Biological Molecules (Water + Carbohydrates) Flashcards
How are atoms in a molecule of water linked?
Via covalent bonds
Hydrogen bonds between molecules of water are formed between…
Electronegative oxygen & electropositive hydrogen
Name 6 properties of water
Metabolite
Solvent
Molecules of water form hydrogen bonds between each other
High specific heat capacity
High latent heat of vaporisation
Ice is less dense than water
How is water being a metabolite useful for living organisms?
It allows water molecules to be used in hydrolysis reactions and made in condensation reactions
How is water being a solvent useful for living organisms?
It allows water molecules to dissolve solutes for reactions
How is water being able to form hydrogen bonds between each other useful for living organisms?
It allows water molecules to be cohesive which is essential for transpiration
How is water having a high specific heat capacity useful for living organisms?
It allows the temperature of water to remain relatively stable which is useful for aquatic organisms who have habitats in the water
How is water having a high latent heat of vaporisation useful for living organisms?
It allows organisms to cool themselves via sweat
How is ice being denser than water useful for living organisms?
Organisms that have their habitats in the water under the ice are insulated
What are monomers?
Monomers are individual molecules that can make up a polymer
What are polymers?
Polymers are long chains of many individual monomers that have been bonded together in a repeating pattern
How do condensation reactions occur?
When two molecules combine to form a more complex molecule with the removal of water
How do hydrolysis reactions occur?
When larger molecules are broken down into smaller molecules with the addition of water
What joins monomers together?
Covalent bonds
What joins polar molecules together, and what does this do?
Hydrogen bonds, this stablises larger structures
What are monosaccharides?
The simplest carbohydrates
Give 2 properties of monosaccharides
Soluble
+
Full of carbon-hydrogen bonds for energy storage
How are monosaccharides structured?
As rings or as straight chains of carbon atoms
Monosaccharides
In solution, what do tri/tetr-oses exist as?
Chains
In solution, what do pent/hex-oses exist as?
Rings
What are isomers, and can you give an example of one?
Molecules with the same formula but different atom arrangements, such as glucose
How are disaccharides formed?
When two monosaccharides react in a condensation reaction, forming a glycosidic bond
Give 4 common disaccharides, along with how they are formed
α Glucose + α Glucose → Maltose
α Glucose + β Galactose → Lactose
α Glucose + Fructose → Sucrose
β Glucose + β Glucose → Cellobiose
How is the presence of reducing and non-reducing sugars detected?
What is the experiment that uses [answer] called?
By using Benedict’s solution
The experiment which uses Benedict’s solution = Benedict’s test
What is the colour change in a Benedict’s test?
Give the colour change in order
Blue → Green/Yellow/Orange-red
Why can’t non-reducing sugars reduce Benedict’s?
The glycosidic bond is not hydrolysed
What is the test for a non-reducing sugar?
1) Boil with hydrochloric acid to break into monosaccharides (reducing sugars)
2) Cool and add sodium hydrogencarbonate to neutralise
3) Test with Benedict’s and look for the same colour changes as before
What is used to quantitatively measure the concentration of reducing sugars?
Colorimetry
How is colorimetry carried out?
1) Centrifuge separates precipitate and unreacted Benedict’s
2) Supernatant placed in a cuvette and into a colorimeter with red filter
3) Transmission of light measured using zero reading with water
What is the formula of glucose?
C₆H₁₂O₆
What are the only elements that are present in carbohydrates?
Carbon
Hydrogen
Oxygen
Give 3 examples of monosaccharides
Glucose
Galactose
Fructose
Why are monosaccharides soluble in water?
Monosaccharides have a large number of OH groups (hydroxyl groups)
Hydroxyl groups can form hydrogen bonds with water molecules
Therefore, monosaccharides are hydrophillic (soluble in water)
