CELLS

1. CELLS • All organisms are made up of cells • The cell is the unit of structure and function of all living things • Life arises from the interaction of all cellular components.

2. You must check this web site • www.cellsalive.com

3. There is correlation between the structure of cells and their function Ex: The shapes of muscles cells, sperm cells, red blood cells,, nerve cells are appropriate for their function. Example: the flat tile like epithelial cells of the skin fit closely together making a barrier to bacterial entrance, water loss etc. Another way to say this is that “shape reflects function”

4. 10 m Human height 1 m Length of somenerve andmuscle cells 100 mm(10 cm) Unaided eye Chicken egg 10 mm(1 cm) Frog egg 1 mm 100 m Light microscope Most plant andanimal cells 10 m Nucleus Most bacteria Mitochondrion 1 m Mycoplasmas(smallest bacteria) 100 nm Viruses Electron microscope Ribosome 10 nm Proteins Lipids 1 nm Small molecules Atoms 0.1 nm How small are cells? Most cells are microscopic • Cells vary in size and shape

5. History • Robert Hook (1665) named “cells” after observing tiny compartments in cork . • Anton VanLeeuwenhoek (1600’s) improved the primitive microscopes and observed one celled organisms, even bacteria. He documented his findings with letters and diagrams to the Royal Society (of Science) in London. • Robert Brown (1600’s)discovered the nucleus • Electron microscope was developed in the late 1930’s and allows scientist to see up to 0.5 nanometers. About 1000 times larger than regular microscopes.

6. Eyepiece Ocularlens Objective lens Specimen Condenserlens Lightsource How are cells studied? Microscopes and Biochemistry • The light microscope (LM) magnify cells up to 1000 times • Enables us to see the overall shape and structure of a cell Figure 4.1A

7. TEM 2,800  SEM 2,000  Figure 4.1D Figure 4.1C • The electron microscope • Allows greater magnification and reveals cellular details

8. The cell theory (mid-1800’s) • Mathew Schleiden and Theodor Schwann examined plant and animal tissues and came to the conclusion that they both consist of cells • Rudolph Virchow came to the conclusion that young cells come from the division of other cells •  1.    All organisms are made up of cells • 2.    Cells are the units of structure and function of all living things, that is cells have all the properties of life. • 3.    All cells come from pre-existing cells

9. Prokaryotic cell Nucleoidregion Colorized TEM 15,000  Nucleus Eukaryotic cell Organelles • Prokaryotic cells are structurally simpler than • eukaryotic cells • There are two kinds of cells • Prokaryotic- No nucleus- Bacteria and Archeae • Eukaryotic- have nucleus- plants, animals and fungi Figure 4.3A

10. Prokaryoticflagella Ribosomes Capsule Cell wall Plasmamembrane Nucleoid region (DNA) Pili • TYPE OF CELLS: Prokaryotic and Eukaryotic • Prokaryotic cells are small, relatively simple cells • That do not have a membrane-bound nucleus

11. Eukaryotic cells have a nucleus and are partitioned into functional compartments. • All other forms of life( plants and animals) are composed of complex eukaryotic cells • Membranes form compartments inside eukaryotic cells to facilitate metabolic activities

12. 10 m 30 m 30 m 10 m Surface areaof one large cube 5,400m2 Total surface areaof 27 small cubes 16,200m2 • A small cell has a greater ratio of surface area to volume • Than a large cell of the same shape

13. Smooth endoplasmicreticulum Nucleus Roughendoplasmicreticulum Flagellum Not in mostplant cells Lysosome Ribosomes Centriole Golgiapparatus Peroxisome Microtubule Plasma membrane Intermediatefilament Cytoskeleton Mitochondrion Microfilament • A typical animal cell • Contains a variety of membranous organelles

14. Tubulin subunit Actin subunit Fibrous subunits 25 nm 10 nm 7 nm Microtubule Microfilament Intermediate filament THE CYTOSKELETON AND RELATED STRUCTURES The cell’s internal skeleton helps organize its structure and activities • A network of protein fibers • Make up the cytoskeleton.

15. Functions of the cytoskeleton • Tubules and filaments are made up of protein fibers • Microfilaments of actin • Enable cells to change shape and move • Intermediate filaments • Reinforce the cell and anchor organelles • Microtubules give the cell rigidity • provide anchors for organelles and act as tracks for organelle movement

16. Overview: Many cell organelles are connected through the endomembrane system

17. All cells on earth are enclosed in membranes that maintain internal conditions different from the surroundings, have DNA as their genetic material and can convert forms of energy from one to another. • Membranes form the boundaries of many eukaryotic cells • Compartmentalizing the interior of the cell and facilitating a variety of metabolic activities

18. Nucleus Chromatin Two membranesof nuclearenvelope Nucleolus Pore Roughendoplasmicreticulum Ribosomes • The nucleus is the cellular control center • Containing the cell’s DNA, which directs cellular activities Figure 4.5

