Unit 2 Module 1: Biological Molecules

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Preview of Unit 2 Module 1: Biological Molecules

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
Module 1: BIOLOGICAL MOLECULES (biochemistry)
o All living organisms are composed of biological molecules that may be synthesised.
o All biological molecules are under carbohydrates, proteins, lipids (fats), nucleic acid (DNA) & H2O
o Carbohydrates : C, O, H
o Proteins : N, C, H, O, (S)
o Lipids : C, O , H
o Nucleic Acids: C, O , H, P
o Water: H2O
o Metabolism: total amount of chemical reactions occurring in a living organism (in their cell), the main
function is to transfer energy to keep organisms alive.
metabolites: chemicals reacting to keep you alive
catabolic:- breaking down larger molecules into smaller ones (e.g. digestion, exogonin release energy)
anabolic : - synthesise new molecules (e.g. 3 AA protein)
uses ATP (endergonic reaction) [growth]
A + B AB or AB A + B
Substrate/reactant(s) product(s)
enzymes control speed of metabolic reaction
o Carbohydrates energy storage
o Proteins antibodies, structures of cells, enzymes, hormones, transport.
o lipids chemical messengers, insulation, thermal/electrical energy source
o Nucleic acid instructions & coding for life
o All biological molecules contain C (excl. H2O ) chemical reactions involving C are in organic chemistry
o C can bond to other atoms easily due to the 4 bonds valence (4e- in outer shell) and forms covalent bonds
(sharing e- )
o Monomer: 1 single unit molecule (e.g. glucose)
o Polymer: made up of many monomer units (e.g. starch) bonded together
Molecule Monomer Polymer
Carbohydrate Monosaccharide (e.g. Polysaccharide (e.g. starch)
glucose)
Protein AAs (e.g. A, T, C, G) Polypeptides
Nucleic Acid Nucleotide DNA/RNA strand
o Condensation: type of reaction which creates polymer from monomer and always releases H2O & covalent
bond formed
o Hydrolysis: type of reaction which polymer monomers covalent bond is broken and H2O always used up/
added

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
H-BONDS
o weak
o slightly -vely charged ( -
) atom comes into contact w/
slightly +vely ()charged H atom, H-bond formed
+
o stabilises structures e.g. enzyme, DNA
PROPERTIES OF H2O
a) SURFACE TENSION
o Due to H-bonds, H2O molecules are 'pulled' together more strongly habitat can survive on surface of
H2O & animals such as pond runners can walk on the water.…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
SPECIFIC HEAT CAPACITY (thermal stability)
o Has a v large one absorbs lots of heat energy before temp greatly. (or temp )
o bodies = composed greatly of H2O (70-80%) so w/ shc, can be v thermostable less prone to heat
damage by changes in environmental changes in environmental temp.…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
TRANSPARENCY
o water allows visible light through it
means that photosynthesis & associated food chains = possible in quite shallow aquatic
environments
VOLALITY/STABILITY
o Balanced at Earth's temp.…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
metabolic processes take part in H2O; free to move around and react with each other
High latent heat of vaporisation
o lhv definition: amount of energy required to change a given quantity of liquid into gas
o Large as energy = required to break H bonds between molecules; explains why H2O = mainly l on Earth.
o E.g. important in temp regulation in mammals.…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
Hydrophobic interaction
o Non-polar mol (e.g. lipids, cellulose and starch) don't in H2O and if surrounded by H2O as H2O molecules
are attached to each other. Is important in hydrophobic interactions in proteins & phospholipid bilayers s
stability of these structures
Reactivity
o water= important reactant
o e.g. hydrolysis [such as hydrolysis of proteins to AAs]
o e.g.…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
Glucose: 2 isomers
glucose (= beta)
glucose (= alpha)
Disaccharides:
2 monosaccharides disaccharide ( + H2O)
forms covalent bond called glycosidic bond
Examples:
1. maltose glucose and glucose
2. sucrose glucose and fructose
3. lactose glucose and galactose
C12H22O11
Polysaccharide:
(C6H10O5)n
insoluble
not sweet
3 types
Starch; i) amylose ii) amylopectin
i. Amylose (20%)
-glucose
1,4 links (glycosidic bonds)
unbranched
coiled spring (helix) H bonds
ii.…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
sucrase = sucrose glucose & fructose
lactase = lactose glucose & galactose
amylase = amylose from starch
Glycogen
similar to amylopectin BUT shorter chain
lots of branching
1,4 and 1,6 glycosidic bonds
granular (granules)
-glucose
Cellulose
-glucose
1,4 glycosidic bonds
alternating molecules = 180oC (anti-parallel)
long chains lie parallel; joined by h-bonds
forms microfibrils
forms macrofibrils (called pectin)
need cellulase to break it down…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
SUMMARY OF CARBOHYDRATES
Starch
o -glucose
o 1,4 links (amylose) + 1,4 & 1,6 links (amylopectin)
o amylose coiled, unbranched
o amylopectin long branched chains, some coiling
o in plants
o function: carbohydrate energy store
o general structure = grains
Glycogen
o -glucose
o 1,4 and 2,6 links
o short, many branched chains, some coiling
o occurrence: animals, fungi
o function: carbohydrate energy source
o general structure = small granules
Cellulose
o -glucose
o…read more

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UNIT 2 BIOLOGY MODULES 1 + 2 + 3 NOTES 2013-4
= supports/strength for cell & whole plant
= has H2O channels to allow H2O to pass
= plant cells don't burst become turgid gives even more support to plant
= e.g.…read more

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