biochemistry unit 1. nucleus proton proton (positive charge) (positive charge) neutron neutron...
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BiochemistryBiochemistry
Unit 1Unit 1
Nucleus
Proton Proton (Positive charge)(Positive charge)
Neutron Neutron (Neutral charge)(Neutral charge)
Shells outside NucleusShells outside Nucleus
Electron Electron (Negative charge)(Negative charge)
Arrangement of electrons determine reactions and nature of bonds
Atomic Structure
Ionic Bonds
One or more electrons completely One or more electrons completely transferredtransferred
Receiving atom gains negative chargeReceiving atom gains negative charge Donating atom gains positive chargeDonating atom gains positive charge ION=atom with a positive or negative ION=atom with a positive or negative
chargecharge Attraction between charges bonds Attraction between charges bonds
atomsatoms e.g. Nae.g. Na++ and Cl and Cl-- form NaCl form NaCl
Covalent Bonds
Electrons shared between atomsElectrons shared between atoms Single covalent bond shares 2 electronsSingle covalent bond shares 2 electrons Double covalent bond shares 4 electronsDouble covalent bond shares 4 electrons Triple covalent bond shares 6 electronsTriple covalent bond shares 6 electrons Nonpolar covalent bond = 2 eNonpolar covalent bond = 2 e-- shared shared
equallyequally Polar covalent bond = 2 e= 2 e-- shared differently shared differently
Larger nucleus pulls on eLarger nucleus pulls on e-- stronger stronger Creates charged poles in moleculeCreates charged poles in molecule
Covalent BondsCovalent Bonds
Polar Covalent Bond
Hydrogen Bonds Weak bond between oppositely charged Weak bond between oppositely charged
poles of different moleculespoles of different molecules e.g. Water moleculese.g. Water molecules
Properties of WaterProperties of Water
Hydrogen bonds give water special properties Excellent solventExcellent solvent High degree of cohesionHigh degree of cohesion Temperature is stableTemperature is stable
Water as a SolventWater as a Solvent
Ionic substances are soluble because of + Ionic substances are soluble because of + and – charges on water molecules’ polesand – charges on water molecules’ poles
Polar covalent substances are soluble Polar covalent substances are soluble because they have hydrogen bonding because they have hydrogen bonding with waterwith water Hydrophilic = water lovingHydrophilic = water loving
Nonpolar covalent substances do not Nonpolar covalent substances do not dissolve because the do not have charged dissolve because the do not have charged polespoles Hydrophobic = water hatingHydrophobic = water hating
Water Cohesion Strong surface Strong surface
tensiontension
Strong capillary actionStrong capillary action
Stable Temperature of Stable Temperature of WaterWater
Relatively large amount of energy to Relatively large amount of energy to warm (and boil) or cool (and freeze)warm (and boil) or cool (and freeze)
Removes a lot of heat when Removes a lot of heat when perspiration evaporatesperspiration evaporates
Oceans provide a temperature-Oceans provide a temperature-constant environmentconstant environment
Organic MoleculesOrganic Molecules
Based on Carbon (C)Based on Carbon (C) Has 4 eHas 4 e-- available for covalent bonding available for covalent bonding
Organic MoleculesOrganic Molecules Carbon chains form complex structuresCarbon chains form complex structures
Chains Chains Rings Rings
Organic MoleculesOrganic Molecules
Other atoms add varietyOther atoms add variety Hydrogen (H)Hydrogen (H) Oxygen (O)Oxygen (O) Nitrogen (N)Nitrogen (N) Sulfur (S)Sulfur (S) Phosphorus (P)Phosphorus (P)
They form They form functional groups that give that give organic molecules specific propertiesorganic molecules specific properties
Functional GroupsFunctional Groups
PolarPolar HydrophilicHydrophilic
Functional GroupsFunctional Groups
Weak acidWeak acid
Functional GroupsFunctional Groups
Weak baseWeak base
Functional GroupsFunctional Groups
AcidAcid
Functional GroupsFunctional Groups
HydrophobicHydrophobic
