Biological Molecules Flashcards

Question

What is the test for starch?

Answer 1

Add iodine/potassium iodide. If solution turns blue/black starch is present

Answer 2

Lipids are biological molecules made up of Caron, oxygen and hydrogen molecules which are only soluble in organic solvents like alcohols. Main types of lipids are triglycerides and phospholipids.

Answer 3

They are lipids made up of one molecule of glycerol and three fatty acids joined together by ester bonds in a condensation reaction. Unsaturated - double C-C bonds - plants Saturated- no double C-C bonds - animal fat

Answer 4

High ratio of energy storing carbon-hydrogen bonds to carbon atoms which make them an excellent energy store. Low mass to energy ratio so they are a good storage molecule. Large and non-polar molecules makes them insoluble, therefore storage doesn’t affect water potential of cells. High ratio of hydrogen-oxygen atoms meaning they release water when oxidised = good source of water for organisms that live in a dry environment.

Answer 5

Where one of the fatty acids in a triglyceride is replaced with a phosphate group. Hydrophilic heads Hydrophobic tails Polar molecule

Answer 6

In aqueous environments being polar means a bilayer can be formed. Their structure allows them to form glycolipids with carbohydrates on the cell surface membrane for cell recognition.

Answer 7

The Emulsion test: - grease free test tube add sample and ethanol - shake thoroughly - add water and shake again - positive result = cloudy-white precipitate is formed (Control - test water and final result should be clear)

Answer 8

Made form Amino Acids (AA), which contain an amino group (NH2), a carboxylic acid group (-COOH) and a variable R group. 20 types of amino acids determined by their R group. They join together with peptide bonds formed in condensation reactions. Dipeptide contains two AAs and a Poly peptide contains 3 or more.

Answer 9

The structure is determined by the order and number of AAs and the bonding and shape of the protein: - Primary structure = initial sequence of amino acids - Secondary structure = EITHER Beta pleated sheet or Alpha helix formed by weak hydrogen bonds caused by the slight positive charge of the hydrogen in the -NH and the slight negative charge in the oxygen in -C=O. - Tertiary structure = the 3D shape caused by the three types of bonds: Disulphide bridges (between sulphur and cysteine, strong and hard to break), Ionic bonds (carboxyl and amino acids, weaker and easily broken by pH), Hydrogen bonds (numerous and easily broken). Globular proteins - compact e.g. enzymes Fibrous proteins - long and can form fibres e.g. keratin

Answer 10

The Biuret test, to test for the peptide bonds: - add sodium hydroxide - add very dilute copper sulphate solution and mix - positive result = purple colour

Answer 11

They increase rate of reaction by lowering activation energy of the reaction it is catalysing. The active site is an area made up of only a few AAs and forms a depression in the enzyme. Enzymes are complementary to the substrate and will form enzyme-substrate complexes - lock and key. Induced fit model - active site changes shape to fit the substrate.

Answer 12

- Temperature = rate of reaction (ROR) increases to the optimum temperature as the kinetic energy of the enzymes increase. Beyond nth optimum temp the enzymes active site changes shape due to the tertiary structure changing and the enzyme denatures. - pH = same as temp - Enzyme concentration = ROR increase as enzyme concentration increases up to a certain point where there are more enzymes than substrates, so substrate becomes limiting factor. - Substrate concentration = ROR increases as substrate concentration increase until enzymes become the limiting factor. - Competitive inhibitors = ROR decreases as concentration of competitive inhibitors increases as active sites are blocked. - Non-Competitive inhibitors = ROR decreases as the concentration of non-competitive inhibitors increases as the active site is altered.

Answer 13

DNA nucleotides consist of deoxyribose sugar, a phosphate group and one nitrogen containing base A, T, C, G. Carries genetic information, it is also a polymer of nucleotides. Nucleotides join together by phosphodiester bonds formed in condensation reactions. DNA is a double helix composed of two polynucleotides joined together by hydrogen bonds. Phosphodiester backbone Three hydrogen bonds between G and C and two between A and T.

Answer 14

RNA nucleotides consist of a ribose sugar, a phosphate group and one of the nitrogen containing bases A, U, C, G. RNA transfers the info from DNA to ribosomes for protein synthesis. RNA is a relatively short polynucleotide chain.

Answer 15

Semi-conservative replication of DNA ensures genetic continuity between generations of the cells meaning that genetic information can be passed from one to the next. The steps : 1. DNA helicase causes the strands to unzip, breaking the hydrogen bonds between the bases. 2. One strand is used as the template and there is complimentary base paring occurs between the strand and free nucleotides. 3. DNA polymerase joins them together by forming phosphodiester bonds, resulting in two identical strands of DNA.

Answer 16

Adenosine triphosphate consists of ribose, adenine and three phosphate groups. - Energy is released when ATP is hydrolysed to from ADP and a phosphate molecule. This process is catalyse by ATP hydrolyse - Inorganic phosphate can be used to phosphorylate other compounds. - Condensation of ADP and inorganic phosphate is catalysed by ATP synthase produces ATP during photosynthesis and respiration.

Answer 17

- It is an immediate source of energy. - ATP isn’t stored and can be reformed from ADP in seconds. - Metabolic processes, movement, active transport, secretion and activation of molecules.

Answer 18

It is a polar molecule, a metabolite, a solvent, has a high specific heat capacity, large latent heat of vaporisation and a strong cohesive.

Answer 19

- Polar Molecule = due to uneven distribution of charge, allows many water molecules to stick together. - Metabolite = in condensation and hydrolysis. - Solvent = things can dissolve in it. - High SHC = minimises temp fluctuations so it acts as a buffer. - Large LHV provides a cooling effect. - Strong cohesion = supports columns of water so the surface tension at the water-air boundary is high.

Answer 20

They occur in solution in the cytoplasm and body fluid of organisms.

Answer 21

Hydrogen ions = determine the pH (the higher the concentration of hydrogen ions the lower the pH. Iron ions = component of haemoglobin. Sodium ions = involved in co-transport of glucose and amino acids. Phosphate ions = component of DNA and ATP.