PPT GROUP 6 HOW DO ORGANIZMNS GET ENERGY_20250917_142415_0000.pptx

HOW DO
ORGANISMS GET
ENERGY?
GROUP 6

Son
Lola
Alis
Tacuban
MEET OUR TEAM

HOW DO ORGANISMS GET
ENERGY?
Organisms usually get the chemical energy they need from food.
Food consists of organic molecules that store energy in the form
of chemical energy Different animals have different ways of
obtaining food. Autotrophs are organisms that make their food.
Most autotrophs use energy from sunlight to make their food.
They are also called producers. Plants, most algae, and some
bacteria are photosynthetic autotrophs. They can make food
through photosynthesis.
Producers make food not only for themselves, they inadvertently
make food for other living organisms as well. This is the reason
why the autotrophs are the starting organisms in all food chains.

Organisms that cannot
make their food obtain
food by consuming other
organisms. These
organisms are referred to
as heterotrophs. They
may consume
autotrophs, other
heterotrophs, or both.
Heterotrophs include
animals, fungi, and some
single-celled organisms

ENERGY-GIVING MOLECULES: GLUCOSE AND
ATP
What are the energy giving molecules?
All organisms mainly use two types of energy-giving molecules: glucose and ATP.
Glucose is made during the process of photosynthesis. With the help of light energy
from the sun, water, and carbon dioxide, plants create glucose where chemical energy is
stored in a concentrated and stable form. In the human body, glucose is transported by
the blood and taken up by the cells as energy source. The stored energy in glucose is
released in a reverse reaction of photosynthesis called cellular respiration
Adenosine triphosphate (ATP) molecules store smaller amounts of energy, but each
molecule releases enough energy to do the work within the cell. It is the energy-carrying
molecule used by the cell. ATP is made during the first half of photosynthesis and is
used during the second half where glucose is made. It is also used for energy by the
cells for other important cellular processes. But how does ATP give energy? The energy
from ATP is released when it gives up one of its three phosphates. Doing so changes its
form from ATP to ADP (adenosine diphosphate), as shown by the following reaction:
.

The flow of energy through living things begins with
photosynthesis in producer This process stores the energy from
the sun in the chemical bonds of glucose molecule These bonds
are broken to release ATP in a process called cellular respiratic
Photosynthesis and cellular respiration are like the two sides of a
coin: the produ of one process are the reactants of the other. In
summary, the two processes store a release energy in living
things. Both processes are also essential in the recycling oxygen
on Earth.

PHOTOSYNTHETIC ORGANELLES
Photosynthetic pigments, are unique pigments found in all
photosynthetic organisms, such as plants and some bacteria.
These pigments capture light energy necessary for
photosynthesis. Plants have two groups of pigments-chlorophyl
and carotenoids. Chlorophyll a and chlorophyll b are green
pigments that absorb al wavelengths of light in the red, blue, and
violet ranges. Carotenoids are yellow, orange and red pigments.
They absorb light in blue, green, and violet ranges. The pigment
found in red algae, called the phycobilins, which give them their
reddish color, absort light in blue and green ranges.

Chloroplasts are cell organelles found in plants and algae. Figure 6-3 shows the structure of a
chloroplast. Each chloroplast contains grana (singular: granum), where the light reaction occurs.
Each granum is made up of layers of sac-like membranes called the thylakoids. The thylakoid is
the site of photosystem I and photosystem II. Photosystems are groups of molecules, which
include chlorophyll, that are involved in photosynthesis. The light-dependent reactions in
photosynthesis occur in the thylakoid membranes. The stroma is the space found outside the
thylakoids. It is where the Calvin cycle takes place.

Photosystems are important parts of the thylakoid membrane.
These are light-harvesting complexes. There are a few hundreds
of photosystems in each thylakoid. Each photosystem has a
reaction center containing chlorophyll a, and a region containing
other pigments that funnel the energy into chlorophyll a. The two
types of photosystems, the photosystem I (PS I) and the
photosystem II (PS II), are named in order of their discovery.
However, PS II operates first followed by PS L. PS I absorbs light
best in 680 nm range; hence, it is sometimes called P680. On the
other hand, PS II absorbs light best in 700 nm range, hence it is
also called P700.

