Overview.
Structure.
ATP energy.
ATP from food.
Energy storage.
ATP in plants.
ATP in animals.
ATP in mitochondria.
Sodium, potassium pump.
ATP and membrane transport.
ATP and muscles.
ATP and proteins.
ATP and DNA.
ATP recycling.
LUCA.
ATP is the unit of energy currency.
Most of the living cells, in plants, animals, bacteria,
and all living organisms, use ATP to derive energy.
Some of the earliest forms of life, single cellular organisms,
which existed billion of years ago, used ATP for energy.
The same basic design has been carried forward by nature,
to all living organisms, that exists today.
In the evolution of the metabolism of life, using ATP to store energy,
was one of the earliest developments.
This fundamental concept was adapted by all forms of life.
ATP stands for Adenosine triphosphate.
Adenine is the purine base.
It is nitrogenous.
Adenine is also one of the bases, found in DNA.
It has a sugar base called Ribose.
Adenine plus Ribose, is called Adenosine.
ATP has three phosphate groups attached to Adenosine.
When two phosphate groups are attached to Adenosine,
it is called Adenosine diphosphate, or ADP.
When one phosphate group, is added to ATP,
it is called Adenosine monophosphate.
Creation of ATP from ADP, requires energy.
Conversion of ATP to ADP releases energy.
The removal of a phosphate group, releases energy.
Chemical compounds contain energy, in their bonds.
Typically breaking of the bond, would release this energy.
In the case of ATP, we use the energy, contained in the phosphate bonds.
We can consider that third phosphate group,
like a spring which contains potential energy.
ATP can be compared to a charged battery.
It is ready to give energy.
In a chemical reaction, when one of the phosphate bonds,
in ATP is broken off, it releases energy.
When cells need energy, they convert Adenine triphosphate, or ATP to ADP.
ADP stands for Adenine diphosphate.
The released phosphate group, has energy, which can be used wherever required.
The released phosphate group, is denoted as pi,
which means it is a inorganic phosphate.
ADP can be compared to a discharged battery.
It has given off its energy.
It needs to be recharged, to store energy.
The conversion of ATP to ADP, is a catabolic process.
It involves breaking down a molecule.
It is also an exergonic reaction, since it releases energy.
ATP is the currency of energy, in many biochemical reactions.
Whenever and wherever energy is required, ATP is converted to ADP,
to release energy.
A molecule of ATP, has a fixed amount of energy.
The amount of energy released, is also fixed.
We can measure this energy.
Glucose is a basic food, used by cells.
Electrical energy is stored, in a chemical form,
in the carbon bonds of glucose.
Breaking these bonds releases energy.
Breaking down one molecule of glucose,
results in production of 30 plus molecules of ATP energy.
Carbohydrates we consume are broken down, to produce glucose.
Fats that we consume, are triglycerides.
These are metabolised to produce fatty acids, and glycerol.
Breaking down a fatty acids, will result in a production of much more ATP.
So, we can say that fats store, more energy than sugars, and carbohydrates.
Since ATP has a fixed amount of energy,
it is referred to as the currency of biochemical energy.
The process of producing ATP from food,
is called as cellular respiration.
This typically requires the presence of oxygen.
ATP can also be produced, by a process called fermentation.
In this process oxygen is not required.
Glucose is oxidised to produce, lactic acid and ATP.
Living organisms require a constant source of energy.
The supply of energy, however, is not constant.
Plants source their energy, from the sun.
Daylight is not always available.
Animals source their energy, from the food they eat.
Food is not consumed constantly.
Because of this, living organisms have a strong need,
to store energy.
Living organisms break down food to derive energy,
in the form of ATP, for living.
Food and energy supply is intermittent.
Plants and animals, also have a metabolism to store food.
Energy storage molecules, are synthesised, from smaller molecules.
This requires energy.
ATP provides this energy, to synthesise, food or energy storage molecules.
Plants synthesise molecules like glucose, to store energy.
Glucose can then be used to produce other molecules,
like carbohydrates and fats, to store energy.
To synthesise large molecules like glucose, and other food molecules,
energy input is required.
This energy goes into creating more chemical bonds.
Plants harvest the sun's energy.
They use this energy to create ATP energy molecules.
They do this by converting ADP to ATP.
This is done by adding a phosphate group, to ADP.
This process requires energy.
The energy required to do this, is harvested from the sun.
ATP is then used to synthesise molecules like glucose.
Animals including human beings,
break down food to derive energy.
The process of breaking down, starts with digestion.
Food in the form of carbohydrates, is broken down to glucose.
Food in the form of fat, is broken down to fatty acids.
Food in the form of protein, is broken down to amino acids.
These simple molecules, are transported to all cells,
by the blood circulating system.
Cells absorb these nutrient molecules.
Glucose is the most common nutrient molecule.
The cell breaks down glucose, into smaller molecules.
In the presence of oxygen, these intermediate molecules,
are further broken down to provide ATP.
In animals, and human beings, the organelle for producing ATP,
is the mitochondria.
Mitochondria is an important organelle, found in most cells,
of a living organism.
Mitochondria is the energy factory, of the cell.
Most of the living cells have multiple mitochondria organelles,
depending on their energy needs.
For example, muscle cells have many more mitochondria organelles.
They supply energy to the cell, in the form of ATP.
ADP diffuses from the mitochondria, to different part of the cell,
where it is required.
The cell uses energy from ATP, for various metabolic process,
required for living.
Cells in animals and human beings,
are enclosed in a membrane.
The membrane is selectively permeable only to certain substances.
Substances are transported in and out of the membrane.
Cells also maintain, different concentration levels, of certain substances,
inside and outside the cell.
