2.1 - Molecules to metabolism

Question 1

Molecular biology

Answer 1

• Molecules are very important to life some include: nucleic acids and proteins
• Nucleic acids comprise DNA and RNA (used to make genes)
• Proteins carry out many tasks one being enzymes controlling chemical reactions of the cell
• explains living processes in terms of chemical substances involved

Question 2

Carbon compounds

Answer 2

• Carbon is very diverse and allows for many chemical compositions and activities in their cell
• Carbon atoms from a covalent bond with two other atoms
• A covalent bond is formed when two adjacent atoms share a pair of electrons (strongest type of bond between atoms)
• Each carbon can form up to four covalent bonds (can bind to other carbons) (bonds can create rings or chains): Fatty acids contain chains of up to 20 carbon atoms
• Bonds can also be made with elements such as: hydrogen, oxygen, nitrogen and phosphorus
• Carbon atoms can bond to just one other element or more than one other element, the four bonds can be all single or two single and one double bond (covalent)

Question 3

Classifying carbon compounds

Answer 3

• Carbon compounds include carbohydrates, lipids, proteins and nucleic acids
• Carbohydrates: composed of carbon, hydrogen and oxygen in a ratio of 1:2:1
• Lipids: broad class of molecules, water insoluble, e.g. steroids, waxes, fatty acids, and triglycerides.
• Triglycerides are fats if solid and oil if liquid
• Proteins: composed of one or more chains of amino acids, all amino acids in these chains contain; carbon, hydrogen, oxygen and nitrogen. Two out of 20 amino acids contain sulphur
• Nucleic acids: chains of nucleotides, contain; carbon, oxygen, hydrogen, nitrogen and phosphorous. Two types of nucleic acid: RNA + DNA

Question 4

Metabolism

Answer 4

• All enzyme catalysed reactions in a cell / organism

Question 5

Anabolism

Answer 5

• Synthesis of complex molecules from simpler molecules including formation of macromolecules from monomers by condensation reactions
• Reactions that build up larger molecules from smaller ones
• Requires ATP
• Anabolism process: protein synthesis using ribosomes, DNA synthesis during replication, photosynthesis including production of glucose from carbon dioxide and water, synthesis of complex carbohydrates including starch + cellulose + glycogen

Question 6

Catabolism

Answer 6

• Breakdown of complex molecules intro simpler molecules including hydrolysis of macromolecules into monomers
• Sometimes produces ATP
• Larger molecules broken down into smaller ones
• Catabolism processes: digestion of food in the mouth + stomach and small intestine, cell respiration in which glucose lipids are oxidized to carbon dioxide and water, digestion of complex carbon compounds in dead organic matter by decomposers

Question 7

What is life based on?

Answer 7

life is based on carbon compounds including carbohydrates, lipids, proteins, and nucleic acid

Question 8

Synthesis of urea

- Urea as an EXAMPLE of a compound that is produced by living organisms but can also be artificially synthesised

Answer 8

• Urea is a nitrogen-containing compound with a relatively simple molecular structure
• It is a component of urine, where is was discovered
• It is produced when there is an excess of amino acids in the body, as a means of excreting the nitrogen
• A cycle of reactions is used to produce it
• This occurs in the liver
• Urea is then transported by the blood stream to the kidneys where it is filtered out and passes out of the body in the urine
• -> Urea can also be synthesised artificially
• ammonia + carbon dioxide –> ammonium carbonate —–> urea + water
• 100 million tonnes produced annually for nitrogen fertiliser on crops