Describe flow of energy through living systems Compare chemical processes of autotrophs and heterotrophs Describe role of ATP in metabolism Describe how energy released.

1. Energy Changes in Cells
(Assimilation to Utilization)
Dr. Muhammad Awais
Department of Biosciences
COMSATS University Islamabad
Sahiwal Campus

2. Objectives:
• Describe flow of energy through living
systems
• Compare chemical processes of autotrophs
and heterotrophs
• Describe role of ATP in metabolism
• Describe how energy released.

3. Catabolic and Anabolic
Reactions
Catabolic-give off energy by breaking
down molecules
Anabolic—use energy to build
molecules
Energy released by catabolic
pathways used to drive anabolic
pathways

4. Thermodynamics
Study of the flow and transformation
of energy in the universe.

5. 1st Law of Thermodynamics
Law of conservation of energy
Energy can be converted but not
created nor destroyed.
Example:Energy stored in food converted
to chemical energy when we eat and
mechanical energy when you run.

6. 2nd Law of Thermodynamics.
Energy cannot be converted without the loss of
usable energy.
(Energy “lost” is converted to thermal energy)

7. Entropy
• Measure of disorder, or usable energy, in a
closed system (not available for useful
work)
• 2nd Law “Entropy Increases”
• Food Chain –Useful energy available to
next level decreases

8. Entropy

9. Where does Cell Energy Come
From?
Sun → Autotrophs → Food → ATP

10. Adenosine Triphosphate (ATP)
Multipurpose chemical energy
storage molecule
POWERS CELLULAR WORK
Carbon = 10
Nitrogen = 5
Oxygen = 13
Hydrogen = 16

11. • Adenine molecule
• Ribose sugar
• three phosphate groups

12. AMP/ADP/ATP
AMP
Adenosine
Monophosphate
ADP
Adenosine
Diphosphate
ATP
Adenosine
Triphosphate-
Number of
phosphate
groups
1 2 3
Energy to
form bonds
Small
Amount
More
Energy
Substantial
Energy
Energy
stored in
chemical
bonds
Minimal Greater
Amount
Greatest
amount

13. ATP Cycle
•Doesn’t exist all the time as ATP.
•Phosphate available--cell has an unlimited supply of
energy.

14. Energy from Fuels
• Digest large molecules into smaller ones
– break bonds & move electrons from one molecule
to another
• as electrons move they “carry energy” with them
• that energy is stored in another bond,
released as heat or harvested to make ATP

15. Two Reactions of Photosynthesis
1. Light Reaction ☼ – Light energy (sun)
into chemical energy.
• Thylakoid Disk
• Produces ATP to power Light Independent
Reaction.
• Oxygen Released
2. Light Independent Reaction/Dark Reaction
(Calvin Cycle) – Uses chemical energy to
“Fix” Carbon dioxide into sugar.
• Uses ATP and Electrons from Light Reaction
• Stroma

16. Mesophyll Cells
Specialized cells in the middle of the leaf that
contain a lot of chloroplast for photosynthesis

17. Fall Colors
• Pigments other then chlorophyll
• Chlorophyll reduced revealing other pigments
(carotenoids that are red, orange or yellow)

18. Light Dependent Reactions

20. Light Independent Reaction

21. Cellular Respiration
Mitochondria break down glucose to
produce energy (ATP)

22. Overview
•Every cell (plants and animals)
•Exergonic Reaction(produces energy)
•Equation-
C6H12O6 + ADP 6CO2 + 6H2O + ATP

24. Oxidation/Reduction Reactions
• Oxidation
– adding O
– removing H
– loss of electrons
– releases energy
– exergonic
• Reduction
– removing O
– adding H
– gain of electrons
– stores energy
– endergonic
C6H12O6 6O2 6CO2 6H2O ATP+ + +
oxidation
reduction

25. Cellular Respiration
Overview three stages:
– Glycolysis
• Cytoplasm
• Glucose splits
• Forms pyruvate (Intermediate-Acetyl CoA)
– Citric acid cycle (Kreb Cycle)
• Converts Acetyl CoA into CO2
• Occurs in Mitochondrial Matrix
– Electron transport chain
• ATP Synthesized

28. Pyruvic acid forms Acetyl CoA
Pyruvic Acid combines with Coenzyme A to
form acetyl CoA

30. Electron Transport Chain