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Organization of the Cell. Cell theory Cell theory Cells are the basic living units of organization and function Cells are the basic living units of organization.

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Presentation on theme: "Organization of the Cell. Cell theory Cell theory Cells are the basic living units of organization and function Cells are the basic living units of organization."— Presentation transcript:

1 Organization of the Cell

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

3 Cell organization and size permit homeostasis Homeostasis: The balanced internal environment of the body; the automatic tendency of an organism to maintain such a steady state. Homeostasis: The balanced internal environment of the body; the automatic tendency of an organism to maintain such a steady state.

4 Cell surface area-to-volume ratio Cell surface area-to-volume ratio Plasma membrane must be large enough relative to cell volume to regulate passage of materials Plasma membrane must be large enough relative to cell volume to regulate passage of materials

5 Organization is basically the same in all cells All cells have a plasma membrane, which is a selective barrier All cells have a plasma membrane, which is a selective barrier Cells have internal organelles that are specialized for various functions Cells have internal organelles that are specialized for various functions Cell size is limited by the surface to volume ratio, so cells remain small Cell size is limited by the surface to volume ratio, so cells remain small Cell shape and size are related to function. Cell shape and size are related to function.

6 Surface to volume ratio As the cell size increases, the volume becomes too large for the surface membrane to handle. As the cell size increases, the volume becomes too large for the surface membrane to handle.

7 Cell surface area-to-volume ratio

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9 Biological size and cell diversity

10 Small size… (add) Molecules must be transported to the locations where they are converted into other forms Molecules must be transported to the locations where they are converted into other forms With small cell size, distances molecules travel within them are relatively short which speeds up many cellular activities With small cell size, distances molecules travel within them are relatively short which speeds up many cellular activities

11 Cells are studied by a combination of methods Robert Hooke: identified the cell walls and gave the structure the name “cell”. Robert Hooke: identified the cell walls and gave the structure the name “cell”. Study of the cell was not possible until microscopes. Study of the cell was not possible until microscopes.

12 Microscopes Microscopes Light microscope, referred to as compound microscope, used by most students Light microscope, referred to as compound microscope, used by most students Two features determine how clearly an object is viewed Two features determine how clearly an object is viewed Magnification: how much larger Magnification: how much larger Resolution: how clear Resolution: how clear Light microscope has 500 times more resolution than human eye Light microscope has 500 times more resolution than human eye

13 Electron microscope Electron microscope Developed in the 1950s Developed in the 1950s Allows study of the ultrastructure of cells Allows study of the ultrastructure of cells 10,000 times more resolution than human eye 10,000 times more resolution than human eye

14 Types of electron microscope Types of electron microscope Transmission electron microscope: used for studying ultra structure. Specimen must be specially prepared and sliced very thin. Transmission electron microscope: used for studying ultra structure. Specimen must be specially prepared and sliced very thin. Scanning electron microscope: bounces electrons off a thin metallic coating on the object. Enables surface area to be viewed. Scanning electron microscope: bounces electrons off a thin metallic coating on the object. Enables surface area to be viewed.

15 Comparing light and electron microscopy

16 Cell fractionation Cell fractionation Used to determine function of organelles Used to determine function of organelles Cells broken apart and the resulting cell extract spun in a centrifuge Cells broken apart and the resulting cell extract spun in a centrifuge Centrifugal force separates extract Centrifugal force separates extract Pellet: solid particle Pellet: solid particle Supernatant: fluid material Supernatant: fluid material

17 Cell fractionation

18 Types of Cells Prokaryotic Cells: Bacteria and Archea Prokaryotic Cells: Bacteria and Archea 1. lack membrane bound organelles 2. smaller in size than eukaryotes 3. DNA is located in nucleoid area and is not bound by a nuclear membrane 4. Most have cell walls 5. Have ribosomes and storage granules

19 Eukaryotic cells: all other organisms Eukaryotic cells: all other organisms 1. nucleoplasm: contains chromosomes which package DNA 2. cytoplasm: area outside the nucleus; contains cytosol and organelles, many of which are membrane-bound 3. type of cell determines which organelles are present and in what numbers

20 Functions of cell membranes Functions of cell membranes Divide cell into compartments, allowing for specialized activities Divide cell into compartments, allowing for specialized activities Interacting membranes form endomembrane system Interacting membranes form endomembrane system Vesicles transport materials between compartments Vesicles transport materials between compartments

21 Diagram of a plant cell plant cellplant cell

22 Diagram of an animal cell animal cellanimal cell

23 The cell nucleus The cell nucleus Contains DNA Contains DNA Bounded by Bounded by Nuclear envelope Nuclear envelope Double membrane perforated with nuclear pores Double membrane perforated with nuclear pores DNA forms chromatin, which is organized into chromosomes DNA forms chromatin, which is organized into chromosomes Nucleolus Nucleolus RNA synthesis and ribosome assembly RNA synthesis and ribosome assembly

