lecture 3: chemistry of life
TRANSCRIPT
![Page 1: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/1.jpg)
Lecture 3: Chemistry of Life
http://pearl1.lanl.gov/periodic/default.htmhttp://www.chemsoc.org/viselements/pages/pertable_fla.htm
![Page 2: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/2.jpg)
Chemical Benefits and Costs
• Understanding of chemistry provides fertilizers, medicines, etc.
• Chemical pollutants damage ecosystems
![Page 3: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/3.jpg)
Bioremediation
Use of living organisms to withdraw harmful substances
from the environment
![Page 4: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/4.jpg)
ElementsElements• Fundamental forms of matter
• Can’t be broken apart by normal means
• 92 occur naturally on Earth
Less than 12 occur on the examLess than 12 occur on the exam
![Page 5: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/5.jpg)
Most Common Elements in Living Organisms
Oxygen
Hydrogen
Carbon
Nitrogen
![Page 6: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/6.jpg)
What Are Atoms?
• Smallest particles that retain properties
of an element
• Made up of subatomic particles:
– Protons (+)
– Electrons (-)
– Neutrons (no charge)
![Page 7: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/7.jpg)
Fig. 2.3, p. 22
HYDROGEN HELIUM
electron
proton
neutron
Hydrogen and Helium Atoms Hydrogen and Helium Atoms
![Page 8: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/8.jpg)
Atomic NumberAtomic Number
• Number of protons
• All atoms of an element have the same atomic number
• Atomic number of hydrogen = 1
• Atomic number of carbon = 6
![Page 9: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/9.jpg)
Mass NumberMass Number
Number of protons
+Number of neutrons
Isotopes vary in mass number
![Page 10: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/10.jpg)
Atomic MassAtomic Mass
IsotopesIsotopes• Atoms of an element
with different numbers of neutrons (different mass numbers)
• Carbon 12 has 6 protons, 6 neutrons
• Carbon 14 has 6 protons, 8 neutrons
RadioisotopesRadioisotopes• Have an unstable
nucleus that emits energy and particles
• Radioactive decay transforms radioisotope into a different element
• Decay occurs at a fixed rate
![Page 11: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/11.jpg)
Radioisotopes as TracersRadioisotopes as Tracers• Example: Tracer Drug Study
– How long does a drug stay in the patient?– Determine dose guidelines
• Compound synthesized with a radioisotope
• Emissions from the tracer can be detected with special devices– Track levels in the blood, urine and feces
• Following movement of tracers is useful in many areas of biology
![Page 12: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/12.jpg)
High SensitivityHigh Sensitivity
Very Low DoseVery Low Dose
![Page 13: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/13.jpg)
Other Uses of RadioisotopesOther Uses of Radioisotopes• Drive artificial pacemakers• Internal structure
– Thyroid and bone scans
• Radiation therapyEmissions from some radioisotopes can destroy cells. Some radioisotopes are used to kill small cancers.
![Page 14: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/14.jpg)
Thyroid ScanThyroid Scan
• Measures health of thyroid by detecting radioactive iodine taken up by thyroid gland
normal thyroid enlarged cancerous
![Page 15: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/15.jpg)
What Determines Whether What Determines Whether Atoms Will Interact?Atoms Will Interact?
