Biology Matter and Energy. Unit 1 Matter and Energy

Transcription

1 Biology 2201 Matter and Energy Unit 1 Matter and Energy 1

2 What is Biology? The study of life and living organisms. This includes their structure, function, growth, evolution, distribution, and taxonomy. Unit 1 Matter and Energy 2

3 Cells: An Introduction PA Unit 1 Matter and Energy 3

4 Living things are much more than a mere set of chemical reactions or a physical machine. They are composed of individual units called cells, considered to be the basic unit of structure and function and the smallest independent unit capable of displaying the characteristics of life. A one-celled organism is said to be UNICELLULAR. Organisms with more than one cell are said to be MULTICELLULAR. Unit 1 Matter and Energy 4

5 Unicellular organisms Ex: Algae (diatoms, euglena, amoeba, etc) Bacteria Unit 1 Matter and Energy 5

6 Multicellular Ex: Plants, Animals Unit 1 Matter and Energy 6

7 Cell Theory (First staed in 1858) Cell Theory is composed of 4 main points: 1. All living organisms are composed of one or more cells. 2. Cells are the basic units of structure and function in all organisms. 3. All cells are derived from pre-existing cells. 4. In a multicellular organism, the activity of the entire organism depends on the total activity of its individual cells. Unit 1 Matter and Energy 7

8 Historical Development of Cell Theory SPONTANEOUS GENERATION states that living things come from non living sources ; (eg.) maggots appear on meat if left out too long ; after it rains frogs, insects and plants seem to come out of mud in ponds. All ideas of spontaneous generation were supported by observation. In 1870, Thomas Henry Huxley used the term ABIOGENESIS to describe the concept of spontaneous generation. In actual fact, we know that life only arises from life or that living things come from other living things ; this is known as BIOGENESIS. Unit 1 Matter and Energy 8

9 Spontanteous Generation (Abiogenesis) Unit 1 Matter and Energy 9

10 Biogenesis Unit 1 Matter and Energy 10

11 Significant Events in Biological History Relating to Cell Theory For hundreds of years a debate raged amongst scientists about the origin of living things. The debate centered around two theories: 1. Abiogenesis (Spontaneous Generation) 2. Biogenesis Unit 1 Matter and Energy 11

12 Abiogenesis - The idea that living organisms can arise from nonliving matter. - Many examples are sited by early scientists: - Appearance of mushrooms on logs - Maggots forming on rotting meat - Micro-organisms apprearing in a sterilized flask of meat broth. (John Needham s experiment) Unit 1 Matter and Energy 12

13 Biogenesis - The idea that living organisms can only come from other living things. - Scientifically shown to be correct by several scientists. Unit 1 Matter and Energy 13

14 Assignment #1 Create a cue card timeline that describes each scientists contribution to the cell theory. Include the following: - Name - Date of his work - A couple of points outlining his contribution or what he's famous for. - Describe any specific experiment that is famous for that scientist. - Optional- draw a pic that is associated with his finding. - If possible, state whether he supported bio or abiogenesis INCLUDE: Aristotle Redi Needham Spallanzani Pasteur Brown Schleiden Schwann Braun Virchow Hooke Leeuwenhoek Unit 1 Matter and Energy 14

15 Francesco Redi (1688) performs an experiment to show that maggots will not appear on rotting meat if flies are kept away. Unit 1 Matter and Energy 15

16 Louis Pasteur (1860) designs and performs an experiment that shows that micro-organisms that appear in a sterilized meat broth actually come from microorganisms found in the air and do not formspontaneously from the non-living broth. Unit 1 Matter and Energy 16

17 Other scientist who contributed to the development of the Cell Theory: Robert Hooke (1665) using a primitive set of lenses to form a simple microscope, observes empty room like aprtments in samples of once living tree bark. Hooke names these compartments cells. Unit 1 Matter and Energy 17

18 Anton Van Leeuwenhoek (1667) designs his own microscopes that are far more powerful than any of the primitive forms at the time. Over the next number of years Leeuwenhoek writes extensively about is observations of tiny organisms. Unit 1 Matter and Energy 18

19 Mathias Jacob Schleiden (1883) writes, all plants are made of cells. Theodor Shwann (1839) writes all animals are made of cells and cells are organisms and entire animals and plants are collectives of these organisms. Rudolph Virchow (1858) formulates the points of the cell theory. Writes, all cells come from preexisting cells. Unit 1 Matter and Energy 19

