1.1 - Biological Compounds Flashcards
(a)
Name the four key inorganic ions and their roles in living organisms
Magnesium ions (Mg2+):
Used to produce chlorophyll
Iron ions (Fe2+):
Manufacture of haemoglobin
Calcium ions (Ca2+):
Strengthening bones and teeth
in animals; cell walls in plants.
Phosphate ions (PO43-):
Used to produce ADP and ATP
(b)
The importance of water in terms of its polarity
Water is polar because it has a positive atoms (hydrogen) and a negative atom (oxygen), due to uneven sharing of electrons.
(b)
The importance of water in terms of its ability to form hydrogen bonds
Water is a polar molecule which allows hydrogen bonds between molecules giving water
important properties.
(b)
The importance of water in terms of its surface tension and as a solvent
Surface tension:
Support and buoyancy.
Solvent:
Polar molecules dissolve in water and are
able to be transported.
(b)
The importance of water in terms of its thermal properties and as a metabolite
Thermal properties:
High specific heat capacity- a lot of energy is required to change the temperature of water so aquatic/cellular environments remain stable.
High latent heat of vaporisation- evaporative cooling.
Metabolite:
Water is a reactant in photosynthesis and
hydrolysis, produced in aerobic respiration
and condensation reactions.
(c)
What are monosaccharides?
Monosaccharides are the simplest form of carbohydrates, made up of a single sugar unit.
(c)
Name three types of monosaccharides based on the number of carbon atoms.
Triose (3 carbons), pentose (5 carbons), and hexose (6 carbons).
(c)
Give an example of a hexose sugar.
Glucose is an example of a hexose sugar.
(c)
What are disaccharides?
Disaccharides are carbohydrates made of two monosaccharide units bonded together.
(c)
Name three common disaccharides.
Sucrose, lactose, and maltose.
(c)
Which monosaccharides make up sucrose?
Glucose and fructose linked in a condensation reaction where one molecule of water is lost and a glycosidic bond is formed.
(c)
Which monosaccharides make up lactose?
A dimer formed from glucose and galactose.
(c)
Which monosaccharides make up maltose?
.α−glucose and α−glucose linked in a condensation reaction where one molecule of water is lost and a glycosidic bond is formed.
(c)
What are polysaccharides?
Polysaccharides are polymers made up of hundreds of monosaccaharide units.
(c)
Name four examples of polysaccharides.
Starch, glycogen, cellulose, and chitin.
(c)
Starch
Function:
Compact energy storage in plants with little osmotic effect.
Strucure:
A polymer of α−glucose (composed of straight-chain amylose and branched
amylopectin).
(c)
Glycogen
Function:
Energy storage in animals.
Structure:
A polymer of α−glucose.
(c)
Cellulose
Function:
A strong structure for plant cell walls.
Structure:
A polymer of β−glucose, adjacent monomers twisted through 180° to each other, allowing hydrogen bonds between chains, forming microfibrils.
(c)
Chitin
Function:
Strong, lightweight and waterproof for exoskeletons.
Structure:
As cellulose but with some –OH groups replaced by nitrogen-containing acetylamine groups.
Role of triose, pentose and hexose sugars in cells
Triose:
Important in respiration and
photosynthesis.
Pentose:
Important in nucleotides.
Hexose:
It is used in respiration.
(d)
How do alpha-glucose and beta-glucose differ?
alpha−glucose OH group points down on carbon 1 but on beta−glucose it points up.
(f)
Types of lipids
Triglyceride and Phospholipids
(f)
Functions of lipids
Functions of lipids include insulation, energy storage and protection
(f)
Explain how a triglyceride is formed
One molecule of glycerol forms ester bonds with three fatty acids via condensation reactions
(f)
Explain how a phospholipid is formed
Glycerol linked to 2 fatty acid chains and a phosphate molecule. A phospholipid has a hydrophilic head and hydrophobic tail. These properties explain the plasma
membrane lipid bilayer.
(g)
Saturated and unsaturated fats
**Unsaturated – **
mono-unsaturated fatty acids have one carbon-to carbon double bond and poly-unsaturated fatty acids contain two or more carbon-to-carbon double bonds.
Saturated – have only single carbon-to-carbon bonds.
(g)
Implications of saturated fat on human health
A high intake of saturated fats is a contributory factor in heart disease as it raises the low-density lipoprotein (LDL) cholesterol level, which increases the incidence of atheromas in coronary arteries.
(h)
Describe the general structure of an amino acid
Amine group (-NH2 )
Variable side chain (R)
Carboxyl group (-COOH)
H atom
(h)
Proteins
Proteins are constructed from 20 types of amino acid. The R group is different in each of the 20. Two amino acids linked form a dipeptide. A polymer is called a
polypeptide.
(i)
Primary structure of proteins
The sequence of amino acids as coded by the DNA. Amino acids are linked together by condensation
reactions that form peptide bonds.
(i)
Secondary structure
Hydrogen bonds formed between the amino acids in the chain cause it to fold into an alpha helix or beta pleated sheet.
(i)
Tertiary structure of proteins
Hydrophobic interactions between the variable groups within the secondary structure form disulphide and ionic bonds which form a very specific folded structure e.g. the active site of an enzyme.
(i)
Quaternary structure of proteins
More than one polypeptide chain linked to form a molecule.
(j)
Fibrous proteins
Structural function
(j)
Globular proteins
Metabolic function
SPECIFIED PRACTICAL WORK
Test for proteins
Biuret solution – blue.
Positive reaction – a purple/violet colour is seen.
SPECIFIED PRACTICAL WORK
Test for starch
Iodine solution – yellow/orange/red.
Positive reaction – a blue/black colour is seen.
SPECIFIED PRACTICAL WORK
Test for reducing and non-reducing sugar
Benedict’s reagent – blue.
Heat mixture
Positive reaction - Colour change from green to yellow to orange to brown to brick red depending on the quantity of reducing sugar present.
