Presentation is loading. Please wait.

Presentation is loading. Please wait.

Cell Theory, Microscopy, Prokaryotes

Similar presentations

Presentation on theme: "Cell Theory, Microscopy, Prokaryotes"— Presentation transcript:

1 Cell Theory, Microscopy, Prokaryotes
CELLS Cell Theory, Microscopy, Prokaryotes

2 CELL THEORY All living things are composed of cells and cell products.
New cells are formed only by the division of existing cells. The cell contains inherited information (genes) that are used as instructions for growth, functioning and development.

3 CELL THEORY, continued The cell is the functioning unit of life; the chemical reactions of life take place within cells.

4 Possible Exceptions to the Cell Theory

5 The structure of skeletal muscle
Bundle of muscle fibers Single muscle fiber (cell) Plasma membrane Myofibril Light band Dark band Z line Sarcomere TEM 0.5 m I band A band M line Thick filaments (myosin) Thin filaments (actin) H zone Nuclei Muscle consists of bundles of long cells called fibers. Each fiber has a membrane around the outside like a single cell But each fiber has hundreds of nuclei.

6 Figure 31.2: Structure of a multicellular fungus
Reproductive structure. The mushroom produces tiny cells called spores. Hyphae. The mushroom and its subterranean mycelium are a continuous network of hyphae. Spore-producing structures 20 m Mycelium

7 Figure 31.3: Structure of fungal hyphae
Cell wall Cell wall Nuclei Pore Septum Nuclei (a) Septate hypha (b) Coenocytic hypha

8 SOME (but not most!) biologists consider unicellular organisms to be acellular.
Examples: Amoeba and Acetabularia instead of separate cells for separate functions, cytoplasm must carry out all vital functions usually much larger than typical cells Amoeba proteus ~ µm Acetabularia > 7 cm in length



11 The animal cell

12 The plant cell

13 Cell differentiation



16 Task Look at the diagram and list similarities and differences between the two cells.

17 Prokaryotic Cells

18 Prokaryotic Cells Pro – before Karyon – nucleus Comprise domains Bacteria and Archaea (Archaebacteria)

19 Electron microscope views of prokaryotic cells



22 Functions of the parts of a prokaryotic cell
Cell wall – forms protective outer layer which prevents damage from outside and bursting if internal pressure is high Plasma membrane – controls entry and exit of substances, pumping some in by active transport

23 Functions of the parts of a prokaryotic cell, cont’d.
Mesosome – increases the area of membrane for ATP production; may move DNA to poles during cell division Cytoplasm – contains enzymes that catalyze chemical reactions of metabolism; also contains cell’s DNA, in region known as nucleoid

24 Functions of the parts of a prokaryotic cell, cont’d.
Ribosomes – synthesize proteins by translating mRNA; some proteins remain in cell and others are exported Naked DNA – stores genetic information that controls cell and is passed onto daughter cells.

25 Metabolic activities in prokaryotes
Photosynthesis – carried out by Cyanobacteria (sometimes called blue-green “algae”)

26 Metabolic activities in prokaryotes, cont’d.
Nitrogen fixation – nitrogen fixing bacteria convert nitrogen gas from the air into nitrogen compounds some are free-living bacteria some live in symbiosis with plants, such as Rhizobium, forming root nodules on legumes

27 Metabolic activities in prokaryotes, cont’d.
Fermentation - process by which an sugar is broken and energy released. occurs during times of low oxygen supply and is therefore known as a type of anaerobic respiration


Download ppt "Cell Theory, Microscopy, Prokaryotes"

Similar presentations

Ads by Google