20 Microscopes Unit 1 Matter and Energy 20

21 Microscopes Cells are tiny structures. The smallest object that the human eye can view is around 100 µm (1 µm = 1-6 m = m) ; (the limit of human sight). A microscope consists of a lens or combination of lenses that produce enlarged images of small objects. Microscopes are an important tool used to extend the abilities of human vision. The earliest microscope consisted of a single strongly curved lens mounted on a metal plate. In the late 1600's, a Dutch naturalist, ANTON VON LEEUWENHOEK, made a simple microscope (a single lens) with a magnification of 400 x. He was the first person to observe microscopic organisms. Later, the COMPOUND LIGHT MICROSCOPE was developed. Compound Light Microscope- named for its use of two lenses (ocular and objective) and a light source to view objects. Unit 1 Matter and Energy 21

22 Compound Light Microscope Unit 1 Matter and Energy 22

23 Unit 1 Matter and Energy 23

24 How to view a prepared slide: 1. Put low power obj. lens in place 2. Lower the stage with coarse adj. 3. Adjust the diaphragm for brightest light. 4. Place the specimen on the stage and clip in place. 5. Focus with course adj. 6. Change to Med. Power and focus with fine adjustment. 7. Change to high power and focus with fine adjustment only. (So as not to crack the slide or damage the lens) Unit 1 Matter and Energy 24

25 Magnification Multiply the power of the ocular lens by the power of the objective lens in place. Low power mag = Med power mag = High power mag = Unit 1 Matter and Energy 25

26 Field of View: Is the size of the area you see when looking down a microscope. For low power: place a ruler across the field of view and measure the diameter in millimeters. Ex: next slide Unit 1 Matter and Energy 26

27 Field of View (F of V) F of V (low) = mm = µm To convert to µm : 1mm= 1000µm Or 1µm = mm Unit 1 Matter and Energy 27

28 For medium power F of V = Low power F of V x Magnification of low power Magnification of med. Power For high power F of V = Med power F of V x Magnification of med power Magnification of high power Unit 1 Matter and Energy 28

29 Depth of Field distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Unit 1 Matter and Energy 29

30 How to prepare a Wet-Mount slide: Get a clean slide and cover slip. Hold each by their edges so as not to get finger prints on them. Place your specimen in the middle of the slide. With a medicine dropper, place one drop of water on your specimen. Hold your coverslip at a 45-degree angle with one edge of the coverslip touching the surface of the water. Slowly lower the opposite edge of the coverslip over the sample. Make sure there are no bubbles. Unit 1 Matter and Energy 30

31 How to Irrigate your slide: If your slide has dried out, or a big bubble has formed, try these steps: Place one drop of water on one edge of the coverslip. Using a piece of tissue or paper towel, draw the water underneath the coverslip by placing the tissue on the opposite edge of the coverslip. Unit 1 Matter and Energy 31

32 Biological Drawings: Guidelines: Use a pencil. Use a Compass to draw a circle to represent your field of view. It should be large enough to take up at least a third of your paper. Use a ruler divide the circle into four equal sections. Draw the specimen in the circle such that it appears the same on your paper as it does in the field of view. Do not shade. Use solid lines to draw. If an area appears darker, then use stippling. Write the title of your drawing above your drawing in the center of the page in capital letters. The title is what you see. All labels must be kept in line on the side of the drawing. Use a ruler to draw lines from the specimen to the label. No lines should cross. Show the magnification and scale of drawing calculations at the bottom of the page. Unit 1 Matter and Energy 32

33 Biological Drawing Unit 1 Matter and Energy 33

34 Unit 1 Matter and Energy 34

35 Microscopes- Imaging Today Microscope Imaging Today (pp ) : Light microscopes have limited resolving power (around 200 nm) due to the nature of visible light itself. To overcome the limitation of the light microscope, a new source of illumination (the electron) was used and electron microscopes were invented (1932). An ELECTRON MICROSCOPE is a microscope that uses a beam of electrons instead of light to illuminate objects. Electrons are able to penetrate the small spaces between cell components much better than light. Unit 1 Matter and Energy 35

36 Transmission Electron Microscopes (TEM) Unit 1 Matter and Energy 36

37 Scanning Electron Microscope (SEM) Unit 1 Matter and Energy 37

38 Light Vs Electron Microscopes Type Light Source Magnification Resolution Specimen Prep Compound Light Visible Light (light bulb) Up to 2000x Aprox 0.2 micrometers Killed, fixed and stained Electron Beam of electrons x (TEM) o.2 nm (TEM) Killed, dried an fixed (TEM) , 000 x (SEM) 1-10 nm (SEM) Killed, fixed, cleaned and coated with metal Unit 1 Matter and Energy 38

