2.2 biological molecules definitions Flashcards
Adhesion
A property of water molecules that creates an attraction between them and surfaces that they are in contact with.
Amino acid
The monomers containing an amino group (NH2), a carboxyl group (COOH) and a variable R group that make up proteins
Amylopectin
A branched polysaccharide made up of alpha glucose monomers joined by α-1,6 glycosidic bonds due to the presence of many side branches it is rapidly digested
by enzymes therefore energy is released quickly
Amylose
An unbranched polysaccharide chain made up of alpha glucose monomers joined by α-1,4 glycosidic bonds in a coiled structure making it very compact meaning it can store a lot of energy.
Anions
An ion with a negative charge
Benedict’s test
A biochemical test used to detect the presence of a reducing or non reducing sugar in a solution and distinguish between solutions of different reducing sugar concentrations
Biuret test
A biochemical test that produces a purple colour when protein is present
Cations
An ion with a positive charge
Cellulose
A linear polysaccharide that is the main component of the cell wall in plants and is made up of many beta glucose molecules joined by β-1,4 glycosidic bonds
Chromatography
A technique used to separate different molecules in a solution by their different properties
Cohesion
A property of water molecules that creates an attraction between them which causes them to stick together
Collagen
A type of fibrous protein that provides strength to many different cell types and makes up connective tissues
Condensation reaction
A type of reaction that joins two molecules together with the formation of a chemical bond involving the elimination of a molecule of water.
Conjugated protein
A protein with a prosthetic group bound to it
Elastin
A type of fibrous protein that allows tissues and structures like blood vessels to stretch and return to their original shape.
Fibrous protein
A class of long chain proteins that are generally insoluble in water and typically have structural roles form fibres such as keratin
Globular protein
A class of spherical shaped proteins that are generally water soluble and typically have metabolic roles usually an enzyme
Glucose
A hexose monosaccharide that is the main respiratory substrate in eukaryotes
Glycogen
A highly branched polysaccharide that is used as the main energy storage molecule in animals and is made up of alpha glucose monomers joined by α-1,4 glycosidic bonds
Haemoglobin
A type of conjugated globular protein used to transport oxygen and is water soluble
Hexose monosaccharide
A simple sugar that contains 6 carbon atoms
Hydrogen bond
A type of weak bond formed between an electropositive hydrogen and an electronegative atom like oxygen or nitrogen
Hydrolysis
Breaking a chemical bond between two molecules involving the use of a water molecule
Insulin
A globular protein hormone that is made in the pancreas in response to detection of high glucose levels in the blood
Iodine test
A biochemical test that produces a blue/black colour when it is added to a solution containing starch
Keratin
A type of fibrous protein that provides strength to hair and nails
Lactose
A disaccharide made of a molecule glucose and galactose joined by a glycosidic bond
Lipid emulsion test
A biochemical test that produces a cloudy emulsion when performed on lipids
Maltose
A disaccharide made of two molecules of glucose joined by a glycosidic bond
Monomer
An individual unit that can be bonded to other identical monomers to make a polymer
Monomers
The smaller units from which larger molecules are made
Pentose monosaccharide
A simple sugar that contains 5 carbon atoms
Phospholipid
A type of amphipathic lipid made from a molecule of glycerol bonded to two fatty acid molecules and a phosphate group.
Polymer
A molecule made from many repeating monomers joined together.
Polymers
Molecules made from a large number of monomers joined together
Primary structure
The individual sequence of amino acids in a protein
Quaternary structure
A structure only applicable to proteins with multiple polypeptide chains that describes the interactions of the different chains.
Ribose
A pentose monosaccharide which composes the backbone of RNA
Saturated fatty acid
A type of fatty acid molecule containing only single bonds between the carbon atoms
Secondary structure
The local interactions of the amino acids in the polypeptide chain
Solvent
A liquid that solutes can dissolve in to form a solution
Starch
A polysaccharide used for energy storage in plants that is made up of alpha glucose joined together in the forms of amylose and amylopectin.
Sucrose
A disaccharide made of a molecule glucose and fructose joined by a glycosidic bond.
Tertiary structure
The way that the whole protein folds to make a 3D structure can be globular or fibrous
Triglyceride
A type of lipid formed from a molecule of glycerol joined by ester bonds to three fatty acid molecules used as energy reserves in plant and animal cells.
Unsaturated fatty acid
A type of fatty acid molecule containing at least one
double bond in the carbon chain
Why is water a polar molecule
uneven distribution of charge within the molecule
– the hydrogen atoms are more positive than the oxygen atom causing one end of the
molecule to be more positive than the other
Water is a very important molecule which is a major component of cells why
- It is a metabolite in metabolic reactions such as condensation and hydrolysis
- It is a solvent
- has a high heat specific capacity
- minimises temperature fluctuations in living things (buffer)
- large latent heat of vaporisation
- Strong cohesion
- Maximum density of water is at 4 degrees
- incompressible therefore it provides good support
explain how high heat specific capacity is important
a lot of energy is required to warm water up so minimising temperature fluctuations in living things therefore it acts as a buffer
why is a high latent heat of vaporisaton important
having a high latent heat of vaporisation meaning evaporation of water provides a cooling effect with little water loss
why is a strong cohesion useful in water
enables effective transport of water in tube-like
transport cells as the strong cohesion supports columns of water. As a result of strong cohesion the surface tension at the water-air boundary is high
explain the importance of ice being less dense than water
the ice floats on top of the water creating an insulating layer, this increases the chance of survival of organisms in large bodies of water as it prevents them from freezing
give examples of monomers
monosaccharides(glucose)
amino acids
nucleotides
carbohydrate
molecules which consist only of carbon, hydrogen and oxygen and they are long chains of sugar units called saccharides
what are the 3 types of saccharides
monosaccharides
disaccharides
polysaccharides
monosaccharides
join together to form disaccharides and polysaccharides by glycosidic bonds which are formed in condensation reactions
what is the chemical formula for glucose
C6H1206
name 3 disaccharides
maltose
sucrose
lactose
name 3 monosaccharides
glucose
fructose
galactose
name 3 polysaccharides
glycogen
cellulose
starch
function of glycogen
main energy storage in animals
has a large number of side branches meaning that glucose & therefore energy, can be released quickly.
