organic materials Flashcards

1
Q

amino acid ‘R-group’ properties

(side chain)

A

polar (OH) / non-polar (CH₃)

proton donor (COOH) / proton acceptor (NH₂)

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2
Q

acid-base properties of amino acids

A

di-functional from NH₂ & COOH

∴ amphoteric depending on pH of the solution environment

NH₂ → NH₃⁺ & COOH → COO⁻

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3
Q

zwitterion in solution

(dipolar ion)

A

overall neutral amino acid containing both positive & negative change

present at isoelectric point (pH)

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4
Q

amino acid in low pH (pH < pI)

A

zwitterion + abundance of H₃O⁺ → cation + H₂O

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5
Q

amino acid in high pH (pH > pI)

A

zwitterion + abundance of OH¯ → anion + H₂O

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6
Q

condensation polymerization reaction of 2-amino acids (α-amino acids)

A

NH₂ & COOH react together to form a peptide (amide) link (CONH) + H₂O

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7
Q

N-terminal amino acid

A

end of the polypeptide chain with a free amino group

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8
Q

C-terminal amino acid

A

end of the polypeptide chain with a free carboxyl group

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9
Q

primary structure of protein

A

sequence of amino acids joined by covalent peptide bonds

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10
Q

secondary structure of protein

A

hydrogen bonding between N-H & C=O causes folding into α-helices (polypeptide coils into a spiral) or β-pleated sheets (polypeptide folds into parallel layers)

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11
Q

tertiary structure of protein

A

3D shape formed through forces between R-groups of amino acids

e.g. covalent disulfide bridge (S-S) & ionic salt bridge (NH₃⁺/COO⁻)

(hydrogen bonding, dipole-dipole attraction, dispersion forces)

interial hydrophobic & exterial hydrophilic R-groups

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12
Q

quarternary structure of protein

A

multiple polypeptide chains (& sometimes non-protein molecules) form large complex functional units held together by dispersion forces

(e.g. haemoglobin)

hydrogen bonding, dipole-dipole attraction & ionic interactions may also be present

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13
Q

characteristics of biological enzymes

A

proteins that catalyze biochemical reactions by providing an alternate reaction pathway with lower activation energy

sensitive as changes in temperature or pH may disrupt the forces that determine their tertiary structure

active sites are substrate specific

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14
Q

describe the effect of changing temperature/pH on an enzyme ?

A

enzymes are are temperature/pH specific

changes can disrupt the forces that determine their tertiary structure

active sites no longer binds to the substrate

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15
Q

triglycerides

A

condensation reaction between glycerol (propane-1,2,3-triol) & 3 fatty acids

OH (glycerol) + COOH (fatty acid) → ester link (COO) + H₂O

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16
Q

saturated fatty acids

A

hydrocarbon chains with only C-C bonds

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17
Q

unsaturated fatty acids

A

monosaturated : hydrocarbon chains with one C=C bond

polysaturated : hydrocarbon chains with multiple C=C bonds

18
Q

omega & alpha carbons

A

omega : last carbon furthest away from COOH

alpha : first carbon within COOH

19
Q

melting point of triglycerides

A

↑chain length = ↑melting point

∵ ↑dispersion forces

↑C=C bonds = ↓melting point

∵ cis-arrangement bends the hydrocarbon chain

∴ ↓dispersion forces (fatty acids cannot pack tightly)

20
Q

saponification (hydrolysis)

A

triglyceride + 3NaOH → glycerol + 3 fatty acid-COO⁻Na⁺ (soap)

21
Q

soap as a medium between water & oil

A

charged COO⁻Na⁺ (hydrophilic) forms ion-dipole bonding with H₂O

non-polar hydrocarbon tail (hydrophobic) forms weak dispersion forces with oil

22
Q

soap in water

A

soap clumps together to form a spherical micelle

hydrophilic ends (charged carboxylate group) face outwards & hydrophobic ends (non-polar hydrocarbon tail) face inwards

23
Q

cleaning action of soap

A

agitation (washing) breaks the micelle & non-polar ends attach to the oil

ion-dipole bonding with water lifts the oil particles & non-polar ends surround the oil molecules to trap them (forming a micelle again)

24
Q

soap in hard water

A

hard water contains metal ions (e.g. Mg²⁺, Ca²⁺) which react with soap (sodium stearate)

this creates magnesium/calcium stearates, which are insoluble in water

∴ poorly washed clothes & soap scum

25
Q

glucose in solution

A

α-glucose (cyclic) : OH group on C₁ points down

β-glucose (cyclic) : OH group on C₁ points up

26
Q

aldose vs ketose

A

glucose : aldose (terminal C=O)

fructose : ketose (non-terminal C=O)

27
Q

disaccharides

A

condensation reaction between two monosaccharides’ OH groups (C₁ - C₄)

glycosidic bond (C₁-O-H + H-O-C₄ → C₁-O-C₄ + H₂O)

e. g. glucose + glucose → maltose + H₂O
e. g. glucose + fructose → sucrose + H₂O
e. g. glucose + galactose → lactose + H₂O

(C₁ loses H & C₄ loses OH)

28
Q

starch (amylose)

A

linear glucose polymer with α-1,4-glycosidic bonds

29
Q

starch (amylopectin)

A

branched glucose polymer with α-1,4-glycosidic bonds & α-1,6-glycosidic bonds

30
Q

cellulose

A

linear glucose polymer with β-1,4-glycosidic bonds

31
Q

amorphous regions

A

tangled arrangement of polymer chains

∴ weaker intermolecular forces

32
Q

crystalline regions

A

ordered arrangement of polymer chains

∴ stronger intermolecular forces

33
Q

low-density polyethene

A

created under high pressure & temperature; contains many disordered branches

∴ amorphous

∵ molecules cannot pack tightly (weak dispersion forces)

(low melting point, low density, soft)

34
Q

high-density polyethene

A

created under low pressure & a transition metal catalyst; contains few ordered branches

∴ crystalline

∵ molecules pack tightly (strong dispersion forces)

(high melting point, high density, hard)

35
Q

isotactic polypropene

A

regularly arranged methyl side groups all on one side of the polymer chain

∴ semi-crystalline

36
Q

atactic polypropene

A

randomly arranged methyl side groups on either side of the polymer chain

∴ amorphous

37
Q

syndiotactic polypropene

A

regularly arranged methyl side groups on alternating sides of the polymer chain

∴ crystalline

38
Q

polytetrafluoroethene

A

↑melting point from strong C-C & C-F bonds

non-polar from symmetrical nature (although dipoles are present)

chemically inert from fluorine atom coating

(insoluble & non-stick)

39
Q

polyester

A

condensation reaction between a di-ol & di-oic acid

ester link + H₂O

(e.g. PET)

co-polymer

40
Q

advantages & disadvantages of polymers

A

advantages : mechanical strength; low density; generally chemically resistant

disadvantages : derived from non-renewables; not biodegradable; toxic when burnt