Structure and functions of triglycerides:
The high ratio of carbon-hydrogen bonds to carbon atoms means they are a good [blank_start]source of energy[blank_end].
The low mass to energy ratio means they are good [blank_start]storage molecules[blank_end].
The large and insoluble molecules are [blank_start]good storage molecules[blank_end] and don't affect the [blank_start]water potential[blank_end] of the cells.
The high ration of hydrogen to oxygen atoms mean they are a good [blank_start]source of water[blank_end].
Structure and function of phospholipids:
The hydrophilic heads and hydrophobic tails form a [blank_start]bilayer[blank_end] in [blank_start]aqueous[blank_end] environments.
The [blank_start]hydrophilic[blank_end] heads help hold the surface of the cell-surface membrane.
They can form [blank_start]glycolipids[blank_end] with carbohydrates which are important for cell recognition.
Test for lipids:
1. Add 2cm^3 of your sample and 5cm^3 of [blank_start]ethanol[blank_end] to a test tube
2. Shake the tube to dissolve any [blank_start]lipids[blank_end] in the sample
3. Add 5cm^3 of [blank_start]water[blank_end] and shake gently
4. If lipids are present then the solution will turn [blank_start]cloudy-white[blank_end]
Amino acids are the basic [blank_start]monomer[blank_end] units for proteins and the polymer is called a [blank_start]polypeptide[blank_end].
The process of joining many amino acid monomers together is called polymerisation.
The primary structure of a protein is formed by the specific sequence of [blank_start]amino acids[blank_end]. The primary structure determines its [blank_start]shape[blank_end] and therefore function so changing just a single amino acid in the chain could potentially change the way the whole protein works.
The [blank_start]secondary[blank_end] structure of a protein is the long polypeptide chain being twisted into a [blank_start]3D[blank_end] shape. This is caused by the [blank_start]hydrogen[blank_end] bonds that form between the H from the [blank_start]positive[blank_end] NH group of one and the O of another's [blank_start]negative[blank_end] C=O.
The tertiary structure of the protein is formed by the secondary structure being further coiled and twisted into a more [blank_start]complex[blank_end] and recognisable shape. This shape is maintained by three types of bonds: hydrogen bonds, [blank_start]ionic[blank_end] bonds and disulfide bridges. The [blank_start]hydrogen[blank_end] bonds are numerous but easily broken. The ionic bonds are stronger than the hydrogen bonds however they are easily broken by a change in [blank_start]pH[blank_end]. The disulfide bridges are the [blank_start]strongest[blank_end] out of the three.
The [blank_start]quaternary[blank_end] structure is the most complex and consists of many individual polypeptide chain linked in various ways. Some of these molecules have non-protein ([blank_start]prosthetic[blank_end]) groups associated with them e.g. the [blank_start]iron[blank_end] containing haem group in haemoglobin.
What is the test for proteins called?
What are the steps in the test for proteins?
1. Place your sample and an equal volume of sodium hydroxide in a test tube
1. Place your sample and an equal volume of sodium disulphate in a test tube
!. Place your sample and an equal volume of hydrochloric acid in a test tube
2. Add a few drops of high concentration copper sulphate and mix gently
2. Add a few drops of very dilute copper sulphate and mix gently
3. If it goes red there are peptide bonds and therefore proteins present but stays blue in their absence
3. If it goes purple there are peptide bonds and therefore proteins present but stays blue in their absence
3. If it goes green there are peptide bonds and therefore proteins present but stays blue in their absence
Enzymes are globular proteins that act as [blank_start]catalysts[blank_end]. They do this by lowering the [blank_start]activation energy[blank_end] of a reaction by providing an alternative pathway for the reaction without being [blank_start]used up[blank_end] themselves.
The functional region of an enzyme is called the...
The molecule upon which the enzyme acts is called the...
Scientists used to use the [blank_start]lock and key[blank_end] model to explain how enzymes work but this is now out-dated. Instead, we use the [blank_start]induced-fit[blank_end] model. It suggests that the enzyme's active site changes shape when in close proximity to the [blank_start]substrate[blank_end] as a result of the [blank_start]charges[blank_end] in each molecule. The active site [blank_start]moulds[blank_end] itself around the substrate to form an [blank_start]enzyme-substrate complex[blank_end] which distorts bonds in the substrate to lower the [blank_start]activation[blank_end] energy.
lock and key
For an enzyme to work, it must...
Come into contact with the substrate
Be diluted in solution
Have the correct orientation so the active site and substrate collide
Have a complementary active site to the substrate
Be at body temperature (37°C)
The two changes most frequently measured to measure the rate of enzyme-catalysed reactions are...
Dissapearance of substrate
Amount of gas released
Formation of products
Measuring rate of change on a graph involves drawing a tangent to the curve and then working out the change in x divided by the change in y.
Label this graph of the effects of temperature on enzyme activity
[blank_start]Competitive[blank_end] inhibitors interfere with the functioning of an enzyme by binding to the active site and getting in the way of the substrate. [blank_start]Non-competitive[blank_end] inhibitors interfere with the functioning of an enzyme by binding to it in a place other than the active site, changing its shape so the active site is no longer [blank_start]complementary[blank_end] to the substrate.