19. ORGANELLES OF THE ENDOMEMBRANE SYSTEM The nucleus is the cell’s genetic control center • The largest organelle is usually the nucleus • Which is separated from the cytoplasm by the nuclear envelope

20. Inside the nucleus • Chromatin fibers made up of DNA These thin fibers coil up during cell division becoming thicker and visible. They are called now a chromosome Nucleolus makes ribosomes

21. Transport vesiclebuds off 4 Ribosome Secretory(glyco-) proteininside trans-port vesicle 3 Sugar chain 1 2 Glycoprotein Polypeptide Rough ER • Ribosomes on the surface of the rough ER • Produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles

22. Smooth ER Rough ER Nuclearenvelope Ribosomes Rough ER Smooth ER TEM 45,000 The endomembrane system is a collection of membranous organelles • That manufactures and distributes cell products\ Smooth endoplasmic reticulum has a variety of functions • Smooth endoplasmic reticulum, or smooth ER • Synthesizes lipids • Processes toxins and drugs in liver cells • Stores and releases calcium ions in muscle cells

23. Smooth endoplasmicreticulum Nucleus Roughendoplasmicreticulum Flagellum Not in mostplant cells Lysosome Ribosomes Centriole Golgiapparatus Peroxisome Microtubule Plasma membrane Intermediatefilament Cytoskeleton Mitochondrion Microfilament • A typical animal cell • Contains a variety of membranous organelles

24. Golgi apparatus “Receiving” side ofGolgi apparatus Golgiapparatus Transportvesiclefrom ER TEM 130,000 New vesicleforming Transportvesicle fromthe Golgi “Shipping” sideof Golgi apparatus The Golgi apparatus finishes, sorts, and ships cell products • Stacks of membranous sacs receive and modify ER products • Then ship them to other organelles or the cell surface Figure 4.9

25. Transport vesicle fromGolgi to plasma membrane Transport vesiclefrom ER to Golgi Rough ER Plasmamembrane Nucleus Vacuole Lysosome Nuclear envelope Smooth ER Golgi apparatus The endomembrane system • The various organelles of the endomembrane system • Are interconnected structurally and functionally

26. Mitochondrion Outermembrane Intermembranespace Innermembrane TEM 44,880 Cristae Matrix Mitochondria gets chemical energy from food • Mitochondria carry out cellular respiration It uses the chemical energy in food to make ATP for cellular work

27. Rough ER 1 Transport vesicle(containing inactivehydrolytic enzymes) Golgiapparatus Plasmamembrane Lysosomeengulfingdamagedorganelle 2 Engulfmentof particle Lysosomes 3 5 4 Foodvacuole Digestion Lysosomes are digestive compartments within a cell • Lysosomes are sacs of enzymes that function in digestion within a cell “Food”

28. Lysosome Nucleus TEM 8,500 • Lysosomes in white blood cells • Destroy bacteria that have been ingested • lysosomes also help to digest worn out , damaged cell parts, recycle materials within the cell and fuse with food vacuoles to digest nutrients. Figure 4.10B

29. Lysosomes in white blood cells destroy bacteria and lysosomes also can digest other parts of the cell Abnormal lysosomes can cause fatal diseases • Lysosomal storage diseases. These are rare. • Interfere with various cellular functions • Ex: Tay- Sachs, does not break down lipids in nerve cell membranes. Lipids accumulate • Pompe’s disease, lysosomes cannot digest glycogen and it accumulates in muscle and liver cells

30. Peroxisomes • Specialized vesicles that contains enzymes (catalase) that digest hydrogen peroxide H2O2 • Our cells produce hydrogen peroxide during metabolism and the enzymes in peroxisomes break it down into water and oxygen gas which are harmless to the cell.

31. Plant Cells • Three organelles animals do not have Chloroplasts Cell wall Central vacuole

32. Roughendoplasmicreticulum Nucleus Ribosomes Smoothendoplasmicreticulum Golgiapparatus Microtubule Centralvacuole Intermediatefilament Cytoskeleton Not inanimalcells Microfilament Chloroplast Cell wall Mitochondrion Peroxisome Plasma membrane • A typical plant cell has some structures that an animal cell lacks • Such as chloroplasts and a rigid cell wall

33. Chloroplast Stroma Inner and outermembranes TEM 9,750 Granum Intermembranespace ENERGY-CONVERTING ORGANELLES Chloroplasts convert solar energy to chemical energy. This is where PHOTOSYNTHESIStakes place • Chloroplasts, found in plants and some protists Convert solar energy to chemical energy in sugars

34. Nucleus Chloroplast Centralvacuole Colorized TEM 8,700 Vacuoles function in the general maintenance of the cell • Plant cells contain a large central vacuole, • Which has lysosomal and storage functions

