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
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• The cell is the basic structural, functional and biological unit of life.
• Cells are the smallest living unit; the building blocks of life.
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First to View CellsFirst 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
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Anton van Leeuwenhoek
• In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organism (living things)
• Father of Microbiology
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Beginning of the Cell Beginning of the Cell TheoryTheory
• In 1838, a German botanist named Matthias Schleiden concluded that all plants were made of cells
•Schleiden is a cofounder of the cell theorycopyright cmassengale
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Beginning of the Cell Beginning of the Cell TheoryTheory
• In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells
•Schwann also cofounded the cell theory
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Beginning of the Cell Beginning of the Cell TheoryTheory
• 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
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Discoveries Discoveries SinceSince the the
Cell TheoryCell Theory
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ENDOSYMBIOTIC THEORYENDOSYMBIOTIC 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
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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 NO NUCLEUS or Membrane Bound OrganellesOrganelles• Small, simple, single celledSmall, 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 & reproduceGrow & 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
Golgiapparatus
Ribosomes
NucleusSmooth endoplasmicreticulum
Roughendoplasmicreticulum
Mitochondrion
Not in most plant cells
Cytoskeleton
Flagellum
Lysosome
Centriole
Peroxisome
Microtubule
Intermediatefilament
Microfilament
Figure 4.5B
Nucleus
Golgiapparatus
Not inanimal
cells
Centralvacuole
Chloroplast
Cell wall
Mitochondrion
Peroxisome
Plasma membrane
Roughendoplasmicreticulum
Ribosomes
Smoothendoplasmicreticulum
Cytoskeleton
Microtubule
Intermediatefilament
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 envelopeFound 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: PowerhouseFound 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 microtubulesFunction: 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.