24 The cell nucleus

25 Endoplasmic reticulum (ER) Endoplasmic reticulum (ER) Network of folded internal membranes in the cytosol Network of folded internal membranes in the cytosol Smooth ER Smooth ER Site of lipid synthesis Site of lipid synthesis Site of detoxifying enzymes Site of detoxifying enzymes Rough ER Rough ER Ribosomes manufacture proteins Ribosomes manufacture proteins Proteins may be moved into the ER lumen Proteins may be moved into the ER lumen

26 Endoplasmic reticulum (ER)

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28 Golgi complex Golgi complex Cisternae that process, sort, and modify proteins Cisternae that process, sort, and modify proteins In animal cells, Golgi complex also manufactures lysosomes In animal cells, Golgi complex also manufactures lysosomes Glycoproteins transported to the cis face Glycoproteins transported to the cis face Golgi modifies carbohydrates and lipids and packages into vesicles; which then may leave the cell Golgi modifies carbohydrates and lipids and packages into vesicles; which then may leave the cell

29 Golgi complex

30 Lysosomes break down worn-out cell structures, bacteria, and other substances Lysosomes break down worn-out cell structures, bacteria, and other substances Primary lysosomes bud from the Golgi complex Primary lysosomes bud from the Golgi complex Secondary lysosomes form by fusion of a primary lysosome with a vesicle containing ingested material Secondary lysosomes form by fusion of a primary lysosome with a vesicle containing ingested material Involved in apoptosis (programmed cell death) Involved in apoptosis (programmed cell death)

31 Lysosomes

32 Peroxisomes metabolize small organic compounds Transfer hydrogen from various compounds to oxygen, forming hydrogen peroxide Transfer hydrogen from various compounds to oxygen, forming hydrogen peroxide Catalase is an enzyme that breaks down hydrogen peroxide Catalase is an enzyme that breaks down hydrogen peroxide Most common in cells that synthesize, store, and degrade lipids Most common in cells that synthesize, store, and degrade lipids

33 Peroxisomes and lysosomes

34 Vacuoles Large, fluid-filled sacs with a variety of functions. Large, fluid-filled sacs with a variety of functions. May function in storage of toxins or pigments May function in storage of toxins or pigments Plant vacuoles are typically large and allow the cell to increase in size Plant vacuoles are typically large and allow the cell to increase in size Protist vacuoles may involve digestion or excretion. Protist vacuoles may involve digestion or excretion.

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37 Mitochondria Mitochondria Sites of aerobic respiration Sites of aerobic respiration Organelles enclosed by a double membrane Organelles enclosed by a double membrane Cristae and matrix contain enzymes for aerobic respiration Cristae and matrix contain enzymes for aerobic respiration Nutrients broken down and energy packaged in ATP Nutrients broken down and energy packaged in ATP Carbon dioxide and water by-products Carbon dioxide and water by-products

38 Mitochondria

39 Chloroplasts Chloroplasts Plastids that carry out photosynthesis Plastids that carry out photosynthesis Inner membrane of chloroplast encloses the stroma Inner membrane of chloroplast encloses the stroma During photosynthesis, chlorophyll traps light energy During photosynthesis, chlorophyll traps light energy Energy converted to chemical energy in ATP; sugars/food for the plant are manufactured. Energy converted to chemical energy in ATP; sugars/food for the plant are manufactured.

40 Chloroplast

41 Cellular respiration and photosynthesis

42 Equation for photosynthesis 6H 2 O + 6CO 2  C 6 H 12 O O 2 6H 2 O + 6CO 2  C 6 H 12 O O 2 If you turn the arrow around, you have the equation for cellular respiration. If you turn the arrow around, you have the equation for cellular respiration.

43 Cytoskeleton Cytoskeleton Internal framework made of Internal framework made of Microtubules Microtubules Microfilaments Microfilaments Intermediate filaments Intermediate filaments Provides structural support Provides structural support Involved with transport of materials in the cell Involved with transport of materials in the cell

44 The Cytoskeleton

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

46 Structure of cilia

47 Cilia and flagella

48 Glycocalyx, cell coat formed by polysaccarides extending from plasma membrane Glycocalyx, cell coat formed by polysaccarides extending from plasma membrane Many animal cells also surrounded by an extracellular matrix (ECM) Many animal cells also surrounded by an extracellular matrix (ECM) Most bacteria, fungi, and plant cell walls made of carbohydrates Most bacteria, fungi, and plant cell walls made of carbohydrates

49 Extracellular matrix

50 Plant cell walls


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