C3- Biological molecules Flashcards
What is hydrophilic?
A molecule which is attracted to water.
What is hydrophobic
A molecule that repels water.
Why is water a polar molecule
An unequal distribution of charge between the covalent bond. Electrons have stronger forces of attraction tot h oxygen atom.
What is a dipolar molecule
A molecule with 2 charged regions
What holds water molecules together
hydrogen bonds
6 properties of water
- Cohesion
- Adhesion
- solvent
- High surface tension
- ice is less dense than water
- transparent
What is water cohesion
How water molecules are attracted to other water molecules by hydrogen bonds, which allows water to be pulled as one continuous column.
What is water adhesion
Water molecules stick to the sides of walls of xylem due to forces of attraction, this aids the transpiration stream
How does water act as a solvent
Water dissociates ions and causes the ions to move to the either of the polar ends of the water molecule
then surrounds ions in solution
Is a soluble substance hydrophilic or hydrophobic
hydrophilic
Why do metabolic reactions take place in solvents
Substances dissolve in water and are free to move, this increases the chances of collisions and therefore reactions
Thermal properties of water
High latent heat of vaporisation, high heat capacity
Why does water have high heat capacity
Hydrogen bonding. It will absorb or loose a large amount of energy before its temperature changes. Temperature ‘buffer’
Why is waters density important
Ice floats, provides habitat and insulation
Why is waters constant temperature important
Maintains enzyme function, due to its narrow range of temperatures for optimum
Uses of waters high latent heat of vaporisation (2)
Sweating. Cooling effect as water evaporates from skin as energy is used up
Same effect but for transpiration
Water metabolite reactions (3)
Hydrolysis reactions- Large Molecules are broken down into smaller ones using water
Condensation reactions- water is produced when smaller molecules join together
Photosynthesis
Why is the fact that water is a solvent useful
Most biological reactions take place in a solution
Dissolved substances can be transported around the body
Hydroxyl Group
OH
Polar functional group
-> when added to a molecule it helps it mix with water
3 functions of carbohydrates
1- Energy source
-> Sugars
2- Energy store
-> Glycogen and starch
3- Structural
-> Cellulose, Chitin
Alpha glucose Vs Beta Glucose
Both are hexose monosaccharides
C1 OH and H Group are swapped around, OH down on alpha
What bond joins a disaccharide of alpha glucose
1,4 Glycocidic bond
Pointed downwards as OH groups were down`
Isomer
Same molecular formula but a different structural formula
E.g Alpha vs beta Glucose
Ribose Vs Deoxyribose
Both pentose Monosaccharides
-> 5C
C2OH Group on ribose looses oxygen on Deoxyribose