relatively large but compact molecule thus maximising the amount of energy it can store.
fucntion of starch
stores energy in plants and it is a mixture of two polysaccharides called amylose and amylopectin (which are made of alpha glucose molecules)
function of cellulose
component of cells wells in plants and it’s composed of long, unbranched chains of beta glucose which are joined by glycosidic bonds.
what are microfibrils
strong threads which are made of long cellulose chains joined together by hydrogen bonds which
provide structural support in plants cells.
lipids
biological molecules which are only soluble in organic solvents such as alcohols.
what are the 2 types of lipids
saturated and unsaturated
what are saturated lipids
found in animal fats – saturated lipids DON’T contain any carbon-carbon double bonds melt at higher temperatures than unsaturated
what are unsaturated lipids
found in plants – unsaturated lipids contain carbon-carbon double bonds and melt at lower temperatures than saturated fats.
what does a greater number of unsaturated bonds in lipids result in
more unsaturated bonds means weaker intermolecular bonds
lower melting point
saturated fats are solid at room temperature
unsaturated fats are liquid at room temperature.
why do phosopholipids form micelles
Phosphate heads are hydrophilic and the tails are hydrophobic so when they are in contact with water heads are on the outside as they are attracted to water and tails are on the inside as they repel the water.
what are micelles
collodial suspension (insoluble) lipid molecules that arrange themselves in a spherical form in aqueous solutions.
inorganic ions
occur in solution in the cytoplasm and body fluid of organisms, some in high concentrations and others in very low concentrations
list of inorganic ions
hydrogen ions
iron ions (lol)
sodium ions
phosphate ions
importance of hydrogen ions
determine the pH of substances such as blood – the higher the concentration of hydrogen ions the lower the pH (more acidic)
importance of irons ions
component of haemoglobin which is an oxygen carrying molecule in red blood cells
importance of sodium ions
involved in co-transport of glucose and amino acids
importance of phosphate ions
component of DNA and ATP
how is the structure of proteins determined
by the order and number of amino acids, bonding
present and the shape of the protein
why is collagen a strong fibrous protein
presence of both hydrogen and covalent bonds in the structure. they wrap around each other and form fibrils which form the strong collagen fibres
what does collagen form
bones
cartilage
connective tissue
main component of tendons (which connect muscles to bones)
structure of haemoglobin
two alpha and two beta polypeptide chains each containing a haem group
how to carry out a benedicts test
An alkaline solution of blue copper (II) sulphate is added to the sugar and subsequently
heated, in the presence of reducing sugar, a red precipitate of copper (I) oxide is
formed. In the absence of reducing sugar, the Benedict’s reagent does not change
colour.
what is a reducing sugar
a reducing sugar is one which can donate electrons and includes all monosaccharides and some disaccharides
how to carry out a biuret test
Firstly, a sample of the solution is placed in a test tube and subsequently an equal amount of NaOH is added. Afterwards, a few drops of dilute copper (II) sulfate solution is added and gently mixed. In the presence
of a protein, the solution turns lilac/ as an indicator of peptide bonds. In the absence of protein, the solution remains blue.
how to carry out an emulsion test
Firstly, 2ml of sample is added to 5ml of ethanol. Subsequently, the contents are mixed thoroughly by shaking to ensure that the lipids dissolved. Upon addition of 5ml of water and mixing, the solution turns
cloudy indicating the presence of lipid due to the formation of an emulsion where the light is refracted as it passes from droplets of oil to droplets of water.
how to carry out a test for starch
add iodine - if the solution/substance tested goes blue/black starch is present
How many bonds can carbon form
4
How many bonds can nitrogen form
3
How many bonds can oxygen form
2
How many bonds can hydrogen form
1
What are ions in solution called
Electrolytes
Roles of calcium (Ca2+) cations
Nerve impulse transmission
Muscle contraction
Roles of sodium (Na+) cations
Nerve impulse transmission
Kidney function
Roles of potassium (K+) cations
Nerve impulse transmission
Stomatal opening
Roles of hydrogen (H+) cations
Catalysis of reactions
pH determination
Roles of ammonium (NH4+) cations
Production of nitrate ions by bacteria
Roles of nitrate (NO3-) anions
Nitrogen supply to plants for amino acid protein formation
Roles of hydrogen carbonate (HCO3-) anions
Maintenance of blood pH
Roles of chloride (Cl-) anions
Balance +ve charge of sodium and potassium ions in cells
Roles of phosphate (PO4³-) anions
Cell membrane formation
Nucleic acid and ATP formation
Bone formation
Roles of hydroxide (OH-) anions
Catalysis of reactions
pH determination
What is capillary action
Process by which water can rise up a narrow tube against the force of gravity due to adhesion and cohesion properties
