Biological Molecules Flashcards
Explain the polarity of water.
The shared hydrogen and oxygen electrons are pulled towards the oxygen atom. Hydrogen is left with a slight positive charge and oxygen has a slight negative charge. Making it a polar molecule.
What are the key functions of water?
Reactant is important chemical reactions
Helps transport substances - good solvent and cohesive
Temperature control - high specific heat capacity and high latent heat of evaporation
Good habitat because it has a high specific heat capacity, less dense when it freezes.
Explain why hydrogen bonding occurs in water.
Hydrogen bonds occur between the slightly positively charged hydrogen atom and slight negatively charged atom in another molecule. This happens in water because hydrogen is slightly positive and oxygen is slightly negative - causing an attraction.
Why does water have a high specific heat capacity and why does this help organisms?
A lot of energy is required to break of the bonds between the molecules, there is less energy left over to raise the temperature of the water. This is useful for temperature stability.
Why does water have a high latent heat of evaporation and why is this useful?
A lot of energy is required to break the bonds between water, so a lot of energy is needed when water evaporates. Changing state from liquid to a gas requires a lot of energy. Therefore giving it a high latent heat of evaporation. Great for cooling things as it takes a lot of heat away.
Why is water so cohesive and why is this useful?
They are very cohesive because water molecules are so polar. This makes them great for transporting substances.
Why does water have a lower density when solid and why is this useful?
Water molecules are held further apart when they are solid as the hydrogen bonds elongate. Making it less dense. This forms an insulating layer as ice floats to the top. So organisms below don’t freeze.
Why is water a good solvent and why is this useful?
ionic compounds are most important for biology. Water is slightly positively charged and slightly negatively charged. Ions will surround why water molecules. Therefore dissolves. This is good for transporting substances in blood, xylem, phloem etc…
Proteins are made up of…
Polypeptide chains
Two amino acids form…
Dipeptide
Two or more amino acids form…
Polypeptide chains
Name the different parts of an amino acids
R variable group, carboxyl group and amino group.
Peptide bonds are formed by which reaction?
Condensation reaction.
Peptide bonds are broken by…
Hydrolysis reactions (addition of water)
What is the primary structure of a protein?
It is the sequence of amino acids that are determined by the gene that they are coded for by.
What is the secondary structure?
Hydrogen bonds form between the -NH and -CO groups between chains of amino acids. This makes them coil and fold into alpha helices and beta pleated sheets.
What is the tertiary structure?
It is determined by many different bonds related to the r groups on amino acids in polypeptide chains.
Ionic interactions - weak attractions between negatively charged r groups and positively charged r groups on different parts of the molecule.
Disulphide bonds - whenever two molecules of cysteine come close the sulphur atoms in their r groups form Disulphide bonds. Or other sulphur containing r groups. They are covalent bonds.
Hydrophobic and hydrophilic interactions - when hydrophobic r groups and close together they clump together and hydrophilic r groups and pushed onto the outside. Affecting how the protein folds.
Hydrogen bonds - weak bonds between slight positive charge of a hydrogen atom in one r group and slightly negative charged atoms in other r groups on polypeptide chains.
Explain 3 difference between globular and fibrous proteins.
Globular proteins role to form balls, where as fibrous form fibres. Globular are soluble in water where as fibrous aren’t. Globular form metabolic functions where as fibrous have structural roles.
