2.1.2 biological molecules Flashcards
Name four macro molecules
Proteins, fats, water, carbohydrates
Name the components of the macro molecules
protein: made up of amino acids
fat: made from glycerol and fatty acids
water: contains hydrogen and oxygen only
Carbohydrate: simple sugars to complex polysaccharides
Name the function of the four macro molecules
Protein: Used to make enzymes, hormones and structural components such as muscle
fat: energy source and storage, installation, buoyancy and protection
water: components of tissues, medium for chemical reactions and transport medium
carbohydrate: Source of energy and structural uses
Define a condensation reaction
Two molecules join together. A water molecule is removed during the reaction
Define a hydrolysis reaction
A molecule is split into two molecules. Water is needed for the reaction to occur
Define a monomer
A small molecule that can be bound to other identical monomers by condensation
Describe a polymer
A large molecule, made from many monomers
What are the bonding rules
bonding can be determined by the number of electrons in the outer orbital.
Carbon atoms can form 4 bonds with other atoms
nitrogen atoms form 3 bonds
oxygen forms 2 bonds
Hydrogen forms 1 bond
Name the monomer and polymer of a carbohydrate
monomer: monosaccharide
Polymer: polysaccharide
Name the monomer and polymer of a protein
monomer: amino acids
Polymer: polypeptides and proteins
Name the monomer and polymer of nucleic acids
monomer: nucleotides
Polymer: DNA and RNA
Name the monomer and polymer of fats
monomer : fatty acids and glycerol
Polymer: triglycerides
Why is water described as a polar molecule
water is described as polar as it has an unequal distribution of charge in the molecule. Oxygen is slightly negative (delta negative) and hydrogens are slightly positive (delta positive)
How do hydrogen bonds form between water molecules
water is polar: oxygen is more electronegative than hydrogen, so attracts electron density in covalent bonds more strongly.
There are intermolecular forces of attraction between a lone pair of oxygen Delta negative of one molecule and hydrogen Delta positive on an adjacent molecule
State some biologically important properties of water
it has a high surface tension which enables organisms to walk on water
it has a high specific heat capacity: because of the high amount of hydrogen bonds, it means that it can absorb a lot of heat and provides relatively constant temperatures
universal solvent: it can dissolve many ionic and polar substances which enables many biochemical reactions to take place in the cell cytoplasm and it enables substances to be transported
it provides a habitat
it transports into and around cells in the blood, xylem, lymph fluid
it is a liquid at room temperature which allows the transport, habitat and is a medium for reactions
it has a high latent heat of vaporisation and is a coolant because heat energy is needed to break the hydrogen bonds when the water evaporates
it is dense so ice floats, has an insulating layer
cohesion between molecules
Define cohesion
Attraction to other water molecules
Define adhesion
Attraction to other polar substances
Why is the incompressible nature of water important for organisms
It provides turgidity to plant cells and provides Hydro static skeleton for some small animals like earthworms
Explain why ice floats on water. And why is this important for organisms
Ice is less dense than water because hydrogen bonds holding molecules in fixed positions further away from each other. It insulates water in Arctic climates so aquatic organisms can survive and water acts as a habitat
Why is the high surface tension of water important for organisms
It slows water loss due to transpiration in plants. Water rises unusually high in narrow tubes, lowering demand on route pressure.
