1. Cell Transport

2. Concentration Gradient
-When a substance is more concentrated in one area than another, it forms a concentration gradient

3. Concentration Gradient
-Molecules and ions are in constant motion because they have energy. They will naturally move from a region of high concentration to a region of low concentration.
-This is called movement down a concentration gradient. It requires no energy input to occur as the particles already have energy.

5. Passive Transport
-allows substances to pass through the cell membrane down the concentration gradient from high to low concentration without the cell using energy

6. 3 Different Types of Passive Transport
1. Diffusion 2. Facilitated Diffusion 3. Osmosis

7. Diffusion
small nonpolar molecules like oxygen and carbon dioxide cross the phospholipid bilayer, easily slipping between phospholipids in and out of the cell

8. Continuing movement of particles
-Even when equilibrium is reached, particles of a solution will continue to move across the membrane in both directions but this movement is not considered diffusion because diffusion requires a concentration gradient to occur.

9. Facilitated Diffusion
- special diffusion
-substances diffuse across the membrane through special transport proteins
-each protein only allows a specific substance to pass through the cell membrane

10. Facilitated Diffusion
-Molecules that cannot directly diffuse across the membrane, such as large molecules, charged ions, and polar molecules, pass through special protein channels.

13. Osmosis
-the diffusion of water through a selectively permeable membrane

14. Osmosis: An Example of Facilitated Diffusion
-The inside of a cell’s lipid bilayer is hydrophobic—or “water-hating.”
-water molecules have a tough time passing through the cell membrane

15. Osmosis: An Example of Facilitated Diffusion
-Many cells contain channel proteins, known as aquaporins, tubes with hydrophilic centers, that allow water to pass right through them.

16. Osmosis
-For organisms to survive, they must have a way to balance the intake and loss of water.
-The net movement of water out of or into a cell exerts a force known as osmotic pressure.

17. Volume changes
-Because the plasma membrane is impermeable to some solutes, osmosis can change the volume of fluid inside a cell.

18. Water in or out?
-Placing cells in solutions of different concentrations affects whether water will enter or exit the cell; there are 3 possible types of solutions a cell can be exposed to

19. 1. Isotonic Solutions
- there is an equal amount of water and solute inside the cell as outside the cell
- when cells are placed in isotonic solutions, water will enter and exit the cell at the same rate
-cell will remain the same size

21. 2.Hypotonic Solutions
-when cells are placed in hypotonic solutions, water will flow into the cell because there is more solute in the cell than outside the cell
-causes the cell to swell

23. 3.Hypertonic Solutions
-when cells are exposed to hypertonic solutions, water will flow out of the cell because there is more solute outside of the cell than inside the cell
-causes the cell to shrink

25. If the cell is placed in a solution that is…..

27. Using energy
- Some cells require creation and maintenance of a concentration gradient, and others require materials too large for membrane proteins to enter or exit.

28. Active Transport
-the movement of materials against a concentration gradient -allows substances to move across the cell membrane from an area of low concentration to an area of high concentration -requires energy in the form of ATP

29. -The active transport of ions across a cell membrane is generally carried out by ion pumps, proteins found in the membrane.
Active Transport

30. Ion pumps Ex> a nerve cell needs a high concentration of
sodium ions outside the
cell and a high
concentration of potassium
ions in the cytoplasm

31. Molecular Transport
-Macromolecules and other large materials can also be actively transported across the cell membrane by processes known as endocytosis and exocytosis.

32. Transport into and out of the cell
1. Exocytosis 2. Endocytosis

33. Exocytosis
-movement of materials out of the cell -The membrane of the vesicle surrounding the material fuses with the cell membrane, forcing the contents out of the cell.

35. Endocytosis -movement of materials into the cell
-Endocytosis is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane.
-The pocket that results breaks loose from the outer portion of the cell membrane and forms a vesicle within the cytoplasm.

36. Endocytosis

37. Types of Endocytosis
1.Phagocytosis -the plasma membrane surrounds a large solid piece of material and brings it into the cell Ex>Amoebas use this method for taking in food.

