lesson 1: EN, IMF's, H2O

Question 1

biochem big idea

Answer 1

understand how the unique structures and properties (functional groups, EN, polarity) of critical biological molecules impact their functions in the body

Question 2

chem review

Answer 2

• rules of fundamental chem control cell activities
• structure determines function
• H, O, C, N make up 96% of weight in organism
• ionic vs covalent bonds
• properties determined by individual atoms

Question 3

covalent bonds (intramolecular bonds)

Answer 3

• form when atoms share one or more pairs of valence electrons
• the strength of a covalent bond depends on the EN of the atoms involved

Question 4

electronegativity (EN)

Answer 4

• the measure of an atom’s attraction to shared valence electrons
• the strength with which an element will attract a shared pair of valence electrons (e-) in a bond
• when EN is high (low), the element has a high (low) tendency to attract electrons in a bond and vice versa
• in covalent bonds, elements with high EN develop a slightly negative charge and elements with low EN develop a slightly positive charge

Question 5

polar molecule

Answer 5

• molecules that develop a slightly negative or slightly positive charge
• unequal sharing of electrons between 2 atoms

Question 6

non-polar covalent

Answer 6

difference in EN: 0-0.39

Question 7

polar-covalent

Answer 7

difference in EN: 0.4-1.7

Question 8

ionic

Answer 8

difference in EN: 1.71-4

Question 9

a molecule’s biological function is determined by the 3 following factors:

Answer 9

• overall molecular shape
• overall molecular polarity
• types of bonds between atoms

Question 10

intramolecular forces

Answer 10

• forces that hold atoms together within a molecule
• forces that exist within a molecule
• ie. ionic and covalent bonds

Question 11

intermolecular forces (vanderwaal forces)

Answer 11

• can form between molecules
• forces of attraction between molecules
• there are 3 types: london forces, dipole dipole forces and hydrogen bonds

Question 12

london forces

Answer 12

• weakest of the three

- exist between all atoms and molecules (including non polar ones)

Question 13

dipole dipole forces

Answer 13

• stronger than london forces

- formed between the S+ and S- sides of polar molecules

Question 14

hydrogen bonds

Answer 14

• a very strong dipole dipole force will form between H atoms and neighbouring N, O, or F atoms
• very important biologically (water, DNA, proteins)
• strongest force
• individually weak compared to covalent and ionic bonds but significant in large #’s
• crucial to the function of cells and other cellular processes

Question 15

characteristics of water

Answer 15

• colourless, tasteless, odourless
• a polar molecule
• water has a very high specific heat capacity (4.18J/g *C) (result of hydrogen bonds, can absorb a lot of heat energy with minimal temp change, a lot of energy is needed to convert water from a liquid to a gas)
• ice is less dense than liquid water due to crystal formation so ice floats on water due to fewer/slower formations of hydrogen bonds
• water is densest at 4 degrees Celsius

Question 16

cohesion

Answer 16

• water will form hydrogen bonds with other water molecules

- one bond is very weak but thousands of bonds become strong

Question 17

adhesion

Answer 17

water molecules will also form hydrogen bonds with other polar molecules

Question 18

why is water important?

Answer 18

• for temp regulation, moisture (eyes, lungs), lubrication (joints, saliva), chemical reactions, diffusion/osmosis and as a solvent
• properties of water (polar) drive the fundamental reactions to support life

Question 19

could life exist without polar bonds?

Answer 19

no because they are what hold molecules together such as water which are essential to life