And some insects can skim across the surface of water
Why is water an important solvent for organisms
polar universal solvent dissolves and transports charged particles involved in intra and extracellular reactions
Why are the high specific heat capacity and latent of vaporisation water important for organisms
Acts as a temperature buffer which enables endotherm is to resist fluctuations in core temperature, to maintain optimum enzyme activity. Cooling affect when water evaporates from skin surface as sweat/from mouth when panting
Name the elements found in carbohydrates, lipids, proteins and nucleic acids
carbohydrates and lipids: carbon, hydrogen, oxygen ( CHO)
proteins: carbon, hydrogen, oxygen, nitrogen, sulfur ( CHONS)
nucleic acids: carbon, hydrogen, oxygen, nitrogen, phosphorus ( CHONP)
carbohydrates: Draw the structure of alpha glucose and beta glucose
they are both hexose monosaccharides with a ring structure
carbohydrates: State the three carbohydrates and the example molecules
monosaccharide are small, simple sugars e.g. glucose, fructose and ribose
disaccharides are large sugars e.g. lactose and sucrose
Polysaccharides are long chain carbohydrates e.g. glycogen, Celulose and starch
carbohydrates: describe glucose
glucose is an abundant and very important monosaccharide. It contains six carbon atoms so it is a hexose sugar and its general formula is C6 H12 O6
Glucose is the major energy source for most cells. It is highly soluble and is the main form in which carbohydrates are transported around the body of animals
carbohydrates: How do we make disaccharides and polysaccharides
Condensation reaction
carbohydrates: Describe pentose monosaccharides
They contain five carbon atoms. Two important pentose molecules are the structural isomers ribose and deoxyribose. The only difference between them is that ribose has one hydrogen atom and 1 OH group attached to carbon 2, whereas deoxyribose has two H atoms and no OH group
carbohydrates: How is maltose formed (disaccharide)
Glucose + glucose = maltose
carbohydrates: How is sucrose formed (disaccharide)
glucose + fructose
carbohydrates: How is lactose formed (disaccharide)
glucose + galactose = lactose
carbohydrates: What are polysaccharides
Polysaccharides are polymers containing many monosaccharides linked bike like acidic bonds. Like disaccharides, polysaccharides are formed by condensation reactions
The major polysaccharides are starch and cellulose in plants and glycogen in animals
carbohydrates:
What type of bond forms when monosaccharides react
(1,4 or 1,6) glycosidic bonds
two monomers= one chemical bond = disaccharide
multiple monomers = many chemical bonds = polysaccharides
carbohydrates: do you find it in humans or plants
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = Plants
(II) amylopectin =Plants
(III) glycogen =Animals
carbohydrates: Where in the organism is it stored
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose= Grains in the chloroplasts
(II) amylopectin =Grains in the chloroplasts
(III) glycogen =Liver and muscles
carbohydrates: Is it a form of starch
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = Alpha glucose
(II) amylopectin = Alpha Glucose
(III) glycogen = Alpha Glucose
carbohydrates: Is it branched
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = No it is straight
(II) amylopectin = Yes
(III) glycogen = Yes loads of branches
carbohydrates: Is it soluble
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = No
(II) amylopectin = No
(III) glycogen = Yes
carbohydrates: Which glycosidic bonds does it have
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = 1,4
(II) amylopectin 1,4 and 1,6
(III) glycogen 1,4 and 1,6
carbohydrates: are they spiralled
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = Yes
(II) amylopectin =No
(III) glycogen = No
carbohydrates: Are hydrogen bonds important in holding the structure in place
(I) amylose
(II) amylopectin
(III) glycogen
(I) amylose = Yes
(II) amylopectin = no
(III) glycogen = no
carbohydrates: Describe glycogen
Animals do not store carbohydrate as starch but as glycogen. Glycogen is stored as small granules, particularly in muscles and liver. Glycogen is less dense and more soluble than starch and breaks down more rapidly. And the reason glycogen is more soluble than starch is because it has loads of branches which make it more compact enabling it to store more energy
carbohydrates : What is Celulose
Celulose is another polysaccharide and is the main part of plant cell walls.
Unlike starch, Celulose is very strong, and prevents cells from bursting when they take in excess water.
Celulose consist of long chains of beta glucose molecules joined by beta 1,4 glycosidic bonds.
The glucose chains form ropelike microfibrils which are layered to form a network
lipids: What are the characteristics of lipids
lipids contain C, H and O.
