B Biological moleculesContent• Structure of carbohydrates, lipids and proteins and their roles in living organisms
The 4 most common elements are :
Carbon , Hydrogen , Oxygen , Nitrogen Macromolecule :
A 'GIANT' moleculePolymer : A
MACROMOLECULE made up of
MANY,REPEATED subunits called
MONOMERS Examples of polymers -> Proteins
(POLYPEPTIDES) , Carbohydrates
(POLYSACCHARIDES),NUCLEIC ACIDS,DNA/RNA
(POLYNUCLEOTIDES)Carbohydrates are made of the following ELEMENTS: Carbon , hydrogen and Oxygen General Formula :
Cx(H2O)yThe Subunits of Carbohydrate are -
MONOSACCHARIDES (or
hexoses which is the maximum no. of Carbon bonds we are supposed to know)
Properties of
MONOSACCHARIDES - General Formula : (CH20)x
- Readily*(very) soluble in water, sweet , reducing sugar
Types of
MONOSACCHARIDES ->
- Trioses -> C3H6O6 ->Is an INTERMEDIATE product in respiration
- Pentoses* [ eg.Ribose , deoxyribose] -> C5H10O5 -> Ribose (builds RNA & ATP) Deoxyribose (Builds DNA)
- Hexoses (eg. Glucose)-> C6H12O6 ->1. Used in respiration to release energy & make ATP 2. Used to build di-&polysaccharides
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CONDENSATION REACTION : LOSS OF WATER AND FORMATION OF BONDSHYDROLYSIS REACTION : GAIN OF WATER AND BREAK BONDS .i.e DIGESTION Properties of
DISACCHARIDES ( Monosaccharides + Monosaccharides ) - General Formula : (C12H22011) loss of a WATER molecule- LOOK AT ATTACHED DIAGRAM TO UNDERSTAND.
- soluble in water , sweet , reducing sugar Except SUCROSE[/b]
- Made of 2 MONOSACCHARIDES by a CONDENSATION REACTION
- Sucrose: Translocated in phloem , lactose : milk sugar , maltose : In germinating seeds
NB : IN DRAWING OF DISACCHARIDE IT IS SUPPOSED TO BE CONDENSATION NOT HYDROLYSIS
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Properties of
POLYSACCHARIDES-Macromolecules and polymers made of many
MONOSACCHARIDES- General Formula : (C6/H10/O5)
- More or less insoluble in water , not sweet , not reducing sugars
- Starch: Storage material in plant cells (Chloroplasts , tubers ,seeds).Glycogen : Storage material in animals cells. Cellulose: Cell wall
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NB: STRUCTURE OF , STARCH AND CELLULOSE AND GLYCOGEN IS VERY IMPORTANT , SEE ATTACHED TO UNDERSTAND
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STRUCTURE OF STARCH [AMYLOSE + AMYLOPECTIN]
- Amylose : Unbranched Chain-Made of Alpha Glucose molecules linked by 1,4 Glycosidic Bonds-Chain coiled into a Helix [ Not to react ] See diagram
- Amylopectin : branched Chain-Made of Alpha Glucose molecules linked by 1,4 Glycosidic Bonds & 1,6 glycosidic bonds form BRANCHES. See diagram
PROPERTIES OF STARCH [AMYLOSE + AMYLOPECTIN]
- More or less INSOLUBLE in water , doesn't leave cell
- Compact , occupies little space
- Intert , doesn't react in cell ( HELIX + COMPACTNESS AND BRANCHING )
- Has no osmotic effect
- Easily hydrolysed to sugar when needed
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STRUCTURE OF GLYCOGEN [AMYLOPECTIN ] - Amylopectin : branched Chain-Made of Alpha Glucose molecules linked by 1,4 Glycosidic Bonds & 1,6 glycosidic bonds form BRANCHES (MORE BRANCHES THAN STARCH ) . See diagram
PROPERTIES OF GLYCOGEN [AMYLOPECTIN]
SAME AS STARCH EXACTLY BUT IT HAS MORE BRANCHES THEREFORE MORE COMPACT ( OCCUPIES LESS SPACE )
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STRUCTURE OF CELLULOSE - UNbranched Chain-Made of BETA Glucose molecules linked by 1,4 Glycosidic Bonds . - Chain is FLAT , OH groups stick out , hydrogen bonds form cross links with other chains to form Microfibrils & Fibres . See diagram.
PROPERTIES OF CELLULOSE- Insoluble in Water
- Compact
- High tensile strength
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LIPIDS - Triglycerides and Phospholipids
See attached diagram.
Lipids Subunits - GLYCEROL ( BOTH ) FATTY ACID chains/tails ( BOTH ) PHOSPHATE GROUP ( ONLY PHOSPHOLIPIDS )
NB:Glycerol is the
SAME in all Lipids
The
FATTY ACIDS differ BY :
the number of hydrocarbons in the chainIf it is Saturated or Unsaturated
Saturated -> The hydrocarbon chain DOES NOT have any C-C double bonds. Or only has single C-C bonds.
Unsaturated->The hydrocarbon chain has 1 OR MORE C-C double bonds.
Unsaturated ->Causes lipids to 1. MELT EASIER 2. CAUSE KINK IN HYDROCARBON CHAINS.
NB: If ONE double bond : monoUNSATURATED bond. If MORE than ONE : PolyUNSATURATED. If NO double bonds then : SATURATED
Fatty acid tails are -> NON POLAR ( i.e no charge ) , HYDROPHOBIC ( Hates water ) therefore INSOLUBLE
Animal lipids are often SATURATED (solid at room temperature ) . Plant lipids are often UNSATURATED ( Liquid at room temperature )
- Subunits of Triglycerides:3 [tri]Fatty acid tails ATTACHED TO &glycerol head
-Bonded by ESTER BONDS . See Diagram
- Subunits of Phospholipids:2 Fatty acids tails ATTACHED TO &glycerol&Phosphate group to make a Glycerol Phosphate Head
See Diagram.
