BTEC Level 3 National Extended Diploma in Applied
Science
Unit 10:
photosynthesis
Learning Aim A:
Understand the structure and function of biological molecules and their
importance in maintaining biochemical processes.
Assignment Title:
Biological Molecules and Biochemical Processes
Structure of biological molecules:.................................................................................................................2
Structure and function of starch, cellulose, glycogen, lipids, proteins, water...............................................5
Why Sulphur, nitrogen, phosphorus effects the structure proteins............................................................11
Side group structure and function:..............................................................................................................13
Comparison between DNA and RNA:...........................................................................................................14
Evaluation of the disruption of biochemical processes in living organisms:................................................19
Plant growth regulators and their disruption..............................................................................................21
,Structure of biological molecules:
Disaccharides:
Disaccharides are created by the condensation of two simple sugar molecules. Condensation
is the loss of water during a chemical reaction. Each sugar molecule's two OH groups unite to
release water and create an oxygen bridge, which connects the two sugar molecules.
Examples of disaccharides:
Glucose-fructose is a disaccharide that makes up sucrose. To make this kind of table sugar,
sugar cane and sugar beets are utilized. In maple syrup, you will find sucrose.
Glucose and galactose monomers are the building blocks of the disaccharide lactose. In milk, it
occurs naturally.
A disaccharide created when two glucose molecules are dehydrated is maltose, also referred
to as malt sugar.
A polar molecule is a disaccharide. Since they may dissolve in water thanks to hydrogen
bonding, they are soluble in water. Their flavor is pleasant, and they are unable to pass
through cellular membranes.
,
,Polysaccharides:
A long chain of monosaccharides joined together by glycosidic connections is referred to as a
polysaccharide. The chain may be unbranched or branched, and it may include different types
of monosaccharides. The molecular weight of a polysaccharide can increase to 1000 Daltons or
more if enough monomers are bonded together. Living things require polysaccharides like
starch, glycogen, cellulose, and chitin.
Starch is an illustration of this: Plants employ the polysaccharide starch, which combines the
molecules amylose and amylopectin, to store carbohydrates (both polymers of glucose). To
meet their immediate energy needs, plants can produce glucose from the light energy they
absorb during photosynthesis. Any excess glucose is then stored as starch in various plant
parts, such as the roots and seeds. The starch in the seeds serves as both a food source for
people and animals and as fuel for the developing embryo. Digestion enzymes are used to
convert the starch into glucose monomers.
Amylopectin with small sidechain branching distances is glycogen. The hydrolysis of plant starch
produces glucose in the organism. As it reaches the cell, glucose is transformed into energy. In
the cell, glucose can be polymerized to create glycogen, a kind of carbohydrate energy storage.
The third polymer, cellulose, is created from glucose. However, the polymer molecules are "straight" this
time and are formed of -glucose molecules.
,Structure and function of starch, cellulose, glycogen,
lipids, proteins, water.
Starch:
two distinct polysaccharides are used to construct:
With 1,4 glycosidic linkages separating each a-glucose molecule, amylose (10–30%) is an
unbranched, helix-shaped chain. It is more digestible because of its ability to be more compact
because of the helix structure.
(70 to 90 percent) Amylopectin A branched molecule is created when glucose molecules make
1,4 and 1,6 glycosidic linkages, respectively, between one other.
Plants use starch as a form of storage polysaccharide. It is kept as granules in plastids such
chloroplasts and amyloplasts. In plant cells, plastids are membrane-bound organelles. They
serve a specialised purpose, such as amyloplasting starch granules. A starch molecule contains
more monomers than glucose, which causes it to breakdown more slowly. The amylopectin in
starch has branches that lead to several terminal glycose molecules that can be easily
hydrolyzed for use during cellular respiration or added for storage.
Cellulose:
This polysaccharide is one that plants contain. consists of 1,4 glycosidic linkages holding long
chains of b glucose together. Since B glucose is an isomer of glucose, it is necessary to rotate
subsequent B glucose molecules 180 degrees from one another to produce the 1,4 glycosidic
linkages. The strength of cellulose is due to the many hydrogen bonds that develop between
the long chains because of the inversion of the B glucose molecules.
1. Due to cellulose's strength, which comes from the numerous hydrogen atoms located
in between parallel strands of microfibrils, it serves as the primary structural element
of cell walls.
2. The cellulose can be stretched without breaking thanks to its great tensile strength.
3. The cellulose fibers and other chemicals in the cell wall create a matrix that makes
the cell wall stronger.
4. The plant is supported by reinforced cell walls.
5. Since cellulose fibers are freely permeable, water and other solutes can pass through
or reach the cell surface membrane.
6. The enzyme that hydrolyzes cellulose, which is rare among organisms, is a source
of fiber.
,Glycogen:
Several molecules of alpha glucose are bound together by 1, 4, and 1–6 glycosidic linkages to
create the major energy storage molecule in mammals, called glycogen. Its extensive side
branches allow enzymes to operate on them concurrently, allowing energy to be released
swiftly. The amount of energy it can store is further increased by the fact that it is a big, but
compact molecule. The fact that it is insoluble also means that it won't change the water
potential of cells and won't be able to diffuse out of them.