Methyl
Functional GroupsFunctional Groups
PolarPolar
Organic MoleculesOrganic Molecules
Other atoms add varietyOther atoms add variety Hydrogen (H)Hydrogen (H) Oxygen (O)Oxygen (O) Nitrogen (N)Nitrogen (N) Sulfur (S)Sulfur (S) Phosphorus (P)Phosphorus (P)
They form They form functional groups that give that give organic molecules specific propertiesorganic molecules specific properties
Carbohydrates Monosaccharides are simplestMonosaccharides are simplest
Consist of one sugarConsist of one sugar Have formula (CHHave formula (CH22O)O)nn where where nn is between 3 and 8 is between 3 and 8
Glucose and fructose: and fructose: nn = 6 (i.e. C = 6 (i.e. C66HH1212OO66) but ) but configuration is differentconfiguration is different
Small changes in shape can cause dramatic chemical Small changes in shape can cause dramatic chemical changeschanges
CarbohydratesCarbohydrates
Disaccharides are two linked sugar Disaccharides are two linked sugar moleculesmolecules Sucrose is glucose and fructose linkedSucrose is glucose and fructose linked
CarbohydratesCarbohydrates Polysaccharides are a chain of monosaccharidesPolysaccharides are a chain of monosaccharides
Any molecule of repeating units is a polymerAny molecule of repeating units is a polymer Starch is a chain of thousands of Starch is a chain of thousands of αα-glucose units-glucose units
Food storage in plantsFood storage in plants e.g. Potatoese.g. Potatoes
Cellulose is a chain of thousands of Cellulose is a chain of thousands of ββ-glucose units-glucose units Storage and structureStorage and structure e.g. Wood and cell walls in plantse.g. Wood and cell walls in plants
LipidsLipids
Insoluble in water, but soluble in nonpolar Insoluble in water, but soluble in nonpolar substancessubstances
Fats, oils, and waxes have three fatty acids Fats, oils, and waxes have three fatty acids attached to a glycerolattached to a glycerol
LipidsLipids
Saturated fatty acids—carbons have Saturated fatty acids—carbons have single bonds between them with single bonds between them with hydrogens attachedhydrogens attached
Unsaturated fatty acids—carbons Unsaturated fatty acids—carbons have double bonds between themhave double bonds between them
Polyunsaturated fatty acids have Polyunsaturated fatty acids have multiple double bondsmultiple double bonds
Fatty acids differ by size of chain and Fatty acids differ by size of chain and number of double bondsnumber of double bonds
LipidsLipids
Phospholipids have Phospholipids have phosphate functional phosphate functional groupsgroups
Structural Structural foundation of cell foundation of cell membranesmembranes
Occur in double Occur in double membrane with membrane with hydrophilic heads hydrophilic heads outside and outside and hydrophobic tails hydrophobic tails insideinside
LipidsLipids
Steroids have a Steroids have a backbone of four backbone of four linked carbon ringslinked carbon rings CholesterolCholesterol Some hormonesSome hormones
ProteinsProteins
A variety of functionsA variety of functions Structural (hair, fingernails, eggs, Structural (hair, fingernails, eggs,
muscles, etc.)muscles, etc.) Enzymes (catalysts in biological Enzymes (catalysts in biological
systems)systems) Polymers of amino acidsPolymers of amino acids
Bonds between amino acids are called Bonds between amino acids are called peptide bondspeptide bonds
Proteins are polypeptidesProteins are polypeptides
ProteinsProteins
ProteinsProteins
ProteinsProteins
Four levels of structureFour levels of structure Primary—order of amino acidsPrimary—order of amino acids Secondary—three-dimensional shape caused Secondary—three-dimensional shape caused
by hydrogen bonding (by hydrogen bonding (αα-helix or -helix or ββ-pleated -pleated sheet)sheet)
Tertiary—three dimensional shape caused by Tertiary—three dimensional shape caused by interaction of R-groups (forming globular interaction of R-groups (forming globular proteins)proteins)
Quaternary—two or more separate Quaternary—two or more separate polypeptides joining to form a larger proteinpolypeptides joining to form a larger protein
