U4AOS2 - Key food molecules

Question 1

Definition of Amino Acids (inc. alpha-amino-acids, chirality, key chemical process)

Answer 1

Building blocks of proteins

Alpha-Amino Acids:
- also referred to as 2-amino-acids
- has a central carbon, bound directly to the carboxyl and amino functional groups
- can be chiral if R is not a lone hydrogen

Amino acids often undergo condensation

Question 2

Purpose of Amino Acids

Answer 2

to balance the pH in the body by reacting with the excess H⁺ or OH^-

Similar principle to LCP - partially opposes the change, tries to return the body to the correct pH

Question 3

Properties of Amino Acids in Acids

Answer 3

NH₂ group(s) accepts a proton/hydrogen (acting as a base) to form NH₃⁺

Will become a cation

Question 4

Properties of Amino Acids in Bases

Answer 4

COOH group(s) donates a proton/hydrogen (acting as an acid) to form COO^-

Will become an anion

Question 5

Solubility of Amino Acids (in water)

Answer 5

Soluble in water - as a result of the polar amino and carboxyl groups (from neutral pH)

Question 6

Essential Amino Acids

Answer 6

Amino Acids that cannot be synthesized (produced) by the body, but instead - must be consumed in diet

Question 7

Non-Essential Amino Acids

Answer 7

Amino Acids that can be synthesized by the human body - do not need to be supplemented through diet

Question 8

Properties of Amino Acids in Neutral Solutions (inc. name & overall charge)

Answer 8

The Amino Acid will act as an acid and a base:

NH₂ group(s) will become NH₃⁺ <strong>AND</strong> COOH group(s) will become COO^-

Referred to as a zwitterion

Overall charge, typically 0, but if the R chain contains NH₂ (amino) or COOH (carboxyl) then the overall charge may be different

Question 9

Formation of Peptides (inc. name of functional group produced)

Answer 9

Condensation Reactions between Amino Acids

An amino group from one amino acid will react with the carbonyl group, creating an amide link (or peptide link - but only if it’s actually a protein)

(and producing a water)

Note - order matters with peptides, Aly-Gly and Gly-Ala are different

Question 10

Dipeptides

Answer 10

Two 2-amino-acids combined

Question 11

Polypeptides (inc. specific name of reaction that creates them)

Answer 11

Many 2-amino-acids combined

Created through condensation polymerization

Question 12

Primary Proteins (inc. structure & bonding)

Answer 12

Very large polypeptides

There will always be a carboxyl terminal and amino terminal.

Bonding is covalent intramolecular - through the amide link

Question 13

Secondary Proteins (inc. bonding & types of structures)

Answer 13

Hydrogen bonding between the amide links of a single protein

Question 14

Tertiary Proteins (inc bonding, importance of this form)

Answer 14

Bonding between R-chains

<strong>ADD TYPES</strong>

This is the functional form of a protein - if the tertiary structure is disrupted - the protein will lose its function

Question 15

Quaternary Proteins

Answer 15

Combinations and interactions between two or more tertiary proteins

Intermolecular bonds between side chains R

Question 16

Structure of Carbohydates (inc. general formula)

Answer 16

Large amounts of carbon, hydrogen and oxygen

General Formula: C_a(H₂O)_b
This means that carbohydrates will have very high densities of oxygen (higher than alcohols etc)

Question 17

Monosaccharides (inc. form & inter bonding)

Answer 17

Smallest building blocks of carbohydrates

Exist in a straight-chain form or cyclic forms, however, in aqueous solutions, the cyclic form predominates

Theyre polar and soluble in water (due to hydroxyl groups)

Question 18

Alpha vs Beta Monosacchardies

Answer 18

Question 19

Examples of Monosaccharides (3)

Answer 19

Glucose & Fructose (which exist in fruits and living systems)
Galactose (found as a breakdown of lactose)

Question 20

Disaccharides (inc. form & name of functional group)

Answer 20

(also called two ring sugars)

Links two Monosaccharides together with a condensation reaction (producing water)

Creates a glycosidic linkage (or ether) between the two monosaccharides

Question 21

Formula & Molar Mass of Glucose

Answer 21

C₆H₁₂O₆

MM: 180

Question 22

Examples of Disaccharides (3)

Answer 22

Sucrose (alpha-glucose + beta-fructose - used in fruits)

Maltose (2x alpha-glucose)

Lactose (glucose + galactose - found milk)

Question 23

Polysaccharides (inc. production)

Answer 23

(complex carbohydrates)

Made up of many individual monosacchardies

Creates a glycosidic linkage (or ether) between the each monosaccharide (polymer) - and releases a water for every unit added

Question 24

Amylose (inc monomer, structure, intermolecular forces, enzyme)

Answer 24

Type of Starch

Uses α-glucose as its monomer

CH₂OH points in the same direction & no branching (results in a tightly coiled helices)

Strong intermolecular forces (packed close together - but not locked like cellulose)

