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2 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

3 First to View Cells Hooke is responsible for naming cells Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells

4 Anton van Leeuwenhoek In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organism (living things) Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth

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

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

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

Cell Theory Cells Cells are the basic living units of organization and function come from other cells All cells come from other cells Schleiden, Schwann, and Virchow Work of Schleiden, Schwann, and Virchow contributed to this theory Each cell is a microcosm of life

9 ENDOSYMBIOTIC THEORY In 1970, 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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11 Number of Cells Although ALL living things are made of cells, organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize into tissues, etc.

Biological Size and Cell Diversity 12

13 How Big is a Micron ( µ ) ? 1 cm = 10,000 microns 1” = 25,000 microns

14 Multicellular Organisms Cells in multicellular organisms often specialize (take on different shapes & functions)

Cell surface area-to-volume ratio Plasma membrane must be large enough relative to cell volume to regulate passage of materials Volume increases faster than surface area so cells must divide Cell size and shape related to function Ex: Nerve cells, skin cells, sperm cells 15

Cell Surface Area-to-Volume Ratio 16

Microscopes Light microscope (LM) compound Light microscope (LM), referred to as compound microscope, used by most students Two features determine how clearly an object is viewed Magnification-increase in size Magnification-increase in size Resolution-capacity to distinguish fine details Resolution-capacity to distinguish fine details Wavelength decreases=resolution increases Wavelength decreases=resolution increases Light microscope has 500 times more resolution than human eye 17

Electron microscope (EM) Developed in the 1950s Allows study of the ultrastructure of cells 10,000 times more resolution than human eye Because electrons have very short wavelengths 18

Types of electron microscope TEM) Transmission electron microscope (TEM) internal cell structures Used to view internal cell structures. Specimen is embedded in plastic, cut thin, placed on a metal grid and shot with a beam of electrons. SEM) Scanning electron microscope (SEM) Specimen is coated with gold or other metal Specimen is coated with gold or other metal 3-D picture of cell surface Produces 3-D picture of cell surface ***Can’tview living cells ***Can’t be used to view living cells 19

Comparing light and electron microscopy 20

Cell fractionation Cell fractionation Used to isolate & study of organelles Cells broken apart and the resulting cell extract spun in a centrifuge Centrifugal force separates extract Pellet Pellet – heavier cell organelles Found at the bottom of the tube Supernatant Supernatant – liquid poured off lighter particles (dissolved molecules and ions) 21

Cell fractionation 22

Two Basic Types of Cells Prokaryotes: Includes bacteria (archaeabacteria and Eubacteria) Eukaryotes: All other known organisms (protists, fungi, plants and animals) 23

24 Prokaryotes – The first Cells Cells lack a nucleus or membrane-bound organelles Simplest and smallest type of cell Single, circular chromosome Most have a cells wall

25 Prokaryotes Nucleoid region (center) contains the DNA Surrounded by cell membrane & cell wall (peptidoglycan) Contain ribosomes (no membrane) in their cytoplasm to make proteins

Highly organized membrane- enclosed organelles Cytoplasm-includes the cytosol (fluid) and the organelles other than the nucleus Nucleoplasm Eukaryotes 26

Diagram of a plant cell 27

Diagram of an animal cell 28

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The Cell All Living things are composed of cells All Living things are composed of cells All Cells have/contain the following: All Cells have/contain the following: Cell Membrane - Lipid Bilayer - Separates inside from outside Cell Membrane - Lipid Bilayer - Separates inside from outside 30

Functions of cell or plasma membranes Maintains homeostasis Maintains homeostasis Divides cell into compartments Divides cell into compartments, allowing for specialized activities endomembrane system Interacting membranes form endomembrane system Vesicles Vesicles transport materials between compartments (ER  Golgi, Golgi  plasma membrane…) 31

32 Cell or Plasma Membrane Outside of cell Inside of cell (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains Composed of double layer of phospholipids and proteins Surrounds outside of ALL cells Controls what enters or leaves the cell Living layer

33 The Cell Membrane is Fluid Molecules in cell membranes are constantly moving and changing

34 Endomembrane System Includes nuclear membrane connected to ER connected to cell membrane (transport)

Cytoplasm Cytoplasm - everything but DNA/Nucleus Cytoplasm - everything but DNA/Nucleus 35

Major Organelles of the Eukaryotic Cell The Nucleus “eukaryotic” means “true nucleus” Contains & protects the cell’s DNA Helps coordinate the division of cells Surrounded by a Nuclear Envelope Envelope is double layered with an Inner & Outer membrane Has perforations called Nuclear Pores which allow large molecules to pass in/out of the nucleus Contains a Nucleolus Ribosomes are made in this region Contains DNA packaged in structures called chromosomes Chromosomes 36

37 Inside the Nucleus - The genetic material (DNA) is found DNA is spread out And appears as CHROMATIN in non-dividing cells DNA is condensed & wrapped around proteins forming as CHROMOSOMES in dividing cells