![Page 16: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/16.jpg)
ElectronsElectrons
• Carry a negative charge
• Repel one another
• Are attracted to protons in the nucleus
• Move in orbitals - volumes of space that surround the nucleus
Z
X
When all p orbitals are full
y
![Page 17: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/17.jpg)
Electron OrbitalsElectron Orbitals
• Orbitals can hold up to two electrons
• Atoms differ in the number of occupied orbitals
• Orbitals closest to nucleus are lower energy and are filled first
![Page 18: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/18.jpg)
Shell ModelShell Model
• First shell
– Lowest energy
– Holds 1 orbital with up to 2
electrons
• Second shell
– 4 orbitals hold up to 8
electrons
CALCIUM20p+ , 20e-
![Page 19: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/19.jpg)
Electron VacanciesElectron Vacancies
• Unfilled shells make atoms likely to react
• Hydrogen, carbon, oxygen, and nitrogen all have vacancies in their outer shells
CARBON6p+ , 6e-
NITROGEN7p+ , 7e-
HYDROGEN1p+ , 1e-
![Page 20: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/20.jpg)
Chemical Bonds, Molecules, Chemical Bonds, Molecules,
& Compounds& Compounds• Bond is union between electron
structures of atoms
• Atoms bond to form molecules
• Molecules may contain atoms of only one element - O2
• Molecules of compounds contain more than one element - H2O
![Page 21: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/21.jpg)
Chemical BondsChemical Bonds
Electrostatic
Covalent
Metallic
![Page 22: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/22.jpg)
1. Ionic Bonding1. Ionic Bonding
• One atom loses electrons, becomes positively charged ion
• Another atom gains these electrons, becomes negatively charged ion
• Charge difference attracts the two ions to each other
![Page 23: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/23.jpg)
Ion FormationIon Formation
• Atom has equal number of electrons and protons - no net charge
• Atom loses electron(s), becomes positively charged ion
• Atom gains electron(s), becomes negatively charged ion
![Page 24: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/24.jpg)
Formation of NaClFormation of NaCl
• Sodium atom (Na) – Outer shell has one electron
• Chlorine atom (Cl) – Outer shell has seven electrons
• Na transfers electron to Cl forming Na+ and Cl-
• Ions remain together as NaCl
![Page 25: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/25.jpg)
7mm
SODIUMATOM11 p+
11 e-
SODIUMION
11 p+
10 e-
electron transfer
CHLORINEATOM17 p+
17 e-
CHLORINEION
17 p+
18 e-
Fig. 2.10a, p. 26
Formation of NaClFormation of NaCl
![Page 26: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/26.jpg)
2. Covalent Bonding2. Covalent Bonding
Atoms share a pair or pairs of electrons to fill outermost shell
•Single covalent bond
•Double covalent bond
•Triple covalent bond
![Page 27: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/27.jpg)
Two Flavors of Two Flavors of Covalent BondsCovalent Bonds
Non-polarNon-polar Covalent Covalent• Atoms share electrons
equally• Nuclei of atoms have
same number of protons
• Example: Hydrogen gas (H-H)
PolarPolar Covalent Covalent• Number of protons in
nuclei of participating atoms is NOT equal
• Molecule held together by polar covalent bonds has no NET charge
• Electrons spend more time near nucleus with most protons– Example: Water – Electrons more attracted
to O nucleus than to H nuclei
![Page 28: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/28.jpg)
Example+
O
H H
slight negative charge at this end
slight positive charge at this end
molecule hasno net charge( + and - balanceeach other)
KEEP YOUR EYE ON THE ELECTRONS
![Page 29: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/29.jpg)
Hydrogen BondingHydrogen Bonding
A bond by Hydrogen between two atoms
• Important for O and N
• Lets two electronegative atoms interact– The H gives one a net + and the other one
that is still – is attracted to it.
• The H proton becomes “naked” because its electron gets pulled away.
![Page 30: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/30.jpg)
Hydrogen bond figure
- -
- + -
Like Charge Atoms Repel Each Other
Opposite Charge Atoms Attract Each Other
KEEP YOUR EYE ON THE ELECTRONS
![Page 31: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/31.jpg)
onelargemolecule
anotherlargemolecule
a largemoleculetwistedbackonitself Fig. 2.12, p. 27
Examples of Hydrogen BondsExamples of Hydrogen Bonds
![Page 32: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/32.jpg)
Properties of WaterProperties of Water
•Polarity
•Temperature-Stabilizing
•Cohesive
•Solvent
![Page 33: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/33.jpg)
Water Is a Polar Water Is a Polar Covalent MoleculeCovalent Molecule
• Molecule has no net charge
• Oxygen end has a slight negative charge
• Hydrogen end has a slight positive charge
O
H H
![Page 34: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/34.jpg)
O
H
HO
H
H
+ _
++
+
_
+
+
Liquid WaterLiquid Water
![Page 35: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/35.jpg)
Hydrophilic & HydrophobicHydrophilic & HydrophobicSubstancesSubstances
• Hydrophilic substances– Polar– Hydrogen bond with water – Example: sugar
• Hydrophobic substances– Nonpolar– Repelled by water– Example: oil
![Page 36: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/36.jpg)
Temperature-Stabilizing Temperature-Stabilizing EffectsEffects
• Water absorbs a lot more heat than oil before its temperature rises.
• Why?