This differential concentration, results in a concentration gradient,
across the cell membrane.
Sodium and potassium ions are examples, of substances,
which have a concentration gradient, across the cell membrane.
Neurons use this gradient, to generate action potential.
This gradient is also used by cells, to transport substances,
in and out of the cell.
Almost all cells maintain a sodium and potassium ions concentration gradient.
Cells maintain a higher concentration of sodium ions, outside the cell.
They maintain a higher concentration of potassium ions, inside the cell.
To achieve this, they have to constantly pump sodium ions, out of the cell,
and pump potassium ions into the cell.
This is done by the sodium potassium pump.
The sodium potassium pump, is a special protein, which acts like a pump.
In one cycle it transports three sodium ions, out of the cell,
and two potassium ions into the cell.
Sodium is pumped, from inside the cell, which has a lower concentration,
to outside the cell where it has a higher concentration.
Potassium is pumped, from outside the cell, which has a higher concentration,
to inside the cell which has a lower concentration.
This process requires input of energy.
This energy is supplied by ATP, produced in the mitochondria.
The sodium potassium pump is constantly at work.
It never stops.
This means it needs a continuous and steady supply of ATP energy.
Mitochondria continuously produces ATP, to drive this pump.
A significant portion of the energy we derive from food,
about 20%, goes to run the sodium potassium pump.
This process is essential for cell metabolism and continuous to operate,
even while we are resting.
All cells are enclosed in a membrane.
Membranes are composed of two phospholipid layers.
Membranes are selectively permeable to certain substances.
For example, oxygen and glucose are transported into the cell.
Carbon dioxide and waste are transported out of the cell.
Proteins embedded in the membrane, are the channels through which,
substances are transported.
ATP facilitates the transport of larger molecules, called macro molecules,
across cell membranes.
We discussed that ATP is required, even when we are resting.
When we are active, our skeletal muscles are working.
Skeletal muscles require energy to work.
Even day to day activities like walking and talking,
requires muscles to work.
Muscles cells have the organelle mitochondria to generate ATP.
Where ever more energy is required, muscle cells have more mitochondria.
When we exercise, apart from growing muscle cells,
individual cells develop more mitochondria.
This is the reason that people who do regular exercise, have more energy.
For cells to be healthy, they need to be exercised.
If we consume more energy than we use,
the excess energy is converted to fat, or adipose tissue.
Active people use more energy, in their cells.
This also helps to maintain appropriate weight.
Muscles work by contracting some muscle,
and relaxing another.
Muscle cells have protein fibres, called myosin and actin.
These fibres are arranged in parallel, inside the muscle cell.
When the actin fibres, slide over the myosin fibre,
it causes the muscle to contract.
This act of sliding, which leads to contraction, requires energy.
ATP provides the energy for muscles to contract.
Proteins are long chains of amino acids.
There are 20 basic amino acids.
The proteins that we eat as food, is broken down,
into the constituent basic amino acids.
Proteins are the molecular bio chemical machinery of the body.
Our body synthesises thousands of these proteins.
It uses combinations of the 20 basic amino acids,
to build these proteins.
Proteins are very long chains of amino acids.
They curl up into balls of many shapes,
to provide a myriad of functions,
ranging from detecting light in the eyes,
to building muscles in the body.
To synthesise these proteins, DNA sends out instructions,
in the form of RNA.
These instructions are used by an organelle called Ribosomes.
It stitches together one amino acid at a time,
like the beads of a necklace.
This process of stitching together, or synthesising, requires energy.
This energy is provided by ATP.
DNA is present in the nucleus, of most cells in the body.
DNA is the encyclopaedia of life.
DNA is a long chain, built from nuclei acids.
RNA which DNA uses to send instructions,
is also a long chain of nuclei acids.
Nucleotides are building blocks of nuclei acids.
Energy is required to synthesise RNA and DNA,
from nucleotides.
This energy is supplied by ATP.
ATP stands for Adenosine triphosphate.
Adenosine is one of the basic nucleotides of DNA, and RNA.
ATP is a part of the basic genetic code, present in cells.
The structure of ATP is similar to structure of DNA.
ATP is not meant for long storage.
Typically the energy of ATP is used,
shortly after its production.
The human body continuously recycles its ATP.
In the presence of water, ATP can be easily hydrolysed to ADP.
This involves replacing the phosphate groups,
with the hydroxyl group.
When ATP is converted to ADP,
the inorganic phosphate groups p i is released.
P i contains energy, which can be used for most metabolic reactions.
When there is excess energy ADP is converted to ATP,
which stores the energy.
This process of converting ATP to ADP,
and ADP to ATP is continuously happening in the body.
Typically, ADP molecule, is recycled about 500 to 750 times, in a day.
The body could turnover about 10 million molecules, of ATP every second.
The mitochondria is the organelle, responsible for this process.
ATP produced in the mitochondria diffuse to other parts of the cell,
where energy is required.
ADP diffuses from the cytoplasm of the cell, back to the mitochondria.
The diffusion process is driven by the concentration gradient.
This recycling helps to store or release energy,
as per current needs, of a particular cell.
At any point of time, the body stores only 250 gm, of ATP.
During the day, the body might turnover,
the equivalent of its own weight, of ATP.
Scientist believe that all living cells had a common ancestor.
This cell has been named as LUCA.
L U C A stands for, Last Universal Common Ancestor.
This cell had certain properties.
It had DNA, RNA, glucose, ribosomes, proteins,
membranes, ion channels and ATP.
This cell existed more than a billion years ago.
ATP is one of the first things, that nature designed for
use in its cell.
It is still in use in most living organisms.