Honors Biology Ch. 8

1
HonorsBiologyCh. 8

• Cellular Energy

2
I. How Organisms Obtain Energy

• - Cells are miniature factories where thousands
  of reactions using energy occur constantly.

3
A. Transformation of Energy

• 1. First Law of Thermodynamics
• - Energy cannot be created or destroyed, but can
  be transformed and transferred.

4
2. Second Law of Thermodynamics

• - When energy is transformed, some energy is lost
  as heat.

5
3. All Organisms Use Energy

• a. Autotrophs
• - organisms that make their own food
• - photosynthesis
• - producers

6
b. Heterotrophs

• - organisms that obtain energy from other
  organisms
• - consumers

7
B. Metabolism

• - all the chemical reactions in a cell
• 1. Catabolic Pathways
• - break down large molecules into smaller
  molecules releasing energy
• - cellular respiration
• 2. Anabolic Pathways
• - build up larger molecules from small
  molecules using energy
• - photosynthesis

8
C. ATP

• - adenosine triphosphate
• - energy transfer molecule
• - provides energy for cellular functions

9
Energy Flow and Chemical Recycling in Ecosystems
10
II. Photosynthesis

• - light energy is converted to chemical energy
• A. Chloroplasts
• - organelle of photosynthesis

11
B. Photosynthetic Pigments

• - Pigments are substances that absorb light energy

12

• - chlorophyll absorbs violet-blue and red light
• - Chlorophyll a is the primary photosynthetic
  pigment.

13
- Chlorophyll b and carotenoids are accessory
pigments.
Chlorophyll a, Chlorophyll b, and ß - Carotene
are found in plants.
Phycoerythrin is found in red algae
Phycocyanin is found in blue-green algae
14
Photosynthetic Pigments Found in Spinach leaves
15
Molecular Structure of Cellulose
16
C. Light Reactions

• - Light energy is used to produce ATP and NADPH
  for the Calvin Cycle.

17
C. Light Reactions

• - Light energy is used to produce ATP and NADPH
  for the Calvin Cycle.

18
1. Light absorbed by Photosystem II

• - Water molecules are split, oxygen released.
• - Electron becomes excited and enters electron
  transport chain.

19
2. The Electron Transport Chain

• - Energy from electrons pumps H into thylakoid
  space as it passes along the electron transport
  chain.

20
3. More Light Absorbed by Photosystem I

• - Electron becomes re-excited.
• - NADPH (an electron carrier and energy transport
  molecule) is formed.

21
4. Chemiosmosis

• - Hydrogen ions (protons) move down their
  concentration gradient out of the thylakoid space.

22
5. ATP Synthase

• - ATP synthesized by ATP synthase as hydrogen
  ions pass out of the thylakoid space.

23
D. Calvin Cycle

• - Glucose produced with energy from ATP and NADPH
  from the light reactions.

24
1. Carbon Fixation

• - 6 CO2 are joined to 6 5-C molecules of RuBP to
  form 12 3-C molecules of PGA.

25
The Calvin Cycle
26
2. G3P Produced

• - Energy from 12 ATP and 12 NADPH is used to
  produce 12 G3P (glyceraldehyde 3-phosphate)
  molecules.
• - 2 G3P molecules are used to make glucose.

27
The Calvin Cycle
O2
6
28
3. Calvin Cycle Completed

• - 6 RuBP molecules produced from 10 G3P molecules
  to complete the Calvin Cycle.

29
The Calvin Cycle
O2
6
30
Alternative Photosynthesis PathwaysC4 and CAM
C4 Photosynthesis
CAM Photosynthesis
CO2
Organic acids release CO2 to Calvin cycle
Organic acids release CO2 to Calvin cycle
31
III. Cellular Respiration

• - Organic molecules (glucose) are broken down to
  release energy in the form of ATP to do cellular
  work.

32

• - Occurs in 2 main parts glycolysis and
  aerobic respiration

33
A. Glycolysis

• - splits glucose (6-C) into pyruvate (3-C) to
  release energy
• - produces 2 ATP and 2 NADH
• - occurs in the cytoplasm
• - does not require oxygen

34
B. Krebs Cycle

• - completes the energy yielding break down of
  pyruvate
• - produces (for each glucose) 2 ATP, 6
  NADH, 2 FADH2, and 3 CO2
• - takes place in the matrix of the
  mitochondrion

35
C. Electron Transport Chain

• - a series of protein molecules embedded in the
  inner membrane of the mitochondrion
• - requires oxygen

36

• - Energy from electrons from NADH and FADH2 pumps
  H ion into the intermembrane space creating a H
  gradient.

37

• - At the end of the chain, electrons are passed
  to oxygen, forming water.

38
D. Chemiosmosis

• - H ions move down their concentration gradient
  out of the intermembrane space.
• - ATP synthesized by ATP Synthase as H
  ions pass out of the intermembrane
  space.

ATP Synthase
39
D. Chemiosmosis

• - H ions move down their concentration gradient
  out of the intermembrane space.
• - ATP synthesized by ATP Synthase as H
  ions pass out of the intermembrane
  space.
• - Produces 32 ATP

ATP Synthase
40
IV. Anaerobic Respiration (Fermentation)

• - Uses glycolysis to produce ATP in the absence
  of O2.
• - Regenerates NAD from NADH.
• - Produces only 2 ATP from glucose.

41
A. Lactic Acid Fermentation

• - Occurs when skeletal muscles use up O2 faster
  than lungs can supply O2.
• - Lactic acid produced from pyruvate and NADH
  converted to NAD.

42

• - Also produced by bacteria when processing milk
  into yogurt and cheese.

43
B. Alcohol Fermentation

• - Occurs in yeast and some bacteria.
• - Ethanol and CO2 produced from pyruvate and
  NADH converted to NAD.

44
How Cells Obtain Energy A Review of Cellular
Respiration and Photosynthesis (1402)
45

• The
• End