NB : GLYCEROL PHOSPHATE is POLAR ( HAS CHARGE BECAUSE OF PHOSPHATE GROUP ) , HYDROPHILIC(loves water) , Soluble in water.
Roles of Lipids : ( Triglycerides )
Economic storage material ( When used in respiration , release more than double the energy released from carbs or proteins )
Heat insulation ( Adipose tissue underskin)
Electric Insulation ( myelin sheath)
Source of Metabolic water ( during respiration )
Buoyancy
: ( Phospholipids)
Form cell membranes.
SEE DIAGRAMS TO UNDERSTAND LIPIDS
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PROTEINS
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Elements : Carbon , Hydrogen , Oxygen , Nitron +- SULFUR +- PHOSPHOROUS
Subunits : Amino Acids
Amino Acids is Made of A carbon atom attached to
CARBOXYL GROUP
AMINE GROUP
AND H ATOM
A RESIDUAL GROUP ( R GROUP ) ( SIDE CHAIN ) , The only part that differs between aminoacids
Proteins can be classified on to the following stuctures :
PRIMARY -> the TYPES & SEQUENCE of amino acids in a POLYPEPTIDE CHAIN
Linked by PEPTIDE BONDS
SECONDARY-> the COILING of a POLYPEPTIDE chain into an ALPHA HELIX or a B PLEETED SHEET
Linked by HYDROGEN BONDS
TERTIARY-> the folding of the ALHPA HELIX into a 3 dimensional shape
Linked by HYDROGEN , IONIC , DISULFIDE bonds AND HYDRPHOBIC interactions
QUARTENARY -> Association of MORE THAN ONE DIFFERENT polypeptide chains (e.g haemog)
Linked by same bonds as in tertiary.
DIAGRAMS OF TYPES OF BONDS ARE ATTACHED , THEY MAKE NO SENSE AT ALL BUT THEY ARE TO LEARNED BY HEART.
There are TWO types of Proteins .
GLOBULAR ( FUNCTIONAL ) & FIBROUS ( STRUCTURAL ) GLOBULAR FIBROUSCoiled into Ball or Globe shape Long chains or forms helixHas hydrophilic R groups outside making it soluble in water Insoluble in water ( Helix shape )
Has hydrophobic R groups pointing inside forming
hydrophobic interactions protecting the globe shapeTertiary structure is important as it helix coils to form Secondary structure is important ( only helix )
a 3D structure ( GLOBE )HAEMOGLOBIN Collagen
Made of 4 polypeptide chains. (2 Alpha , 2 Beta ) Made of 3 polypeptidechains.Each chain has a HAEM goup that has an IRON ion Each collagen molecule is
attached that combines with one OXYGEN MOLC. formed by a triple helix forming a triple helix held by hydrogen atoms.
Hb Molecule combine with 4 oxygen 1/3 of AA is small AA Glycine ( has short R groups),
molecules (8 oxygen atoms ) to form helix have to come close to bond to each other
OXYHAEMOGLOBIN. Each molecule of collagen forms cross-links with other collagen
End of molecule is staggered , so no weak points ->great tensile str.
HAEMOGLOBIN ROLE COLLAGEN ROLE
Transport of oxygen as OXYHAEMOGLOBIN from lungs to Structural material in skin , bld. vessels , bone
body organs
Other roles of Globular proteins Other roles of fibrous proteins1.Enzymes( catalyse)2.Hormones3.antibodies4.Found in cell membranes 1.Keratin : from structural material in hair , nails , wool , hornProsthetic group : A permanent part of a protein molecule that is not made of amino acids.
WATER [polar - has uneven distrib. of charge ]
Weak Hydrogen bonds form between H+ of one water molecule and O- of another
Properties of Water :
Solvent properties : Good solvent for Polar molecules ( water molecules are attracted to them and collect around them ) Why is it important ? Metabolic reactions occur in solution and water is a transport medium in plants and animals.
Thermal properties :
1. Has high specific heat capacity ( large amount of energy needed to raise its temperature Why is it important ? Bodies of water are a stable habitat and keeps body temperatue stable
2. Has high latent heat of vaporisation ( large amount of energyy needed to change to gas )
Why is it important ? Water on earth has not evaporated so life goes on and eveaporation is effective in cooling the body
3.To change to solid ( ice ) large amount of energy is need, so less likely to freeze Why? Bodies of water are stable habitat .
Density and freezing properties
Below 4* water starts to decrease in density so ice floats and insulates water beneath it ( Bodies of water will not freeze completely therefore its a stable habitat )
Cohesion : Water molecules stick to each other [ due to large no. of hydrogen bonds] Why is it important ? For transport in vascular tissues in plants and causes high surface tenstion
High Surface Tension : The force that causes the surface of the liquid to contract to occupy lease area { due to cohesion due to large no of hydrogen bonds } why is it important ? water surface is a habitat for organisms i.e pond skater
Roles of Water
Solvent for metabolic reactions in cells
Reactant in metabolic reaction in cells like hydrolysis and photosynthesis
Keeps temp of cells constant
Keeps plant Turgid to support plantInorganic ions.
Calcium: Component in bones and teeth
Iron : To build haemoglobin that transports oxygen
Sodium ions : For nerve impulse transmission along neurones
Potassium : For nerve impulse transmission along neurones
Magnesium: To build chlorophyll that traps light
Nitrate ions : In plants to make amino acids and nucleotides
Phosphate : To make nucleotides , ATP
Chloride : To balance the +ve charge of cations in and around cells