As Biology Biological Molecules

Front 1

What is the definition of a Polymer and Monomer?

Back 1

Polymer: Molecules made up of a large number of monomers joined together

Monomer: The smaller units from which larger molecules are made

Front 2

How are disaccharides and polysaccharides formed?

Back 2

Disaccharides are formed by the condensation of two monosaccharides.

Polysaccharides are formed by the condensation of many glucose of monosaccharide units e.g Starch from Alpha Glucose. Cellulose from Beta.

Front 3

How are Maltose, Sucrose and Lactose formed?

Back 3

Maltose from Condensation of two glucose

Lactose from Condensation of glucose and galactose

Sucrose from Condensation of Glucose and Fructose

Front 4

How can disaccharides be be broken down into monosaccharides?

Back 4

Hydrolysis reaction by boiling with acid.
Or by warming with an Enzyme at optimum temperature.

Front 5

State the purpose of Sodium Ions In living things

Back 5

Co-Transport of glucose and amino acids across cell membranes

Front 6

State the purpose of Iron ions in living things

Back 6

A component of Haemoglobin which transports oxygen

Front 7

State the purpose of Hydrogen ions in living things

Back 7

They are important in determining pH, thus affecting enzyme activity and protein structure

Front 8

State the purpose of Phosphate ions in living things

Back 8

They are important as a structural component in DNA, RNA and ATP

Front 9

Explain ways in which water has an important role in Metabolic Reactions

Back 9

Water is a solvent in which metabolic reactions can occur

Water is a metabolite in Metabolic Reactions such as Hydrolysis and Condensation

Water is required for photosynthesis

Water is a metabolic product of respiration. Particularly important for creatures in dry habitats

Front 10

Explain ways in which water is an important solvent

Back 10

Water can transport dissolved nutrients such as glucose in the blood and sucrose in the phloem of plants

Water can remove excretory products such as urea and ammonia by dissolving them

Water is an important solvent for metabolic reactions to occur in

Front 11

Explain ways in which water is important for Temperature Regulation

Back 11

Water has a Relatively High Specific Heat Capacity.

Takes a lot of energy to heat up 1 gram of water by 1 degree.

This minimises temperature changes in cells due to heat given off by biochemical reactions , keeping them at optimum temp.

Prevents dangerous fluctuations in temperature of aquatic habitats.

Water has a large latent heat of vaporisation.

Provides a cooling effect through sweating as heat energy is absorbed by the water in order to break its bonds and make it evaporate.

Allows animals to maintain a constant body temperature .

Allows plants to cool themselves via transpiration, prevent overheating

Front 12

Offer an explanation for the properties of water in Temperature Control and Support

Back 12

Hydrogen bonds form between water molecules with cohesive forces between molecules which form a cohesive structure.

Water has a High Specific Heat Capacity because a large amount of heat energy can be absorbed by the bonds between molecules before the molecules themselves begin to heat.

Buffers temperature change.

Similarly, water has a Large Latent Heat of Vaporisation because it takes energy to break the hydrogen bonds between molecules and allow the molecules to become gaseous.

Front 13

Describe / Draw the general structure of an Amino Acid

Back 13

Carbon, with an attached Carboxylic Acid (-COOH-), an Amine Group (-NH2), one Hydrogen and a Carbon Containing R group which differs between different amino acids.

Front 14

State the enzymes used in the hydrolysis and condensation of Adenosine Triphosphate (ATP)

Back 14

ATP Hydrolase hydrolises ATP into Adenosine DiPhosphate and a Phosphate, releasing energy.

ATP Synthase resynthesizes ATP from ADP and a Phosphate using energy from photosynthesis and respiration

Front 15

What is the structure of ATP?

Back 15

The nitrogen containing base Adenine bound to a molecule of the pentose suger Ribose and Three Phosphates

Front 16

Besides energy, give another use of ATP

Back 16

The inorganic phosphate released can be used to phosphorylate other compounds, making them more reactive.

e.g Glucose can be phosphorylated to form a more reactive Glucose Phosphate

Front 17

What is DNA made of?

Back 17

The pentose sugar Deoxyribose

A phosphate group

One of the four different nitrogen containing bases (Cytosine, Thymine, Adenine, Guanine)

Front 18

What are the properties of Triglycerides?

How does this relate to their function?

Back 18

• Have high proportion of carbon-hydrogen bonds. Excellent source of Energy. Ideal for storage.
• High ration of hydrogen to oxygen atoms. Release lots of metabolic water. Dry land animals storage!
• Non-Polar. Osmotically inactive and insoluble. Ideal for storage.

Front 19

What are the properties of Phospholipids?

How does this relate to their function?

Back 19

Hydrophobic tails. Hydrophilic head.

Lets them be used in Phospholipid Layers for cell membranes.

Front 20

What can cause the denaturation of proteins?

Back 20

The breaking of hydrogen and ionic bonds is caused by High Temperatures, Extreme pH Changes and Heavy Metals

Front 21

What would be the control for an investigation into the effect of temperature on enzyme activity?

Back 21

Use a thermostatically controlled water bath.