Lipids are nonpolar molecules, so are insoluble in water but they are soluble in organic solvents. They are generally water repelling(hydrophobic) The building blocks of fatty acids and glycerol and they do not form polymers
lipids: What are triglycerides
triglycerides are lipids made from glycerol and 3 fatty acid chains
lipids: How do triglycerides form
Condensation reaction between one molecule of glycerol and three fatty acids which forms ester bonds
lipids: describe a fatty acid’s structure
A fatty acid has a hydrocarbon chain, ending in an acidic carboxyl group
- COOH
A carboxyl group is what makes the hydrocarbon chain acidic
lipids: What are the differences between fats and oils
Fats are solid at room temperature and oils are liquid at room temperature
lipids: What are the differences between saturated and unsaturated fatty acids
Saturated: contain only single bonds, straight chain molecules have many contact points, higher melting point which means they are solid at room temperature, and they are found in animal fats
unsaturated: contain C=C double bonds, kinked molecules have fewer contact points, Lower melting point which means they are liquid at room temperature and are found in plant oils
lipids: Relate the structure of triglycerides to their function
High energy: mass ratio = hi calorific value from oxidation (energy storage)
insoluble hydrocarbon chain = No affect on water potential of cells and used for waterproofing
slow conductor of heat = thermal insulation eg adipose tissue
less dense than water = Buoyancy of aquatic animals
lipids: Describe the structure of phospholipids
amphipathic: glycerol backbone attached to 2 hydrophobic fatty acid tails and 1 hydrophilic polar phosphate head
phospholipids can form a layer on the surface of water and they can form a sphere
They do not dissolve in water
They are selectively permeable because only nonpolar molecules can get past the polar head of a phospholipid
lipids: Describe the function of phospholipids
they form a phospholipid bilayer in water = component of membranes
tails can splay outwards = waterproofing e.g. for skin
Phospholipids heads can shuffle around but also always protect the tails and this provides stability
lipids: Are phospholipids and triglycerides polymers
No. They are not made from a small repeating units, they are macro molecules
lipids: Describe the structure and function of cholesterol
steroid structure of four hydrocarbon rings. Hydrocarbon tail on one side, hydroxyl group - OH on the other side
cholesterol adds stability to cell-surface phospholipid bilayer by connecting molecules and reducing fluidity
proteins: What are proteins made of
Proteins are made of repeating units of amino acids
Describe an amino acid structure
- COOH carboxyl/ carboxylic acid group
R variable side group consists of carbon chain and includes other functional groups
NH2 = amino/ amine group
All amino acids have the same general structure, the only difference between each one is the nature of the R group. The R group therefore defines an amino acid
proteins: How do polypeptides form
condensation reactions between amino acids form peptide bonds. There are four levels of protein structure
proteins: Define primary structure of a protein
Sequence, number and type of amino acids in the polypeptide, determined by sequence of codons on mRNA
mclaird definition = Simple long chains with no intramolecular bonds or interactions. The order of amino acids determines the primary structure
proteins: define the secondary structure
hydrogen bonds form between oxygen Delta negative attach to -C=O and hydrogen Delta positive attached to -NH
mclaird definition : Hydrogen bonds form causing the molecule chain to either foil or coil
proteins: Describe the two types of secondary protein structure
alpha helix: all N-H Bonds on same side of protein chain, spiral shape, H-bonds Parallel to helical axes
beta pleated sheets: N-H and C=O groups alternate From one side to the other
Define tertiary structure of a protein and describe the bonds present
3-D structure formed by further folding.
