biological molecules. Flashcards
Define polymers.
Large, complex molecules composed of long chains of monomers.
Define monomers.
Small, basic molecular units.
Examples of monomers.
Glucose, ribose.
Examples of polymers.
Starch, glycogen, cellulose.
What happens during condensation?
- New covalent bond is formed.
- H2O is removed.
What happens during hydrolysis?
- Covalent bond is broken.
- H2O is added.
Functions of water?
- Makes up 80% of cell.
- Reactant in loads of important chemical reactions, e.g. Hydrolysis.
- Solvent.
- Transports substances, e.g. glucose, oxygen.
- Temperature control: High specific heat capacity + high latent heat of evaporation.
- Habitat: Less dense when freezes so many organisms can survive and reproduce.
Why is water polar?
Shared electrons in O-H bond are pulled towards the oxygen atom. Hydrogen is left with a slightly positive charge and oxygen left with slightly negative charge.
Why does water have hydrogen bonding?
Negative oxygen attracts positive hydrogen atoms of other water molecules.
Why does water have a high specific heat capacity?
Hydrogen bonds between molecules can absorb a lot of energy. Takes a lot of heat energy to raise temperature.
Why does water having a high specific heat capacity help living organisms?
Good habitat: Doesn’t experience rapid temperature change. Temperature underwater is more stable than on land.
Why does water have a high latent heat of evaporation?
Lots of energy needed to break hydrogen bonds. Lots of energy used when water evaporates.
Why does water having a high latent heat of evaporation help living organisms?
Good for cooling, e.g. Mammals sweat.
Why is water very cohesive?
Polar.
How does water being very cohesive help living organisms?
Helps water to flow, making it great for transporting substances. Helps water be transported up plant stems in the transpiration stream.
Why does water have a lower density when solid?
Water molecules held further apart in ice than liquid because each water molecule forms 4 hydrogen bonds to other water molecules, making a lattice shape.
How does water having a lower density when solid help living organisms?
Ice forms insulating layer on top of water in cold temperatures so the water below doesn’t freeze. Underwater organisms don’t freeze and can move and circulate.
Why is water a good solvent?
Ionic. Positive end of water molecule is attracted to negative ion. Negative end of water molecule is attracted to positive ion. Ions will get surrounded by water molecules and dissolve.
How does water being a good solvent help living organisms?
Important ions can dissolve in the water in blood and be transported, e.g. in humans.