SCIENCE PIONEER
Jan Ingenhousz
In 1779 Jan Ingenhousz discovered
the process of photosynthesis. He
was a Dutch-born British physician.
Many scientists had worked in plant
experimentation but he discovered
that plants need light for
photosynthesis and only the green
part of the plant performs
photosynthesis. From then on, other
scientists focused on the role of light
in the process of food production in
plants

PHOTOSYNTHESIS
What is the importance of photosynthesis and cellular respiration
Imagine Earth as a giant factory, with photosynthesis as its most
important production line. Photosynthesis acts as the factory's
powerhouse, supplying over 99% of the energy needed by all
living things. Just like in a factory, photosynthesis converts raw
materials into valuable products for the consumers.
photosynthesis has many chemical reactions, but it can be
summed up in a single chemical formula
light 600,+6H,0C,H,O, +60,
carbon dioxside water glucose oxygen

Photosynthesis occurs in two stages, Stage I
includes the light-dependent reactions and
stage II includes the light-independent
reactions. Light dependent reactions directly
use light energy to produce ATP and
nicotinamide adenine dinucleotide phosphate
(NADPH), another energy-carrying molecule
that power the light independent reactions.
During this stage, oxygen is also released as
a by-product. In the light independent
reaction, also called Calvin cycle, the ATP and
NADPH from light reactions are used to
create glucose. However, the reactions do not
stop with glucose The end product glucose
and other simple sugars are bonded together
to form starch, sucrose, fructose, and other
carbohydrates. These carbohydrates are
considered as the true end products of
photosynthesis.

PROCESS
Light reactions in the thylakoid
When units of light called photons strike a molecule of
chlorophyll in PS II, the light is absorbed by two electrons
(2) in the chlorophyll, which gives them enough energy to
leave the molecule. At the same time. water (H,O) splits
apart and produces the following
Two electrons, which replace the electron loss of
chlorophyll in PS II during light absorption
Two hydrogen tons (2H), which are positively charged and
are released inside the interior space of the thylakoid
membrane
One oxygen (O) atom that combines with another oxygen
atom, producing one oxygen molecule (O), which is
released into the atmosphere as a by product
1
Electron transport chain (ETC)
The excited electrons from PS II go on a
journey through the electron transport
chain.
Along the way, their energy is used to
pump even more hydrogen ions into the
thylakoid.
This creates a build-up of positive charge
and forms a gradient.
2
ATP production
The build-up of hydrogen ions creates
energy, like a waterfall waiting to power a
turbine.
ATP synthase acts like that turbine, letting
the hydrogen tons flow through.
producing ATP. the plant's energy currency.
This ATP is crucial for the next stage, the
Calvin cycle.
3

PROCESS
Photosystem I (PS 1)
The electrons, now calm, reach
PSI
Here, they get a boost of
energy from more sunlight
and are passed to a primary
acceptor
4
NADPH production
Meanwhile, another important
molecule, NADP, picks up hydrogen
tons from the H2O in PS 11.
This creates NADPH, which carries the
hydrogen atoms to the light
independent reactions, where they
help make glucose.
5

In summary, light reactions in the thylakoid
harness sunlight to split water, create energy (ATP),
and produce molecules (NADPH) that are vital for
making glucose in the Calvin cycle. It's like the
plant's power station working hard to create its
own energy and food.

LIGHT-INDEPENDENT
REACTIONS
The second stage of photosynthesis, called Calvin cycle, happens
in the stroma surrounding the thylakoids in the chloroplast. The
reactions in this stage occur without the direct use of energy
from light; hence, they are often called dark reactions. The
discovery of this reaction by scientist Melvin Calvin won him a
Nobel Prize in 1961. In this cycle, chemical energy NADPH and
ATP from the light reactions are used to create glucose.
The Calvin cycle is like a factory inside plants that take in carbon
dioxide (CO2) from the air and turns it into an energy-rich sugar
(glucose). This cycle consists of three main steps carbon fixation,
reduction reactions, and regeneration

