u1: biochemical interactions

Question 1

when are chemical bonds formed?

Answer 1

when two or more atoms share electrons between them

Question 2

intramolecular vs intermolecular

Answer 2

intra: within a molecule (btwn atoms)
inter: btwn molecules

Question 3

what is the ideal case scenario for electron sharing?

Answer 3

both atoms attract electrons equally so that there is no charge difference

Question 4

non-polar molecule

Answer 4

• atoms pull electrons evenly
• no charge difference bwn atoms in molecule

Question 5

polar molecule

Answer 5

• atoms pull electrons differently
• unequal attraction produces polarity in molecule making partial positive and partial negative regions

Question 6

hydrogen bonding

Answer 6

• H with N, O, F
• weak association between H+ and the partial –ve part of a molecule
• i.e. H2O with H2O

Question 7

what are the intramolecular forces

Answer 7

• covalent
• ionic

Question 8

covalent bonds

Answer 8

atoms share valence electrons

Question 9

electronegativity

Answer 9

how strongly an atom attracts electrons

Question 10

what factors determine polarity

Answer 10

• electrongativity of atom
• bond angle (asymmetrical=polar while symmetrical=non-polar)
• presence of lone pairs/free electrons

Question 11

ionic bonds

Answer 11

• bond btwn cation and anion
• readily dissociate in water (i.e. NaCl)

Question 12

what are intermolecular forces also called

Answer 12

van der Waals forces

Question 13

intermolecular forces

Answer 13

• forces tht occur btwn molecules
• weaker than intramolecular forces
• hydrogen bonding and hydrophobic interactions are important for biological processes

Question 14

london dispersion forces

Answer 14

• weak, momentary interactions of electrons of one molecule to another
• formation of many bonds like this leads to shape of larger molecule, like fat

Question 15

types of london dispersion forces

Answer 15

• hydrophobic: water-fearing
• hydrophillic: water-loving

Question 16

hydrophobic interactions

Answer 16

• type of london dispersion force
• occur btwn non-polar molecules
• non-polar molecules tend to clump together (like oil in water)

Question 17

functional groups

Answer 17

atom clusters w/ atoms like O, N, S, P have chemical properties tht make them reactive parts of molecule

Question 18

what are atoms with just H and C called?

Answer 18

• hydrocarbons
• generally non-reactive (non-polar)

Question 19

is glucose polar or non-polar?

Answer 19

polar bc. OH not evenly spread

Question 20

explain polarity of soap

Answer 20

• soap molecules have polar and non-polar end
• H-C-H bonds are non-polar and cleans oil
• polar end bonds with water when washing

Question 21

why does it burn when we get soap on cuts

Answer 21

• mucousal lining is made up of phospholipids
• non-polar tail of soap bonds with the lipids
• cells are damaged

Question 22

what’s the angle btwn the hydrogens in H2O

Answer 22

104.45 degrees

Question 23

characteristics of water

Answer 23

• water clings
• water absorbs thermal energy
• solid water is less dense than liquid water

Question 24

properties of water clings

Answer 24

• cohesion
• adhesion

Question 25

properties of water absorbs thermal energy

Answer 25

- high specific heat capacity - high specific heat of vapourization

Question 26

cohesion

Answer 26

- water molecules form hydrogen bonds w/ each other - causes high surface tension - i.e. water striders can walk on ponds

Question 27

adhesion

Answer 27

- water molecules form hydrogen bonds with other polar materials - causes capillary action - i.e. water to goes up by clinging to xylem walls

Question 28

high specific heat capacity

Answer 28

- hydrogen bonds make water absorb lots of heat to make temp. significantly go up AND water must lose lots of heat to reduce temp. significantly - effect is: temperature moderation - i.e. helps organisms maintain body temperature

Question 29

high specific heat of vapourization

Answer 29

- hydrogen bonds cause liquid water to absorb lots of heat before becoming vapour/gas - effect is evaporative colling - i.e. organisms lose body heat by evaporating water, like sweating or panting

Question 30

property of solid water is less dense than liquid water

Answer 30

highest density at 4 degrees C

Question 31

highest density at 4 degrees C

Answer 31

- below 4C, water forms crystalline lattice to freeze, the hydrogen bonds btwn water molecules make it spread apart and reduce density of ice - effect is tht ice floats in liquid water - i.e. fish and aquatic organisms can survive thru winter bc ice provides insulation