• Much of the added energy disrupts hydrogen bonding rather than increasing the movement of molecules
![Page 37: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/37.jpg)
Evaporation of WaterEvaporation of Water
• Large energy input can cause individual molecules of water to break free into air
• As molecules break free, they carry away some energy (lower temperature)
• Evaporative water loss is used by mammals to lower body temperature
![Page 38: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/38.jpg)
Why Ice FloatsWhy Ice Floats
• In ice, hydrogen bonds lock molecules in a lattice
• Water molecules in lattice are spaced farther apart then those in liquid water
• Ice is less dense than water
![Page 39: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/39.jpg)
Water CohesionWater Cohesion• Hydrogen bonding holds
molecules in liquid water together
• Creates surface tension
• Allows water to move as continuous column upward through stems of plants
![Page 40: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/40.jpg)
Water Is a Good SolventWater Is a Good Solvent
• Ions and polar molecules dissolve easily in water
• When solute dissolves, water molecules cluster around its ions or molecules and keep them separated
![Page 41: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/41.jpg)
Fig. 2.16, p. 29
Na+
Cl–
– –
––
––
–
––
– –
+ ++
+
+
+
+
+
+
+
+
++ +
+
+
+
+
Spheres of HydrationSpheres of Hydration
![Page 42: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/42.jpg)
WaterWater
• Solvent- polar– Keeps ions in solution– Doesn’t dissolve membranes
• Heat management– Loosing heat– Holding heat– Density Changes
![Page 43: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/43.jpg)
If it wasn’t ugly enough already: If it wasn’t ugly enough already:
Hydrogen Ions: HHydrogen Ions: H++
• Unbound protons
• Have important biological effects
• Form when water ionizes
![Page 44: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/44.jpg)
The pH ScaleThe pH Scale
• Measures H+ concentration of fluid• Change of 1 on scale means 10X
change in H+ concentration
Highest H+ Lowest H+
0---------------------7-------------------14Acidic Neutral Basic
![Page 45: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/45.jpg)
Examples of pHExamples of pHPure water is neutral with pH of 7.0
Acidic
Basic
![Page 46: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/46.jpg)
Acids & BasesAcids & Bases
• Acids
– Donate H+ when dissolved in water
– Acidic solutions have pH < 7
• Bases
– Accept H+ when dissolved in water
– Acidic solutions have pH > 7
![Page 47: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/47.jpg)
BuffersBuffersMinimize shifts in pH
• When blood pH rises, carbonic acid dissociates to form bicarbonate and H+
H2C03 -----> HC03- + H+
• When blood pH drops, bicarbonate binds H+ to form carbonic acid
HC03- + H+ -----> H2C03
AcidosisAcidosis
AlkalosisAlkalosis
Carbonic Acid-Bicarbonate Buffer SystemCarbonic Acid-Bicarbonate Buffer System
![Page 48: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/48.jpg)
Lecture 2:Chemistry of Life
Part 2
![Page 49: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/49.jpg)
Organic Compounds
Hydrogen and other elements covalently bonded to carbon
Carbohydrates
Lipids
Proteins
Nucleic Acids
![Page 50: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/50.jpg)
Carbon’s Bonding Behavior
• Outer shell of carbon has 4 electrons; can hold 8
• Each carbon atom can form covalent bonds with up to four atoms
![Page 51: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/51.jpg)
Bonding Arrangements
• Carbon atoms can form chains or rings
• Other atoms project from the carbon backbone
![Page 52: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/52.jpg)
Functional Groups
• Atoms or clusters of atoms that are covalently bonded to carbon backbone
• Give organic compounds their different properties
![Page 53: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/53.jpg)
Examples of Functional Groups
Hydroxyl group - OH
Amino group - NH3+
Carboxyl group - COOH
Phosphate group - PO3-
Sulfhydryl group - SH
![Page 54: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/54.jpg)
Types of Reactions
Functional group transfer
Electron transfer
Rearrangement
Condensation
Cleavage
![Page 55: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/55.jpg)
Condensation Reactions
• Form polymers from subunits
