No. 1


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                             ASSISTANT PROFESSOR OF BOTANY


                             SIDRA TABASSUM

NO 9524

                             M.Sc 1st morning



 A day
most of our time we spend in eating . For example we take bread , sandwitch r
any other cereal diet . We also take meat , vegetables and grains .  After intake of this food we have to digest
it firstly . Our boday digest it. After digestion these nutrients become
building blocks of our body and we get energy from it  . This energy for body needs is obtained by a
prosess whuch we call metabolism. 

is metabolism?

Metabolism  defined as combination of all the
chemical reactions that are taking place in our body .  It keeps capacity to convert fuel into energy
which we need in our daily tasks . We grow, walk , think and do everything with
this energy

These chemical reactions
are controlled in our body by specific proteins . Every chemical reaction is in
coordination with other body parts . If our body is healty it is only due to
these chemical reactions occurring within it , at the same time hundreds of
chemical reactions are taking place to keep one fit .

 When a new baby borns its metabolism starts
and continuous till its death.

It is not a phenomena for human , every living
thing works under this rule , if metabolism stops one individual will certainly
die .



Examples of human metabolism and its begning by plants


Sun is an energy source for everything in this world either
directly or in directly . Plants receive this energy and is captured by a green
pigment named as chlorophyll. This process is called photosynthesis


When human beings or any other organism that may be a herbivore or
carnivore eats these green plants it gets energy in form of sugars . Like other
building blocks body tends to break at once this sugar into smaller units from
which we get energy .

When one takes food proteins which we call enzymes break it down


Carbohydrates into sugars

Proteins into amino acids

Fats into simple fatty acids


All these molecules are consumeable by our body

These molecules when our body absorbes then it moves to blood
stream in blood streem many other enzymatic reactions take place to speed up

Energy from these compounds is released to our body . We may
utilize it or may store it into our body tissues for future use as in the form
of body fats or in liver or in muscles

in plants

 In plants metabolisms are very complex as they
are non motile and they have toi maintain their activities as


photosynthesis energy strikes to that of plant thallakoids grana and is used
for  photosynthesis . It is very useful
process and its equation is as under

+ h2o + chlorophyll + light____ glucose +
co2 + water




process of photosynthesis is important for life because we may get directly or
indirectly energy from it .



Light strikes the
mesophyll cells . From cell wall it enters to that of thallakoids . Where it
reaches to that of chloroplast. From btotall amount of light 80% is absorbed by
the leaf surface . This light is used for photosynthesis.

Most of the light that
falls on leaves is in the form of visible light. Light spectra is in the form
of white light which is combination of different coloured light .

Reb ang blue lights are
most effective for plants . Wave length of 390 is aiso absorbed by plats . Red
light is of 890 nanometer in  wavelength
which is totally different from far red light.






in plants was under study for several years . There are many types of
chlorophyll but two types are most common that are

1; chlorophyll a


Al these types are
similar in strcture because they all have a magnecium as a central atom that
resembles to heme group of haemoglobin of blood of human. Light on chlorophyll
falls band results in formation of giucose . Major plant reserve.




 This reaction takes place in the granal membranes
and depends on the end products of light reactions. These are called dark
reactions because they does not depend on light directly. But these reactions
cannot proceed without the presence of end products of light reactions as shown

Best example of these
reactions is calvin reaction ‘ in these reactions carbon dioxide is fixed into
a five carbon compound rubisco. This compound is further converted to a carbon
compound like glucose with the help of an enzymatic reactions . Hydrogen in
this process move to NADP to form NADPH . End product of this reaction can be
utilized or it can be further stored


 these reactions there is gain and loss
of protons . These are also called as redox reactions . In oxidation there is
removal of hydrogen and gain of oygen. Substance which itself is oidized
reduces other molecule . On the othet=r hand in reduction there is gain of
hydrogen and removal of oygen.




It is both forms may be wave like
or particle like . That is why it shows dual nature. It is in the form of
discret packets of energy known as quanta.


Hense proved from above discussion
that metaboilism is necessary for plants as well as for animals , if metabolism
stops there is no life because food which we intake is as it is , there is mo
break down of food no gain  of energy ,
no life.