- Water
MPT00303 BIOLOGI - Carbohydrate
TOPIC 1
BIOLOGIC AL MOLECULES
- Lipids
- Protein
- Nucleic acid
• Living organisms are composed of atoms that can
combine together to form biological molecules, e.g.,
carbohydrates, proteins, lipids and nucleic acids.
• Four major atoms (or elements) in organisms, namely
carbon (C), hydrogen (H), oxygen (O), and nitrogen
(N).
PHYS IC AL , CHEMIC AL
PROPERTIES AND • Molecule: a group of atoms bonded together,
PHYS IOL OGIC AL representing the smallest fundamental unit of a
ROLES OF BIOL OGIC AL chemical compound that can participate in a chemical
MOLECUL ES reaction.
• Many organic molecules consist of subunits
(monomers), which can be joined to form polymers
known as macromolecules via condensation or
hydration reactions (create water molecules).
• Macromolecules can be broken down through the
splitting of covalent bonds when water is added via a
process called hydrolysis.
WATER (H 2 O)
One slightly negatively Two slightly positively
charged oxygen (O) atom charged hydrogen (H) atoms
Properties of water based on its: Bond length measured in pm
i. Polarity (picometer):
ii. Ability to form hydrogen bonds
iii. Small size 1 pm = 1x10-9 mm
PROPERTIES OF
WATER (H 2 O) i. High boiling points: 100 C
ii. Surface tension: 72.8 millinewtons per meter
(mN/m) at 20 C
iii. Latent heat of vaporization: 2,260 kilojoule per
kilogram (kJ/kg); e.g., body sweating gives a cooling
effect to the body.
iv. Specific heat capacity: 4,184 J/kgC . Water requires
4, 184 J of heat energy to raise the temperature of
1 kg water by 1C, hence, a thermally stable aquatic
environment for organism living within.
v. Water density: 0.9998395 g/mL; but is usually
rounded to 1 g/mL at 4 C (maximum density). The
density decreases at 0 C and below due to the
formation of ice.
PROPERTIES OF WATER (H2O)
PROPERTIES OF
WATER (H 2 O)
• Molecular structure of maximum 4 hydrogen bonds in liquid water and the
interconnected hexagonally-shaped framework in ice.
• Water molecules expand when water freezes, creating more space in the
lattice structure and thus less water molecules per volume of ice compared
to liquid water.
Make up about 50 – 98%
of the fresh mass of a
living organism
A universal solvent,
particularly for ions Maintain body
and polar molecules temperature
IMPORTANCE OF
WATER (H 2 O) A reactant in
metabolism, e.g., Provide an aqueous habitat
starch hydrolysis for many organisms
• Water readily forms hydrogen bonds with water WATER COHESION
molecules, forming water clusters via cohesion.
• Cohesive forces refer to the attractive force
between the same type of molecules.
➢It causes the water surface to contract to the
smallest area.
➢The inner molecules experience zero net force
because they are bonded to other molecules on
all sides.
➢E.g., unbroken columns of water held by cohesive
forces in the xylem vessels. This creates a
phenomenon called surface tension.
• Water surface tension acts like an elastic membrane,
allowing small organisms with light body weight to
walk on the water surface.
WATER ADHESION & CAPILLARY ACTION
• Attractive forces exist between different types of
molecules, known as adhesive forces.
➢E.g., water adhesion to the wall of xylem vessels
can resist the downward pull of gravity.
➢The adhesive forces between water molecules
and the wall of xylem vessels are stronger than
the cohesive forces between water molecules to
draw water upwards to the top of plants.
• The relative forces between cohesive and adhesive
forces generate capillary action.
• The diameter of the capillary tube, surface
tension and gravity limit the height of capillary
action.
C ARBOHYDRATES
(MONOS AC CHARIDES)
• Monosaccharides are the simplest sugars (monomers) that
make up other carbohydrates, which cannot be further
broken down into smaller molecules by hydrolysis.
• The empirical formula of monosaccharides is (CH2O)n,
where n ranges from 3 to 7. The number of C atoms
determines the characteristics of monosaccharides: trioses
(3C), pentoses (5C), and hexoses (6C).
• Three major types of monosaccharides comprising the
same chemical formula (C6H12O6) with different molecular
structures: glucose, fructose and galactose.
C AR BO HYD RAT ES
(M O NO SACC HARID ES )
• Monosaccharides are reducing
sugars (sweet), soluble in water
and can be crystallised.
• They can combine together by
glycosidic bonds to form larger
carbohydrates (e.g., polysaccharides
or oligosaccharides).
Monosaccharide Molecular Description
structure
Glucose - Precursors for cellular respiration that provide
energy by glycolysis.
- Combine with other monosaccharides to store
energy. E.g., starch in plants and glycogen in
animals.
- Precursors for the plant cellulose.
Fructose - Can combine with other monosaccharides to
form oligosaccharides.
Galactose - Mainly found in mammals that produce milk.
- Combine with glucose to form disaccharide
lactose, which can be broken down by special
enzymes produced in newborn mammals.