ProteinsProteins
Nucleic AcidsNucleic Acids
Nucleic acids store and transmit Nucleic acids store and transmit hereditary informationhereditary information
GenesGenes Are the units of inheritanceAre the units of inheritance Program the amino acid sequence of Program the amino acid sequence of
polypeptidespolypeptides Are made of nucleotide sequences on Are made of nucleotide sequences on
DNADNA
The Roles of Nucleic The Roles of Nucleic AcidsAcids
There are two types of nucleic acidsThere are two types of nucleic acids Deoxyribonucleic acid (DNA)Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)Ribonucleic acid (RNA)
36
Deoxyribonucleic AcidDeoxyribonucleic Acid
DNADNA Stores information for the synthesis of Stores information for the synthesis of
specific proteinsspecific proteins Found in the nucleus of cellsFound in the nucleus of cells
DNA FunctionsDNA Functions Directs RNA synthesis (transcription)Directs RNA synthesis (transcription) Directs protein synthesis through RNA Directs protein synthesis through RNA
(translation)(translation)
1
2
3
Synthesis of mRNA in the nucleus
Movement of mRNA into cytoplasm
via nuclear pore
Synthesisof protein
NUCLEUSCYTOPLASM
DNA
mRNA
Ribosome
AminoacidsPolypeptide
mRNA
Figure 5.25
3’C
5’ end
5’C
3’C
5’C
3’ end
OH
Figure 5.26
O
O
O
O
The Structure of Nucleic The Structure of Nucleic AcidsAcids
Nucleic acidsNucleic acids Exist as polymers called Exist as polymers called
polynucleotidespolynucleotides
(a) Polynucleotide, or nucleic acid
O
O
O
O
Each polynucleotideEach polynucleotide Consists of monomers called nucleotidesConsists of monomers called nucleotides Sugar + phosphate + nitrogen baseSugar + phosphate + nitrogen base
Nitrogenousbase
Nucleoside
O
O
O
O P CH2
5’C
3’CPhosphate
group Pentosesugar
(b) NucleotideFigure 5.26
O
Nucleotide MonomersNucleotide Monomers
Nucleotide Nucleotide monomersmonomers Are made up of Are made up of
nucleosides (sugar nucleosides (sugar + base) and + base) and phosphate groupsphosphate groups
(c) Nucleoside componentsFigure 5.26
CHCH
Uracil (in RNA)U
Ribose (in RNA)
Nitrogenous bases Pyrimidines
CN
NC
OH
NH2
CHCH
OC
NH
CHHN
CO
CCH3
N
HNC
C
HO
O
CytosineC
Thymine (in DNA)T
NHC
N C
CN
C
CH
N
NH2 O
NHC
NHH
C C
N
NH
CNH2
AdenineA
GuanineG
Purines
OHOCH2
HH H
OH
H
OHOCH2
HH H
OH
H
Pentose sugars
Deoxyribose (in DNA)Ribose (in RNA)OHOH
CH
CH
Uracil (in RNA)U
4’
5”
3’OH H
2’
1’
5”
4’
3’ 2’
1’
Nucleotide PolymersNucleotide Polymers
Nucleotide polymersNucleotide polymers Are made up of nucleotides linked Are made up of nucleotides linked
by the–OH group on the 3´ carbon by the–OH group on the 3´ carbon of one nucleotide and the phosphate of one nucleotide and the phosphate on the 5´ carbon on the nexton the 5´ carbon on the next
GeneGene
The sequence of bases along a The sequence of bases along a nucleotide polymernucleotide polymer Is unique for each geneIs unique for each gene
The DNA Double HelixThe DNA Double Helix
Cellular DNA moleculesCellular DNA molecules Have two polynucleotides that spiral Have two polynucleotides that spiral
around an imaginary axisaround an imaginary axis Form a double helixForm a double helix
The DNA double helixThe DNA double helix Consists of two antiparallel nucleotide Consists of two antiparallel nucleotide
strandsstrands3’ end
Sugar-phosphatebackbone
Base pair (joined byhydrogen bonding)
Old strands
Nucleotideabout to be added to a new strand
A
3’ end
3’ end
5’ end
Newstrands
3’ end
5’ end
5’ end
Figure 5.27
A,T,C,GA,T,C,G
The nitrogenous bases in DNAThe nitrogenous bases in DNA Form hydrogen bonds in a Form hydrogen bonds in a
complementary fashion (A with T only, complementary fashion (A with T only, and C with G only)and C with G only)
DNA and Proteins as DNA and Proteins as Tape Measures of Tape Measures of
EvolutionEvolution Molecular comparisons Molecular comparisons
Help biologists sort out the Help biologists sort out the evolutionary connections among evolutionary connections among species species
