Biochemistry 2.1-2.4 Flashcards
1
Q
What is the difference between covalent and ionic bonds?
A
- covalent share electrons (stable)
- ionic bonds easier to separate
- dissociation
- electrons move
2
Q
Why is water bipolar?
A
- oxygen negative
- hydrogen positive
- polarity
3
Q
What are hydrogen bonds?
A
- intermolecular force
- dipole-dipole force
- strongest
- between water molecules
- or bases of DNA
4
Q
What are properties of water?
A
- cohesion
- water holds it shape (H-bonds)
- surface tension
- water “membrane” withstands pressure from air
- adhesion
- water reacts with polar substances (also solid)
- capillary action
- water hold together and sticks to glass
- forces pull water upwards
- thermal
- water holds heat
- high boiling point (H-bonds)
- solvent
- for polar and ionic substances
- hydration shells
5
Q
Why is water more dense than ice?
A
- in liquid state molecules are densely packed
- in ice water molecules are arranged in crystal lattice
- more space between them
- highest density at 4ºC
- normally substances in liquid state have more space
- hexagonal structure maximises the amount of hydrogen bonds between molecules
- water reservoirs freeze at the top
- organisms live underneath
- isolates water from further freezing
6
Q
Boiling point of water vs methane
A
- hydrogen bonds are stronger and don’t allow for movement
- b.p. of water higher
- more energy to break H bonds
7
Q
What is specific heat capacity and heat of vaporisation?
A
- specific heat capacity
- energy needed to raise temp of 1g by 1ºC
- conductivity regulates temperature of living things
- heat of vaporisation
- energy needed for 1g to change from liquid to gas
- no dehydration
8
Q
Water as a coolant
A
- water evaporation needs a lot of energy
- sweat cools down body
9
Q
Why are biological membranes wet?
A
- alveoli, villi and capillaries
- substances dissolve quickly
- prevent collapsing
10
Q
Benefits of living in water?
A
- high density of water
- swimming and floating
- ice on top, underneath not frozen
- swimming and floating
- transparent
- photosynthesis
11
Q
Why is carbon necessary for living things?
A
> 4 covalent bonds
complex molecules
gives and receives e-
12
Q
How are polymers formed?
A
- few molecules combined
- large molecule
- releasing small ones
- ex.: water - dehydration reaction
13
Q
What is hydrolysis?
A
- hydrolysis → opposite of dehydration
- polymer split into monomers + H2O
14
Q
Anabolism vs catabolism
A
- anabolism
- formation of molecules from monomers
- catabolism
- breakdown of complex molecules into monomers
15
Q
How are carbohydrates, proteins and triglycerides synthesised?
A
- carbohydrate
- monosaccharides → disaccharides → polysaccharides
- proteins
- amino acids → dipeptides → polypeptides
- triglycerides
- 3 fatty acids + glycerol → triglyceride