1 Cell Theory, Structure and Function

2 Introduction to Cells - Cells are the basic units of organisms - Cells can only be observed under microscope - Basic types of cells: Animal CellPlant Cell Bacterial Cell

History of Cell Discovery 1665: Robert Hooke observes cork, names tiny chambers CELLS 1683: Anton van Leeuwenhoek discovers single-celled organisms : Scientists discover cell nucleus, propose both animals and plants are made of cell : Louis Pasteur & Robert Koch study bacteria 3

Cell Theory: 3 parts All organisms are composed of one or more cells The cell is the basic unit of organization of organisms All cells come from preexisting cells 4

5 Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize

6  Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles.  Eukaryotes include most other cells & have a nucleus and membrane- bound organelles (plants, fungi, & animals). Cells May be Prokaryotic or Eukaryotic

7 Prokaryotes Nucleoid region contains the DNA Cell membrane & cell wall Contain ribosomes (no membrane) to make proteins in their cytoplasm

8 Eukaryotic Cell Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles

9 Two Main Types of Eukaryotic Cells Plant Cell Animal Cell

10 Organelles Very small size Can only be observed under a microscope Have specific functions Found throughout cytoplasm

11 Organelles Found in Cells Examples of Organelles include: Endoplasmic reticulum (rough & smooth) – canals for movement Golgi Bodies – wrap & export proteins Nucleolus – makes ribosomes Lysosomes – digests & gets rid of wastes Ribosomes – makes proteins

12 Smooth & Rough Endoplasmic Reticulum Smooth ER lacks ribosomes & makes proteins USED IN the cell Rough ER has ribosomes on its surface & makes proteins to EXPORT

13 Golgi Bodies Stacks of flattened sacsStacks of flattened sacs Have a shipping side & a receiving sideHave a shipping side & a receiving side Receive & modify proteins made by ERReceive & modify proteins made by ER Transport vesicles with modified proteins pinch off the endsTransport vesicles with modified proteins pinch off the ends Transport vesicle

14 Nucleolus Cell may have 1 to 3 nucleoli Cell may have 1 to 3 nucleoli Inside nucleusInside nucleus Disappears when cell dividesDisappears when cell divides Makes ribosomes that make proteinsMakes ribosomes that make proteins

15 Lysosome Contain digestive enzymesContain digestive enzymes Break down food and worn out cell parts for cellsBreak down food and worn out cell parts for cells Programmed for cell death (lyse & release enzymes to break down & recycle cell parts)Programmed for cell death (lyse & release enzymes to break down & recycle cell parts)

16 Rod shape Site of Cellular respiration Mitochondria - Cell Powerhouse Mitochondrion ( mitochondria )

17 Active cells like muscles have more mitochondria Burn sugars to produce energy ATP In Animal Cells: Mitochondria

18 - Lies immediately against the cell wall in plant cells - Made of protein and phospholipids (lipid bilayer) - Selectively permeable Cell membrane Surrounding the Cell: Cell Membrane

19 - Living layer - Controls the movement of materials into and out of the cell Cell membrane Cell or Plasma Membrane

20 - Jelly-like substance enclosed by cell membrane - Provides a medium for chemical reactions to take place Cytoplasm Cytoplasm of a Cell

21 - Contains organelles to carry out specific jobs - Examples: chloroplast & mitochondrion Cytoplasm More on Cytoplasm

22 - Controls the normal activities of the cell - Bounded by a nuclear membrane - Contains chromosomes Control Organelle: Nucleus Nucleus

23 - Each cell has fixed number of chromosomes that carry genes - Genes control cell characteristics Nucleus

24 - Contains the green pigment chlorophyll - Traps sunlight to make sugars (food) - Process called photosynthesis Plant Cell Organelles Chloroplast

25 - Dead layer - Large empty spaces present between cellulose fibers - Freely permeable Cell wall Plant Cell

26 Plant Cell - Made of cellulose, which forms very thin fibers - Strong and rigid - Found in plant cells Cell wall

27 - Protect and support the enclosed substances (protoplasm) - Resist entry of excess water into the cell - Give shape to the cell Cell wall Plant Cell

28 - Plant cells have a large central vacuole - Contains cell sap - Sugars, proteins, minerals, wastes, & pigments Plant Cell Organelles Vacuole

29 Different kinds of plant cells Onion Epidermal Cells Root Hair Cell root hair Guard Cells

30 mitochondrion nucleus glycogen granule cell membrane cytoplasm Animal cell - No cell wall or chloroplast - Stores glycogen in the cytoplasm for food energy vacuole

31 Animal Cell Organelles Near the nucleus Paired structures Help cell divide

32 Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium

33 Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria

34 Differences between plant cells and animal cells Animal cellsPlant cells Relatively smaller in size Irregular shape No cell wall Relatively larger in size Regular shape Cell wall present

35 Animal cellsPlant cells Vacuole small or absent Glycogen as food storage Nucleus at the center Large central vacuole Starch as food storage Nucleus near cell wall Differences between Plant Cells and Animal Cells