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?
A protein is held together by hydrogen bonds that form between the -NH region of one amino acid and the -C=O region of another
What are the two types of secondary protein?
Alpha helix
Beta pleated sheet
What is a tertiary protein?
Additional bonds are formed between the R groups of a secondary protein
What bonds are formed between the R groups on a tertiary proteins
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
What is a quaternary protein?
A protein with more than one polypeptide chain working together as a functional macromolecule, for example, haemoglobin
