Biological molecules

What is covalent bonding?

In hydrogen bonding, the individual bonds are very strong.

The sub-unit of a polysaccharide is a [blank_start]monosaccharide[blank_end]. Two of these together form a disaccharide.

Formation of polypeptides and polysaccharides are ____________ reactions.

A molar solution is a solution that contains [blank_start]1 mol of solute in a litre of solution[blank_end]

[blank_start]Monomers[blank_end] join together to make [blank_start]polymers[blank_end].

Monosaccharides are...

The test for reducing sugars involves adding hydrochloric acid

A reducing sugar is a sugar that can reduce another substance by [blank_start]donating its electrons[blank_end]

To test for reducing and non-reducing sugars we use...

What are the results of the Benedict's test for reducing sugars?

Glucose plus [blank_start]glucose[blank_end] forms maltose.

Glucose plus [blank_start]fructose[blank_end] forms sucrose.

Glucose plus [blank_start]galactose[blank_end] forms lactose.

What is this molecule?

What is this molecule?

How does the Benedict's test for non-reducing sugars differ to that of reducing sugars? (tick all appropriate)

Polysaccharides are insoluble

The test for starch uses [blank_start]iodine[blank_end]. If starch is present it will turn from [blank_start]orange[blank_end] to [blank_start]black[blank_end].

Starch is made of alpha glucose.

Tick the correct answers.

Lipids are insoluble in [blank_start]water[blank_end] but soluble in [blank_start]organic solvents[blank_end]

What are some roles of lipids?

Phospholipids...

What is this molecule?

The fatty acids in triglycerides are unsaturated.

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].

What is this molecule?

Phospholipids have...

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].

Amino acids provide indirect evidence for...

Label this amino acid structure

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?

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.

For an enzyme to work, it must...

The two changes most frequently measured to measure the rate of enzyme-catalysed reactions are...

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

Label this graph of the effects of pH on enzyme activity

Label this graph of the effects of enzyme concentration on enzyme activity

Label this graph of the effects of substrate concentration 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.

What is this?

What is this?