39 Characteristics of Living Cells: 1. obtain food and energy 2. convert energy from an external source into a form that the cell can use 3. construct and maintain the molecules that make up cell structures 4. carry out chemical reactions 5. eliminate wastes 6. reproduce 7. keep records of how to build structures The unit of life that carries out all these functions is Unit 1 Matter and Energy 39 the CELL

40 Cells (Two Types) Prokaryotic cells (prokaryotes) do not contain a NUCLEUS; (eg.) all bacterial cells. Pro means before and Karyon means nucleus. Prokaryotes have no membrane-bound organelles and lack a true membrane-bound nucleus. Their DNA is concentrated in an area called the NUCLEOID REGION. Ex: Figure 1.10 ; p. 23 the bacterium, Escherichia coli. Eukaryotic cells (eukaryotes) are cells that contain a nucleus. Eu means true and Karyon means nucleus. The nucleus is an enclosed region that separates the DNA from the rest of the cell contents. Eukaryotes contain a number of specialized structures called ORGANELLES. Ex: Animal and Plant cells Unit 1 Matter and Energy 40

41 Prokaryotic Cell (Bacterial) Draw this! Unit 1 Matter and Energy 41

42 The Eukaryotic Animal Cell (DRAW THIS!) Unit 1 Matter and Energy 42

43 The Eukaryotic Plant Cell (Draw This) Unit 1 Matter and Energy 43

44 Eukaryotic Cells cells that contain a distinct nucleus and have membrane bound organelles. They are found in more complex unicellular organisms and all multicellular organisms. Eukaryotic cells have distinct parts that are responsible for carrying out certain functions within the cell. These are called organelles. Unit 1 Matter and Energy 44

45 Organelles work together to carry out basic life processes. Eukaryotic cells display what is known as a division of labour. Within all eukaryotic cells, there are three distinct areas: 1. The cell membrane 2. The nucleus 3. The Cytoplasm Unit 1 Matter and Energy 45

46 1. The Cell Membrane- The Control Gate. - Composed of a double layer of lipids (fats), with proteins embedded in these layers. - The cell membrane is selectively permeable. This means that some substances can pass through it and enter the cell, while other substances cannot pass through. This allows the membrane to maintain homeostasis- keeping the internal physiological environment of the cell constant. Unit 1 Matter and Energy 46

47 2. The Nucleus- The Command Center. It controls most activity in the cell. The nucleus contains chromatin- uncoiled chromosomes that contain DNA. The DNA contains the information required for proper functioning of the cell. The nucleus also contains a darkened structure known as the nucleolus- responsible of production of ribosomes. Unit 1 Matter and Energy 47

48 The nuclear envelope surrounds the nucleus and has pores that allow materials to enter and leave the nucleus. 3. The Cytoplasm- The gel-like portion of the cell that contains each of the cells organelles. The liquid of the cytoplasm also contains many dissolved substances that creates a chemical environment necessary for proper functioning of the cell structures. Unit 1 Matter and Energy 48

49 Cellular Organelles Using your textbook, page 25 (animal cell) and page 32 (plant cell), complete the table in your notes. You should summarize the function in your own words so it is easier to remember. Unit 1 Matter and Energy 49

50 Organelles in BOTH plant and animal cells -Ribosomes- spherical two-part structures that play a role in the production of proteins. Located on the E.R or the cytoplasm. -Endoplasm Reticulum (E.R)- These structures are involved in the transport of proteins through the cell. It s made of folded membrane. May be rough, which means it is covered with ribosomes, or smooth, which means it has no ribosomes Unit 1 Matter and Energy 50

51 The proteins that are made from the ribosomes on the rough ER are transported from rough to smooth ER then forms a bubble and pinches off, forming a vesicle. This vesicle transports the protein to the Golgi Apparatus. - Vesicles- small transport sacs. Unit 1 Matter and Energy 51

52 Golgi Apparatus- These structures are involved in the refinement, packaging and shipping of proteins for the purpose of excretion. Unit 1 Matter and Energy 52

53 Mitochondria- The power house. These structures break down simple carbohydrates in order to release their energy. This is called cellular respiration. Unit 1 Matter and Energy 53

54 Vacuoles- areas of storage within the cell for water and other substances. In plants, these can be quite large. Unit 1 Matter and Energy 54

