biological molecules Flashcards
What are the 4 main biological molecules and which elements are they made from?
carbohydrates - carbon, hydrogen oxygen
proteins - carbon hydrogen, oxygen, nitrogen, sulfur
lipids - carbon, hydrogen, oxygen
nucleic acids - carbon, hydrogen, oxygen, phosphorous , nitrogen
which monosaccarides join through a condensation reaction to form these polysaccarides:
- maltose
- sucrose
- lactose
- cellobiose
maltose - a-glucose + a-glucose
sucrose - a-glucose + fructose
lactose - B-galactose + a-glucose
cellobiose - B-glucose + B-glucose
what is the structure of a water molecule?
water molecules are made up of two hydrogen atoms covalently bonded to an oxygen molecule. However there is an unequal amount of sharing in the covalent bond, making the oxygen delta negative and the hydrogen delta positive because the oxygen atom attracts the electrons more strongly than the hydrogen atoms
what is a polar molecule and name one
a polar molecule is a molecule that has one end with a positive charge and the other with a negative charge.
water is a polar molecule (along with ethanol, ammonia, sulfur dioxide ect.)
what is a dipole?
the separation of charge due to the electrons in the covalent bond being unevenly shared
what is the name of the bond between water molecules
hydrogen bond
which atoms are the hydrogen bonds between?
the delta negative oxygen and the delta positive hydrogen
are hydrogen bonds weak or strong
weak when there are only a small amount but strong when in large numbers
what properties of water do hydrogen bonds contribute to?
- An excellent solvent – many substances can dissolve in water
- A relatively high specific heat capacity
- A relatively high latent heat of vaporisation
- Water is less dense when a solid
- Water has high surface tension and cohesion
- It acts as a reagent
what two properties of water effect the functions of water?
- The polarity of water molecules
- The presence and number of hydrogen bonds between water molecules
what makes water a good solvent and what does this allow it to do?
As water is a polar molecule many ions and covalently bonded polar substances will dissolve in it. This allows chemical reactions to occur within cells (as the dissolved solutes are more chemically reactive when they are free to move about) and metabolites (a chemical substance involved in metabolism) can be transported efficiently (except non-polar molecules which are hydrophobic)
what makes water have a relatively high specific heat capacity and what does this allow it to do?
The high specific heat capacity is due to the many hydrogen bonds present in water. It takes a lot of thermal energy to break these bonds and a lot of energy to build them, thus the temperature of water does not fluctuate greatly. This means that it is able to provide stable habitats as it can absorb a lot of heat without big temperature fluctuations, maintaining temperatures that are optimal for enzyme activity.
Water in blood plasma is also vital in transferring heat around the body, helping to maintain a fairly constant temperature
As blood passes through more active (‘warmer’) regions of the body, heat energy is absorbed but the temperature remains fairly constant
Water in tissue fluid also plays an important regulatory role in maintaining a constant body temperature
what makes water have relatively high specific latent heat and what does this allow it to do?
there are many hydrogen bonds meaning that a lot of energy is needed to make the water evapourate. This is an advantage for living organisms as only a little water is required to evaporate for the organism to lose a great amount of heat. This provides a cooling effect for living organisms, for example the transpiration from leaves or evaporation of water in sweat on the skin
what is cohesion and what does it allow water to do?
the attraction of the same molecules to each other.
This allows columns of water to move through the xylem of plants and through blood vessels in animals
This also enables surface tension where a body of water meets the air, these hydrogen bonds occur between the top layer of water molecules to create a sort of film on the body of water (this is what allows insects such as pond skaters to float)
what is a monomer?
the smaller units from which larger molecules are made