The Theme of Emergent The Theme of Emergent Properties in the Chemistry of Properties in the Chemistry of
Life: Life: A ReviewA Review
Higher levels of organizationHigher levels of organization Result in the emergence of new Result in the emergence of new
propertiesproperties OrganizationOrganization
Is the key to the chemistry of lifeIs the key to the chemistry of life
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
ATP provides the chemical energy for ATP provides the chemical energy for many metabolic reactionsmany metabolic reactions
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Reaction needs to reach activation Reaction needs to reach activation energyenergy
Catalyst accelerates reaction by Catalyst accelerates reaction by lowering required activation energylowering required activation energy
Catalyst does not change during the Catalyst does not change during the reactionreaction
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Reactions in biological systems are Reactions in biological systems are part of the metabolismpart of the metabolism Catabolism breaks downCatabolism breaks down Anabolism or synthesis builds upAnabolism or synthesis builds up Energy is transferred from one Energy is transferred from one
substance to anothersubstance to another
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Net direction of Net direction of reaction is reaction is determined by determined by concentrations of concentrations of reactants and end reactants and end productsproducts
Chemical equilibrium Chemical equilibrium occurs when occurs when concentrations of concentrations of both reactants and both reactants and end products are the end products are the samesame
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Enzymes are catalysts in biological Enzymes are catalysts in biological reactionsreactions Enzymes are globular proteinsEnzymes are globular proteins Specific to one reactionSpecific to one reaction Enzymes are named with “ase” suffixEnzymes are named with “ase” suffix Enzymes act on the substrateEnzymes act on the substrate
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Induced fit model—active site of enzyme attaches to substrate changing its shape for easier reaction
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Enzymes operate at optimum Enzymes operate at optimum temperature and pHtemperature and pH
If temperature or pH is off, the If temperature or pH is off, the enzyme’s structure can denatureenzyme’s structure can denature If denatured, it does not revert to If denatured, it does not revert to
original structureoriginal structure
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Cofactors are nonprotein molecules Cofactors are nonprotein molecules that assist enzymes in lowering the that assist enzymes in lowering the activation energyactivation energy MineralsMinerals
Organic cofactors are called Organic cofactors are called coenzymescoenzymes VitaminsVitamins
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Reactions are regulated byReactions are regulated by Allosteric enzymesAllosteric enzymes Feedback inhibitionFeedback inhibition Competitive inhibitionCompetitive inhibition
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Allosteric enzymes Allosteric enzymes have two binding have two binding sitessites One for substrateOne for substrate One for allosteric One for allosteric
effectoreffector Effector can either Effector can either
activate or inhibit activate or inhibit reactionreaction
Chemical Reactions in Chemical Reactions in Metabolic ProcessesMetabolic Processes
Feedback inhibitionFeedback inhibition End product serves as an allosteric End product serves as an allosteric
effector to shut down reactioneffector to shut down reaction Competitive inhibitionCompetitive inhibition
A substance other than the substrate A substance other than the substrate occupies the active site and keeps the occupies the active site and keeps the reaction from happeningreaction from happening