55 Centrioles- involved in cell reproduction. They ensure even distribution of cell components when the cell divides. Located in centrosome Unit 1 Matter and Energy 55

56 - Lysosomes- The Recycling Center. These structures are involved in the breakdown of large particles as well as warn out cell parts. Unit 1 Matter and Energy 56

57 Organelles found ONLY IN PLANT CELLS: 1.Cell Wall- This structure is composed of cellulose and surrounds the cell membrane. The function of the wall is to give support and shape to plant cells. Unit 1 Matter and Energy 57

58 2. Plastids, including chloroplasts and chromoplasts, are involved in the trapping of sunlight and the process of photosynthesis. 3. Central Vacuole- Provides support and storage for food, water and toxins. It s large and fluidfilled. Unit 1 Matter and Energy 58

59 The Cell Membrane As was stated earlier, the purpose of the cell membrane is to separate one cell from another cell. It also controls the movement of materials into and out of the cell. It is this function that is of great importance in terms of regulating the movement of materials.

60 Functions of the Cell Membrane 1. Transport raw materials into the cell. 2. Transport manufactured products and wastes out of the cell. 3. Prevent entry of unwanted materials into the cell. 4. Prevent escape of matter needed to perform cellular functions.

61 Cell Membrane Structure The cell membrane is a DOUBLE LAYER of PHOSPHOLIPIDS with PROTEINS embedded throughout. This is known as a PHOSPHOLIPID BILAYER.

62 Cell Membrane Function A living cell must maintain a good internal environment or homeostasis. This homeostasis refers to THE MAINTENANCE OF A STEADY INTERNAL STATE, so that the cell can perform its life functions. It is a process of keeping a balance of solutes and solvent within a cell. The environment of the cell interior is kept at a CONSTANT, despite changes in the conditions of the external environment. Unit 1 Matter and Energy 62

63 Materials have to pass into or out of the cell membrane. The cell membrane is said to be SELECTIVELY PERMEABLE, allowing some molecules to pass through it while preventing others from doing so. The cells of a multicellular organism are bathed in a thin layer of EXTRACELLULAR FLUID, containing a mixture of water and dissolved materials. Dissolved materials such as OXYGEN can enter/leave a cell while other materials such as CARBON DIOXIDE can leave a cell. Unit 1 Matter and Energy 63

64 THE FLUID-MOSAIC MEMBRANE MODEL The phospholipid bilayer contains a mosaic of different components scattered throughout it, like raisins in slice of bread. But, the proteins that are embedded are able to drift sideways, hence the term fluid-mosaic.

65 Drawing of a Cell Membrane

66 Components of the fluid mosaic: Phospholipid Bilayer- Contains a phosphate head that is water-loving or hydrophillic, and two fatty acid tails that are hydrophobic, or water-hating. The heads are soluble in water while the tails are insoluble.

67 Components of Cell Membrane con t The Proteins are used mainly for transporting various materials in and out of cells. Cholesterol- is a lipid that is also embedded throughout the membrane allowing the cell to function in a wide range of temperatures. Carbohydrate Chains- like the fingerprint of the cell, it distinguishes one cell from another.

68 Transport Across the Cell Membrane There are two broad categories of transport across the cell membrane: Passive Transport (Requires NO ENERGY) Active Transport (ENERGY REQUIRED)

69 Passive Transport: Three ways this occurs: Simple Diffusion Facilitated Diffusion Osmosis Unit 1 Matter and Energy 69

70 1. Simple Diffusion Diffusion is the driving force for substances to move around in cells. Diffusion results from the random motion of molecules. If some regions are more concentrated than others, diffusion will occur from the more concentrated region to the less concentrated region until the concentrations of both regions have become equal; (ie.) have reached a state of equilibrium. This difference in concentrations between regions is known as a concentration gradient. Unit 1 Matter and Energy 70

71 How Diffusion Works /student_view0/chapter2/animation how _diffusion_works.html Unit 1 Matter and Energy 71

72 Diffusion Examples 1. Diffusion of dye in water 2. Diffusion of oxygen into the cell Unit 1 Matter and Energy 72

73 Draw: Simple Diffusion Unit 1 Matter and Energy 73

74 Molecules that move across the cell membrane by simple diffusion are small, uncharged particles, including: 1.Oxygen 2.Carbon Dioxide Unit 1 Matter and Energy 74

