This document discusses cells and their structure and function. It defines cells as the basic unit of life and outlines several key aspects of cells including their origins, requirements for life, types (prokaryotic and eukaryotic), organelles, sizes, and whether they are single-celled or multicellular. Important milestones in cell discovery are highlighted, such as Anton van Leeuwenhoek first observing cells in the 1600s and the development of the cell theory in the 1800s. The roles and structures of key cell organelles like the cell membrane, nucleus, mitochondria and chloroplasts are summarized.

1. CellsIS3

2. LifePossible origins:ExtraterrestrialSupernatural (religious)Chemical Evolution (inorganic -> organic -> cells)Requirements for life:C, H, O, N, P, SSunlight/chemical energyUV radiation protectionWater“Found: first amino acid on a comet” 17 August 2009 by Maggie McKeehttp://www.newscientist.com/article/dn17628-first-amino-acid-on-a-comet-found.html

3. Cell DiscoveryLinked to microscope development1595 – Hans Janssen + son Zacharias (Dutch): credited with microscope inventionTwo main types: light and electron

4. Light MicroscopeLight passes through an object and 2 or more lensesPossible to see living cells – not a lot of detailAdvantages: Object: can be livingStaining not requiredReal colors visibleEasy to work withBut low resolution: up to 200 nm +low magnification: up to 2000X

5. Electron MicroscopeTwo typesScanning Electron (SEM)uses electron beams that bounce off the specimenTransmission Electron (TEM)Used electron beams that pass through specimenAdvantages: more detail / higher resolution (0.2nm) / magnification: close to 1 million XBut specimen must be dead + colors aren’t real.

6. Transmission Microscope (guess what these structures are...)Scanning Microscope

7. TimelineAnton 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. TimelineRobert 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. TimelineMathias Schleiden – (German botanist – 1804-1881) all plants are made of cellsTheodor Schwann (German zoologist – 1810-1882) all animals are made of cellsRudolf Virchow (German physician – 1821-1902)concluded that all cells come from other cells

10. Cell TheoryAll 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 MulticellularOrganisms can be made up of one cell (single-celled) or many cells (multicellular).Single-celled organisms are the bottom of the food chainThere are more single-celled organisms than multicellular organisms in the world.

12. Single Cell OrganismsOne cell carries out all functions:Metabolism: all chemical reactions happening at the same timeResponse: sense environmentHomeostasis: regulate/balance reactions in the body according to the environment conditionsGrowth: production of new organellesReproduction: division Nutrition: release energy from foodAmoebaParamecium

13. Multicellular OrganismsInteractionCommunicationCells specialize: they differentiate because some genes are expressed and some are not (on/off) depending on the type of cell.NeuronMuscle cellSkin cellStem cells = not specialized = ability to differentiate into specialized cells

14. TrypanosomaDiatoms

15. Why are cells small?Surface area to volume ratio limits cell sizeRate of heat production/waste/resource consumption – volumeRate or exchange material/energy – surface areaAs cell size increases, the surface area to volume ratio decreasesMetabolic 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 structuresMolecules: 1 nmMembranes (on organelles): 10 nmViruses: 100 nmBacteria: 1 umOrganelles: up to 10 umMost cells: up to 100 umMeasurements above in 2d, remember all structures have 3d shape.

17. Cell OrganizationCells differ:SizeShape

18. Types of CellsTypes: Prokaryotic (no nucleus + naked DNA in cytoplasm + only ribosomes)Example: BacteriaEukaryotic (with nucleus + organelles)Example: Animals, Plants, Fungi, Protists

21. Cell MembraneOuter boundary: phospholipid bilayerCommunication between cellsSelects what goes in and out (using energy – active transport or without using energy – passive transport)Animal cells have cholesterol in the membrane

22. Cell OrganellesOrganelle - 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

23. Cell OrganellesMitochondria – produce ATP (“power plant”)Golgi apparatus – makes, packages and releases products inside/outside cell (“factories”)

24. Cell OrganellesLysosome (animal only) – contain digestive enzymes. Breaks down and recycles substance (“garbage company”)Vacuoles – (mainly plants) store waste, food, pigments (“storage”)

25. 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)

26. Plant CellsCell wall – rigid structure that provides support/protection for the cellChloroplasts – contain chlorophyll – green pigment responsible for photosynthesis

28. Stem CellsUnspecialized: pluripotent or multipotentSelf-renewingGive rise to mature, specialized cellsSources: Embryonic – cells from human blastocystsFetal – cells from aborted fetusesUmbilical cord stem cells – cells from the umbilical cord of newbornsPlacenta derived stem cells – cells from the placenta and amniotic fluid of newbornsAdult – cells from adult tissue (bone marrow, fat...)

30. Example Adult stem cell found in bone marrow red blood cells, white cells, platelets

31. 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 cellshttp://www.csa.com/discoveryguides/stemcell/overview.php

32. ImportanceUse: 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, neurodegenerativePotential Therapeutic Applications: Cardiac – following heart damage Nervous system – stroke/spinal cord, Parkinson’s, Alzheimer’s Burns Diabetes Solid organ regeneration

33. IssuesEmbryo destruction: ethics/religionTissue rejectionGovernment fundingUncontrolled cell division / misdirected growthhttp://www.youtube.com/watch?v=3Axkn8G18t8&feature=related