1. Cellular Transport and Processes
Unit 4
Obj , 4.2.1, 4.2.2

2. The Cell Membrane
The gateway to the cell

3. Cell Membrane
Flexible
Allows unicellular organisms to move

4. Functions of the Cell Membrane
Protection
Regulates what comes in and out
Allows cell recognition
Anchoring sites for cytoskeleton
Attachment sites for enzymes
Binds cells together at junctions
Contains cytoplasm

5. Structure and Components of Cell Membrane
Phospholipid = phosphate head (hydrophilic) and lipid tails (hydrophobic)
Bilayer = two layers
Studded with proteins (peripheral = partially through and integral = all the way through) and carbohydrates

6. Phospholipids
Contains two fatty acid chains that are non-polar (tail) and a polar head made of -PO4 (phosphate)

7. Selective Permeability
Hydrophobic and hydrophilic
Polar and non-polar
Allows membrane to “choose” what comes across and maintain homeostasis
Hydrophobic molecules (can dissolve in lipids) pass easily, hydrophilic molecules(can dissolve in water) do not

8. Semi-permeable membrane
Hydrophobic molecules can pass through freely even if they are large
Hydrophilic molecules can only pass through freely if they are very small and can “slip through the cracks”
Examples: CO2, O2, H2O

9. Homeostasis Balanced internal condition of cells
Also called equilibrium
Maintained by plasma membrane controlling what enters and leaves the cell

10. Types of Transport

11. Simple Diffusion Requires no energy  passive transport
Molecules have a natural kinetic energy
Molecules move from an area of high concentration to an area of low concentration

12. Diffusion in Liquids

13. Diffusion Through a Membrane
Solute moves down the concentration gradient  from high to low

14. Osmosis
Diffusion of water across a membrane  water is so special, it gets its very own transport!
Moves from high water potential to low water potential

15. Osmosis High water potential, Low solute concentration
Low water potential,
High solute concentration

16. Aquaporins
Special channels for water to pass through during osmosis

17. Comparing Solutions
Isotonic = when the concentration of two solutions is the same
Hypotonic = when comparing two solutions, the solution with the lesser concentration of solutes
Hypertonic = when comparing two solutions, the solution with the greater concentration of solutes

18. Cell in Isotonic Solution
The Plasma Membrane
4/25/2017
Cell in Isotonic Solution
10% NaCL 90% H2O
ENVIRONMENT
CELL
NO NET MOVEMENT
10% NaCL
90% H2O
What is the direction of water movement?
equilibrium
The cell is at _______________.
G. Podgorski, Biol. 1010

19. Cell in Hypotonic Solution
The Plasma Membrane
4/25/2017
Cell in Hypotonic Solution
10% NaCL 90% H2O
CELL
20% NaCL
80% H2O
What is the direction of water movement?
G. Podgorski, Biol. 1010

20. Cell in Hypertonic Solution
The Plasma Membrane
4/25/2017
Cell in Hypertonic Solution
15% NaCL 85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
What is the direction of water movement?
G. Podgorski, Biol. 1010

21. Cells in Solutions

22. What can happen to a cell in different solutions?
Cytolysis = the cell bursts from water rushing in and making it swell up, occurs in hypotonic solutions
Plasmolysis = the cell shrivels up from water rushing out, occurs in hypertonic solutions
isotonic hypotonic hypertonic

23. Cytolysis and Plasmolysis

24. Osmosis in Red Blood Cells
The Plasma Membrane
4/25/2017
Osmosis in Red Blood Cells
Isotonic
Hypertonic
Hypotonic
G. Podgorski, Biol. 1010

25. isotonic hypotonic hypertonic hypertonic isotonic hypotonic
The Plasma Membrane
4/25/2017
isotonic
hypotonic
hypertonic
hypertonic
isotonic
hypotonic
G. Podgorski, Biol. 1010

26. Facilitated Diffusion
Does not require energy  passive transport
Needs some help from transport proteins  they allow the molecules through
Molecules move from high to low concentrations
Channel proteins = embedded in the cell membrane and have pore for materials to cross
Carrier proteins = can change shape to move material from one side to the other

27. Channel Proteins

28. Carrier Proteins

29. Active Transport Requires energy or ATP to occur
Moves materials from low to high concentrations = against the concentration gradient

30. Other forms of cell transport
Exocytosis = cell releases large amount of material
Endocytosis = cell takes in a large amount of material by folding it in the cell membrane
Pinocytosis = cell takes in liquid, “cell drinking”
Phagocytosis = extensions of cytoplasm surround and engulf large particles and take them into the cell

