Grade 12 Biology Unit 1 - Biochemistry

Exam Review

Nutrients

A substance required by an organism to live and grow

Macronutrients vs micronutrients

• A nutrient required in large amounts

• A nutrient required in small amounts

Matter

• Biology is the study of life and all living things are made up of matter

• Matter is composed of elements and the smallest particle of an element is an atom

Atoms are composed of 3 subatomic particles

• Electrons ( - charge and 0 mass)

• Protons ( + charge and 1 mass)

• Neutrons ( 0 charge and 1 mass)

Standard atomic notation

• Mass number on the top

• Atomic number on the bottom

Isotopes

• Atoms of an element with the same number of protons but different number on neutrons

• Different mass but same atomic number

Radioisotope

• An unstable isotope that decays (known as radioactive decay) overtime emitting particles and energy

• All isotopes of the same element behave the same way in chemical reactions

Valance electrons

• Electrons that occupy the outermost shell of an atom

• Valence electrons participate in chemical bonding

• Atoms form bonds to become more stable.

• An atoms is most stable when their outer shell is either empty or full of

• To do this atoms move electrons between their valance shells

Valance Electrons Pt 2

• For most atoms, a full valance shell is an octet of 8 electrons

• Some smaller atoms such as H, Li, and Be, are stable with a valance duet of 2 electrons

Chemical Bonding

• Ions are a particle that has become charged due to the addition or removal of an electron

• Cations are positively charged

• Anions are negatively charged

Ionic Bond

• The electrostatic force of attraction between two oppositely charged ions

• Very strong

• Due to their charges, ionic compounds are often readily soluble in polar solvents like water

Covalent Bonds

• The sharing of electrons between two atoms

Molecule

• Two or more covalently bonded atoms

Carbon

• Carbon is the main molecule of life because of its abundance on Earth and its versatility

• It can make up to 4 covalent single bonds and it can form double or triple bonds

Carbon Pt 2

• The 109 degree angle between the atoms bonded to a carbon provides space for many bonding possibilities for attached atoms and the possibility of ring formations

Electronegativity

• The measure of an atoms attraction to shared electrons

• Covalently bonded atoms do not always share electrons equally

• The EN values of the bonded atoms are compared to determine if the bond is polar or non polar

Polar Covalent Bond

• Unequal sharing of electrons in a covalent bond

• EN = 0.50+

Non polar covalent

• Functionally equal sharing of electrons in a covalent bond

• EN = 0-0.50

Molecule Polarity

• Since polar bonds have a positive side and a negative side, this may cause a molecule to also have a positive side and a negative side

• The positive and negative sides of a polar molecule are molecular dipoles

Molecules are non polar if

• They contain only non polar bonds

• They contain polar bonds that are equally distributed

Intermolecular Forces

• Attraction between two molecules

• LDF, DD, and H-B

Dipole Dipole

• Occurs between the positive dipole and - dipole of two molecules

• Only occurs in polar molecules

Hydrogen Bonding

• Forms when an H atom bonded to a NOF atom is attracted to the lone pair on the NOF atom of another molecule.

• Strongest

London Dispersion Force

• Attractive force between particles caused by attraction of the electron on one particle to the protons on the other particle and vice versa

• Non polar molecules

Intermolecular Forces

• LDF exists between all particles

• They rely on the random motion of electrons within particles and thus are temporary and very weak

• When electrons are dispersed unsymmetrical LDF attraction occurs

• The strength increases with the surface area (more electrons) of the molecule and the number of electrons contained within it

IMFs

• Combined with the shape and size of molecules, IMFs help determine the physical properties of substances such as

  • Melting Point

  • Boiling Point

  • Hardness

Chemical Reactions - Dehydration Synthesis

• A larger molecule is made from smaller molecules via the removal of water

• AKA condensation reaction

Chemical Reaction - Hydrolysis

• Water is used to break larger molecules down into smaller molecules

Chemical Reactions - Anabolism vs Catabolism

• Anabolism is where a larger molecule is made from smaller subunits

• Catabolism is where a larger molecule is broken down into smaller subunits

Chemical Reactions - Neutralization

• An acid and base are combined to make a salt and water

Water

• Life would not exist without water

• All cellular processes occur in aqueous environments

• By mass humans are about 60% water

Water pt 2

• Water is the most abundant liquid on Earth

• It is a polar molecule that can form 4 H-bonds with other H2O molecules

Water - Heat Capacity

• When water is heated, a liquid water molecule can only escape as a vapour molecule once enough energy to break all surrounding IMFs has been provided.

• Due to its very strong IMFs, water has a higher melting point and boiling point than molecules of similar shapes and sizes.

Specific Heat Capacity

• The amount of energy required to raise the temperature of 1 kg of a substance by 1 degree celsius

Ice

• Most substances become more dense as they get colder

• Water actually gets less dense when it freezes

• When water freezes its molecules spread into a crystal lattice structure

Ice Formation

• On water this protects and insulates aquatic life at temperatures below freezing

Cohesion

• The attraction of particles within the same substance

Adhesion

• The attraction of particles within different substances

Adhesion and Cohesion in Water

• Water is pulled up the stem of a plant because of its adhesion to the cell wall and cohesion to its own particles

• This is capillary action

Aqueous Solutions

• When an ion or polar molecule is placed in water, it is surrounded by H2O molecules in a layer called a Hydration Shell

• The positive or negative sides of water will attract to the ion’s charge

Dissociation

• When water breaks down a larger molecule

• Ionic crystals dissociate in water as the H2O molecules form dipole ion IMFs with them and form hydration shells

• The large number of dipole ion IMFs with H2O can overcome the strength of the original ionic bonds

Hydrophobic

• Non polar molecules that are not attracted to water

Hydrophilic

• Polar or ionic molecules that are strongly attracted to water

Authorization of water

• Water can react to make H3O+ (hydronium) and OH- (hydroxide)

• H2O + H2O = H3O + OH

Acid

• A compound that makes the concentration of H3O ions in water greater than the concentration of OH ions

• Sour, watery, red litmus colour, conducts electricity, 0-7 pH

• Often have an ionizable hydrogen (an H+ that can dissociate) in their chemical structure

Base

• A compound that makes the concentration of OH ions in water greater than the concentration of H3O ions

• Bitter, slippery, blue litmus colour, conducts electricity, 7-14 pH

There are 2 ways for a base to increase the concentration of OH in a solution

• A base may have an ionizable hydroxide (an OH that can dissociate) in their chemical structure

• A base may remove an H ion from a water molecule

pH (Power of Hydrogen)

• A measurement of the concentration of Hydrogen in a solution

• At 25 degrees pure water has equal concentrations of H and OH and has a pH of 7

Carbon

• Carbon is the main element of almost all biological molecules

• Carbon containing molecules are called organic molecules

• In biology C is commonly bonded to other non metals such as H, N, O, and S

Carbon Structures

• Carbons commonly form cyclic structures

• Hydrocarbons can hall under different classifications depending on their arrangement

  • Alkane (Linear with only single bonds)

  • Alkene (Linear with double bonds)

  • Alkyne (Linear with triple bonds)

  • Aromatic Ring (Cyclic with alternating double bonds)

  • Aliphatic Structures are structures that are not aromatic

Functional groups

• A specific combination of atoms that affects the chemical properties of a molecule