UNIT 2 – THE CELLChapter 6 – Chemistry in Biology

Section 1 – Atoms, Elements & Compounds Everything we see, are and experience

comes from stardust

Atoms

Chemistry is the study of matterAtoms are building blocks of matterAlthough discussion began in the 5th century

B.C., evidence was not in place until the 1800’s for the existence of the “atom”

Atoms are made up of even smaller particlesNucleus (made up of p+’s and n0’sProtons (+)Neutrons (0)Electrons (-)

○ Move around the nucleusAtom is a result of attraction between

particlesOverall charge on an atom is zero

Examples of “H” and “O” Atoms

Elements

Pure substance that cannot be broken down by physical or chemical means

Collected in the periodic tableAtomic massChemical & physical

behavior/characteristicsState92 naturally occurringHorizontal rows called periods & vertical

columns called groups/families

Isotopes When atoms have different # of

neutrons

Isotopes will have the same chemical characteristics

Radioactive Isotopes

Changing the number of neutrons can affect the stability of the nucleus

Radiation can be given off as a result Ages can be taken by measuring the

rate of decay in these radioactive isotope

Compounds

Two or more different elements combined i.e. water, sodium chloride, methane Must be in a fixed ratio Are chemically & physically different from

the elements that make them up Cannot be broken down by physical

means Can be separated by chemical means

(i.e. electrolysis

Chemical Bonds

Force that holds substances together Energy levels & electrons control

bonding Forming chemical bonds stores energy

while breaking them provides energy for life processes

There are two typesCovalentionic

Covalent Bonds

Share electrons in the outer shell Majority of compounds in a living

organism Called a molecule Can have single, double or triple bonds

Covalent Bond Example

Ionic Bond

Higher melting points Give or take an electron Electrical attraction Most dissolve in water Called ions most solid at room

temperature Helps maintain homeostasis in

organisms Transmits signals

Ionic Bond Example

Van de Waal Forces

Attraction between molecules Dutch physicist named Johannes Depends on the size, shape & ability to

attract electrons Not as strong as covalent or ionic Key role in biological processes This is why water droplets form

HOMEWORK 6-1

Find a covalent (molecule) & ionic (ion) example not mentioned in the text or in class. Give the formula and explain the bond in picture form or words

Write a poem about the difference between ionic & covalent. Have at least one line dedicated to Van de Waals forces (no examples from class or text)

Section 2 – Chemical Reactions

This is why we grow, develop, reproduce & adapt

Reactant & productsChemical reactions (i.e. rust)

○ Creates a new substance (change in color, production of heat or light, formation of new gas, liquid or solid)

Chemical equation○ reactants on the left → products on the right○ “→” meaning yields or reacts to form○ Balanced equations – conservation of mass – use of coefficients

Unbalanced

Balanced

Energy of Reactions

Most compounds cannot undergoes chemical reactions without energy

Activation energy – the minimum amount of energy that it takes for reactions to occur (high or low)

Example: a candle will not light without a flame

Energy change in chemical reactionsExothermic – releases energy in the form of

heat (i.e. candle)

Endothermic – it absorbs heat energy (i.e. internal body homeostasis)

Enzymes

All living functions require numerous chemical reactions

Catalyst – a substance that lowers the activation energy & does NOT get used up in the reaction

Enzymes or biological catalysts will speed up biological processes, are essential to life & can be reused.i.e. amylase that is found in salivaMost enzymes are specific to one reactionSubstrates (reactants that bind to enzyme)Active site is where the substrates attach

themselves (like puzzle pieces)Once binding occurs, active site changes to

an enzyme-substrate complexpH, temperature & other substances can

affect the enzyme

Example of Enzyme as catalyst

Substrate at Active Site of Enzyme

6-2 Homework

Apple Lab pg. 159 at home. Create a table to record findings and take photographs (possible groups of 2)

Give an example of enzyme not mentioned in book or class and tell me name and function of said enzyme

Balance equations on the handout and list products and reactants

Other than book or class topics, let me know a specific example (real world please) of an endothermic and exothermic reaction.

Section 3 – Water and Solutions

Water’s Polarity Is water covalent or ionic? Unequal distribution of electrons in the water

molecule Polar molecules (i.e. tug o war) Opposites attract (electrostatic attraction) –

in water this is called a hydrogen bond (F,O,N) – Van de Waal force

So what is the formula for water? What is it made of? What is the formula for ice? For water vapor?

Mixtures

Combo of two or more substance

Homogeneous (solution)Solvent & solute

HeterogeneousSuspensioncolloid

Acids & BasesAcids (release H+ ions when dissolved in

H O)₂Bases (release OH- ions when dissolved in

H O)₂

pH & Buffers○ Biological processes carried out in pH range of 6.5 to 7.5○ Buffers are mixtures that react with acid & bases to keep pH in that safe range

6-3 Homework

Paragraph on H O importance in the ₂body Examples (that were not mentioned in class or text) of a solution, a colloid, a suspension and a homogenous mixture with the reasons why.

Section 6-4 The Building Blocks of Life (Carbon based)

Organic Chemistry

Study of organic compounds (containing C)

Can be a straight, branched or

ringed molecule – which leads to diversity of life on the planet

Macromolecules Large molecules formed by joining

smaller organic molecules together Also called polymers which are large

molecules made up of repeated molecules called monomers

There are 4 types of macromolecules/polymersCarbohydratesLipidsProteinsNucleic acids

Carbohydrates (see pg. 168)

CarbohydratesStores energy, provides structureMade up of 1 C, 2 H’s, 1 O (CH₂O) nWhere “n” is 3 – 7 then the carb. is a simple sugar ( see glucose illustration)When 2 monosaccharides are put together (ex. Sucrose or lactose) it is called a disaccharideEven longer chained monosaccharides are called polysaccharidesMakes up plants mass, exoskeletons, ect.

LipidsStore energy, provide barriersFats, oils & waxesFatty acids, glycerol & other compoundsPrevents water loss from plantsNeeded to carry out body functionsSaturated (will not accept H’s) &

unsaturated (will accept H’s)Polyunsaturated can accept more H’sPhospholipids – responsible for structure

and function of cell membrane since lipids are hydrophobic they create wonderful barriers between cells

Steroids○ Cholesterol & hormones

Proteins Transport substances, speed reactions,

structural support, hormones Made up of amino acids (C,N,O,H and

sometimes S) Bonds covalently with H, amino group (-

NH ), carboxyl (-COOH) & ₂variable(-R) There are 20 variables Peptide bonds amino acids together forming proteins Makes up 15% of body mass

Amino Acids Making a Protein

Protein Shapes

Nucleic acidsStore and transmit genetic informationMade up of nucleotides (C, N, O, P, H)6 major nucleotides (all have)

○ A phosphate○ A nitrogenous base○ A ribose sugar

DNA & RNA (deoxyribonucleic acid & ribonucleic acid)

ATP (Adenosine triphosphate)

Nucleic Acids

6-4 Homework

Comprehension Sentences Handout Tutorials Awesome grade on test