The document discusses the process of seed germination. It explains that germination begins with the resumption of growth of the embryo after a dormant period. Stored food materials like carbohydrates, proteins, and nutrients are broken down by enzymes into soluble compounds that are transported to the growing embryo. The embryo then grows, sending the plumule upwards and radicle downwards. For germination to occur, conditions like moisture, temperature, oxygen, and seed treatment must be favorable. This stimulates respiration where stored foods are used to produce energy for embryonic growth.

1. K.VENKATASALAM
I M.Sc., (Soil science and Agricultural chemistry)
ADAC & RI, Trichy
Tamil Nadu Agricultural University.

2. The resumption of the growth of embryo after this
dormant period is called germination.

3.  The reserve food material consist of fats, carbohydrates, proteins
and other organic compounds along with inorganic elements like
macro and micronutrients.
 The plant food materials present in unavailable form are acted upon
by these enzymes and converted into soluble and available form
which are translocated to the growing point of the embryo
 The embryo grows in size and sending the plumule upwards and the
radicle downwards

4.  When seeds are placed in favourable environment for germination,
the slow metabolism of resting seed becomes rapid and intense and
reactions like hydrolysis, oxidation and synthesis occur.
 Enzymes like carbohydrases, proteinases, aminases, oxidases and
deosmolases becomes active.
 Stored food is changed from insoluble and immovable substances to
soluble and transportable compounds which are translocated to the
embryo.

5.  These are moisture, temperature, light, sufficient oxygen, seed
treatment, age of seed, etc.
 The conditions of germination are diametrically opposite to those of
the conditions of storage.
 It is necessary to provide the requisite conditions for germination so
that respiration is stimulated and fats, carbohydrates, etc. are utilised
to produce heat and energy required for the growth of embryo

6. The main storage of carbohydrate of seeds is Starch.
Starch amylases Glucose, maltose, dextrins
Maltose maltase Glucose

7.  Starch is the nutritional polysaccharide and major storage
carbohydrate found in the plants which are formed by
photosynthesis.
 Photosynthesis is a process in which green plants convert the
light energy from the sun into chemical energy with evolution
of O2.
6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O
(Glucose)

8. Glucose-1-P AGPase ADP- glucose pyrophosphate
+ ATP + Diphosphate
2 Glucose Starch synthase α-amylase + ADP
+ADP-Glucose
2 α-amylase Starch branching enzyme amylopectin
De-branching enzyme

9.  An anaerobic phase of catabolism of carbohydrate is succeed
by aerobic phase called tri-carboxylic acid cycle.
 For each molecule of glucose used, two molecules of ATP are
gained.
 The hydrogen of the DPN. Hydrogen is converted into water
by reactions with oxygen

10. Legends
 ATP=Adenosine
Tri Phosphate
 ADP=Adenosine
Di Phosphate
 NAD+=Nicotinamide
adenine dinucleotide
 Pi = Inorganic Phosphate

11. Amino acids are synthesized in two ways:
 Reductive amination
 Transamination

12. Reductive amination
 NH3 formed from NO3 reduction. Combines with keto acids
formed during respiration (kreb’s cycle) to produce respective
AAs.
 Both α keto glutaric acid & oxalo acetic acid are intermediates
of kreb’s citric acid cycle – Aerobic oxidation of sugars.
 Dehydrogenase enzymes are responsible for reductive
amination.

13.  Synthesis of glutamic acid:
α keto glutaric acid Glutamic dehydrogenase Glutamic acid
+ NH3 + DPNH2 + DPN + H2O
 Synthesis of Aspartic acid
Oxalo acetic acid Aspartic dehydrogenase Aspartric acid
+ NH3 + DPNH2 + DPN + H2O
 Synthesis of Alanine from pyruvic acid
Pyruvic acid Alanine dehydrogenase Alanine
+ NH3 + DPNH2 + DPN + H2O

14. Transamination
 Glutamic acid & aspartic acid can now synthesis act as precursors
in the synthesis of other amino acids by group of enzymes known as
transaminases. (they carry pyridoxal PO4 as the prosthetic group)
 Mechanism
Amino group from pyridoxal PO4 forms pyridoxamine PO4 it
transfers the amino group to other organic acids to form respective
AAs.

15. Most of the AAs required for protein synthesis are formed
through process of transamination of glutamic acids & aspartic
acids
 Synthesis of Aspartic acid
Glutamic acid α keto glutaric acid
+ Oxalo acetic acid + Aspartic acid
 Synthesis of Alanine from pyruvic acid
Pyruvic acid Alanine
+ Glutamic acid + α keto glutaric acid

16. Condensation of amino acids
Proteins are synthesized by condensation of number of
AAs molecules & held by peptide linkages (-CO-NH).
several hundred molecules of AAs are required to form
a single protein molecules.

