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Transcript of Protons (+), neutrons (0) and electrons (-) Isotopes – same proton, different neutron number ...
AP CHEMISTRY REVIEW – CH. 2 CLIFFS Protons (+), neutrons (0) and electrons
(-) Isotopes – same proton, different
neutron number Ionic bonds vs. covalent bonds (non-
polar covalent and polar covalent) Interaction of electrons determine
bonding
IONIC BONDING
Sharing of valence electrons to create molecules
Non-polar covalent – electrons are shared equally
Polar-covalent – not shared equally (water molecule)
Double and triple bonds
COVALENT BONDING
WATER – POLAR COVALENT
HYDROGEN BONDING Weak bonds between molecules Water molecules display H-bonding
HYDROGEN BONDS
Water and ammonia Water with Water
Water is cohesive - because of hydrogen bonds – because of polarity
Water has surface tension due to cohesion
Water displays capillary action due to adhesion, which allows it to crawl up tubes.
Ice is less dense than water, therefore it floats
Water heats and cools slowly because of high specific heat.
Water is a biological solvent Water has high heat of vaporization
PROPERTIES OF WATER
ACIDS AND BASES pH scale Acids – H+
Bases – OH- (alkaline) Tenfold change – pH 3 is ten times more
acidic than pH of 4
Polymers - Large molecules made by chains of small molecules
Carbohydrates, Lipids, Proteins, Nucleic Acids are all polymers
Organic – contain carbon Inorganic – no carbon (except for CO2) Watch this video Functional groups – pg. 14
ORGANIC MACROMOLECULES
CARBOHYDRATES Mono, di, poly saccharides Glucose and fructose are
monosaccharides Dehydration synthesis yields a
disaccharide – glycosidic linkage Lose water Hydrolysis breaks the bonds Gain water maltose= glucose + glucose Lactose= glucose + galactose Sucrose= glucose + fructose
DEHYDRATION SYNTHESIS
Starches - Carbohydrates stored by plants
Glycogen – Carbohydrates stored by animals in liver and muscle cells. Alpha glucose
Cellulose – forms the cell walls of plants and gives the plant structural support. Beta glucose
Chitin – exoskeletons of arthropods and cell walls of fungi. Beta glucose
STARCH, GLYCOGEN, CELLULOSE
CELLULOSE VS. STARCH
Lipids – Fats, oils, phospholipids, steriods
Nonpolar – they do not dissolve in water Long term energy storage, insulation,
and protection Major component of the cell membrane Glycerol molecule and 3 fatty acid
chains – ester linkage Unsaturated vs. saturated
LIPIDS – DEHYDRATION SYNTHESIS
TRIGLYCERIDE SYNTHESIS
PHOSPHOLIPID STRUCTURE
Amphipathic – hydrophilic head and hydrophobic tails
CHOLESTEROL
Many uses in the cells and are integral in most every process in an organism’s body.
PROTEINS
PEPTIDE BONDING – DEHYDRATION SYNTHESIS
Lose water Dipeptide then
polypeptide Many polypeptides
folded and twisted becomes a functional protein
Primary to tertiary structure
As polypeptide advances in structure, binding sites are formed
POLYPEPTIDE CHAINS – PRIMARY STRUCTURE
SECONDARY STRUCTURE Fibrous proteins
Hydrophobic interactions between amino acids with nonpolar side chains cluster in the core of the pleated sheet or alpha helix.
Disulfide bonds between two cysteine amino acids also occur.
TERTIARY STRUCTURE
Made up of two or more polypeptide chains.
Ex. Collagen and Hemoglobin
QUATERNARY STRUCTURE
PROTEIN STRUCTURES
TYPES OF PROTEINS IN THE BODY1. Structural – keratin, collagen, silk2. Storage – albumin in eggs3. Transport proteins on cell membranes4. Defensive – antibodies5. Enzymes – regulate all chemical rxns.
in the body
Polymers of nucleotides - polynucleotides
Nucleotide – sugar, phosphate group, and nitrogen base
4 nitrogen bases – adenine, guanine, cytosine, thymine
DNA – double helix – deoxyribonucleic acid – deoxyribose sugar
RNA – single strand – ribonucleic acid – ribose sugar
NUCLEIC ACIDS
Single ring Cytosine, thymine and uracil
PYRIMIDINES
Adenine and Guanine Double Ring
PURINES
NUCLEIC ACID STRUCTURE
FLOW OF INFORMATION IN CELLS
Cellular Energetics Bioenergetics – our cells’ ability to release the
energy in glucose, starch, and fat We do this by chemical reactions catalyzed by
enzymes Exergonic reactions vs. endergonic reactions Exergonic – nutrients being oxidized in the
mitochondria Endergonic – plants using CO2 and water to
form sugars Activation energy – energy barrier that must
be broken for exergonic rxns to proceed.