75 2. Facilitated Diffusion Facilitated diffusion describes the passive movement of larger or charged molecules from an area of high concentration to an area of low concentration. In order for these molecules to pass through the cell membrane, the cell membrane has such structures as protein channels and carrier proteins to carry out the material transport. Watch: animation how_facilitated_diffusion_works.html Unit 1 Matter and Energy 75

76 Molecules that move across the cell membrane by facilitated diffusion include: 1. Carbohydrates and amino acids, large particles that require a carrier protein. 2. Sodium and potassium, charged ions that requires channel proteins. Unit 1 Matter and Energy 76

77 Draw: Facilitated Diffusion A. Channel Protein B. Carrier Protein Unit 1 Matter and Energy 77

78 3. Osmosis Water flows smoothly across the cell membrane without needing any carrier. This free movement of water, (or diffusion of a solvent), across a semi-permeable membrane is known as osmosis. Unit 1 Matter and Energy 78

79 Osmosis The diffusion of water across the cell membrane. Results in three conditions: 1. Isotonic Conditions 2. Hypotonic conditions 3. Hypertonic conditions Unit 1 Matter and Energy 79

80 1. Isotonic Water concentration outside (extracellular fluid) must equal the water concentration inside the cell. Since most cells contain about 0.9% dissolved salts + solutes, isotonic environments must contain 0.9% salt. In this situation, water flow out equals water flow in. Unit 1 Matter and Energy 80

81 Draw: Isotonic conditions Unit 1 Matter and Energy 81

82 2. Hypotonic Water concentration outside the cell is higher (eg. pure water) than inside the cell. In other words, the solute concentration outside cell is lower than inside cell. The net result is that water moves in at greater rate than it moves out. A cell placed in a hypotonic solution will gain water. For an animal cell, it may swell until it bursts. For a plant cell, the cell wall inhibits bursting. Unit 1 Matter and Energy 82

83 Draw: Hypotonic conditions Unit 1 Matter and Energy 83

84 3. Hypertonic Water concentration outside the cell is lower (eg. brine, syrup) than inside the cell. In other words, the solute concentration outside the cell is higher than inside the cell. The net result is that water moves out at greater rate than it moves in. Unit 1 Matter and Energy 84

85 Draw: Hypertonic Conditions Unit 1 Matter and Energy 85

86 Hypertonicity consequences Two possible results: 1. If a cell lacks a wall, it will shrivel up like a raisin. The cells stop metabolizing, but are not immediately killed. 2. If the cell has a wall, the membrane will shrink away from the wall as water leaves the cell, the rigid wall remains where it is. This leads to plasmolysis. This is undesirable state for walled cells because the cells stop metabolizing. Unit 1 Matter and Energy 86

87 Draw: Overview of Osmosis in cells Unit 1 Matter and Energy 87

88 Passive vs Active Passive transport relies on the random motion of particles to establish equal concentrations. The cell does not expend energy. Active transport moves molecules against the concentration gradient. It will move a solute against a concentration gradient, so it can concentrate material even if diffusion would favor the opposite direction of flow. There is an energy requirement by a cell for this process to occur. Unit 1 Matter and Energy 88

89 Active Transport When a cell must spend energy in order to move materials against the concentration gradient. Active transport involves moving materials from areas of low concentration to high concentration through a transport pump in the membrane. Energy in the form of ATP is used to work the pump.

90 Active Transport

91 Examples of Active Transport At rest, 40% of your energy is being used to perform active transport! How? Kidney cells move glucose (sugar) and amino acids (building blocks of proteins) into the bloodstream. Intestinal cells move nutrients in from the gut.

92 More examples Root cells of plants move nutrients from soil into the plant cells. Gill cells of fish pump out sodium ions.

93 Compare Active and Passive Transport Similarities Particles enter and exit the cell. Both use proteins in the membrane as doorways Differences Active Transport: moves particles against the conc. grad. requires energy expenditure by the cell Passive Transport: moves particles with the conc. grad. does not require energy from the cell. Unit 1 Matter and Energy 93

94 Bulk Membrane Transport Occurs by active transport. Molecules that are too large are moved across the membrane by way of the membrane folding in on itself to create a membraneenclosed, bubble-like sac, called a vesicle Draw

95 Bulk Membrane Transport

96 Bulk Membrane Transport When materials enter the cell in this manner, it s called Endocytosis. When materials exit the cell in this manner it s called Exocytosis.

97 Three kinds of Endo/Exocytosis 1. Pinocytosis- Cell drinking. Here, the cell takes in extracellular fluid that has dissolved particles, as if drinking. 2. Phagocytosis- Cell eating. Here, the cell takes in extracellular fluid that contains particulate or organic matter in it.