17. Oils and fats are mixed triglycerides (esters of glycerol
and fatty acids)
 Simple glycerides
All three hydroxyl groups are esterified with same fatty acids.
 Mixed glycerides
The hydroxyl groups are esterified with more than one fatty
acid. Fatty acids contain even number of carbon atoms.
Glycerol + 3 Fatty acids Fat (or) Oil +3H2O

18. There are three distinct steps in the biosynthesis of fat &
oils.
 Synthesis of glycerides
 Synthesis of fatty acids
 Condensation of glycerol & fatty acids

19. Synthesis of Glycerides
In plants, glycerol can be synthesized by more than one
mechanism
1,6 fructose Aldalose Di Hydroxy Acetone Phosphate
diphosphate + Phospho Glyceraldehyde
+ NADH2 + H3PO4
- H2O
Dephosphorylation
Glycerol 1,3 DHAP or Glycero PO4
ATP ADP

20. Fatty acid synthesis:
 Most important fatty acids commonly found in plant tissues
have even number of carbon atoms (C-16 &C-18 fatty acids
are most abundant).
 Some of the two carbon compounds which serve as starting
materials for fatty acids synthesis are ethanol (C2H5OH),
acetaldehyde (CH3CHO) and Acetic acid (CH3COOH).
 Acetyl co-A & Acetyl carrier protein serve as precursors for
fatty acid synthesis.

21. Under anaerobic conditions, a bacterium called clostridium can
synthesize Butyric & caproic acid from ethyl alcohol & acetic acids.
C2H5OH + CH3COOH CH3CH2CH2COOH
2C2H5OH + CH3COOH CH3(CH2)4COOH
Condensation of glycerol & fatty acids:
This take place in the presence of an enzyme ‘Lipase’ & requires
less energy only.
Glycerol + 3 Fatty acids Fat (or) Oil +3H2O

22.  Respiration is the process during which simple carbohydrates
like glucose, break down into simpler substances and liberate
carbon dioxide and energy
 The compound used or oxidized during respiration is called a
respiratory substrate
 Carbohydrates, fats and proteins are examples of respiratory
substrates
 The rate of respiration can be measured in terms of gas
exchange
i.e.) Consumption of respiratory substrate oxygen or
evaluation of carbon dioxide

23. Legends
 ATP=Adenosine
Tri Phosphate
 ADP=Adenosine
Di Phosphate
 NAD+=Nicotinamide
Adenine Dinucleotide
 Pi = Inorganic Phosphate
 FAD+= Flavin Adenine
Dinucleotide

24.  During Aerobic respiration, oxygen is consumed and carbon
dioxide is released.
 The Respiration Quotient (RQ) is the ratio of CO2 produced to
that of the O2 consumed while food is being metabolized
Volume of CO2 evolved
RQ =
Volume of O2 consumed

25.  Provides energy needed by the cell and gives to the whole organism
 During Respiration, food energy is changed into an available form
that plant cell can used
 Aerobic respiration returns CO2 to the atmosphere to be used again
in photosynthesis
 Plants are known their ability to convert Carbon dioxide to Oxygen
 During Respiration, Seeds used sugars and other molecules as a
substrate for respiration

26.  Reactions are catalyzed by enzymes
 Main food substance which oxidized in cells is Glucose
C6H12O6 + 6O2 6CO2 + 6H2O + energy
 As it take place in all living cells, it is called cellular
respiration which is used to produce energy for cells to used.
Two types:
i. Anaerobic respiration
ii. Aerobic respiration

28.  Anaerobic respiration is a type of respiration that does not use
oxygen
Glucose Lactic acid + energy
 Anaerobic respiration in plant cells and some microorganisms
(such as yeast) produces ethanol and carbon dioxide
Glucose Ethanol + Carbon dioxide + energy
 Aerobic respiration releases more energy per glucose molecule
than Anaerobic respiration.

29. Aerobic respiration is the chemical reaction used to
release energy from glucose. It is called aerobic because oxygen
from the air is also needed.
Glucose + Oxygen Carbon dioxide + water + (energy)

30. These are four steps for aerobic respiration
 Glycolytic breakdown of glucose to pyruvic acid
 Oxidative decarboxylation of pyruvic acid to acetyl co-A
 Kreb's cycle
 Terminal oxidation and phosphorylation in respiratory chain

31. Legends
 ATP=Adenosine
Tri Phosphate
 ADP=Adenosine
Di Phosphate
 NAD+=Nicotinamide
adenine dinucleotide
 Pi = Inorganic Phosphate

32. Legends
 ATP = Adenosine
Tri Phosphate
 ADP = Adenosine
Di Phosphate
 NAD+=Nicotinamide
Adenine Dinucleotide
 Pi =Inorganic Phosphate
 FAD+ =Flavin Adenine
Dinucleotide
 CO-A = Coenzyme-A

33. Legends
 ATP =Adenosine
Tri Phosphate
 ADP =Adenosine
Di Phosphate
 NAD+ =Nicotinamide
adenine dinucleotide
 Pi =Inorganic Phosphate
 FAD+ =Flavin Adenine
Dinucleotide

34. The environmental factors effecting the rate of respiration are:
 Oxygen content of the atmosphere
 Effect of temperature
 Effect of light
 Effect of water contents
 Effect of respirable material
 Effect of carbon dioxide concentration
 Protoplasmic conditions

35. Plant Biochemistry and Chemistry of Crops
- Dr.M.Dhakshinamoorthy

36. THANK YOU