• Enzymes remove -OH from one molecule, H from another, form bond between two molecules
• Discarded atoms can join to form water
![Page 56: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/56.jpg)
Fig. 3.4a, p. 37
enzyme action at functional groups
CONDENSATION
![Page 57: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/57.jpg)
Hydrolysis
• A type of cleavage reaction
• Breaks polymers into smaller units
• Enzymes split molecules into two or more parts
• An -OH group and an H atom derived from water are attached at exposed sites
![Page 58: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/58.jpg)
enzyme action at functional groups
HYDROLYSIS
Fig. 3.4b, p. 37
![Page 59: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/59.jpg)
Carbohydrates
Monosaccharides(simple sugars)
Oligosaccharides(short-chain carbohydrates)
Polysaccharides(complex carbohydrates)
![Page 60: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/60.jpg)
Monosaccharides
• Simplest carbohydrates
• Most are sweet tasting, water soluble
• Most have 5- or 6-carbon backbone
Glucose (6 C) Fructose (6 C)
Ribose (5 C) Deoxyribose (5 C)
![Page 61: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/61.jpg)
Two Monosaccharides
glucose fructose
![Page 62: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/62.jpg)
Disaccharides
• Type of oligosaccharide
• Two monosaccharides covalently bonded
• Formed by condensation reaction
+ H2O
glucose fructose
sucrose
![Page 63: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/63.jpg)
Polysaccharides
• Straight or branched chains of many sugar monomers
• Most common are composed entirely of glucose– Cellulose
– Starch (such as amylose)
– Glycogen
![Page 64: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/64.jpg)
Cellulose & Starch
• Differ in bonding patterns between monomers
• Cellulose - tough, indigestible, structural material in plants
• Starch - easily digested, storage form in plants
![Page 65: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/65.jpg)
Cellulose and Starch
![Page 66: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/66.jpg)
Glycogen
• Sugar storage form in animals
• Large stores in muscle and liver cells
• When blood sugar decreases, liver cells degrade glycogen, release glucose
![Page 67: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/67.jpg)
Chitin
• Polysaccharide
• Nitrogen-containing groups attached to glucose monomers
• Structural material for hard parts of invertebrates, cell walls of many fungi
![Page 68: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/68.jpg)
• Most include fatty acids– Fats– Phospholipids– Waxes
• Sterols and their derivatives have no fatty acids
• Tend to be insoluble in water
Lipids
![Page 69: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/69.jpg)
Fatty Acids
• Carboxyl group (-COOH) at one end
• Carbon backbone (up to 36 C atoms)
– Saturated - Single bonds between carbons
– Unsaturated - One or more double bonds
![Page 70: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/70.jpg)
Three Fatty Acids
stearic acid oleic acid linolenic acid
![Page 71: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/71.jpg)
Fats
• Fatty acid(s)
attached to
glycerol
• Triglycerides
are most
common
![Page 72: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/72.jpg)
Phospholipids
• Main components of cell
membranes
![Page 73: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/73.jpg)
Sterols and Derivatives
• No fatty acids
• Rigid backbone of four
fused-together carbon
rings
• Cholesterol - most
common type in
animals
![Page 74: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/74.jpg)
Waxes
• Long-chain fatty acids linked to
long chain alcohols or carbon
rings
• Firm consistency, repel water
• Important in water-proofing
![Page 75: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/75.jpg)
•Omega-6 fatty acids are the predominant polyunsaturated fatty acids (PUFAs) in the Western diet.
•The omega-6 and omega-3 fatty acids are metabolically distinct and have opposing physiologic functions.
•The increased omega-6/omega-3 ratio in Western diets most likely contributes to an increased incidence of heart disease and inflammatory disorders.
•Omega-3 PUFAs suppress cell mediated immune responses and reduce inflammation
Polyunsaturated Fatty Acids
Omega-3
Omega-6
![Page 76: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/76.jpg)
•Bioactive Lipids•Made in all cells•Short range signaling•Eicosanoids?