38. Types of Endocytosis 2. Pinocytosis
-In pinocytosis, cells take in liquid from the surrounding environment by forming tiny pockets along the cell membrane.
-The pockets fill with liquid and pinch off to form vesicles within the cell.

40. Cellular Respiration and Photosynthesis

41. Adenosine Triphosphate (ATP)
-One of the most important compounds that cells use to store and release energy is adenosine triphosphate (ATP)

42. ATP
-ATP can easily release and store energy by breaking and forming bonds between its phosphate groups.
-The “energy currency” of the cell

43. Composition of ATP Adenine + Ribose = Adenosine 1.Adenine
2.Ribose (5-C Sugar)
3. 3 Phosphate Groups
Adenine + Ribose = Adenosine

44. Adenosine Triphosphate (ATP)

45. Composition of ADP
ADP is structurally like ATP, except that it has two phosphate groups instead of three.
1. Adenine
2. Ribose
3. 2 Phosphate Groups
ADP contains less energy than ATP. ADP is formed by the hydrolysis of ATP.

46. ADP

47. Converting between ATP and ADP

48. Building or breaking
-When your body needs to use energy, you break down ATP to ADP. -When your body is storing energy, you are building up ADP to ATP.

49. The need for ATP
-ATP is continuously produced and then consumed in our cells. Without it, our cells would not be able to perform all of the functions we need to survive.
How can our cells continuously reassemble ATP? Where does the energy come from?
Cellular Respiration

50. Cellular Respiration
-Process by which the chemical energy of “food” molecules is released & captured in the form of ATP

51. Cellular Respiration can be divided into 3 processes
1. Glycolysis
2. Krebs Cycle
3. Electron Transport Chain
-Each step releases more and more of the energy stored in glucose.

52. Stages of Cellular Respiration

53. Where does this happen? 1. Glycolysis 2. Krebs Cycle
in the cytoplasm
2. Krebs Cycle
in the mitochondrial matrix
3. Electron Transport Chain
at the surface of the inner mitochondrial membrane

54. ATP production -Each molecule of glucose can generate a total of 36 ATP molecules during the 3 steps of cellular respiration.

55. Glycolysis
-Process in which glucose is broken down in order to utilize potential energy stored in the molecule

56. Gylcolysis Products -Net gain of 2ATP molecules & 2NADH molecules
-Glucose is broken down into pyruvate (Pyruvic acid)
-Glycolysis does not require oxygen; it is an anaerobic process.

57. Glycolysis

58. If oxygen is present after glycolysis:
Pyruvate will move to the Krebs cycle when oxygen is present (aerobic respiration)

59. If oxygen is not present after glycolysis:
-If oxygen is not present (anaerobic respiration), then pyruvate will go through the process of fermentation.

60. Fermentation
-Fermentation is a process by which energy can be released from food molecules in the absence of oxygen. Fermentation occurs in the cytoplasm of cells.

61. Fermentation
-During fermentation, cells convert NADH produced by glycolysis back into the electron carrier NAD+, which allows glycolysis to continue producing ATP.

62. 2 types of fermentation 1.Lactic Acid Fermentation
-In animals, pyruvic acid is converted to lactic acid when it accepts electrons from NADH, regenerating NAD+

63. Lactic Acid Fermentation

64. Alcoholic Fermentation
-Only occurs in yeast and some other microorganisms
-Pyruvic acid is broken down into alcohol & CO2

65. Alcoholic fermentation
-Causes bread dough to rise, produces tiny bubbles in beer & sparkling wine as well as the alcohol content

67. Alcoholic Fermentation

68. In aerobic conditions…
-In the second stage of cellular respiration, pyruvic acid produced in glycolysis is broken down into carbon dioxide in a series of energy-extracting reactions.

69. Energy Capture
-Energy released by the breaking and rearranging of carbon bonds is captured in the forms of ATP, NADH, and FADH2.

70. Kreb’s Cycle Products Per Glucose Molecule
-For each glucose molecule, 6 CO2 molecules, 2 ATP molecules, 8 NADH molecules, and 2 FADH2 molecules are produced.
-FADH2 accepts electrons from FAD the same way NADH does from NAD+.

