2.1.2 Biological Molecules Flashcards
From original set - Not Checked
Why do cells need water?
Makes up 80% of the cell content:
A reagent of hydrolysis
A solvent
For Transport
For temperature Control
Providing a habitat
What is the structure of water?
One Oxygen - two hydrogens
Oxygen and hydrogen share a negitive electron from hydrogen. The pull of electrons is slightly greater towards the oxygen atom.
Hydrogen has a slightly positive charge - forming a polar molecule
How do water molecules bond together?
slightly negitive oxygen attracts the slightly positive hydrogen from another molecule - forming a hydrogen bond
What properties does water have?
Polar solvent
High specific heat capacity
surface tension
incomprecability
less dence when solid
Why is water a solvent?
As water is polar lots of substances can dissolve in water
Why is water important as a solvent?
It is a usefull transport medium. Water has the ability to ionise molecules.
Polar molecules disolve in water.
Non-polar molecules do not.
What does a high specific heat capacity mean?
Lots of energy is needed to increase the temperature of water.
Lots of energy needs to be lost in order to reduce the temperature of the water.
What is the specific heat capacity of water?
4.2j/g/c
Why is the SHC of water important?
Acts as a buffer against rapid temperature change.
-it absorbs sun energy during the day and retains it at night.
-it acts as a habitat as the constant temperatures of the water allow organisms to survive
What is cohesion and surface tension?
Water molecules ‘sticking together’ due to hydrogen bonds.
Water molecules also stick to ther molecules - cohesion
the strong inwards cohesion force creates surface tension.
What advantage does cohesion and surface tension of water bring?
allows the surface of water to act as a habitat for small organisms - like pond skimmers
What is the importance of the dencity of water?
Ice is less dence than liquid water so floats on it.
This allows it to act as a habitat for animals to live on top of. It also insulates the water below to provide a habitat for aquatic creatures in sub-zero temperatures
Why is ice less dence than water?
Particals have less kinnetic energy at lower temperatures so move slower. meaning more hydrogen bonds form and due to a long bond length spreading the molecules out - decreacing the density
What is important about waters latent heat of vapourisation?
Water requires a lot of energy to evaporate.
This allows it to be used as a cooling agent for animals - sweating and panting - and plants - transpiration.
lots of energy is transfered to the water from the organism to cause it to evaporate - cooling it down.
Why is water important for metabilic reactions?
Water is a reactant in many reactions.
e.g. hydrollysis and photosynthesis.
It is also a product in many reactions.
e.g. condensation reactions and aerobic respiration
What is the general formula for carbohydrates?
CnH2nOn
What are the 3 main categories of carbohydrates?
Monosaccharides
Disaccharides
Polysaccharides
What are examples of monosaccarides?
Glucose - Fructose - Galactose
What are examples of Disaccarides?
Maltose, sucrose, lactose, cellobiose
What monosaccharides make up maltose?
Two molecules of a-glucose
What monosaccharides make up sucrose?
a-glucose and Fructose
What monosaccharides make up lactose?
b-galactose and a-glucose
What monosaccharides make up cellobiose?
b-glucose and b-glucose
What type of reaction joins monosaccarides?
Condensation (using water)