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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