The second stage of photosynthesis, called Calvin cycle, happens
in the stroma surrounding the thylakoids in the chloroplast. The
reactions in this stage occur without the direct use of energy
from light; hence, they are often called dark reactions. The
discovery of this reaction by scientist Melvin Calvin won him a
Nobel Prize in 1961. In this cycle, chemical energy NADPH and
ATP from the light reactions are used to create glucose.
The Calvin cycle is like a factory inside plants that take in carbon
dioxide (CO2) from the air and turns it into an energy-rich sugar
(glucose). This cycle consists of three main steps carbon fixation,

The second stage of photosynthesis,
called Calvin cycle, happens in the
stroma surrounding the thylakoids in
the chloroplast. The reactions in this
stage occur without the direct use of
energy from light; hence, they are often
called dark reactions. The discovery of
this reaction by scientist Melvin Calvin
won him a Nobel Prize in 1961. In this
cycle, chemical energy NADPH and ATP
from the light reactions are used to
create glucose.
The Calvin cycle is like a factory inside
plants that take in carbon dioxide (CO2)
from the air and turns it into an energy-
rich sugar (glucose). This cycle consists
of three main steps carbon fixation,

1. Carbon fixation Carbon fixation
occurs when carbon dioxide (CO₂) from
the atmosphere combines with a simple
five-carbon (5-C) sugar compound,
ribulose biphosphate (RuBP), forming
an unstable six-carbon (6-C) molecule.
The 6-C molecule is immediately broken
down into two three-carbon (3-C) sugar
phosphate known as 3-
phosphoglycerate (3-PGA).
2. Reduction reactions The 3-PGA
molecules gain energy from the ATP
and NADPH from the light reactions,
and rearrange themselves to form
glycerate 3-phosphate (G3P). This
molecule also contains three carbon
atoms but is more stable than 3-PGA. A
single G3P molecule goes on to form
into glyceraldehyde 3-phosphate
(PGAL), the three-carbon (3-C)
carbohydrate precursor of glucose and
other sugars. The rest of the G3P
proceed to regeneration step.
It is important to note that some of the
G3P molecules generated in the
reduction reactions are used to
synthesize glucose, which can be used
as an energy source for the cell or
converted into more complex organic
molecules.
3. Regeneration of RuBP The remaining
G3P molecules then use more ATP to
revert back to RuBP, completing the
cycle. Converting the G3P molecules to
the RuBP allows the cycle to repeat.

CELLULAR RESPIRATION
another important life process
is the means by which cells release the stored energy in glucose
to make adenosine triphosphate (ATP). The primary goal of this
life process is to convert stored energy into usable form, such as
ATP, for the cells to carry out their functions. Cellular respiration
involves several chemical reactions. The reactions can be
summed up in the following equation:
C6H12O6 + 60, 6CO₂+ 6H2O + ATP
glucose oxygen carbon dioxide water energy

Aerobic respiration reactions, or cellular respiration that takes
place in the presence of oxygen, can be grouped into three
stages glycolysis. Krebs cycle, and electron transport chain (ETC).

STAGE I: GLYCOLYSIS
Glycolysis is the process that breaks down one molecule
of 6-C glucose into 3-C pyruvates or pyruvic acids. It also
releases four molecules of ATP. This process occurs in the
cytoplasm of the cell. The following is the step-by-step
process of glycolysis. Take note that several enzymes are
involved in this process.

PROCESS
1 The first step of glycolysis requires energy. It can only proceed when the two ATP
molecules donate energy to the glucose by transferring a phosphate group with
the help of an enzyme, producing glucose 6-phosphate.
2. Then, a specific enzyme promotes the rearrangement of the
atoms, producing the fructose 6-phosphate.

PROCESS
3. The action of the enzyme in step 2 promotes the transfer of a
phosphate group from another ATP molecule, forming fructose 1,6-
bisphosphate.
4. The resulting fructose 1,6-bisphosphate molecules, with the help of another
enzyme, splits into two molecules, each with three carbon backbones. These two
sugars are dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

PROCESS
5. Another important enzyme then rapidly interconverts the molecules
of dihydro-xyacetone phosphate and glyceraldehyde 3-phosphate.
This produces two molecules of glyceraldehyde 3-phosphate or 3-
phosphoglyceraldehyde (PGAL).
6. The succeeding step involves another enzyme-mediated action. The hydrogen
(H) from PGAL is transferred to the oxidizing agent, nicotinamide adenine
dinucleotide (NAD), which forms NADH. A phosphate (P) is also added from the
cytosol of the cell to oxidize the two molecules of PGAL, forming two 1,3-
bisphosphoglycerate.