,Water:
Due to the molecular makeup of water, it is unique. Water is a very small molecule made up of two
hydrogen atoms bound covalently to an oxygen atom. To prevent an even distribution of electrons, the
oxygen atoms attract electrons to themselves and away from the hydrogen atoms. Because each
covalent bond's electron distribution is not uniform across the molecule due to oxygen's higher
electronegative valence than hydrogen is, the distribution of oxygen molecules inside a given system is
uneven. Oxygen repels negatively charged electrons from it, in contrast to hydrogen. Water is a polar
molecule because of this. Near the oxygen and the hydrogens, the water molecule possesses small
areas of minor negative charge.
Types of bonding that occur between water molecules:
Hydrogen bonds are created between oxygen atoms in neighboring water molecules and between
hydrogen atoms. The water molecules' attraction creates a hydrogen bond.
,Why is water important:
Water is essential because it serves as a solvent for chemical reactions that take place in living
things. It also serves as a catalyst for other chemical reactions. Additionally, water has a high
specific heat capacity, making it an ideal environment. Additionally, it keeps the ideal Ph
temperature within our bodies' cells. Water also has an electrolyte balance. This implies that
it will conduct electricity in solutions.
Water is a solvent which means that:
1. It permits chemical processes to take place inside the cells.
2. All metabolites except non-polar compounds, which are hydrophobic, can
be transported effectively.
Water is an excellent vehicle for transporting living organisms since it can stay liquid
throughout a wide temperature range. For all metabolic processes in organisms to take place,
chemical molecules must be able to interact in a solution. Water is a great solvent for chemical
reactions because it disperses polar molecules. The chemical that needs to dissolve has a
molecular molecule with an uneven distribution of charges. Both the slightly negative ends of
the substance and the slightly positive ends of the water molecule will be attracted to one
another. The water molecule interacts with the charged part of the solute, and as a result,
gathers around it. After being split, the solutes dissolved.
(Hydrophobic means it has a fear of water).
Hydrogen bond: They are fragile because they frequently split and reform. They exist
between molecules and are made up of a hydrogen atom that is slightly positively charged
and an atom that is slightly negatively charged.
Cohesion and adhesion
Water molecules can adhere tightly to one another thanks to hydrogen bonding. This makes it
possible for water columns to pass through the xylem of plants and the blood arteries of
animals. These hydrogen connections between the top layer of water molecules permit surface
tension at the point where a body of water and air collide, coating the body of water with a
thin film as a result (this is what allows insects such as pond skaters to float)
,The process of adhesion occurs when hydrogen is bound to other molecules, such cellulose, by
water. Due to transpiration, this also makes it possible for water to ascend the xylem.
Carbohydrates:
The majority of carbon-based molecules in living things are carbohydrates. Since H and O are
always present in the ratio 2:1, all molecules in this group contain C, H, and O. They come in
three different forms: monosaccharides, disaccharides, and polysaccharides. A group of
chemical substances known as carbohydrates are made of carbon, hydrogen, and oxygen.
Ratio of Carbon, hydrogen, and oxygen:
1:2:1
proteins
Carbon, hydrogen, oxygen, and nitrogen make up the organic compounds that make up
proteins. With a carbohydrate to protein CHO ratio of 1,4, the proteins group had 30%
protein, 41% carbohydrate, and 29% fat, whereas the COH group had only 16% protein, 58%
carbohydrate, and 26% fat with a ratio of 3.5.
Carbon Hydrogen oxygen
protein 7 3 3
lipids 1 2 Less than one
carbohydrates 1 2 1
Nucleic acid DNA 2 7 2
Nucleic acid RNA 2 7 23
Biological molecules' function and why they are important for the body.
lipids Proteins Carbohydrates Importance to the
body.
structure Lipids are an Protein Carbohydrates Carbohydrates
essential structure is the consist of are used for
component of three- carbon, energy
the cell
membrane. The dimensional hydrogen, and (glucose). Fats
structure is arrangement of oxygen. The are used for
typically made of atoms in an general energy after
a glycerol amino acid- empirical they are
backbone, 2 chain structure for broken into
fatty acid tails molecule. carbohydrates fatty acids.
(hydrophobic),
Proteins are is (CH2O) n. Protein can
, and a phosphate polymers – They are also be used
group specifically organic for energy, but
(hydrophilic). polypeptides – compounds the first job is
formed from organized in to help with
sequences of the form of making
amino acids, aldehydes or hormones,
the monomers ketones with muscle, and
of the polymer. multiple other proteins.
A single amino hydroxyl Broken down
acid monomer groups coming into glucose,
may also be off the carbon used to supply
called a chain. energy to cells.
residue.
Function The main Protein has Carbohydrates,
biological many roles in also known as
functions of your body. It carbs, are vital
lipids include helps repair at every stage
storing energy, and build your of life. They're
as lipids may body's tissues, the body's
be broken allows primary source
down to yield metabolic of energy and
large amounts reactions to the brain's
of energy. take place and preferred
Lipids also coordinates energy source.
form the bodily
structural functions
components of
cell
membranes,
and form
various
messengers
and signaling
molecules
within the body.
