BIOENERGETICS is the study of the transformation of energy in living organisms.
ROLE OF ATP AS ENERGY CURRENCY ATP is composed of adenine and ribose sugar with 3-phosphate groups
ATP plays role in several endergonic reaction such as synthesis of protein, lipids, carbohydrates, active transport etc.
In exergonic reactions like anaerobic glycolysis and oxidative phosphorylation, ATP also plays its role and acts as coenzyme.
PHOTOSYNTHESIS
CELLULAR RESPIRATION
PHOTOSYNTHESIS VS CELLULAR RESPIRATION (Chemical Reactions)
STRUCTURE OF CHLOROPHYLL
Chemical formula: C55H72MgN4O5
ROLE OF CHLOROPHYLL AND OTHER PIGMENTS
The most important pigments required in the process are the chlorophylls, the carotenoid and phycobilin pigments.
We can separate these pigments by paper chromatography with suitable solvent these pigment travel up by the paper at different speed due to their structures and size, In this way they are readily separated. Carotene,
phaelophytin, xanthophyll, chlorophyll-a, chlorophyll b will give orange,
grey, yellow, blue-green and yellow green appearance respectively.
The empirical formula of the chlorophyll-a molecule is C55 H72 O5 N4 Mg and that of Chlorophyll-b molecules is C55 H70 O6 N4 Mg.
STRUCTURE OF CHLOROPLAST
THYLAKOID MEMBRANES The thylakoid membranes of a chloroplast is an internal system of interconnected membranes, that carry out the light reactions of photosynthesis. They are arranged into stacked and unstacked regions called grana and stroma.
ROLE OF LIGHT
The plant is capable of using only a very small portion of incident electromagnetic radiation that falls on a leaf or the radiation that is absorbed by the pigment complex of the leaf. Each pigment has its own absorption spectrum.
When a photon of light hits chlorophyll-a molecules the energy of these photons is absorbed and results in the elevation of an electron from the ground state to an excited state.
ROLE OF WATER
Photosynthesis is a redox process. It requires H+ and electron, to fulfill this
requirement H2O is split and electrons are transferred along with Hydrogen ion
(H+) from H2O to CO2, reducing it to sugar
As water molecules are split, their oxygen atoms combine to form molecules of
oxygen (O2). From this discussion we can conclude that the water thus provides
H+ and e-
necessary for the reduction steps leading to assimilation of CO2.
ROLE OF CO2
CO2 provides the carbon for the basic
skeleton to photosynthetic product.
LIGHT REACTION
THE ELECTRON TRANSFER CHAIN
In the chloroplast, the light capturing chlorophyll molecules, membrane-bound proteins and electron carriers are components which together constitute the electron transfer chain
Four major groups of complexes are present in the membrane. These are photosystem I (PS I), Photosystem II (PS II), the cytochrome b/f complex (cyt b/f) and an ATPase complex. Mobile electron carriers transport the excited electrons between the complexes. These mobile electron carriers are plastoquinone(Pq), plastocyanin(Pc) and ferredoxin(Fd).
LIGHT INDEPENDENT REACTION (Dark reaction) or Calvin-Benson Cycle
ALTERNATIVE MECHANISMS OF CARBON FIXATION IN HOT, ARID CLIMATE
(C4 plants and CAM)
CELLULAR RESPIRATION
2-Anaerobic Cellular Respiration
It is the process of creating energy without the presence of oxygen.
Fermentation is an alternative term used for anaerobic respiration.
1- Aerobic Cellular Respiration
(i) Glycolysis (Breakdown of Glucose)
(ii) Kreb’s Cycle (Citric Acid Cycle)
(iii) Electron Transport Chain (Oxidative Phosphorylation)
(i) Glycolysis (Breakdown of Glucose)
Glycolysis is a series of reactions that extract energy from glucose by splitting it into two three-carbon molecules called pyruvates.
BREAK DOWN OF PYRUVIC ACID
The molecular remains of glycolysis are two molecules of pyruvic acid.
There are three major pathways by which it is further processed.
Under anaerobic conditions it either produces ethyl alcohol (Alcoholic fermentation)
or lactic acid (Lactic acid fermentation)
or produces carbon dioxide and water via Kreb's Cycle under aerobic conditions.
Alcoholic fermentation
pyruvic acid is decarboxylated under the action of enzyme to produce acetaldehyde, a two carbon molecule. NADH+ H+ reduces acetaldehyde to ethyl alcohol.
Lactic acid fermentation
When NADH+H+ transfers its hydrogen directly to pyruvic acid, it results in formation of lactic acid.
During extensive exercise such as fast running, muscle cells of animals and human beings respire anaerobically. Due to inadequate supply of oxygen, pyruvic acid is convert into lactic acid.
Formation of Acetyl Co A
Pyruvic acid diffuses from cytoplasmic fluid (Cytosol) into mitochondrion, the site of Kreb'scycle. Before entering into Kreb'sCycle it undergoes chemical changes.
THE CITRIC ACID CYCLE, refers to the first molecule that forms during the cycle's reactions—citrate, or, in its protonated form, citric acid. However, you may also hear this series of reactions called the tricarboxylic acid (TCA) cycle, for the three carboxyl groups on its first two intermediates, or the Krebs cycle, after its discoverer, Hans Krebs
ENERGY FLOW THROUGH THE ECOSYSTEM
ENERGY TYPES
UNIDIRECTIONAL FLOW OF ENERGY AND ITS SUBSEQUENT LOSSES
In ecology, productivity is the rate at which energy is added to the bodies of organisms in the form of biomass. Biomass is simply the amount of matter that's stored in the bodies of a group of organisms. Productivity can be defined for any trophic level or other group, and it may take units of either energy or biomass. There are two basic types of productivity: gross and net.
To illustrate the difference, let's consider primary productivity (the productivity of the primary producers of an ecosystem).
Gross primary productivity, or GPP, is the rate at which solar energy is captured in sugar molecules during photosynthesis (energy captured per unit area per unit time). Producers such as plants use some of this energy for metabolism/cellular respiration and some for growth (building tissues).
Net primary productivity, or NPP, is gross primary productivity minus the rate of energy loss to metabolism and maintenance. In other words, it's the rate at which energy is stored as biomass by plants or other primary producers and made available to the consumers in the ecosystem.
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