Disulphide bridges: strong covalent S-S Bonds between molecules of the amino acid cysteine
ionic bonds: relatively strong bonds between charged r groups (pH changes cause these bonds to break)
hydrogen bonds: numerous and easily broken
mclaird definition: Hydrophilic/phobic interactions, hydrogen bonds, ionic bonds and disulphide bonds hold the molecules together in shape. Disulphide bonds are formed only when sulfur is present in the r group
proteins: define quaternary structure of a protein
Functional proteins may consist of more than one polypeptide. Precise 3D structure held together by the same types of bond as tertiary structure. May involve addition of prosthetic groups e.g. metal ions of phosphate groups
mclaird definition : These are the same as tertiary but with two separate polypeptide chains interlinked
proteins: Describe the structure and function of globular proteins
they are spherical and compact. Hydrophilic R groups face outwards and hydrophobic R groups face inwards = usually water soluble
they are involved in metabolic processes e.g. enzymes such as amylase, insulin and haemoglobin
proteins: Describe the structure and function of fibrous proteins
They can form long chains of fibres, insoluble in water and are useful for structure and support e.g. collagen in skin
List the functions of collagen, elastin and keratin
collagen: component of bones, cartilage, connective tissues and tendons
elastin: provides elasticities to connective tissue, arteries, skin, lungs, cartilage, ligaments
Keratin: structural components of hair, nails, whose, horns, epithelial cells of outer layer of skin
proteins: Describe the structure and function of conjugated proteins
they are globular proteins that contain a nonprotein component called a prosthetic group. It functions in interaction with other non-polypeptide chemical groups attached by covalent bonds. E.g. haemoglobin
proteins: Describe the structure of haemoglobin
globular conjugated protein with prosthetic group.
Two alpha chains, two beta chains, four prosthetic haem groups.
Water soluble also dissolves in plasma.
Fe 2+ haem group forms coordinate bond with O2
tertiary structure changes so it is easier for subsequent oxygen molecules to bind (cooperative bonding)
Describe how to test for proteins in a sample
biuret
add an equal volume of biuret solution and observe the colour change.
If the sample is positive for protein it will go from blue to lilac
and if the sample is negative for protein it will stay blue
Describe how to test for lipids in a sample
emulsion test:
add ethanol to the food to dissolve the fat, then add water and shake
If the sample is positive for lipids then a milky white emulsion will form with a white or cloudy appearance
If the sample is negative it stays colourless
describe how to test for reducing sugars
add benedicts solution to the food and boil in a water bath for five minutes
if the sample is positive for reducing sugars it will form a brick red precipitate
If the sample is negative it will stay blue
Describe the benedicts test for non-reducing sugars
add the test sample with dilute hydrochloric acid. Neutralise the test sample by adding sodium hydrocarbonate. And heat the test sample with benedicts solution
if the sample is positive for a non-reducing sugar it forms a brick red precipitate
if the sample is negative It stays blue
Describe the test for starch
add 2 to 3 drops of iodine on the specimen
if the sample is positive for starch then the colour will change from Orange to blue / black
If the sample is negative it will stay orange / brown
Outline the principles and process of chromatography
Use capillary tube to spot solution onto pencil start line 1 cm above bottom of paper
place chromatography paper in solvent, the origin should be above solvent level
let solvent to run until it almost touches the other end of the paper. Molecules in mixture move different distances based on relative solubility in the solvent/attraction to paper
chromatography : what are Rf Values and how can they be calculated
ratios to allow comparison of how far molecules have moved in chromatograms
Rf value = Distance between origin and centre of pigment spot ÷ Distance between origin and solvent front
also known as Rf = distance moved by the solute ÷ distance moved by the solvent
ppq: Name the bond that joins the unit in a molecule of sucrose
glycosidic bond
ppq: Name the type of reaction that breaks a glycosidic bond
Hydrolysis reaction
ppq: Name the precise group of carbohydrate molecules of which glucose is an example
Monosaccharides
ppq: State and explain two ways in which the glucose molecule is well suited to its function in living organisms
Glucose is a ready source of energy e.g. in cellular respiration energy is released from glucose which helps make ATP. And it is highly soluble in water which allows the glucose fuel to be transported easily e.g. in the bloodstream
ppq: How does the structure of glycogen help its function as an energy storage molecule
Glycogen has many short branches, which are easily digested by carbohydrase enzymes
ppq: How are the bonds between triglycerides broken
The ester bonds are broken by a hydrolysis reaction
ppq: Haemoglobin has a high affinity for oxygen, how does the shape of haemoglobin aid its function
Each subunit of the quarternary protein contains an iron based haem group. Each heam groups binds a molecule of oxygen
ppq: Which is the strongest bond strength
disulphide is the strongest bond strength
It goes hydrogen, ionic, disulphide
ppq: Name the covalent bond between two adjacent amino acids in a chain of amino acids
Peptide bond
ppq: Name the type of reaction involved in breaking a peptide bond and describe what happens in this reaction
hydrolysis and in this reaction water is needed
ppq: lipids form an essential part of a balanced diet. Some food, such as Mycoprotein is produced by micro organisms.