71. ETC
-The electron transport chain produces the bulk of the energy in cellular respiration by using oxygen, a powerful electron acceptor.

72. Electron Transport Chain
ETC
-The electron transport chain uses high-energy electrons to convert ADP into ATP; it allows the release of the large amount of chemical energy stored in NADH and FADH2

73. Energy Totals
-In the presence of oxygen, the complete breakdown of glucose through cellular respiration results in the net production of 36 ATP molecules.
-This represents about 36 percent of the total energy of glucose. The remaining 64 percent is released as heat.

74. Overall equation for Cellular Respiration

75. Photosynthesis

76. What is photosynthesis?
-Photosynthesis is the process by which green plants and certain other organisms use the energy of light to convert carbon dioxide and water into glucose. -The glucose can be used in cellular respiration, used structurally (cellulose), or stored (starch).

77. Glucose source for animals
-Humans and other animals depend on glucose as an energy source, but they are unable to produce it on their own and must rely ultimately on the glucose produced by plants.

78. Take a breath…
-An extremely important byproduct of photosynthesis is oxygen, the same oxygen humans and other animals breathe.

79. Overall Equation for Photosynthesis

80. Pigments
-Plants gather the sun’s energy with these light-absorbing molecules.
-The plants’ principal pigment is chlorophyll.

81. Leaf structures
- A leaf takes in carbon dioxide through openings called stomata, small pores on the underside of the leaf. Stomata open to let carbon dioxide in and oxygen out. They close to prevent water loss when temperatures are high.
-Water enters through the roots into tube like vascular tissue where it is transported to the cells where it is needed.

82. Where does photosynthesis occur?
-Photosynthesis occurs in leaves and green stems within specialized cell structures called chloroplasts that surround the central vacuole. -One plant leaf is composed of tens of thousands of cells, and each cell contains 40 to 50 chloroplasts.

83. Chloroplasts
-The chloroplast, an oval-shaped structure, is divided by membranes into numerous disk-shaped compartments containing chlorophyll, called thylakoids suspended in a fluid known as stroma.

84. Stages Photosynthesis is divided into two stages:
1. Light –dependent reactions
2. Light-independent reactions

85. Light-Dependent Reactions

86. Summary of Light-Dependent Reactions
-The light-dependent reactions produce oxygen gas and convert ADP and NADP+ into the energy carriers ATP and NADPH, which provide the energy needed to build high-energy sugars from low-energy carbon dioxide in the next stage.

87. Light-Independent Reactions
-No light is required to power the light-independent reactions, but products of the first stage are used.
-The light-independent reactions take place outside the thylakoids, in the stroma.

88. Light-Independent Reactions
-During light-independent reactions, ATP and NADPH molecules (unstable) produced in the light-dependent reactions are used to produce high-energy sugars(stable) from carbon dioxide.
-Also known as the Calvin Cycle….

89. Summary of the Calvin Cycle
-When other organisms eat plants, they can use the energy and raw materials stored in plants.
- A single six carbon sugar is produced, but 6 carbon dioxide molecules are removed from the atmosphere to make it.

90. Factors Affecting Photosynthesis
What factors affect the rate of photosynthesis?
-Among the most important factors that affect photosynthesis are
1.Temperature
2. light intensity
3. availability of water
4.Carbon dioxide levels

91. Comparing Photosynthesis and Cellular Respiration
What is the relationship between photosynthesis and cellular respiration?
Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses that oxygen to release energy from food.

92. Comparing Photosynthesis and Cellular Respiration
The release of energy by cellular respiration takes place in plants, animals, fungi, protists, and most bacteria.
Energy capture by photosynthesis occurs only in plants, algae, and some bacteria.

93. Comparing Photosynthesis and Cellular Respiration
Photosynthesis and cellular respiration are opposite processes.
The energy flows in opposite directions. Photosynthesis “deposits” energy, and cellular respiration “withdraws” energy.
The reactants of cellular respiration are the products of photosynthesis and vice versa.

94. Photosynthesis and Cellular Respiration