Biological Molecules Flashcards
Give two properties of lipids
-insoluble in water (non-polar)
-high in energy (rich in C - H bonds)
What is a saturated fatty acid?
a fatty acid that contains the maximum number of hydrogens and no C=C double bonds
How is a saturated fatty acid different from unsaturated?
-only C-C single bonds
-Usually solid at room temp
-higher melting point
-doesn’t contain any kinks
What is the structure of a triglyceride?
a glycerol molecule joined to three fatty acid molecules. join by a condensation reaction and form an ester bond (esterification)
Give 5 functions of triglycerides
-Energy source
-Energy store
-Insulation
-Buoyancy
-Protection
How do you test for a lipid?
- Mix sample thouroughly with an eqaul volume of ethanol
- Filter
- pour filtrate into water
- will form a cloudy emulsion if lipids are present
What is the structure of a phospholipid?
a glycerol molecule joined to two fatty acid molecules and one phosphate group.
What does amphipathic mean?
molecules that contain both hydrophobic and hydrophilic parts
What is the function of cholesterol?
Cholesterol regulates and maintains the fluidity of the membrane - at high temperatures it raises the meltiing point and at low temperatures it intercalates between phospholipids and prevents clustering (makes it more fluid)
What is the structure of proteins?
A chain of amino acids joined by peptide bonds
Give 7 functions of proteins
- Essential component of cell membranes
- all enzymes are proteins
- Antibodies
- Haemaglobin
- collagin
- keratin
- form structural components
What is the structure of an amino acid?
What protein has the simplest R group?
glycine (H)
What is a buffer?
A substance that helps to reduce large changes in pH
What is the primary structure of a protein?
A sequence of amino acids held together by peptide bonds
What is the secondary structure of a protein?
The folding of an amino acid chain into a beta pleated sheet or an alpha helix due to hydrogen bonding between amino acids.
What is the tertiary structure of a protein?
The folding of the secondary structure to form a specific 3D shape, 4 different types of bond hold this structure together - ionic bonds, disulphide bonds, hydrogen bonds, hydrophilic / hydrophobic interactions.
What is the quaternary structure of a protein?
A protein which is made up of two or more polypeptide chains, held together by ionic bonds, disulphide bonds, hydrogen bonds, hydrophilic / hydrophobic interactions.
Give three examples of fibrous proteins
-Collagen
-Elastin
-Keratin
Give two examples of globular proteins
-Enzymes
-Haemoglobin
What is a monomer?
A small molecule which binds to other identical molecules to form a polymer
What is a condensation reaction?
This occurs when molecules are joined together with the removal of water and a covalent bond is formed.
What is a hydrolysis reaction?
Splitting a polymer apart with the addition of water so a covalent bond is broken.
What is a polar molecule?
A molecule that has an uneven charge distribution, it has partial positive and negative charges which do not cancel out
What are the 7 properties of water?
- Liquid at room temperature
- Ice is less dense than water
- Solvent for polar molecules
- water pushes non-polar molecules together (helps formation of PLbilayer)
- Cohesion and surface tension
- High specific heat capacity
- High latent heat of vaporisation
What are the 4 functions of carbohydrates?
- Energy source
- Energy store
- structural role (e.g cellulose)
- part of larger molecules
what are three properties of monosaccharides?
-Soluble in water
-Insoluble in non-polar solvents
-Taste sweet
What is a disaccharide?
Formed from two monosaccharides in a condensation reaction and a glyosidic bond is formed
What are three properties of disaccharides?
-Taste sweet
-Soluble
-Some are reducing and some are non-reducing
Which disaccharide is non-reducing?
Sucrose
Which disaccharide is reducing?
-Maltose
-Lactose
-Cellubiose
What enzyme is needed for hydrolysis of a disaccharide?
Maltase
What bond is formed in the condensation reaction of two alpha glucose molecules?
A 1,4 glyosidic bond
Are all monosaccharides reducing or non-reducing?
They are all reducing
How do you test for a reducing sugar?
Benedict’s Test-
-Add Benedict’s solution and heat in a water bath at 80*C for 3 mins
-If a reducing sugar is present a green / yellow/ orange/ brick red precipitate will form
-If a reducing sugar is not present the solution will remain blue
How do you test for a non-reducing sugar?
-Carry out normal reducing sugar test
-Boil the solution with 1cm^3 of hydrochloric acid and anti-bumping granules
-Cool the solution and add sodium hydrogen carbonate powder to neutralise
-Carry out reducing sugar test again
What is the equation for finding the volume of stock solution required in a proportional dilution?
Volume of stock solution required = (total volume wanted / conc. of stock solution) X conc. wanted
What is starch made up of?
Amylose and Amylopectin
How do you test for starch?
-Add iodine solution
-Will turn from orangey brown to blue black if starch is present
What is cellulose made up of?
Beta glucose molecules - every other beta glucose molecule is rotated by 180*, held together by glyosidic bonds
