This document summarizes key concepts in bioenergetics and cellular respiration. It discusses how living organisms obtain and use energy through redox reactions and electron carriers like ATP. Photosynthesis and cellular respiration are introduced as the two main pathways of energy transformation. Photosynthesis uses energy from sunlight to synthesize glucose from carbon dioxide and water, while cellular respiration breaks down glucose to release energy through glycolysis, the Krebs cycle, and the electron transport chain. The document aims to explain the basic processes of how energy is transformed and utilized in living cells and organisms.

1. BIOENERGETICS
GENERAL BIOLOGY 1
Prepared by: Ms. Louie Jane T. Eleccion
Transformation of Energy in Living Organisms

3. ENERGY
•Needed to perform heavy labor and exercise.
•It is required for both the synthesis and
breakdown of molecules.

4. Process Questions:
•From where, and in what form, does this energy
come?
•How do living cells obtain energy, and how do they
use it?

5. ELECTRONS AND
ENERGY
Redox Reactions

6. OXIDATION-REDUCTION (REDOX)
•Oxidation – removal of an electron in a
compound.
•Reduction – addition of this electron to
another compound.

8. Redox Reactions
•Removal of an electron from a molecule, results in
decreased potential energy, and its addition increases the
potential energy of the other.
•Most of the energy stored in atoms and used to fuel cell
function is in the form of high-energy electrons.
•The transfer of energy in the form of electrons allows the
cell to transfer and use energy in an incremental fashion.

9. ELECTRON CARRIERS
•In living systems, a small class of compounds
functions as electrons.
•They bind and carry high-energy electrons
between compounds in pathways.
•They are derived from the B vitamin group and
are derivatives of nucleotide.

14. ATP: ADENOSINE
TRIPHOSPHATE
The Energy Currency of the Cell

15. •A living cell cannot store significant amounts of energy
•Excess energy would result in an excessive thermal
condition that could damage and destroy the cell.
•A cell must be able to handle that energy in a way that
enables the cell to store energy and release it for use
only as needed.

17. •When ATP is broken down, usually by removal of its
terminal phosphate group, energy is released—which
energy is used by our cells to do work. Usually by the
released phosphate binds to another molecule,
activating it.
•Phosphoanhydride bonds – between phosphate
groups of ATP.

19. ENERGY FROM ATP

20. •Hydrolysis – water is split, resulting hydrogen atom
and hydroxyl group.
•The hydrolysis of ATP produces ADP (Adenosine
diphosphate), with an inorganic phosphate ion (Pi)
and the release of free energy. Hydrolysis is
reversible!

21. •To carry out life processes, ATP is continuously
broken down into ADP.
•ADP is continuously regenerated into ATP by the
reattachment of a third phosphate group.
ENERGY FROM ATP

22. Where does this energy come from?
•In nearly every living thing on earth, the energy
comes from the metabolism of glucose.
•ATP is a direct link between the limited set of
exergonic pathways of glucose catabolism and the
multitude of endergonic pathways that power living
cells.

23. METABOLISM
Sum of all the chemical activities taking place in an organism

24. Catabolism
•Larger molecules broken down into smaller ones
--Stages 1-4 (Digestion; Formation of Acetyl CoA;
Citric Acid Cycle; Electron Transport Chain &
Oxidative Phosphorylation)
•Releases energy (may be stored temporarily as ATP)
•Ex. CELLULAR RESPIRATION

25. •Acetyl-CoA (acetyl coenzyme A) is a molecule that
participates in many biochemical reactions in
carbohydrate and lipid metabolism.
•Its main function is to deliver the acetyl group to the
citric acid cycle (Krebs cycle) to be oxidized for
production.

26. Anabolism
•Complex molecules synthesized from simpler
substances
•Absorbs energy & stores it as chemical bonds
•Ex. PHOTOSYNTHESIS

27. PHOTOSYNTHESIS
Catabolic Pathway

28. Introduction
•From the Greek…
PHOTO = produced by light
SYNTHESIS = a whole made of parts put together.
Definition: PHOTOSYNTHESIS is the process whereby plants, algae,
some bacteria, use the energy of the sun to synthesize organic
compounds (sugars) from inorganic compounds (CO2 and water).

29. Importance
PHOTOSYNTHESIS is one of the most important
biological process on earth!
• Provides the oxygen we breathe
• Consumes much of the CO2
• Food
• Energy

30. 2 Processes of Photosynthesis
• Light-dependent Reaction
-Energy from sunlight is absorbed by chlorophyll and that energy is
converted into stored chemical energy.
-Occurs in the thylakoid lumen.
• Light-independent Reactions (Calvin Cycle)
- Chemical energy harvested during the light-dependent reactions drive
the assembly of sugar molecules from carbon dioxide.
- Occurs in the chloroplast stroma.

31. General Formula
light
6 CO2 + 12 H2O ---------> C6H12O6 + 6 O2 + 6 H2O
pigments, enzymes

32. LIGHT-DEPENDENT REACTION
•Requires only
water and light
to start the
Process.
•Produce NADPH
and ATP as its final
products

33. LIGHT-INDEPENDENT REACTION
• Requires one molecule
of carbon dioxide to
initiate the process.
• Produce glucose
(C6 H12 O6) as its
final product.

35. WATCH THE VIDEOS ABOUT
PHOTOSYNTHESIS AND CALVIN CYCLE
on our facebook page!

36. CELLULAR
RESPIRATION
Anabolic Pathway

37. •Cellular respiration starts with OXYGEN and
GLUCOSE…
•Can make up to 38 molecules of ATP!

38. 3 STAGES:
•GLYCOLYSIS – breaking down of glucose
•THE KREB’S CYCLE - produces NADH and
FADH2 for ETC and fuels production of ATP.
•ELECTRON TRANSPORT CHAIN

40. GLYCOLYSIS (Summary)
• Anaerobic process (requires NO OXYGEN)
• Occurs in the cell’s cytoplasm.
• Invests 2 molecules of ATP in order to work (split glucose into half).
• Energy return of 4 ATP molecules.
• But the ATP Net Yield is only 2 since the process invests 2 ATP
molecules at the beginning of glycolysis.
• Produces 2 NADH molecules (which will enter ETC).
• Also produces 2 pyruvate molecules/pyruvic acid (which will enter The
Kreb’s Cycle).

42. THE KREB’S CYCLE (Summary)
• Aerobic process (Requires Oxygen)
• Occurs in the mitochondrial matrix of the cell.
• Needs the pyruvate from glycolysis to start the process, together with
Acetyl Co-enzyme A.
• Two CO2 and 2 NADH will be released –prep stage.
• Acetyl Co-A combines with Oxaloacetate to make citrate/citric acid.
• Uses FAD+ electron carrier which is reduced to FADH+
• Produce 4 CO2, 6 NADH, 2 FADH2, 2 ATP

44. ELECTRON TRANSPORT CHAIN
• Aerobic process (Requires Oxygen!)
• Occurs in the mitochondrial inner folding (cristae).
• Uses four complexes to transport electrons creating proton
gradient (H+) to generate the function of ATP Synthase.
• Requires NADH and FADH2 molecules to generate 34 ATPs.

46. Don't let your teacher affect your love for science. You
can be a scientist outside of the classroom too. Be
your own teacher. Keep your love of learning and you
will do just fine.
ENJOY THE VIDEOS! 