C ARBOHYDRATES (DISACCHARIDES)
• Disaccharides contain two units of monosaccharide molecules
joined together through glycosidic bonds during a reaction called
condensation.
• It can be crystallised, sweet-tasting and water-soluble. For example,
sucrose, lactose and maltose.
• Sucrose is a non-reducing sugar (or table sugar) due to two glucose
monosaccharides connected at anomeric carbons with no hydroxyl
(-OH) group. Maltose and lactose are reducing sugars because they
can reduce another compound and oxidise themselves.
C ARBOHYDRATES (DISACCHARIDES)
• Maltose is produced in the malt mashing process in brewing and is a
substance for yeast involved in alcoholic fermentation. Maltose is a
breakdown product of starch digested by the enzyme lactase.
• Milk-containing lactose can cause the population’s inability to digest
lactose, leading to lactose intolerance.
• The enzyme sucrase-isomaltase performs the digestion of sucrose and
maltose in the small intestine.
Disaccharide Monomers Molecular structure Description
Sucrose glucose + Found in fruits, vegetables and
(cane sugar) fructose sweetener.
Lactose glucose + Found in milk and dairy products.
(milk sugar) galactose
Maltose glucose + glucose Found in starch and is a
(malt sugar) component of high-maltose
syrup.
C ARBO HYDRATE S
(OLIGOSACCHARIDES)
• It consists of 3 – 14 monosaccharides joined together to
form small chains.
• E.g., Raffinose is a trisaccharide in which glucose acts as a
monosaccharide bridge between galactose and fructose,
which can be found in broccoli, beans, cabbage, whole
grain, etc.
• Humans cannot properly digest these oligosaccharides
due to the lack of digestive enzyme -galactosidase,
which may cause abdominal cramping and excessive
flatulence in some consumers. Nevertheless,
oligosaccharides are thought to have health benefits
associated with dietary fibre.
• They can attach to proteins and lipids, forming
glycoproteins and glycolipids on the plasma membrane.
These are important to act as receptors in cell
recognition (e.g., pathogens) in the immune systems.
C ARBOHYDRATES (POLYSACC HARIDES)
• Polysaccharides are polymers made up of hundreds of monosaccharides in polymerisation via
glycosidic bonds.
• Polysaccharides are insoluble in water, and they are not sweet to taste. E.g., cellulose, chitin,
glycogen, fibres, lignin, murein and starch.
• In plants, starch is formed from the
condensation of -glucose units such as:
• Amyloses is the simplest form of starch
with a linear unbranched polymer (200 –
1500 -glucose residues), held together
by -1,4, glycosidic bonds.
• Amylopectin is a branched polymer
(2000 – 200 000 -glucose residues)
that occurs at intervals of approximately
25 to 30 via -1,6-glycosidic bonds.
C A RBO HYD RATES
(P OLYSACC HARIDES)
• In animals, glycogen is the major
storage for carbohydrates, mostly
present in the muscle and liver
cells where high - cell metabolic
activities take place.
• Glycogen is insoluble in water and
thus has no effect on the cellular
water potential.
• The highly branched glycogen can
be rapidly hydrolysed by enzymes
when energy is needed , and body
glucose concentration is low. This
produces glucose molecules for
cellular respiration in order to
meet the energy requirement.
➢Lipids are organic compounds
insoluble in water but in organic
solvents (e.g., ether, alcohol and
chloroform).
➢Like carbohydrates, lipids contain
C, H and O with lower
proportions of oxygen to
LIPIDS: OILS AND FATS hydrogen.
➢Some lipids have phosphorus (P)
and nitrogen (N) molecules.
➢4 major groups of lipids are
triglycerides (fats and oils),
phospholipids, steroids and
waxes.
LIPIDS ( TRIGLYC ERIDE S)
• Triglycerides are the most commonly available lipids.
• A triglyceride is formed between 3 fatty acid molecules and one glycerol molecule via esterification.
• E.g., glycerol consists of 3 C atoms and 3 hydroxyl (-OH) groups, which can form ester linkages with
the carboxy (-COOH) groups of fatty acids.
• Triglycerides are monounsaturated triglycerides (one double bond) and polyunsaturated triglycerides
(two or more double bonds).
• Saturated triglycerides are found in animal fats and present in a solid state at room temperature.
• Unsaturated triglycerides are found in plant oils (e.g., olive and sunflower oils) and in the liquid at
room temperature.
• A fatty acid has a long, unbranched
hydrocarbon chain consisting of 16 or
18 carbon atoms with a carboxy group
at one end.
FATTY
• The body cannot synthesise
ACID AND essential fatty acids (EFAs) and
ESSENTIAL must be taken via diet.
FATTY
• E.g., alpha-linolenic acid (Omega-3
ACIDS fatty acid) and linoleic acid (Omega-6
fatty acid). These are polyunsaturated
fatty acids (PUFA).
• We need both of them to survive.
PHOSPHOLIPIDS
• A phospholipid
molecule is produced
via a condensation
reaction between one
glycerol molecule and
two hydrocarbon fatty
acid chains.
STEROIDS
• Anabolic (or synthetic) steroids can enter the nucleus of
a cell and increase the rate of gene transcription to
encode actin and myosin proteins, which are the main
components of muscles.