Check regularly to make sure no temperature fluctuations.

Front 22

What would be the control for an investigation into the effect of pH on enzyme activity?

Back 22

Use a buffer. This will resist change in pH

Front 23

What would be the control for an investigation into the effect of Concentrations (of enzymes, substrates or inhibitors) on enzyme activity?

Back 23

Use the same volumes of each solution,

Front 24

Explain the stages of semi-conservative replication of DNA

Back 24

1. The enzyme DNA Helicase unwinds the double helix and breaks the bonds between the two strands.

2. Nucleotides with complimentary bases align next to the exposed bases on the template strand, according to specific complimentary base pairing

3. The enzyme DNA Polymerase joins the new nucleotides with phosphodiester bonds.

4. The two new strands coil up into double helixes after the two strands of DNA join together by hydrogen bonds

Front 25

How is DNA adapted for its function?

Back 25

Sugar Phosphate backbone for Strength

Coiling of DNA makes it compact

Double Helix means 2 strands can be templates, protects base sequence, makes molecule more stable

Large molecule to store all genetic information

Many hydrogen bonds give stability and allow it to be unzipped for replication

Sequence of bases allow genes to code for specific proteins

Complementary base pairing enables accurate and easy replication

Front 26

Outline the Biuret test

Back 26

Add an alkali to the sample such as Sodium Hydroxide

Add Biuret reagent. If it goes from blue to purple protein is present

Front 27

Outline Benedicts Test

Back 27

A sample is mixed with a small amount of Benedict's solution.

This is heated in a water bath.

If a brick red or orange precipitate is seen, it is positive for reducing sugar.

If it stays blue, no reducing sugar.

Front 28

Outline Benedicts Test for a non-reducing sugar (sucrose)

Back 28

Carry out Benedicts Test to confirm a negative result.

Heat another sample with acid to hydolyse it.

Neutralise this sample using an alkali e.g NaOH.

Add benedicts to the hydrolysed sample and heat in water bath.

Look for brick red.

Front 29

What is the difference between Semi Quantitative Benadicts Test and Quantitative Benadicts Test?

Back 29

Semi Quantative looks at the colour or amount of precipitate but is subjective as different people see different things.

Quantitative uses a colorimeter to measure absorbency of known concentrations and then compare these to the unknown using a calibration curve.

Is more accurate as uses numerical data and is objective.

Front 30

When would a Quantitative Benadicts test be done?

Back 30

To compare the concentration of reducing sugar in multiple different solutions.

Front 31

Why is starch suitable as a Storage Molecule?

Back 31

• It is insoluble so Osmotically Inactive. Doesn't draw water into cells.
  
• It is large so cannot cross the cell surface membrane to leave cells
• It has a Helical Shape which makes it compact
• It is branched so that enzymes can act on its branches simultaneously and release alpha glucose more rapidly for respiration

Front 32

Why is Glycogen suitable as a Storage Molecule?

Back 32

• Insoluble and Osmotically Inactive
• Large and insoluble so does not diffuse out of cells
• Compact so lots stored in small space
• More highly branched than starch so can be hydrolysed more rapidly by enzymes as more free ends. Releases more glucose needed for animals.

Front 33

How does Cellulose differ from Glycogen and Starch and how is it suitable for its purpose?

Back 33

It is formed from monomers of Beta Glucose instead of Alpha.

This means it forms straight unbranched chains.

Suitable for its Purpose Because:

• Made of Beta Glucose for form Long Straight Unbranched Chains
• Chains run parallel to other Cellulose Chains and form Hydrogen Bonds
• Hydrogen bonds cause cellulose chains to form Microfibrils which provide strength and allow it to be used in Cell Walls

Front 34

How can proteins be broken down?

Back 34

Hydrolysis by heating with acid

By Enzymes at Optimum Temperature (proteases / peptidases)

Front 35

How does Denaturation of Proteins occur?

Back 35

The Hydrogen and Ionic bonds which cause the protein to be folded into the correct shape break.

This causes the shape of the protein to shape and can cause it to become non-functional.

This can happen due to High Temperature, Extreme pH changes or Heavy Metals (which disrupt disulfide bridges.

Front 36

What are Enzymes and what do they do?

Back 36

They are Biological Catalysts which lower the activation energy of chemical reactions and so increase the rate of reaction.

They do this by forming Enzyme-Substrate complexes and then weakening bonds to allow them to break or react with other compounds.

Front 37

What is the Induced Fit model of Enzyme Action?

Back 37

Enzyme has a unique active site based on tertiary structure which are specific and will only bind to certain substrates to form enzyme substrate complexes

BUT the enzyme active site is not a complementary shape when it is not bound, it is flexible and changes its shape once they bind to become complementary.

Front 38

What is the difference between Competitive Inhibitors and Non-Competitive inhibitors?

Back 38

Competitive have a similar structure to the substrate and compete for attachment to the active site.

Non-Competitive do not have a similar structure but attach to a site on the Enzyme which causes the tertiary structure and shape of the active site to change. This prevents substrate from binding to the active site and forming enzyme-substrate complexes.