2.1.2 Biological Molecules Flashcards
Biological molecules in a healthy diet
Carbohydrates Glucose Protein Water Fibre Iron Fats and oils (lipids) Vitamins and minerals Nucleic acids
Carbohydrates are needed for…
Energy storage and supply, structure
Proteins are needed for…
Structure, transport, enzymes, antibodies, most hormones
Lipids are needed for…
Membranes, energy supply, thermal insulation, protective layers/padding, electrical insulation in neurones, some hormones
Vitamins and minerals are needed for…
Forming parts of larger molecules, take part in metabolic reactions, coenzymes or enzyme activators
Nucleic acids are needed as…
Information molecules that carry instructions for life
Water is needed to…
Take part in many reactions, support in plants, solvent/medium for most metabolic reactions, transport
Elements in biological molecules
Carbon
Hydrogen
Oxygen
Nitrogen
Metabolism
Rate of chemical reactions in your body that breaks down (catabolic) and builds up (anabolic) molecules
Monomers
Single molecules e.g. Amino acids
Dimer
Two monomers joined together
Polymer
More than 2 monomers joined together
Carbohydrates monomers and polymers are called..
Monosaccharides (simple sugars)
Polysaccharides
Proteins monomers and polymers are called..
Amino acids
Polypeptides and proteins
Nucleic acids monomers and polymers are called ..
Nucleotides
DNA and RNA
Condensation reaction
Chemical reaction that links biological monomers together with a covalent bond
Process of a condensation reaction
A water molecule is released
A new covalent bond is formed
A larger molecule is formed by the binding together of smaller molecules
Hydrolysis reaction
Splitting larger molecules into molecules
Process of a hydrolysis reaction
Water molecule is used
Covalent bond is broken
Smaller molecule is formed by splitting a larger molecule
Elements of carbohydrates
Carbon
Hydrogen
Oxygen C6H12O6
Make up 10% of the organic matter of a cell
Functions of carbohydrates
Energy source (glucose) Energy store (starch and glycogen) Structure (cellulose in plants, chitin in insects- held by exoskeleton)
For every carbon present in a carbohydrate….
The equivalent of a water molecule is also present
Monosaccharides
Monomers of carbs
Contain between 3-6 carbon atoms
Properties of monosaccharides
Soluble in water
Sweet tasting
Form crystals
Triose sugars
3 carbon monosaccharides
Pentose sugars
5 carbon monosaccharides
E.g. Ribose C5H10O5
Hexose sugars
6 carbon monosaccharides
Most common
Glucose and fructose
Isomers
Different shaped forms of the same molecule
Ribose
C5H10O5
Component of ribonucleic acid (RNA), ATP and NAD
Pentose sugar
monosaccharide (like glucose)
Disaccharides
The joining of two monosaccharides
A new covalent bond, glycosidic bond forms and water is eliminated
Examples of polysaccharides
Starch Glucose Cellulose Amylose Amylopectin
Forming polysaccharides
Involves the making of glycosidic bonds
They are still sugars
Benedicts test
Test for reducing sugars
General formula for a carbohydrate
(CH2O)n
qualititative tests
indicate only the type of molecule present, not how much is present
polysaccharides as energy stores
glycogen in animals, starch in plants (amylose and amylopectin)
similarities of starch and glycogen
energy stores, bonded by thousands of alpha molecules, glucose molecules in chains can be easily ‘broken off’, insoluble
exoskeletons
polysaccharide chitin forms it in insects
bacterial cell walls
polysaccharide peptigoglycan is the basis of cell walls found around most bacterial cells
uses of proteins
growth and repair enzymes hormones amino acids (monomer) polypeptides build muscle meat antibodies ribosomes (protein synthesis) carrier proteins eg. active transport, facilitated diffusion
proteins
a diverse group of large and complex polymer molecules, made up of long chains of amino acids
biological roles of proteins
structural: main component of body tissues
catalytic: all enzymes are proteins, catalysing many biochemical reactions
signalling: many hormones and receptors
immunological: all antibodies
R group in amino acids
represents a side chain from the central alpha carbon atom
effects the types of bonds in tertiary structure
peptide bonds
link two amino acids together to form a dipeptide in a condensation reaction
polypeptide chains
when more amino acids are added to a dipeptide
protease enzymes
breaking down proteins and polypeptides by formation and breakage of peptide bonds is catalysed by these enzymes
bonds in tertiary structure of protein
disulphide: between cysteine aa, strongest
hydrogen: all levels
hydrophobic: between non-polar sections
hydrophillic: outside in globular proteins
ionic: sometimes carry a charge, form where oppositely charged aa are close to each other
Quaternary structure
Refers to the fact that some proteins are made up of more than one polypeptide subunit joined together or a polypeptide and an inorganic component
Lipids
A diverse group of chemicals that dissolve in organic solvents (alcohol) but not in water
Role of hydrogen bonds in water
Network of bonds allows molecules to move around, continually breaking/making bonds. When water solid, bonds hold structure in semi-crystalline form that is less dense. Also restrict movement of water molecules in liquid water
Why water molecules move less at lower temperature
Reduced kinetic energy and more hydrogen bonds form but don’t break so easily
Cohesion
Property of water molecules sticking to each other when hydrogen bonds pull water molecules to surface
Why water is an ideal transport medium in living organisms
Remains liquids over a large temperature range and can act as a solvent for many chemicals
what type of group is the haem group
prosthetic group
which parts of amino acids are involved in peptide bonds
amino group on one amino acid and carboxyl group on the other
OH
hydroxyl group (needed in condensation/hydrolysis reactions)
how glycosidic bonds between 2 monosaccharides are formed
condensation reaction
in maltose, bonds forms between carbon 1 on the first alpha glucose and carbon 4 so it is an alpha1-4 glycosidic bond
breakdown of glycosidic bonds
hydrolysis reaction and molecule of water is added to break the bond
why is haemoglobin a conjugated protein
it contains a prosthetic group- haem group is not essential and contains an iron ion
how to test for reducing sugars commercially
test strips dipped into solution and compared to a chart indicating how much glucose present (often for urine from diabetic patients)
