TOPIC 1.1 Structure of Water and Hydrogen Bonding
Living systems are organized in a hierarchy of structural levels that interact.
Explain how the properties of water that result from its polarity and hydrogen bonding affect its
biological function.
Water is polar/ hydrogen bonds result in cohesion, adhesion, surface tension
Its polarity makes water a good solvent, gives it the ability to stick to itself (cohesion), stick to
other substances (adhesion), and have surface tension (due to hydrogen bonding).
The subcomponents of biological molecules and their sequence determine the properties of
that molecule.
Subcomponents (monomers)=> Polymers(Macromolecules)
Monosaccharides =>Carbohydrates=> The order of monosaccharides in a carbohydrate
chain determines its structure.
Amino acids => Proteins =>The amino acid sequence of a protein is reflected in its different
3D folded structure. This structure, in turn, determines the protein's function
Nucleotides =>Nucleic acids (DNA, RNA, ATP)=> The sequence of nucleotides (A, T, C, G)
determines the genetic information carried by the DNA
- All properties are influenced by the structure
Living systems depend on properties of water that result from its polarity and hydrogen
Bonding.
- Water=Polar=unequal distribution of charge=good solvent
- Other polar compounds and ions can easily be dissolved in water because polar + polar
= even distribution of charge, and ions have a charge, so it's attracted to the opposite
charge on the water molecule.
- Cohesion, and adhesion of water help it to move from soil to plants. This is necessary for
the growth and development of plants.
- The water freezes on the top and remains in liquid condition because of cohesion::
hydrogen bonding. This allows the aquatic organism to live inside water.
The hydrogen bonds between water molecules result in cohesion, adhesion, and surface
Tension.
Cohesion= holds hydrogen bonds together to create surface tension on water.
Adhesion= pulls the water toward other molecules.
Practice Questions:
1. Would water still have the same properties it has if the electrons shared between oxygen and
hydrogen were equal?
No-equal distribution means that the molecule is nonpolar. Because of the lack of polarity, it
lacks versatility
- Would not be a universal solvent bc nonpolar molecules don’t dissolve polar substances
2. Part of water's universal solvent capability can be detrimental to ocean life. How does this
property contribute to ocean acidification? Does water’s ability to buffer the pH change help?
- When atmospheric carbon dioxide dissolves in seawater, the water becomes more
acidic and the ocean's pH drops.
- Water's buffering system helps resist pH changes but is overwhelmed by excessive CO₂,
so it can't fully prevent ocean acidification.
, 3. When you dissolve salt into a glass of water, the salt will “disappear” as it is dissolved into the
water but at some point, if you keep adding more and more, the salt will instead settle in the
bottom of the glass. Why does this happen?
Reached a point of saturation= put in an excess of salt that surpasses the threshold of being
able to dissolve in the water, so it can’t be dissolved, the salt remains dissolved in the water.
Water
In water, electrons are not shared equally in the bonds between hydrogen and oxygen
○ Hydrogen atoms have a partial positive charge while oxygen atoms has a partial negative
charge
■ Water is polar
➢ Hydrogen bonds
○ Weak attractions that result of water’s polarity
■ Positive end of another polar molecule attracted to oxygen negative charge, and
vice versa with the hydrogen end
■ Hydrogen atom covalently bonded to one electronegative atom is also attracted to
another electronegative atom
■ Weak Individually, but strong on a larger scale
○ Lends watermany special properties
■ Cohesion
● Tendency for water to stick to water
● Important during transpiration
○ Water evaporates, pulls other water molecules with it, pulling all
the way down from leaves to roots
■ Adhesion
● Tendency of water to stick to other substances
● Cohesion + Adhesion = capillary action
○ Allows water to flow up roots/trunks/branches of trees in thin
vessels
Living systems are organized in a hierarchy of structural levels that interact.
Explain how the properties of water that result from its polarity and hydrogen bonding affect its
biological function.
Water is polar/ hydrogen bonds result in cohesion, adhesion, surface tension
Its polarity makes water a good solvent, gives it the ability to stick to itself (cohesion), stick to
other substances (adhesion), and have surface tension (due to hydrogen bonding).
The subcomponents of biological molecules and their sequence determine the properties of
that molecule.
Subcomponents (monomers)=> Polymers(Macromolecules)
Monosaccharides =>Carbohydrates=> The order of monosaccharides in a carbohydrate
chain determines its structure.
Amino acids => Proteins =>The amino acid sequence of a protein is reflected in its different
3D folded structure. This structure, in turn, determines the protein's function
Nucleotides =>Nucleic acids (DNA, RNA, ATP)=> The sequence of nucleotides (A, T, C, G)
determines the genetic information carried by the DNA
- All properties are influenced by the structure
Living systems depend on properties of water that result from its polarity and hydrogen
Bonding.
- Water=Polar=unequal distribution of charge=good solvent
- Other polar compounds and ions can easily be dissolved in water because polar + polar
= even distribution of charge, and ions have a charge, so it's attracted to the opposite
charge on the water molecule.
- Cohesion, and adhesion of water help it to move from soil to plants. This is necessary for
the growth and development of plants.
- The water freezes on the top and remains in liquid condition because of cohesion::
hydrogen bonding. This allows the aquatic organism to live inside water.
The hydrogen bonds between water molecules result in cohesion, adhesion, and surface
Tension.
Cohesion= holds hydrogen bonds together to create surface tension on water.
Adhesion= pulls the water toward other molecules.
Practice Questions:
1. Would water still have the same properties it has if the electrons shared between oxygen and
hydrogen were equal?
No-equal distribution means that the molecule is nonpolar. Because of the lack of polarity, it
lacks versatility
- Would not be a universal solvent bc nonpolar molecules don’t dissolve polar substances
2. Part of water's universal solvent capability can be detrimental to ocean life. How does this
property contribute to ocean acidification? Does water’s ability to buffer the pH change help?
- When atmospheric carbon dioxide dissolves in seawater, the water becomes more
acidic and the ocean's pH drops.
- Water's buffering system helps resist pH changes but is overwhelmed by excessive CO₂,
so it can't fully prevent ocean acidification.
, 3. When you dissolve salt into a glass of water, the salt will “disappear” as it is dissolved into the
water but at some point, if you keep adding more and more, the salt will instead settle in the
bottom of the glass. Why does this happen?
Reached a point of saturation= put in an excess of salt that surpasses the threshold of being
able to dissolve in the water, so it can’t be dissolved, the salt remains dissolved in the water.
Water
In water, electrons are not shared equally in the bonds between hydrogen and oxygen
○ Hydrogen atoms have a partial positive charge while oxygen atoms has a partial negative
charge
■ Water is polar
➢ Hydrogen bonds
○ Weak attractions that result of water’s polarity
■ Positive end of another polar molecule attracted to oxygen negative charge, and
vice versa with the hydrogen end
■ Hydrogen atom covalently bonded to one electronegative atom is also attracted to
another electronegative atom
■ Weak Individually, but strong on a larger scale
○ Lends watermany special properties
■ Cohesion
● Tendency for water to stick to water
● Important during transpiration
○ Water evaporates, pulls other water molecules with it, pulling all
the way down from leaves to roots
■ Adhesion
● Tendency of water to stick to other substances
● Cohesion + Adhesion = capillary action
○ Allows water to flow up roots/trunks/branches of trees in thin
vessels
