Biological Molecules Flashcards
What is a monomer?
Monomers are the smaller units from which larger molecules are made
What is a polymer?
Polymers are molecules made from a large number of monomers joined together in a chain
What is a macromolecule?
A macromolecule is a very large molecule important to biological processes
What is an organic compound?
A molecule made out of ONLY carbon, oxygen and hydrogen
What is a covalent bond?
A type of chemical bond where two atoms share electrons
In what type of reaction is a polymer formed?
Polymerisation reaction
What is a hydrolysis reaction
The breaking down of a bond by adding a water molecule
What is a condensation reaction
Creating a bond by releasing a water molecule
What is a reducing sugar?
A sugar molecule that can donate electrons
What is a non-reducing sugar
A sugar that cannot donate electrons
What is an isomer?
Orgnaic molecules that have the same molecular formula but a different structure asnd therefore different properties
What are the 2 types of glucose molecules?
Alpha / Beta
What is the chemical formula of glucose?
C6 H12 O6
Describe the difference between alpha and beta glucose molecules?
Draw a diagram to show this
On an alpha glucose molecule the OH is below the ring, on a beta glucose molecule the OH is above the ring.
What is a glycosidic bond?
How is it formed?
A glycosidic bond is the covalent bond between two hydroxyl groups (OH) on different saccharides.
It is formed in a condensation reaction.
What is a disaccharide?
Two monosaccharides bonded together via a glycosidic bond
What are the 3 disaccharides?
What are they made of?
Maltose, Sucrose, Lactose
Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = Lactose
What are polysaccharides?
Polymers made up of many monosaccharides
Due to their size they are also classified as macromolecules
How are polysaccharides formed?
Polymerisation reaction where monosaccharides are joined by glycosidic bonds formed in a condensation reaction
What is starch made of?
Alpha glucose
What are the two types of starch?
Amylose
Amylopectin
What are features of amylose
Helical structure
1,4 Glycosidic bonds
Insoluble in water
What are features of amylopectin?
Branched
1,4 + 1,6 glycosidic bonds
Insoluble in water
What is glycogen made of?
Alpha glucose
What are features of glycogen?
Highly branched
1,4 + 1,6 glycosidic bonds
Insoluble in water
What is cellulose made of?
Beta glucose
What are features of cellulose?
Unbranched
Hydrogen bonds between microfibrils
Rigid
Beta glucose molecules alternate
Insoluble in water
What is the use of amylose?
Storage molecule for plants, easier to store as more compact
What is the use of amylopectin?
Storage molecule for plants, easier to break down due to high number of terminal glucose molecules
What is the use of glycogen?
Storage molecules for animals and fungi,
What is the use of cellulose?
Cell walls in plants
What reagent tests for reducing sugars?
Benedicts reagent
If a reducing sugar is present, what colour does Benedicts solution turn?
Blue ==> brick red
How to test for reducing sugars?
1- Break down sample if solid
2- Add Benedicts reagent to a sample solution in a test tube
3- Heat the mixture in a water bath
4- If reducing sugar is present the Benedicts reagent will turn brick red
How to test for non-reducing sugars?
1- Break down sample if solid
2- Add dilute hydrochloric acid to the sample and heat in a water bath
3- Add sodium hydrogencarbonate to sample to neutralise solution
4- Add Benedicts reagent to a sample solution in a test tube
5- Heat the mixture in a water bath
6- If reducing sugar is present the Benedicts reagent will turn brick red
What reagent tests for starch?
Iodine
What colour does iodine turn if starch is present?
Orange/brown ==> blue/black
How to test for starch?
1- Add a few drops of iodine in potassium iodide solution to the sample
2- If starch is present, iodide ions in the solution interact with the centre of starch molecules, producing a blue-black colour
What are lipids?
Organic macromolecules, also known as fats
What are the two types of lipid?
Triglycerides
Phospholipids
What are the features of lipids?
Non-polar
Hydrophobic - therefore insoluble in water
What are the monomers of a triglyceride?
Fatty acids
Glycerol
how many monomers are there in a triglyceride?
Draw a diagram of this
There are 4 in total:
1 glycerol and 3 fatty acids
What is a saturated fatty acid?
A fatty acid where all carbon atoms are bonded to 4 different atoms
What is a Unsaturated fatty acid?
And what are the 2 types of this?
An unsaturated fatty acid is one that contains double carbon bonds
Monounsaturated is where there is only one double bond
Poly unsaturated is where there is more then one double bond
In what reaction are triglycerides formed?
Esterification
What type of reaction is esterification?
Condensation reaction
How are ester bonds formed?
An ester bond forms when a hydroxyl (OH) group on glycerol bonds with the carboxyl (COOH) group of the fatty acid
What are the uses of triglycerides?
Energy storage
Protection
Buoyancy
Insulation
What gives a triglyceride so much energy?
The carbon-hydrogen bonds on the hydrocarbon chain of the fatty acids
What makes a triglyceride able to protect organs?
It is found within adipose tissues
What makes a triglyceride buoyant?
The low density
How do triglycerides insulate cells?
It is found in adipose tissues, which help to prevent heat loss
Also forms a myelin sheath around neurones to increase speed of electrical impulses
What are the monomers of a phospholipid?
Draw a diagram of this
Glycerol
Fatty acids
Phosphate
How many monomers are in a phospholipid?
4 in total:
1 glycerol, 2 fatty acids, 1 phosphate
Phospholipids are amphipathic, what does that mean?
It means that is has both hydrophilic and hydrophobic components
In a phospholipid, what parts are hydrophobic and which are hydrophilic?