PROCESS
7. A phosphate (P) from 1,3-bisphos-phoglycerate is transferred to
ADP to form ATP. This happens for each of the two 1,3-
bisphosphoglycerate, resulting to a yield of two ATP and two 3-
phosphoglycerate molecules.
8. A phosphate is transferred from 3- phosphoglycerate molecules from the
third carbon to the second carbon, forming 2-phosphoglycerate molecules.

PROCESS
9. A hydrogen atom and a hydroxyl (-OH) group is released, which
then combines to form water (H₂O). The removal of HO from 2-
phosphoglycerate results in the formation of two phosphoenolpyruvic
acid (PEP).
10. Phosphate (P) from PEP is transferred to ADP (and forms ATP) and the
final product, pyruvic acid. This reaction yields two molecules of pyruvic
acid and two ATP molecules.

STAGE II: KREBS
The Krebs cycle, named after its proponent Sir Hans Adolf
Krebs, is a cyclical series of enzyme-controlled reactions.
This stage of cellular respiration occurs in the matrix of
the mitochondria. It is sometimes called the citric acid
cycle (CAC) since it produces citric acid. Citric acid
contains three carboxyl (COOH) groups; hence, it is also
called the tricarboxylic acid cycle (TCA). This requires the
pyruvic acids produced during glycolysis. The main
function of this cycle is to produce high-energy-yielding
molecules, namely, NADH and flavin adenine dinucleotide
(FADH) that will later on be used in the electron transport
chain reaction.

An initial process is needed for the Krebs cycle to begin.
As a pyruvate molecule from glycolysis enters the
mitochondrion, it undergoes an important preliminary
reaction. Coenzyme-A (COA) combines with pyruvate to
form acetyl-CoA with the help of an enzymatic complex.
This conversion also produces CO, and NADH

The Krebs cycle is summarized as follows. Take note that
several enzymes are involved in this process.

PROCESS
1. The Krebs cycle technically begins when the acetyl-CoA combines
with oxaloacetic acid (OAA), a 4-C molecule, to produce citric acid, a 6-
C molecule
2. With the aid of an enzyme, the citric acid now goes through a series of
reactions that releases energy. Water molecule is removed from the citric
acid and is returned in a different location. The -OH group is repositioned,
forming the molecule isocitrate.

PROCESS
3. Isocitrate is then oxidized, forming the a-ketoglutarate, a 5-C
molecule. The byproducts of this reaction are NADH and CO,.
4. The a-ketoglutarate loses its CO, and a coenzyme-A is added in its place.
The decarboxylation occurs with the help of NAD, which then becomes
NADH. The resulting molecule is called succinyl-CoA

PROCESS
5. Succinyl-CoA is converted into succinate. Also in this reaction, a molecule of guanosine
triphosphate (GTP) is synthesized. The GTP molecule has similar structure and energy properties
to that of ATP and is used by cells the same way. The free phosphate group attacks the succinyl-
CoA molecule, which detaches the CoA. Then, phosphate is attached to GDP to come up with
GTP, similar to the process that occur in ATP synthesis (from ADP to ATP).
6. Two hydrogens are removed from succinate. A molecule of flavin
adenine dinucleotide (FAD), a coenzyme similar to NAD, is reduced to
FADH, as it takes the hydrogens from the succinate. This reaction produces
the fumarate.

PROCESS
7. Fumarate is then converted into malate as the addition of a water
molecule is catalyzed.
8. The final reaction is the regeneration of oxaloacetate. The resulting
byproduct of this regeneration is NADH.

PROCESS
9. Recall that two pyruvate molecules were produced during
glycolysis, causing the Krebs cycle to turn twice. Each turn produces
three molecules of NADH, a single ATP, one FADH, and the by-product
CO, which is exhaled.

DATA ANALYSIS
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PPT GROUP 6 HOW DO ORGANIZMNS GET ENERGY_20250917_142415_0000.pptx

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