31. Exocytosis

32. Exocytosis

33. Endocytosis

34. Pinocytosis

35. Pinocytosis

36. Phagocytosis

37. Photosynthesis

38. We need energy Energy is the ability to do work
Most energy on earth comes from the sun
Heterotrophs get energy by eating other organisms
Autotrophs make their own food and energy  photosynthesis = when they use the sun (light energy) as their energy source

39. How do we store energy? Chemical bonds are formed = energy is stored
Chemical bonds are broken = energy is released
Adenosine triphosphate (ATP) = main source of energy for cells, provides power for almost all functions
Contains adenine, ribose (5-carbon sugar), and 3 phosphate groups

40. How do we store energy? ATP = “charged” battery, stores energy
Energy is released by breaking off the last phosphate group  Adenosine diphosphate (ADP)
ADP = “dead” battery, energy has been released

41. How does photosynthesis work?
Plants use the energy from the sun to convert water and carbon dioxide into oxygen and glucose (sugar)
Joseph Priestly – discovered that plants make oxygen. He placed a lit candle under a jar and waited until it had consumed all the oxygen. He discovered that if he placed a sprig of mint in the jar and waited a few days, the candle could be lit again, indicating that the plant produced oxygen.

42. Photosynthesis equation
6CO2 + 6H2O light> C6H12O6 + 6O2
Carbon dioxide + water light> glucose + oxygen
Carbon dioxide, water, and light must be present for photosynthesis to occur

43. What kind of light does photosynthesis need to occur?
Sunlight is “white” light  a mixture of different wavelengths of light
Pigment = light-absorbing molecule
Chlorophyll = main pigment of plants, does not absorb green light very well  gets reflected back to our eyes

44. Inside a Chloroplast
Thylakoids = small disc-shaped saclike photosynthetic membranes
Grana = stacks of thylakoids
Stroma = region outside thylakoid membranes

45. Electron Carriers
Electrons gain a great deal of energy when they are excited by the sun  require special carriers
NADP+ (nicotinamide adenine dinucleotide phosphate) = main electron carrier
NADP+ holds 2 high energy electrons and additional hydrogen ion  becomes NADPH
NADPH carries electrons to chemical reactions elsewhere in the cell

46. Two Parts of Photosynthesis
1. Light-dependent reaction = produces energy from solar power (photons) in the form of ATP and NADPH
2. Calvin Cycle or Light Independent Reaction
Also called “carbon fixation” or “C3 Fixation”
Uses energy (ATP and NADPH) from light reaction to make glucose

47. Factors affecting photosynthesis
Temperature
Availability of water
Light intensity
These factors are different in different areas of the world  plants develop special adaptations

48. Respiration

49. What is cellular respiration?
Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.
Two kinds of respiration:
Aerobic respiration = occurs if oxygen is present
Anaerobic respiration = occurs if oxygen is not present

50. Equation
Cellular respiration: 6O2 + C6H12O6  6CO2 + 6H2O + Energy (ATP)
Recall – Photosynthesis equation: 6CO2 + 6H2O light> 6O2 + C6H12O6

51. Process Cellular respiration happens in a series of steps
Energy is released slowly, which allows the cell to trap more of it and store it in ATP

52. Process Step 1: Glycolysis
One molecule of glucose (C6H12O6) is broken in half, producing two molecules of pyruvic acid (C3H6O3)
Uses up 2 molecules of ATP  energy “investment”
4 molecules of ATP are produced  net gain of 2 ATP molecules
Occurs in cytoplasm of cell
Does not require oxygen  can be part of aerobic or anaerobic respiration
Electron carrier = NAD+ (without electron pair)  NADH (with electron pair)

53. Process – Anaerobic respiration
Step 2: Fermentation
Occurs in cytoplasm of cells
In plants, yeasts, etc. it is called “alcoholic fermentation” pyruvic acid + NADH  alcohol +CO2 + NAD+
In animal cells and some prokaryotes, it is called “lactic acid fermentation” pyruvic acid + NADH  lactic acid + NAD+
Lactic acid = burning sensation in muscles during exercise

55. Process – Aerobic respiration
Step 2: Krebs cycle
Occurs in mitochondria
Pyruvic acid is broken down into carbon dioxide
Produces 2 ATP

56. Process – Aerobic respiration
Step 3: Electron transport chain
Occurs in mitochondria
Produces H2O and 34 ATP

57. Comparing aerobic and anaerobic respiration
Produces 36 ATP
Produces CO2 and H2O
Occurs in mitochondria and cytoplasm
Produces 2 ATP
Can produce CO2, lactic acid, and/or alcohol
Occurs in cytoplasm

58. Comparing photosynthesis and cellular respiration
Function
Energy capture
Energy release
Location
Chloroplasts
Mitochondria
Reactants
CO2 and H2O
C6H12O6 and O2
Products
Equation
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6 + 6O2  6CO2 + 6H2O
Energy
Energy