The cell nucleus 38

Endoplasmic reticulum (ER) Network of folded internal membranes in the cytosol Nuclear envelope Connected to Nuclear envelope Smooth ER Smooth ER lipid synthesis Site of lipid synthesis detoxifying enzymes Site of detoxifying enzymes Detoxifies drugs & alcohol Detoxifies drugs & alcohol Stores Ca++ in muscle cells Stores Ca++ in muscle cells Rough ER Rough ER secretory proteins Ribosomes on surface manufacture secretory proteins Proteins may be moved into the ER lumen (interior) 39

Endoplasmic reticulum (ER) 40

41Ribosomes Synthesized by the nucleolus Made of PROTEINS and rRNA Contain the enzyme necessary for making protein bonds (peptide bonds) “Protein factories” for cell Join amino acids to make proteins Process called protein synthesis 

Golgi complex Cisternae (sacs) Cisternae (sacs) that process, sort, and modify proteins animal cells lysosomes In animal cells, Golgi complex also manufactures lysosomes Glycoproteins Glycoproteins cis Transported to the cis face (receiving side) modifies packages into vesicles pinch off the trans face Golgi modifies carbohydrates and lipids and packages into vesicles that pinch off the trans face (shipping side) 42

Golgi complex 43

44 Golgi Animation Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES

Lysosomes Small Vessicles which serve to digest particles and clean-up cells Contain Lysozyme – a powerful digestive enzyme Digests food particles Destroys worn-out organelles and invading bacteria Self-Destructs worn-out cells 45

Peroxisome s Involved in lipid metabolism and detoxification Contain enzymes (catalase) that produce and degrade hydrogen peroxide H 2 O 2  H 2 O + O 2 46

Mitochondria Mitochondria aerobic respiration Sites of aerobic respiration Organelles enclosed by a double membrane own genome Has its own genome apoptosis (programmed cell death) Plays important role in apoptosis (programmed cell death) Cristaematrix Cristae (internal folds) and matrix (innermost space) contain enzymes for aerobic respiration ATP Nutrients broken down and energy packaged in ATP Carbon dioxide water Carbon dioxide and water by-products 47

48 Mitochondrion (plural = mitochondria) “Powerhouse” of the cell Generate cellular energy (ATP) More active cells like muscle cells have MORE mitochondria Both plants & animal cells have mitochondria Site of CELLULAR RESPIRATION (burning glucose)

Mitochondria 49

50 MITOCHONDRIA Surrounded by a DOUBLE membrane Folded inner membrane called CRISTAE (increases surface area for more chemical Reactions) Has its own DNA Interior called MATRIX

Chloroplasts (Plant Cell Only) Cell’s “food” is generated here. Does this by photosynthesis - the conversion of CO 2, H 2 O and sunlight into sugar Contain Chlorophyll - a green pigment - which does this Has it’s own DNA* n* Can divide on its own* 51

Chloroplasts Plastids that carry out photosynthesis Inner membrane of chloroplast encloses the stroma (gel-like liquid) Contains stacks of interconnected sacs called thylakoids Stack of thylakoids called grana During photosynthesis, chlorophyll traps light energy (sunlight) Energy converted to chemical energy in ATP 52

Chloroplast 53

Cellular respiration and photosynthesis 54

The Cytoskeleton 55

Cytoskeleton Network of fibers which help organize the internal arrangement within cells by providing structural support. Involved in transport of materials Three basic types of fibers compose cytoskeleton: Actin Filaments Thinnest fibers Formed from protein Actin Microtubules Largest component of cytoskeleton Formed from protein Tubulin Intermediate filaments Intermediate in size and can vary Form from several proteins including vimentin & keratin 56

Centrioles (Animal Cell Only) Serve as construction/organization points for cellular microtubules Organize and transfer chromosomes and other organelles during Meiosis & Mitosis Occur in some prokaryotes, protists & animals. Do not occur with fungi and plants Tube like structures usually at right angles to each other. Some animals have centriole-like structures at the base of flagella called basal bodies. 57

Cilia and flagella Cilia and flagella Thin, movable structures that project from cell surface Function in movement Microtublesbasal body Microtubles anchored in cell by basal body 58

59 Cilia & Flagella Made of protein tubes called microtubules Microtubules arranged (9 + 2 arrangement) Function in moving cells, in moving fluids, or in small particles across the cell surface

Glycocalyx (cell coat) Cell coat formed by polysaccarides extending from plasma membrane Protects the cell Used in cell recognition, adhesion or communication Many animal cells are also surrounded by an extracellular matrix (ECM) Gel of carbohydrates and fibrous proteins Most bacteria, fungi, and plant cell walls made of carbohydrates 60

Extracellular matrix Integrins- membrane receptors important in cell movement Fibronectins- help organize the matrix and help cells attach 61

Plant cell walls 62

Cell Wall Provides support / protection for plant cell Two layers of cell wall Primary Cell Wall – Outer – Cellulose only Secondary Cell Wall – Inner – Cellulose & Lignin Cell membrane is innermost layer 63

64 Nonliving layer Found in plants, fungi, & bacteria Made of cellulose in plants Made of peptidoglycan in bacteria Made of chitin in Fungi Cell wall Cell Wall

Tonoplast (water vacuole) (plant cells only) Large H 2 O / Lipid / waste storage tank Large H 2 O / Lipid / waste storage tank Provides pressure (Turgor pressure) to maintain cell structure Provides pressure (Turgor pressure) to maintain cell structure 65

66 Plant Cell Organelles

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