Cell Structure and Function

1. Cell Structure and Function Chapter 4 commons.wikimedia.org/wiki/File:SEM_blood_cel... xenophilius.wordpress.com/2008/09/21/

2. What is a Cell? • The smallest unit of matter that can carry all processes of life. • Structure directly related to Function • ≈ 10-100 trillion cell in the human body • All cells are not created equal • cell diversity-cells differ in shape, size, and organization • Limited in size by surface area to volume ratio • Shape indicates function • At least 200 cell types in your body! www.tutorvista.com/.../structure-cell.php

3. Background Check • Cell Discovery: • Possible by development of microscope • Robert Hooke-examined cork • Anton van Leeuwenhoek-1st to observe living cells • Cell Theory: • All living things are composed of one or more cells • Cells are the basic units of structure and function in an organism • Cells come only from the reproduction of existing cells www.microbeworld.org/index.php?option=com_con... askabiologist.asu.edu/.../rhooke.html

4. Eukaryotes Vs. Prokaryotes • Eukaryotes: • Membrane-bound nucleus and organelles • Example(s): YOU, animals, plants, fungi, protists • Prokaryotes: • Lack nucleus and membrane-bound organelles • Example(s): bacteria www.uoregon.edu/~bsl/astronomy/

5. Cell Membrane • Surrounds entire cell • Selectively permeable – some substances pass with ease while others cannot pass at all • Made of: -- Lipids and proteins • Fluid Mosaic Model commons.wikimedia.org/wiki/File:Cell_membrane...

6. Membrane Lipids and Proteins • Phospholipids • Polar head: hydrophilic • Nonpolar tails: hydrophobic • Forms lipid bilayer • Steroids • Cholesterol main steroid in animal cells • Stabilize membrane/maintain fluidity • Proteins • Peripheral proteins: on exterior or interior surface of cell membrane • Integral proteins: embedded in lipid bilayer • Carbohydrates: involved with self recognition and attachment • Transport of molecules through bilayer (channels or pores)

7. Cytoplasm/Cytosol • Cytoplasm: • Area between cell membrane and nucleus contains organelles • Cytosol: • Gelatin-like aqueous in cytoplasm • Salts, minerals, organic molecules

8. Mitochondria • Site of chemical reactions producing ATP – “power house” • Own DNA and grow and divide on own • 2 membranes • Smooth outer: boundary • Inner: cristae (folds)- enlarge surface area for reactions www.yellowtang.org/cells.php

9. Ribosomes • No membrane • Two compounds- proteins and RNA • Assembled in nucleus • Free or attached to Endoplasmic reticulum • Role: protein synthesis www.biologie.uni-hamburg.de/b-online/library/...

10. Endoplasmic Reticulum (ER) • System of membranous tubules and sacs • Function: intracellular highway • 2 types: • Rough- has ribosomes • cells with high rate of proteins being exported out or inserted into membrane • Smooth- no ribosomes • calcium regulation in muscle cells • Breaks down toxic materials www.yellowtang.org/cells.php

11. Golgi Apparatus • The UPS of the cell • Packaging, processing, and secreting proteins • System of membranes/sacs • Works closely with ER www.yellowtang.org/cells.php

12. Lysosomes • Small and spherical • Enclose hydrolytic enzymes • Enzyme use: • Digest- proteins, carbohydrates, lipids, RNA, DNA • Digest- old organelles, viruses, and bacteria • Common in: • Animals, fungi, and protists • RARE in plants

13. Cytoskeleton • Long protein strands in cytosol • maintain cell shape and size • support and movement • No membrane • 2 Components: • Microfilaments- • Actin polymer chains • Smallest • Contribute to movement and contraction of muscle • Microtubules- • hollow tubes • Largest • Active role in cell division- spindle fibers

14. Cilia and Flagella • Cilia • Hair-like organelles • Numerous on cell • Crawling motion • Help unicellular bacteria search for food/escape • On surface of respiratory tract • Flagella • Hair-like organelles • Long, less numerous • Swimming/whipping motion • Quick movement for unicellular organisms

15. Nucleus- “the brain” • Nuclear matrix • Protein skeleton • Maintains shape • Nuclear envelope • Double membrane • Chromatin within • DNA and protein combination • Coil for cell division forming chromosomes • Nuclear Pores-visible • Holes in envelope • Nucleolus-visible • Ribosome synthesis/partially assembled www.cartage.org.lb/.../Nucleus/Nucleus.htm

16. Cell Wall- Plant cells • Outside cell membrane • Rigid- support and protection • Long chains of cellulose • Pores-allow passage of ions and molecules • 2 types • Primary- when cell being formed • Secondary- when cell reaches full size • Between primary wall and membrane • Tough and woody www.microscopy-uk.org.uk/.../fixation.html

17. Vacuoles- Plant cells • Fluid-filled • Often large can occupy up to 90% of cell volume • Storage: • Store enzymes and metabolic waste • Some waste toxic- can be a defense www.yellowtang.org/cells.php

18. Plastids- Plant cells • Double membrane and contains DNA • Store: • Starch, fats, or pigments • Chloroplast- most common • Chlorophyll- green pigment • Thylakoids: system of flattened, membranous sacs • Sunlight converted to chemical energy- Photosynthesis • Other plastids contian pigments that give fruit and flowers color www.yellowtang.org/cells.php