98 3. Receptor-Assisted/Mediated- The cell membrane has receptor proteins that attaches to specific molecules to transport. Like a lock and key, the molecules must match the receptor site.

99 Unit 1 Matter and Energy 99

100 Why are cells so small? EFFICIENCY! It is more efficient for cells to diffuse materials across the cell membrane over short distances. So, having trillions of small cells (as opposed to one large one) provides the best amount of cell membrane over which to transport materials in and out of the cell. Unit 1 Matter and Energy 100

101 The surface area to the volume ratio gets smaller as the cell gets larger. Thus, if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. Unit 1 Matter and Energy 101

102 Poor S.A/Vol vs Good S.A/Vol Unit 1 Matter and Energy 102

103 Surface Area: Volume Unit 1 Matter and Energy 103

104 Cells, Matter and Energy All organisms are composed of cells. They all need food to provide the energy and matter they need for growth and reproduction.

105 The energy that is utilized by a cell has to come from an outside source. In terms of the makeup of feeding relationships for organisms, the basis of all energy will be the SUN. In an ecological relationship, the sun is needed to provide the energy that producers need to make their own food by the process of PHOTOSYNTHESIS. The producers ( green plants, algae and some kinds of bacteria) undergo photosynthesis and are known as AUTOTROPHS. Autotrophs become food for other organisms known as HETEROTROPHS obtain food from other sources. Unit 1 Matter and Energy 105

106 Chemical Energy in Cells Cells control the chemical reactions occurring within. With every chem rxn, there is an energy transformation (a change from one form to another). The total of all the chemical reactions that occur within a cell is known as its METABOLISM.

107 METABOLISM Includes all the building up and breaking down of substances in a cell in addition to the energy transformations that occur simultaneously.

108 TWO MAJOR PROCESSES THAT PROVIDES CELLS WITH ENERGY: 1. Photosynthesis 2. Cellular Respiration Unit 1 Matter and Energy 108

109 Energy Transformations in Cells 1. Photosynthesis: Occurs in chloroplasts of plant cells. The chlorophyll absorbs light energy and give leaves their green colour. Light energy is used to transform carbon dioxide and water into energy-rich food.

110 CO2 + H2O C6H12O6 + O2

111 Energy Transformations con t 2. Aerobic Cellular Respiration: is the process of breaking down food (such as carbohydrates and other molecules) in order to release the (potential) energy present in food. Food is oxidized in the body to release energy. The energy molecule released in cellular respiration is ATP (adenosine triphosphate molecule). ATP is an energy carrier molecule used by an organism for its energy requirements. Occurs in the MITOCHONDRIA of our cells.

112 PS and CR are COMPLEMENTARY! Unit 1 Matter and Energy 112

113 Comparison of PS and CR Process Raw Materials Products Location photosynthesis carbon dioxide sugar water oxygen energy Chloroplasts of Plant Cells respiration sugar carbon dioxide oxygen water energy Mitochondria of Animals and plants Unit 1 Matter and Energy 113

114 There are two types of cellular respiration: Aerobic cellular respiration is a process that requires oxygen. It will release 38 ATP molecules in bacterial cells and 36 ATP molecules in cells with mitochondria. See figure 3.14, p. 82. Anaerobic cellular respiration is a process that will occur in the absence of oxygen. An example would be glycolysis which can occur in muscle cells. It will only release 2 ATP molecules from the breakdown of one glucose molecule. Unit 1 Matter and Energy 114

115 Global Implications of Photosynthesis (PS) and Cellular Respiration(CR) The energy transformations that occur in PS and CR are important for several reasons:

116 1. Autotrophs- manufacture their own food through PS. They form the basis of all food chains. Unit 1 Matter and Energy 116

117 2. Heterotrophs- These organisms must eat to obtain nutrients, therefore they depend indirectly on PS for food. They also depend on CR to release energy from their food. 3. Environment- PS and CR are important parts of the carbon cycle that recycles carbon throughout the land, water and atmosphere.

118 4. Industry- The economy is driven mainly by agriculture, fishing, forestry and mining. PS and CR play key roles in each. Agriculture and forestry- depend on plants to provide food, construction materials, fabrics,and pharmaceuticals. Fishery- The fish depend phytoplankton to perform PS to provide food. The fishers in turn catch the fish. Mining- The fossil fuels being mined today were once ancient forests and oceanbeds.