•Prostaglandins•Inflammation and Pain Perception•Kidney Function•Bone Development•Reproductive Process
•Commercially Important•$4 BILLION/ Year spend on drugs to inhibit prostaglandin synthesis•Vioxx, Celebrex, Ibuprofen, Asprin
Lipids in Cell Signaling
PGE2
![Page 77: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/77.jpg)
Amino Acid Structure
aminogroup
carboxylgroup
R group
![Page 78: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/78.jpg)
Properties of Amino Acids
• Determined by the “R group”
• Amino acids may be:
– Non-polar
– Uncharged, polar
– Positively charged, polar
– Negatively charged, polar
![Page 79: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/79.jpg)
Protein Synthesis
• Protein is a chain of amino acids linked
by peptide bonds
• Peptide bond
– Type of covalent bond
– Links amino group of one amino acid with
carboxyl group of next
– Forms through condensation reaction
![Page 80: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/80.jpg)
Primary Structure
• Sequence of amino acids
• Unique for each protein
• Two linked amino acids = dipeptide
• Three or more = polypeptide
• Backbone of polypeptide has N atoms:
-N-C-C-N-C-C-N-C-C-N-
![Page 81: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/81.jpg)
Protein Shapes
• Fibrous proteins
– Polypeptide chains arranged as strands or sheets
• Globular proteins
– Polypeptide chains folded into compact, rounded
shapes
![Page 82: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/82.jpg)
• Primary structure influences shape in two main ways:– Allows hydrogen bonds to form between
different amino acids along length of chain
– Puts R groups in positions that allow them to interact
Primary Structure & Protein Shape
![Page 83: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/83.jpg)
Secondary Structure
• Hydrogen bonds form between different parts of polypeptide chain
• These bonds give rise to coiled or extended pattern
• Helix or pleated sheet
![Page 84: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/84.jpg)
Examples of Secondary Structure
![Page 85: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/85.jpg)
Tertiary Structure
Folding as a
result
of interactions
between R
groups
heme group
coiled and twisted polypeptide chain of one globin molecule
![Page 86: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/86.jpg)
Quaternary Structure
Some proteins
are made up of
more than one
polypeptide
chain
Hemoglobin
![Page 87: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/87.jpg)
Polypeptides With Attached Organic Compounds
• Lipoproteins
– Proteins combined with cholesterol, triglycerides,
phospholipids
• Glycoproteins
– Proteins combined with oligosaccharides
![Page 88: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/88.jpg)
Denaturation
• Disruption of three-dimensional shape
• Breakage of weak bonds
• Causes of denaturation:– pH
– Temperature
• Destroying protein shape disrupts function
![Page 89: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/89.jpg)
A Permanent Wave
hair wrapped around cuticles
differentbridges form
bridgesbroken
![Page 90: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/90.jpg)
• Sugar
– Ribose or deoxyribose
• At least one phosphate group
• Base
– Nitrogen-containing
– Single or double ring structure
Nucleotide Structure
![Page 91: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/91.jpg)
Nucleotide Functions
• Energy carriers
• Coenzymes
• Chemical messengers
• Building blocks for
nucleic acids
![Page 92: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/92.jpg)
ATP - A Nucleotide
three phosphate groups
sugar
base
![Page 93: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/93.jpg)
• Composed of nucleotides
• Single- or double-stranded
• Sugar-phosphate backbone
Nucleic AcidsAdenineCytosine
![Page 94: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/94.jpg)
DNA
• Double-stranded • Consists of four
types of nucleotides
• A bound to T• C bound to G
![Page 95: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/95.jpg)
RNA
• Usually single strands
• Four types of nucleotides
• Unlike DNA, contains the base uracil in place of thymine
• Three types are key players in protein synthesis
![Page 96: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/96.jpg)
• Normal metabolic products of one
species that can harm or kill a different
species
• Natural pesticides
– Compounds from tobacco
– Compounds from chrysanthemum
Natural Toxins
![Page 97: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/97.jpg)
Synthetic Toxins
atrazine DDTmalathion
![Page 98: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/98.jpg)
Negative Effects of Pesticides
• May be toxic to predators that help fight pests
• May be active for weeks to years
• Can be accidentally inhaled, ingested, or absorbed by humans
• Can cause rashes, headaches, allergic reactions
![Page 99: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/99.jpg)
Producers Capture Carbon
Using photosynthesis, plants and other producers turn carbon dioxide and
water into carbon-based compounds
![Page 100: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/100.jpg)
Atmospheric Carbon Dioxide
• Researchers have studied concentration of CO2 in air since the 1950s
• Concentration shifts with season– Declines in spring and summer when
producers take up CO2 for photosynthesis
![Page 101: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/101.jpg)
CO2 and Global Warming
• Seasonal swings in CO2 increasing
• Spring decline starting earlier
• Temperatures in lower atmosphere increasing
• Warming may be promoting increased photosynthesis
![Page 102: Lecture 3: Chemistry of Life](https://reader035.vdocuments.us/reader035/viewer/2022062309/56649f425503460f94c62a9f/html5/thumbnails/102.jpg)
Humans and Global Warming
• Fossil fuels are rich in carbon
• Use of fossil fuels releases CO2 into atmosphere
• Increased CO2 may contribute to global warming