Figure 8.6
(a) Exergonic reaction: energy released, spontaneous
(b) Endergonic reaction: energy required, nonspontaneous
Reactants
EnergyProducts
Progress of the reaction
Amount of energy
released(G 0)
ReactantsEnergy
Products
Amount of energy
required(G 0)
Progress of the reaction
Fre
e e
nerg
yFre
e e
nerg
y
Figure 8.8b
Adenosine triphosphate (ATP)
Energy
Inorganicphosphate
Adenosine diphosphate (ADP)
(b) The hydrolysis of ATP
How the Hydrolysis of ATP Performs Work
• The three types of cellular work (mechanical, transport, and chemical) are powered by the hydrolysis of ATP
• In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction
• Overall, the coupled reactions are exergonic
© 2011 Pearson Education, Inc.
Figure 8.9
Glutamicacid
Ammonia Glutamine
(b)Conversionreactioncoupledwith ATPhydrolysis
Glutamic acidconversionto glutamine
(a)
(c)Free-energychange forcoupledreaction
Glutamicacid
GlutaminePhosphorylatedintermediate
GluNH3 NH2
Glu GGlu = +3.4 kcal/mol
ATP ADP ADP
NH3
Glu Glu
PP i
P iADP
GluNH2
GGlu = +3.4 kcal/mol
Glu GluNH3 NH2ATP
GATP = 7.3 kcal/molGGlu = +3.4 kcal/mol
+ GATP = 7.3 kcal/mol
Net G = 3.9 kcal/mol
1 2
Enzymes Lower activation energy Specificity Active site binds substrate in lock and
key fit – enzyme/substrate complex Induced fit – when enzyme changes its
shape to accommodate substrate Enzymes are not used up in the reaction Do not work alone – need co-enzymes
like vitamins, iron, and magnesium
Figure 8.13
Course ofreactionwithoutenzyme
EA
withoutenzyme EA with
enzymeis lower
Course ofreactionwith enzyme
Reactants
Products
G is unaffectedby enzyme
Progress of the reaction
Fre
e en
erg
y
Figure 8.14
Substrate
Active site
Enzyme Enzyme-substratecomplex
(a) (b)
Figure 8.15-3
Substrates
Substrates enter active site.
Enzyme-substratecomplex
Enzyme
Products
Substrates are heldin active site by weakinteractions.
Active site canlower EA and speedup a reaction.
Activesite is
availablefor two new
substratemolecules.
Products arereleased.
Substrates areconverted toproducts.
12
3
45
6
Factors affecting reaction rates
1. Temperature Increasing temp. increasing rxn rate Too much heat can damage the
enzyme – denature most human enzymes work at 37
degrees Celsius2. pH3. Enzyme concentration4. Substrate concentration
Figure 8.16
Optimal temperature fortypical human enzyme (37°C)
Optimal temperature forenzyme of thermophilic
(heat-tolerant)bacteria (77°C)
Temperature (°C)(a) Optimal temperature for two enzymes
Rate
of
reacti
on
Rate
of
reacti
on
120100806040200
0 1 2 3 4 5 6 7 8 9 10pH
(b) Optimal pH for two enzymes
Optimal pH for pepsin(stomachenzyme)
Optimal pH for trypsin(intestinal
enzyme)
Enzyme Regulation Allosteric regions on an enzyme can be
bound by inhibitors or activators Allosteric sites are subject to feedback
inhibition – where the product inhibits the rxn.
Competitive inhibition – when the allosteric inhibitor binds the active site of the enzyme
Non-competitive inhibition – when the inhibitor binds another site on the enzyme leading to a conformational change in the active site
Figure 8.17
(a) Normal binding (b) Competitive inhibition (c) Noncompetitive inhibition
Substrate
Activesite
Enzyme
Competitiveinhibitor
Noncompetitiveinhibitor
Figure 8.19
Regulatorysite (oneof four)
(a) Allosteric activators and inhibitors
Allosteric enzymewith four subunits
Active site(one of four)
Active form
Activator
Stabilized active form
Oscillation
Non-functionalactive site
Inactive formInhibitor
Stabilized inactiveform
Inactive form
Substrate
Stabilized activeform
(b) Cooperativity: another type of allosteric activation
Figure 8.21
Active siteavailable
Isoleucineused up bycell
Feedbackinhibition
Active site ofenzyme 1 isno longer ableto catalyze theconversionof threonine tointermediate A;pathway isswitched off. Isoleucine
binds toallostericsite.
Initial substrate(threonine)
Threoninein active site
Enzyme 1(threoninedeaminase)
Intermediate A
Intermediate B
Intermediate C
Intermediate D
Enzyme 2
Enzyme 3
Enzyme 4
Enzyme 5
End product(isoleucine)