down, it accumulates which makes the nerve cell function less efficiently  Seizure, muscle rigidity, blindness, dementia, uncooridated. Usually die before age 5

21. Peroxisomes  Similar to lysosomes but smaller  Contain oxides  Enzymes that can oxidize various organic substances  Abundant in liver where there are a lot of toxic substances  Contain catalase

22. Proteasomes  Contain enzyme called protease  Continuously destroys unneeded, damaged or faulty proteins  Recycles amino acids

23. Mitochondria  Site of cellular respiration (makes ATP)  Active cells have a larger number  Double Membrane  Outer – smooth  Inner –folded  Cristae – folds  Enzymes that catalyze a series of reactions are found in the matrix

26. Check Point Questions  What is the difference between cytoplasm and cytosol?  What is an organelle?  Describe the structure of a ribosome, the Golgi Body and a mitochondrion.