How might the lipid content of mycoprotein differ from food that comes from animals
Overall they have less fat,
less saturated fat and more unsaturated fat
ppq: why is the ability of water to act as a solvent important for the survival of organisms
it means they are a medium for metabolic reactions and because it allows ionic compounds to separate
ppq: State the name given to the sequence of amino acids in a protein molecule
Primary structure
ppq: State one property of collagen that makes it a useful component of blood vessel walls
It is very strong
ppq: Describe the structure of the collagen molecule
there are peptide bonds, between amino acids and every third amino acid is coiled.
Alpha helix which is left-handed
glycine allows closeness
three polypeptide chains
hydrogen bonds between polypeptide chains and a few hydrophilic r groups on the outside of the molecule
ppq: State one function of haemoglobin
Transport of oxygen
ppq: Haemoglobin contains a prosthetic group, collagen does not contain a prosthetic group.
Describe three other ways in which the structure of haemoglobin differs from that of collagen
haemoglobin is globular,
has hydrophobic r groups on the inside and hydrophilic r groups on the outside.
and have four chains (polypeptide)
The subunits are two different types: alpha, helix.
And has a wider range of amino acids
ppq: Name the polymer formed from a chain of amino acids
Polypeptide
ppq: Name the bond that is formed when two amino acids are joined together. And describe the formation of this bond
peptide bond
between, amine Group of one amino acid and carboxyl group of another, H from amine combines with OH (carboxyl) through a condensation reaction
ppq: describe ways in which the physical properties of water allow organisms to survive over a range of temperatures
large amount of heat needed to change from liquid to gas (high latent heat of vaporisation )
Evaporation is an efficient cooling mechanism e.g. sweating, painting, transpiration
water is thermally stable (high specific heat capacity) which enables a thermally stable environment for aquatic organisms and aquatic organisms use less energy on temperature control
Ice is less dense than water and this therefore means that the surface of ice provides habitats for organisms e.g. polar bears on ice.
water beneath us is insulated and doesn’t freeze and therefore aquatic organisms do not freeze and can still swim
it is an effective solvent and is therefore a medium for reactions and is able to delete toxic substances
it has surface tension which creates a habitat for invertebrates
it is transparent so allows underwater photosynthesis
and has high density so allows floatation
ppq: List three examples of where hydrogen bonds are found in biological molecules
protein secondary structure (alpha helix, beta pleated sheet)
protein tertiary structure
Between polypeptide chains in quaternary structure
ppq: State two roles of cholesterol in living organisms
regulates fluidity of membranes e.g. phospholipid bilayer
Waterproof the skin and makes vitamin D
ppq: Identify one way in which the molecular structure of cholesterol is similar to the molecular structure of a carbohydrate
both contain C H O
ppq: cholesterol was transported in the blood within molecules of low-density lipoprotein (LDL)
Name two molecules that combine with cholesterol to form LDLs
Triglycerides and proteins
ppq: Suggest why diets with a high red meat content or associated with high blood cholesterol
Red meat contains large amounts of saturated fats and saturated fats lead to increased amount of LDLs
ppq: Describe the structure of a triglyceride molecule
One glycerol and three fatty acids with an ester bond between the glycerol and fatty acids
ppq: State three roles of lipids in living organisms
thermal insulation
Energy store
protection
Waterproofing
ppq: suggest one difference between lipids from animals and those from plants
saturated fatty acids have fewer double bonds
And animal fats are solid at room temperature
ppq: give three differences between the structure of glycogen and collagen
Glycogen: polysaccharide, alpha glucose units, identical units, glycosidic bonds, branched, one chain per molecule, no cross links, contain C H O
Collagen: polypeptide, amino acid units, different amino acid units, peptide bonds, three chains per molecule, cross links between chains, contains C H O N
