2. Life Possible origins: Extraterrestrial Supernatural Chemical Evolution (inorganic -> organic -> cells) Requirements for life: C, H, O, N, P, S Sunlight/chemical energy UV radiation protection Gravity Water “Found: first amino acid on a comet” 17 August 2009 by Maggie McKee http://www.newscientist.com/article/dn17628-first-amino-acid-on-a-comet-found.html
3. Cell Discovery Linked to microscope development 1595 – Hans Janssen + son Zacharias (Dutch): credited with microscope invention Two main types: light and electron
4. Light Microscope Light passes through an object and 2 or more lenses Possible to see living cells – not a lot of detail Advantages: Object: can be living Staining not required Real colors visible Easy to work with But low resolution: up to 200 nm + low magnification: up to 2000X
5. Electron Microscope Two types Scanning Electron (SEM) uses electron beams that bounce off the specimen Transmission Electron (TEM) Used electron beams that pass through specimen Advantages: more detail / higher resolution (0.2nm) / magnification: close to 1 million X But specimen must be dead + colors aren’t real.
7. Timeline Anton van Leeuwenhoek (Dutch – 1632-1723) Improved simple microscope (single lens – magnification up to 270 X) First to see living cell (red blood cells, sperm cells, single celled organisms)
8. Timeline Robert Hooke (English – 1635-1703) Looked at a piece of cork – first to use the term "cell“ Improved microscope: compound (2 lenses) 1800 – scientists knew cells had a cell membrane, a nucleus, cytoplasm and cell wall
9. Timeline Mathias Schleiden – (German botanist – 1804-1881) all plants are made of cells Theodor Schwann (German zoologist – 1810-1882) all animals are made of cells Rudolf Virchow (German physician – 1821-1902) concluded that all cells come from other cells
10. Cell Theory All organisms are made up of one or more cells. Cells are the basic units of structure and function in all organisms. All cells come from cells that already exist. Exception: Viruses are non-cellular structures of DNA or RNA that are surrounded by a protein coat
11. Single-cell x Multicellular Organisms can be made up of one cell (single-celled) or many cells (multicellular). Single-celled organisms are the bottom of the food chain There are more single-celled organisms than multicellular organisms in the world.
12. Single Cell Organisms One cell carries out all functions: Metabolism: all chemical reactions happening at the same time Response: sense environment Homeostasis: regulate/balance reactions in the body according to the environment conditions Growth: production of new organelles Reproduction: division Nutrition: release energy from food Amoeba Paramecium
13. Multicellular Organisms Interaction Communication Cells specialize: they differentiate because some genes are expressed and some are not (on/off) depending on the type of cell. Neuron Muscle cell Skin cell Stem cells = not specialized = ability to differentiate into specialized cells
15. Why are cells small? Surface area to volume ratio limits cell size Rate of heat production/waste/resource consumption – volume Rate or exchange material/energy – surface area As cell size increases, the surface area to volume ratio decreases Metabolic rates increase faster than the surface area’s ability to exchange nutrients, hence a maximum size is reached. Cell size, therefore, remains small
16. Size of various cells and structures: Molecules: 1 nm Membranes (on organelles): 10 nm Viruses: 100 nm Bacteria: 1 um Organelles: up to 10 um Most cells: up to 100 um Measurements above in 2d, remember all structures have 3d shape.
17. The Metric System Know how to convert from one unit to another. Kilo- 1000 Units Hecto- 100 units Deka- 10 units Multiply Basic Unit Deci- 0.1 units Divide Centi- 0.01 units Milli- 0.001 units
18. What units are used to measure cells? 1 mm = 1000 micrometers (um) 1 mm = 1,000,000 nanometers (nm) Or… A micrometer is 1 x 10-3 mm (0. 001) A nanometer is 1 x 10-6 mm (0.000001 mm)
19. Calculating Linear Magnification What is the actual size of this specimen in um? 60mm/5 = 12mm 12mm x 1000 um = 12,000 um Magnification x 5 60 mm Measuring picture
21. Types of Cells Types: Prokaryotic (no nucleus + naked DNA in cytoplasm + only ribosomes) Example: Bacteria Eukaryotic (with nucleus + organelles) Example: Animals, Plants, Fungi, Protists
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24. Cell Membrane Outer boundary: phospholipid bilayer Communication between cells Selects what goes in and out (using energy – active transport or without using energy – passive transport) Animal cells have cholesterol in the membrane
25. Cell Organelles Organelle - structure within a cell that has a specific function. Endoplasmic Reticulum – membranes that move materials around in the cell (“transport system”) Ribosomes – make proteins (“factories”) Centrioles (animals only) – coordinate cell division
26. Cell Organelles Mitochondria – produce ATP (“power plant”) Golgi apparatus – makes, packages and releases products inside/outside cell (“factories”)
27. Cell Organelles Lysosome (animal only) – contain digestive enzymes. Breaks down and recycles substance (“garbage company”) Vacuoles – (mainly plants) store waste, food, pigments (“storage”)
28. More parts... Cytoplasm – gel-like mixture inside cell. Many chemicals are dissolved in it. Nucleus - largest structure in the cytoplasm (“command center”) Has a nuclear membrane (with pores – materials enter and leave the nucleus) Contains chromosomes (made of DNA – deoxyribonucleic acid)
29. Plant Cells Cell wall – rigid structure that provides support/protection for the cell Chloroplasts – contain chlorophyll – green pigment responsible for photosynthesis
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31. Stem Cells Unspecialized: pluripotent or multipotent Self-renewing Give rise to mature, specialized cells Sources: Embryonic – cells from human blastocysts Fetal – cells from aborted fetuses Umbilical cord stem cells – cells from the umbilical cord of newborns Placenta derived stem cells – cells from the placenta and amniotic fluid of newborns Adult – cells from adult tissue (bone marrow, fat...)
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33. Example Adult stem cell found in bone marrow: hematopoietic rare – have markers red blood cells, white cells, platelets
34. Types of Stem Cells: Totipotent – each cell can develop into a new individual (cells from early embryos – 1-3 days) Pluripotent – cells can form any cell type (over 200) – some cells of blastocyst (5 to 14 days) Multipotent – cells differentiated, but can form other tissues – fetal tissue, cord blood, adult stem cells http://www.csa.com/discoveryguides/stemcell/overview.php
35. Importance Use: Cancer therapy: + 400,000 – leukemia, lymphoma, breast cancer, multiple myeloma Bone marrow/immune regeneration: 2 million – autoimmune diseases, immunodeficiencies, solid organ transplants Tissue repair/regeneration: 18 million – heart and vascular problems, diabetes, liver disease, arthritis, neurodegenerative Potential Therapeutic Applications: Cardiac – following heart damage Nervous system – stroke/spinal cord, Parkinson’s, Alzheimer’s Burns Diabetes Solid organ regeneration
