C ELLS AND THE C ELL T HEORY SC Standard B-2.1 Recall the three major tenets of the cell theory. B-2.2 Summarize the structure and functions of organelles found in a eukaryotic cell. B-2.3 Compare the structures and organelles of prokaryotic and eukaryotic cells.

C ELL THEORY : Came to be from the work of many scientists, but the work and theories of 3 main: Schleiden: noted that all plants are made of cells Schwann: noted that all animals are made of cells Virchow: noted that all cells come from existing cells.

C ELL T HEORY  3 Major Tenets:  All living things are made of one or more cells.  All cells come from existing cells  Cells are the basic unit of structure and function in all living things

C ONTINUED : The ability of cells to divide to form new cells is the basis of all reproduction (both sexual and asexual) and for growth and repair of all multicellular organisms

T HE BASIC UNIT OF STRUCTURE AND FUNCTION : Lowest level of structure capable of performing all the activities of life Unicellular organism- is composed of one cell and all of life’s activities occur within that single cell. Multi-cellular organism- each is composed of many cells and each cell carries on most of the major functions of life.

S TRUCTURE AND F UNCTION : Nucleus- contains the chromosomes which are composed of DNA. Functions in genetic control of the cell. Mitochondria- site of cellular respiration, supplies the cell with energy (powerhouse of the cell). Chloroplasts- found only in plants, contains chlorophyll- which absorbs energy from the sun to convert carbon dioxide and water into sugar through the process of photosynthesis. Lysosomes- contain enzymes necessary for digesting waste in the cell. Vacuoles- store water, salts, proteins and carbohydrates, smaller in animal cells (if present)

C ONTINUED : Ribosomes- site of protein synthesis. Some found on ER, others in cytoplasm. Endoplasmic Reticulum- complex, extensive network that transports materials throughout the cell- smooth and rough- ribosome studded Golgi apparatus- modifies collects, packages and distributes molecules within the cell or outside the cell Cilia- short hair like projections responsible for movement of animal cells or protists Flagella- long whip like projections responsible for movement of some animal cells, bacteria or protists.

C ONTINUED : Cell membrane- encloses the cell and regulates the passage of materials between the cell and it’s environment; protection and support of the cell Nuclear membrane/envelope- membrane that surrounds the nucleus and regulates passage of materials between the nucleus and cytoplasm. Cell wall- provides protection and support in plants, bacteria, fungi and some protists. Cytoplasm- semi fluid material inside the cell containing molecules and the organelles.

P ROKARYOTES / E UKARYOTES Prokaryotes- Do not have a true nucleus The DNA is not completely separated from the rest of the cell by a nuclear membrane and is not arranged in strands called chromosomes Does not contain Mitochondria but they can obtain energy from either sunlight or from chemicals in their environment. Does contain ribosomes- the site of protein synthesis Example- bacteria, other unicellular organisms Does not contain membrane bound organelles

E UKARYOTES : Has a true nucleus DNA is organized into structures called chromosome and are separated by a nuclear membrane. Have membrane bound organelles Contain mitochondria that use both sunlight and food for energy Can be unicellular or multi-cellular