The fatty acids are hydrophobic
The phosphate is hydrophilic
What is the use of phospholipids?
They make up cell membranes
What biochemical test is used to test for lipids?
Emulsion test
How is an emulsion test carried out?
1- Add ethanol to the sample to be tested, shake to mix
2- Add the mixture to a test tube of water
3- If lipids are present, a milky emulsion will form (the solution appears ‘cloudy’); the more lipid present, the more obvious the milky colour of the solution
4- If no lipid is present, the solution remains clear
What are lipids dissolved in?
And why?
They are dissolved in ethanol
As they don’t dissolve in water because they are non-polar
What is a protein?
A polymer, and due to size also a macromolecule
What is the monomer of a protein?
Amino acids
What are the 5 parts of an amino acid?
Draw a diagram to show this
Central carbon atom
An amine group (NH2)
A carboxylic acid group (COOH)
A hydrogen atom (H)
R group
What bond joins two amino acids together?
Peptide bond
How is a peptide bond formed?
A peptide bond is formed in a condensation reaction between a hydroxyl (-OH) is lost from the carboxylic group of one amino acid and a hydrogen atom from the amine group of another amino acid
What is a dipeptide?
two amino acids bonded together by a peptide bond
What is a polypeptide?
More than 2 amino acids bonded together by peptide bonds to form a chain
What is a primary protein?
The sequence of amino acids bonded by covalent peptide bonds is the primary structure of a protein
What is a secondary protein?
Two primary proteins held together by hydrogen bonds that form between the NH region of one amino acid and the C=O region of another
What is a tertiary protein?
Change of the secondary structure leads to additional bonds forming between the R groups
What are the two types of secondary protein?
Alpha helix
Beta pleated sheet
What are the bonds that form on a tertiary protein?
Hydrogen bonds between R groups
Disulphide bonds between cysteine amino acids
Ionic bonds between charged R groups
Weak hydrophobic interactions between non-polar R groups
Example of a tertiary protein?
Globular proteins
What is a quaternary protein?
Proteins that have more than one polypeptide chain working together as a functional macromolecule
Example of a quaternary protein?
Haemoglobin
What is the biochemical test for proteins?
Biuret test
Example of a secondary protein?
Fibrous proteins, e.g. collagen and keratin
Example of a primary protein?
Insulin
How is a biuret test performed?
1- A liquid solution of a sample is treated with sodium or potassium hydroxide to make the solution alkaline
2- A few drops of copper (II) sulfate solution (which is blue) is added to the sample
- Biuret ‘reagent’ contains an alkali and copper (II) sulfate (CAN BE USED INSTEAD)
3- If a colour change is observed from blue to lilac/purple, then protein is present.
What is the shape of a globular protein vs a fibrous protein?
Globular proteins are spherical and compact
Fibrous proteins are long strands
What is the amino acid sequence of a globular protein vs a fibrous protein?
Globular proteins have an irregular and wide range of R groups
Fibrous proteins are repetitive with a limited range of R groups
What is the difference in function of a globular proteins vs a fibrous protein?
Globular proteins are physiological meaning that they can be used in metabolic reactions
Fibrous proteins are structural
Examples of globular proteins vs fibrous proteins?
Globular proteins include: haemoglobin, enzymes, insulin, immunoglobin
Fibrous proteins include: collagen, keratin, myosin, actin and fibrin
What is the solubility of globular proteins vs fibrous proteins?
Globular proteins are generally soluble in water
Fibrous proteins are generally insoluble in water
What are enzymes?
Biological catalysts
They are also globular proteins
What is the difference between intracellular enzymes and extracellular enzymes?
Intracellular enzymes are produced and function inside of the cell
Extracellular enzymes are secreted by cells and work outside cells
What is enzyme specificity?
The idea that one enzyme is specific to one substrate due to complimentary shapes.
What is the active site on an enzyme?
The active site of an enzyme is the part of an enzyme that is complimentary to a specific substrate to allow for binding
What are the 2 types of binding between active site and substrate?
Lock and key model
Induced fit model
What is the lock and key model?
The idea that a substrate and active site are exactly complimentary
What is the induced fit model?
The idea that the active site and substrate are not exactly complimentary, and therefore the active site must undergo a conformational change in order to bind to the substrate
What is an enzyme-substrate complex
Where the enzyme is bound to the substrate
What are all the limiting factors on an enzyme?
Temperature
pH
Enzyme concentration
Substrate concentration
Inhibitors
What is the affect of temperature on an enzyme?
Low temperature will slow down the enzymes rate of reaction as it lowers the enzymes energy, leading to less collisions
High temperature lowers rate of reaction as it denatures the active site of the enzyme
What is the affect of pH on an enzyme?
Enzymes active sites are denatured if the pH is not at the enzymes optimal pH
What is the affect of enzyme concentration on an enzyme?
Higher concentration leads to a higher rate of reaction due to more collisions
Lower concentration leads to a lower rate of reaction due to less collisions
What is the affect of substrate concentration on an enzyme?
Higher concentration leads to a higher rate of reaction due to more collisions, however this will only continue until the active sites become saturated where the rate of reaction will plateau
Lower concentration leads to a lower rate of reaction due to less collisions
What is the affect of an inhibitor on an enzyme?
Inhibitors on an enzyme lower the rate of reaction, some inhibitors can even stop the enzyme entirely
What are the two types of enzyme inhibitor?
Competitive
Non-competitive
What is a competitive inhibitor?
How does it work?
An inhibitor that competes with the substrate for the active site
It blocks the active site from being used
What is a non-competitive inhibitor?
How does it work?
An inhibitor that binds at an alternate site
It changes the shape of the active site