Enzyme for Hydrolysis: Amylase, then Maltase

Question 25

Cellulose (inc monomer, structure, intermolecular forces, enzyme)

Answer 25

Uses β-glucose as its monomer

Used as the cell wall for plants

CH₂OH points opposite directions (allows them to lock into each other) & No Branching

Very strong intermolecular forces (tightly packed)

Enzyme for Hydrolysis: Cellulase (not produced by humans)

Question 26

Amylopectin (inc monomer, structure, intermolecular forces, enzyme)

Answer 26

Type of Starch

Uses α-glucose as its monomer

CH₂OH points in the same direction & branching (roughly every 20 units)

Weaker intermolecular forces (not packed close together)

Enzyme for Hydrolysis: Amylase, then Maltase

Question 27

Glycogen (inc monomer, structure, intermolecular forces)

Answer 27

Used for energy storage in the body (formed from glucose)

Uses α-glucose as its monomer

CH₂OH points in the same direction & branching (roughly every 10 units)

Weaker intermolecular forces (not packed close together)

Question 28

Solubility of Carbohydrates in Water

Answer 28

Soluble in water, due to the carboxyl groups

However - the more branching - the greater the surface area of the carboxyl groups, so its more soluble

Question 29

Storage of excess Glucose

Answer 29

It’ll be converted to glycogen and stored in muscles and the liver

the body will then reconvert to glucose when required

Question 30

Artificial Sweeteners (inc. name, GI index, energy content, relative sweetness)

Answer 30

Aspartame, artificial sweetener - not a protein or carbohydrate

Has a GI index of 0 (compared to glucose’s 100)
Has the same energy content to glucose
Relative sweetness of 200, compared to glucose’s 0.74

Question 31

Triglycerides (inc. structure, formation, intermolec bonding)

Answer 31

Type of lipid, the form of fats or oils in the body

Structure: Has a glycerol backbone, and 3 fatty acids (different or same), connected with an ester in the middle

Formation: formed through condensation reactions, with 3H₂O released

Intermolecular Bonding: mostly non-polar

Question 32

Fatty Acid (inc. structure & how to name)

Answer 32

Building blocks of proteins

Structure: linear carbon chain (single or double bonds), with a carboxyl group on the end

Naming: make sure to add ‘acid’ after the name of the fatty acid from the databook

Question 33

Saturated Fatty Acids (inc. IRL example, effect on melting point)

Answer 33

Only single carbon-carbon bonds

IRL example: butter

Effect on melting point: no C=C means packed closer together, therefore, stronger intermolec bonds, higher melting point

Question 34

Unsaturated Fatty Acids (both types, effect on melting point)

Answer 34

Contains double carbon-carbon bonds

Mono-unsaturated - only one carbon-carbon double bond
Poly-unsaturated - more than one carbon-carbon double bond

Effect on melting point: C=C means ‘kinks’ in chain, not packed as close together (as saturated), therefore, weaker intermolec bonds, lower melting point - this effect is ‘stackable’ - 2 C=C will have lower melting point than 1 C=C

Question 35

Omega-3 vs Omega-6 Fatty Acids (inc. omega carbon)

Answer 35

Omega Carbon: Carbon atom on the methyl group

Omega-3: when the carbon-carbon double bond is on the 3rd carbon relative to the omega carbon
Omega-6: when the carbon-carbon double bond is on the 6th carbon relative to the omega carbon

Question 36

Non-Essential Fatty Acids

Answer 36

Can be synthesized by the human body - don’t need to include in our diet

Question 37

Essential Fatty Acids

Answer 37

Cannot be synthesized in the human body - need to include in our diet

Question 38

Effect of increasing the number of carbons in fatty acids on melting point

Answer 38

More carbons increase the dispersion force.

Increased intermolec bonds -> higher melting point

Question 39

Fats vs Oils - with reference to melting point

Answer 39

Fats - solids @ room temp (usually saturated fatty-acids)
Oiis - liquids @ room temp (usually unsaturated fatty-acids)

Question 40

What are Vitamins (+essential/nonessential)

Answer 40

Organic Compounds that are required for the body to function properly

All vitamins are essential, must be consumed in diet (with the exception of VitD which is synthesized through sunlight, non-essential)

Question 41

Water Soluble Vitamins (Structure, Solubility, Storage, Consumption)

Answer 41

Predominantly Polar Functional Groups
Soluble in Water (Hydrogen Bonding)

Surplus will be excreted if not consumed (often through urine)
Therefore, must be consumed regularly

Question 42

Fat Soluble Vitamins (Structure, Solubility, Storage, Consumption)

Answer 42

Vitamins ADEK

Predominantly Non-Polar Functional Groups
Soluble in Fat (dispersion forces)

Surplus will be stored in fatty issues (for a long time i.e. an adult can store several years worth of VitA supply)
Therefore, can be consumed less often, and if its consumed too quickly, it can be dangerous (as the body cannot dispose of the excess - the conc. can increase too high)