35. Central vacuoles in plants Also help increase the size of cells by absorbing water Are mostly water, minerals and nutrients • Store color pigments (that attract insects) • Store waste products and poisons

36. Nucleus Contractilevacuoles LM 650 • Some protists have contractile vacuoles • That pump out excess water

37. Organelles • NAME LOCATION FUNCTION • CytoskeletoncytoplasmMaintains cell shape facilitates movement and move materials within the cell • Cytosol cytoplasmProtein rich fluid in which organelles and cytoskeleton are immersed • NucleusInside nuclear envelopeSite of most of cell’s DNA and nucleolus • Nucleolus Inside the nucleus Synthesis of ribosomal RNA

38. ORGANELLES NAME LOCATION FUNCTION • Rough Endoplasmic Reticulum cytoplasm Protein synthesis,Cell metabolism, • Smooth Endoplasmic Reticulum cytoplasm Lipid synthesis, storage of calcium, Detoxification of toxic substances • Ribosomes Rough ER and Protein synthesis free in the cytoplasm • Vesiclesmove through cytoplasmTransport • Golgi BodiescytoplasmProcessing, sorting, shipping of proteins and lipids • Mitochondria cytoplasm Gets energy from food (makes ATP during aerobic respiration)

39. ORGANELLES NAME LOCATION FUNCTION • Lysosomes cytoplasm Digestion and breaking down of materials (only in animal cells) ( including the cell’s own) • Peroxisomes cytoplasm Sacs of enzymes that break down substances (alcohol, amino acids) into hydrogen peroxide and then the hydrogen peroxide into water and oxygen. • Plasma Membrane all around the cell Controls substances and signals that go in and out of cells. Maintains shape and volume • Cell wall ( plant cells) cytoplasm Keeps water inside and limits water uptake, protects from outside influences, maintains shape.

40. ORGANELLES NAME LOCATION FUNCTION • Central vacuoles center of plant cell water maintenance, stores waste (plant cells only) • Plastids cytoplasm plastids provide nutrients and (plant cells only) pigmentation • Chloroplast many throughout carry out photosynthesis (plant cells only) the cytoplasm contain chlorophyll

41. CELL JUNCTIONS • What are junctions? Protein or cytoplasmic bridges that serve as physical links between cells. • The junctions between cells help integrate cells into tissues and higher levels of functioning. Junctions make cells living units greater than each individual part. • Junctions serve to send and receive signals and materials and to cement itself to other cells and junctions coordinate cell activities.

42. Plant cells Plants are covered by cell walls composed of cellulose fibers. Cell walls have plasmodesmata, these are channels that pass through adjoining cell walls connecting plant cell to plant cell.

43. Animal cells:Junctions • There are different kinds of intracellular junctions between animal cells, integrating each cell into a greater unit. • Tight junctions • Desmosomes or Anchoring juctions: • Gap or Communication junctions:

44. Tight junctions They fuse cell to cell to prevent leakage. Ex: cells of the lining of the intestines keeping the fluid inside. All cells of most tissues are joined this way. The skin and the lining of internal cavities (epithelial).

45. Gap or Communication junctions: Link the cytoplasm of neighboring cells. They are open channels that allow a flow of materials and signals between cells. • Very common in embryos and in heart tissue to allow for the passage of ions to cause contraction

46. Desmosomes or Anchoring juctions: Joins cells in tissues of the skin, heart and other organs such as the bladder subject to stretching.

47. Tight junctions Anchoring junction Gap junctions Extracellular matrix Space between cells Plasma membranes of adjacent cells • Tight junctions can bind cells together into leakproof sheets • Anchoring junctions link animal cells into strong tissues • Gap junctions allow substances to flow from cell to cell Figure 4.18B

48. Colorized SEM 4,100 LM 600 Figure 4.17A Figure 4.17B Cilia and flagella • move when microtubules bend • Eukaryotic cilia and flagella are locomotor appendages that protrude from some cells

49. Flagellum Electron micrographsof cross sections: Outer microtubuledoublet Centralmicrotubules TEM 206,500 Radial spoke Dynein arms Flagellum Plasmamembrane TEM 206,500 Basal body(structurally identical to centriole) Basal body Clusters of microtubules Drive the whipping action of these organelles .

50. PLASMA MEMBRANE • Function: The cell’s “gate keeper”. Very important. It controls what goes in and out of a cell. Keeps equilibrium between the inside of cells and the outside and promotes homeostasis. Web site to check: http://www.wisc-online.com/objects/index_tj.asp?objid=AP1101 • Function: The cell’s “gate keeper”. Very important. It controls what goes in and out of a cell. Keeps equilibrium between the inside of cells and the outside and promotes homeostasis. Web site to check: http://www.wisc-online.com/objects/index_tj.asp?objid=AP1101