Chemical level: a molecule in the membrane that encloses a cell Cellular level: a cell in the stomach lining Tissue level: layers of tissue in the stomach wall Organ level: the stomach Body system level: the digestive system Organism level: the whole body

2 The cell is the basic structural, functional and biological unit of life. Cells are the smallest living unit; the building blocks of life.

3 First to View Cells In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cell walls) What he saw looked like small boxes copyright cmassengale

4 Anton van Leeuwenhoek In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organism (living things) Father of Microbiology copyright cmassengale

5 Beginning of the Cell Theory In 1838, a German botanist named Matthias Schleiden concluded that all plants were made of cells Schleiden is a cofounder of the cell theory copyright cmassengale

6 Beginning of the Cell Theory In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells Schwann also cofounded the cell theory copyright cmassengale

7 Beginning of the Cell Theory In 1855, a German medical doctor named Rudolph Virchow observed, under the microscope, cells dividing He reasoned that all cells come from other pre-existing cells by cell division copyright cmassengale

8 Discoveries Since the Cell Theory copyright cmassengale

9 ENDOSYMBIOTIC THEORY In 1981, American biologist, Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves Supporting evidence included organelles with their own DNA Chloroplast and Mitochondria copyright cmassengale

10copyright cmassengale

1.All life forms are made from one or more cells. 2.Cells only arise from pre-existing cells. 3.The cell is the smallest form of life. Proposed in 1838 by Schleiden, Schwann and Virchow

NO NUCLEUS or Membrane Bound Organelles NO NUCLEUS or Membrane Bound Organelles Small, simple, single celled Small, simple, single celled A prokaryotic cell is enclosed by a plasma membrane and is usually encased in a rigid cell wall –The cell wall may be covered by a sticky capsule –Inside a prokaryotic cell are its DNA, ribosomes and cytoplasm Grow & reproduce Grow & reproduce Example: E. coli (bacterial cells)Example: E. coli (bacterial cells)

HAVE A NUCLEUS & MEMBRANE-BOUND ORGANELLES Grow & reproduce Some live as single cells Examples: Plants, animals, fungi, protists

Unicellular organisms are made up of only 1 cell All prokaryotes and some protists Multicellular organisms are made up of more than one cell. Cells are often specialized. –plants, animals, fungi and some protists

Plasma membrane Figure 4.5A Golgi apparatus Ribosomes Nucleus Smooth endoplasmic reticulum Rough endoplasmic reticulum Mitochondrion Not in most plant cells Cytoskeleton Flagellum Lysosome Centriole Peroxisome Microtubule Intermediate filament Microfilament

Figure 4.5B Nucleus Golgi apparatus Not in animal cells Central vacuole Chloroplast Cell wall Mitochondrion Peroxisome Plasma membrane Rough endoplasmic reticulum Ribosomes Smooth endoplasmic reticulum Cytoskeleton Microtubule Intermediate filament Microfilament

Organelle = “little organ” Organelles are structures that have specific jobs within the cell. FOUND ONLY IN EUKARYOTIC CELLS

Function: The jelly-like fluid that fills a cell is called cytoplasm. It is made up of mostly water and salt. Cytoplasm is present within the cell membrane of all cell types and contains all organelles and cell parts. FOUND IN ALL CELLS

Function: provide support and protection for the cell; found outside of the cell membrane; allows water, oxygen, carbon dioxide and other things to pass through Made of Cellulose in Plants, Chitin in Fungi, Peptidoglycan in Bacteria FOUND ONLY IN PLANT, FUNGI AND BACTERIA CELLS

Description: Semipermeable Phospholipid Bilayer with proteins embedded in it. Each phospholipid contains a polar (hydrophilic) head and a non- polar (hydrophobic tail. Function: Provides a barrier between the inside of the cell and the external environment. Maintains homeostasis. Found in ALL Cells

Description: Double-membrane layer Function: Selectively allows material to pass into and out of the nucleus via the pores Location: Surrounds the nucleus Found in all EUKARYOTIC CELLS

Function: controls most cell processes and contains hereditary info of DNA; has chromatin which forms chromosomes during mitosis Location: near the center of the cell; surrounded by nuclear envelope Found in all EUKARYOTIC cells

Function: Location where ribosomes are made Location: WITHIN the nucleus. Found in all EUKARYOTIC cells

Description: DNA is spread out and apprears as chromatin in non- dividing cells. Location: WITHIN the nucleus. Description: DNA is condensed and wrapped around proteins forming as chromosomes in dividing cells. Location: WITHIN the nucleus.

TYPES: Free – are floating around in the cytoplasm Bound – are attached to rough endoplasmic reticulum Function: Protein Synthesis Found in ALL cells

Function: use energy from food to make high-energy particles (ATP) for the cell to use; site of cellular respiration Location: in the cytoplasm of the cell Nickname: Powerhouse Found in all EUKARYOTIC Cells

Description: Double membrane structure containing stacks of photosynthetic membranes which contain the green pigment chlorophyll. Function: Use energy from sunlight to make energy-rich food molecules in a process known as photosynthesis. Found ONLY in PLANT Cells

Description: Folded membrane studded with ribosomes that extends from the nuclear envelope Function: Protein synthesis can occur ON the ribosomes and then the proteins are modified on the inside of the rough ER. Found in all EUKARYOTIC Cells

Description: Folded membrane that extends from the rough ER or stands alone in the cytoplasm Function: Contains collections of enzymes for specialized tasks, including assembly of lipids. Found in all EUKARYOTIC Cells

Description: Folded membranes that are stacked and form an assembly line for final modification of proteins Function: Using enzymes, it attaches carbohydrates & lipids to proteins. From the Golgi, proteins are sent to their final destination in vesicles. Found in all EUKARYOTIC Cells

Function: Contain enzymes used to breakdown lipids, carbohydrates, and proteins. Lysosomal Enzymes can: - Digest food - Destroy bacteria - Recycle damaged organelles - Function in embryonic development in animals Found in Animal Cells Only!

Function: Location for storage of water, salts, proteins & carbohydrates. In plant cells there is usually a single, large, central vacuole that stores liquid. Found in EUKARYOTIC Cells Larger in Plant Cells than in Animal Cells

Function: helps the cell maintain its shape; also involved in movement inside the cell Location: network of protein filaments that goes throughout the cell Components: Microtubules & Microfilaments Found in ALL Cells

Function: responsible for protecting the cell against hydrogen peroxide Contains enzymes (catalase) which act in the production and decomposition of hydrogen peroxide Involved in energy metabolism Found in ALL Eukaryotic Cells

Function: used for movement of the cell or for movement of small particles across the cell surface. Cilia are shorter and more numerous on cells Flagella are longer and fewer on cells Found in Animal Cells and Prokaryotic Cells

Structure: paired structures near the nucleus; made of a bundle of microtubules Function: appear during cell division and help to pull chromosome pairs apart to opposite ends of the cell. Found only in Animal Cells

Factors that affect cell size: Surface area Volume of a cell Volume increases faster than the surface area When the surface area is no longer great enough to get rid of all the wastes and to get in enough food and water, then the cell must divide. Therefore, the cells of an organism are close in size.