1. Biological molecules: Biochemicals and bonds
- Created by: Lois
- Created on: 04-04-13 14:55
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- Biochemicals & bonds
- Carbon chains & rings
- Because carbon atoms have 4 electrons in their outer orbitals, they can gain stability by sharing the 4 electrons with other atoms
- The sharing of electrons forms a strong bond between the atoms (covalent bond) and the bonded atoms are called a moelcule
- Carbon is able to make 4 covalent bonds, which can be between other carbon atoms or other elements
- Carbon can form a vast variety of molecules by bonding with other atoms and by forming chains or rings of carbon atoms with other atoms bonded to the chain
- Because carbon atoms have 4 electrons in their outer orbitals, they can gain stability by sharing the 4 electrons with other atoms
- Double bonds can occur
- Carbon can form 2 bonds with another atom, key examples in biology include c=c double bonds in hydrocarbon chains
- and c=o double bonds found in many molecules, including organic acids
- Carbon can form 2 bonds with another atom, key examples in biology include c=c double bonds in hydrocarbon chains
- Monomers & polymers
- Biological molecules are grouped according to their chemical properties
- The most important groups are the carbohydrates, proteins, nucleic acids and lipids
- in the first 3 types large molecules are made by bonding together similar smaller molecules
- The term monomer refers to a single, small molecule, many of which can be joined together to form a polymer
- Although they are made of smaller molecules bonded together, lipids are not polymers because the smaller molecules are very different from each other
- Condensation & hydrolysis
- The chemical reaction that links biological monomers together is called a condensation reaction
- In making a polymer, the same reaction is repeated many times in order to link many monomers together to form a polymer
- they also link the different subunits together in lipid molecules
- In making a polymer, the same reaction is repeated many times in order to link many monomers together to form a polymer
- In condensation reactions: a water molecule is released, a new covalent bond is formed and a larger molecule is formed by the bonding together of smaller molecules
- The chemical reaction that splits larger molecules to monomers is called a hydrolysis reaction, this is the reverse of a condensation reaction
- In all hydrolysis reactions: a water molecules is used, a covalent bond is broken and smaller molecules are formed by the splitting of a larger molecule
- The chemical reaction that links biological monomers together is called a condensation reaction
- Hydrogen bonds
- Polymers can be very large molecules, they often have specific functions that rely on their shape
- Hydrogen bonds form when a slightly -ve charged part of a molecule comes close to a slightly +ve charged hydrogen atom in the same (or another) molecule
- This is most easily seen in water
- Hydrogen bonds are not strong bonds, they are often described as 'interaction'
- However, in some polymers many thousands of hydrogen bonds can form and this helps to stabilise the structure of the molecule
- Hydrogen bonds are not strong bonds, they are often described as 'interaction'
- This is most easily seen in water
- Carbon chains & rings
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