• Sportsmen and women take anabolic steroids to build up
muscle mass illegally.
• Anabolic steroids can be harmful to the liver, heart and
kidneys.
• They inhibit the production of natural sex hormones,
leading to sterility and the development of male
characteristics (e.g., excessive body hair in females).
IMPORTANC E OF FATS AND LIPIDS
Fats are an energy source Fats act as energy Fats stored in Fats are stored Lipids are a
containing more carbon- storage to reduce the adipose around delicate constituent of
hydrogen bonds, which can body weight, make tissue can act as internal organs the myelin
produce more energy locomotion easier heat insulators to protect the sheath, which
compared to the same and roles for motile (e.g., in whales). organs (e.g., acts as an
amount of carbohydrates animals and plant kidneys). electrical
(i.e., 38 J g-1), but fats are structures involved insulator for
hydrolysed slower than in dispersal (e.g., axons and
carbohydrates. seeds). speeds up nerve
transmission.
Production of metabolic water in certain desert
animals during the metabolism of fats and
carbohydrates.
Phospholipids and cholesterols are major components
of plasma membranes.
IMPORTANC E OF Steroid hormones help to coordinate body activities.
FATS AND LIPIDS
Lipids form a protective, waxy cuticle on the plant
epidermis to reduce transpiration and the entry of
pathogens.
Lipids are solvents for fat-soluble vitamins.
PROTEINS & AMINO
ACIDS
• Proteins are organic macromolecules
containing C, H, O and N elements.
• Many proteins also contain
phosphorus (P) and sulphur (S).
• Proteins are polymers formed by
peptide linkages between the acidic
group (-COOH) and base group (-
NH2) of different amino acid
molecules via condensation.
• A single protein molecule has one or
more polypeptide chains.
STRUCTURAL LEVELS OF PROTEINS
PROPERTIES OF PROTEINS
Determined by the acidic carboxyl group and basic amino group, which can
dissolve in water, forming dipolar ions. These groups can act as buffers to
resist small pH changes while maintaining the pH of the body’s fluid.
Amino acids are zwitterion that consist of both negatively and positively
charged groups.
At physiological pH, amino acids can be either acidic with a negatively
charged carboxyl group (COO-) or basic with a positively charged amino
group (NH3+). Both acidic and basic amino acids are hydrophilic and can
form ionic bonds and maintain the three-dimensional structure.
IMPORTANCE OF PROTEINS
• Proteins are essential to:
i. repair and make new body cells,
ii. allow normal body growth and
development,
iii. act as hormones and enzymes,
iv. make antibodies, and
v. provide energy when fats and
carbohydrates are inadequate.
NUCLEIC ACIDS
• Nucleic acids are composed of nucleotides, comprising
a pentose sugar (ribose or deoxyribose), a phosphate
group, and a nitrogenous base (purine or pyrimidine).
• Different nucleotides join together to form
polynucleotide strands via phosphodiester bonds.
• Deoxyribonucleic acid (DNA) and ribonucleic acid
(RNA) are two varieties of nucleic acid that occur
naturally in cells.
Consists of two DEOX YRIBONUCLEIC ACID
Presents in the cell
nucleus of
strands of (DNA)
polynucleotides
eukaryotes and in
coiled in a right-
the nucleoid region
handed spiral,
of prokaryotes
forming antiparallel
(absence of a plasma
(complementary)
membrane).
double helix.
DNA molecules
One strand runs 3’
consist of four types
to 5’ while another of nitrogen-
runs 5’ to 3’. Both
containing bases,
strands are held
namely adenine (A),
together by
cytosine (C), guanine
hydrogen bonding.
(G) and thymine (T)
RIBONUC LEIC ACID (RNA)
• RNA has only one strand of polynucleotides.
• A single RNA nucleotide consists of a ribose sugar, a
phosphate group and one of 4 nitrogenous bases (adenine,
uracil, cytosine or guanine).
• Messenger RNA (mRNA): an intermediate between a
protein-coding gene and a protein synthesised by a
ribosome.
• Transfer RNA (tRNA): a carrier to bring amino acids to
ribosomes as mRNA specifies. It creates a 3D structure,
which is important for molecular functions.
• Ribosomal RNA (rRNA): a major component of the
ribosome to bind mRNA at the correct spot for
translation. Some rRNA are enzymes called ribozymes,
helping to accelerate chemical reactions.
BIOLOGIC AL
FUNCTIONS OF
NUCLEIC ACID
THANK YOU FOR
YOU R ATTE NTION
TUTORIAL 1 (5%)
WATER POLLUTION
Water is an essential natural resource for
sustaining life on Earth. However, water bodies can
be polluted by both living (e.g., pathogenic
organisms) and non-living substances (e.g.,
pesticides, industrial discharges, fertilisers and
other toxic chemicals), mainly due to anthropogenic
activities.
This may pose a risk to the environment and
human health via direct or indirect exposure to
polluted water, such as drinking water and
recreational activities.
Discuss THREE (3) potential problems and TWO
(2) recommendations that can be used to mitigate
the rising water pollution issues at the global level.
