BIOC 2580 Study Guide - Summer 2018, Comprehensive Midterm Notes - Wavelength, Ultracentrifuge, Tyrosine
12 Oct 2018
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BIOC 2580
MIDTERM EXAM
STUDY GUIDE
Fall 2018
-Myoglobin*is*a*protein*that*stores*O2*in*muscle*tissue*
-How*large*is*a*protein*molecule?*
-Most*proteins:*10,000-100,000*g/mol*
-Protein*size*is*expressed*in*kiloDaltons*(kDa)*
-1*Dalton*(Da)*=*1*g/mol*(mass*of*H*atom)*
-1*kDa*=*1000*g/mol*
-Myoglobin*is*16.5*kDa*-small*protein*
-P-glycoprotein*is*170*kDa*-large*protein*
-Amino*acids*are*joined*with*amide*bonds*to*from*a*protein*
-Proteins*are*made*of*amino*acids**
-linear*chains*of*amino*acids*
-linked*by*peptide*bonds*(type*of*amide*bond*
-Each*protein*has:**
-unique*sequence*of*amino*acids*
-a*well*defined*size*and*structure*
-Proteins*have*diverse*functions*including:*
-catalyzing*reactions*(enzymes)*
-forming*complex*subcellular*structures*
-Basic*Amino*Acid*structure:*
-Each*amino*acid*has*an*amino*group*(NH3+)*and*a*carboxylate*acid*group*
(COO-)*
-Each*amino*acid*has*a*different*side*chain*[R]*
-20*different*amino*acids*found*in*proteins*
-Peptide*Bonds*
-Formed*by*reaction*between*the*amino*group*of*one*amino*acid*and*the*
carboxylate*group*of*another*amino*acid*
-Condensation*involves*removal*of*H2O*from*the*units*being*linked*
-Hydrolysis*regenerates*the*original*carboxylic*acid*and*amino*group*
-The*C=O*group*of*the*amide*is*the*point*of*weakness*allowing*H2O*attack*
-Large*numbers*of*amino*acids*can*be*linked*together*to*form*a*peptide*chain*
-The*combination*of*different*side*chains*R*are*what*gives*each*protein*its*
unigue*properties*
-There*are*153*amino*acids*in*myoglobin*(16.5*kDa)*
-There*is*an*amino*terminal*end*(N*terminus)*and*a*carboxyl*terminal*end*(C*
terminus)*
-Amino*acid*side*chain*structures*
-Carbon*atoms*of*the*amino*acid*core*are*identified*with*Greek*letters*
-The*alpha*carbon*is*the*central*backbone*atom*
-The*side*chain*then*gets*the*following*carbon*Greek*letters*(beta,*gamma,*
delta,*epsillon)*
-The*B-carbon*is*the*first*atom*of*the*side*chain,*the*y-*carbon*is*the*second*
etc…*
-Functional*groups*may*be*linked*to*different*core*atoms:*
-a-amino*
-e-amino*
-The*20*natural*amino*acids*
find more resources at oneclass.com
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-Amino*acids*share*a*common*backbone,*but*differ*in*side*chain*
-You*need*to*be*able*to*reproduce*the*structures*of*the*amino*acids*and*know*
their*1-*and*3-*letter*codes*
-You*need*to*be*able*to*associate*particular*properties*with*each*amino*acid*
-Polarity*
-Charge*
-Hydrogen*Bonding*Ability*
-Amino*acids*can*be*grouped*according*to*structures*or*by*similar*properties*
-Amino*acids*with*very*non-polar*side*chains*
-Ala,*Val,*Leu,*Ile,*Met,*Phe*
-The*side*chains*are*dominated*by*hydrocarbon,*and*consist*of*C-C*and*C-H*
bonds*
-Hydrocarbon*is*non-polar*and*hydrophobic*
-Polar*and*non-polar*properties**
-Polarity*is*a*consequence*of*atoms*having*different*electronegativity*or*
tendency*to*hold*bonding*electrons*
-Atoms*with*similar*electronegativity*share*bonding*electrons*equallly*eg.*C-C,*
C-H*and*are*non-polar*
-Pairs*of*atoms*with*different*electronegativity*distribute*electrons*unequally*
and*this*leads*to*unbalanced*charges*and*polar*bonds*
-Moderately*non-polar*amino*acids:*
-Gly,*Cys,*Pro,*Tyr,*Trp*
-Glycine:*has*single*H*atom*as*side*chain,*not*enough*to*be*very*non-polar*
-Hydrophobicity*is*related*to*the*number*of*CH,*CH2*or*CH3*groups*
present*
-Cysteine*contains*the*slightly*polar*SH*group*
-Proline*is*unique*because*the*side*chain*links*to*a-N*as*well*as*to*a-C.*The*
polar*N*moderates*the*non-polar*hydrocarbon*
-Tyrosine*has*a*single*non-polar*group*that*partly*offsets*the*very*non-polar*
benzene*ring.*Trytophan*behaves*similarly.*
-Amino*acids*with*polar*uncharged*side*chains*
-Ser,*Thr,*Asn,*Gln*
-Serine*and*Threonine*have*side*chains*that*include*the*polar*hydroxyl*group*-
OH*
-Asn*and*Gln*both*contain*the*polar*amide*group*
-These*side*chain*groups*do*not*gain*or*lose*H+*in*aqueous*solution*at*pH*7,*so*
they*are*uncharged*
-All*four*side*chains*act*as*good*electron*donors*or*acceptors*
-Hydrogen*bonds*are*electrostatic*attractions*between*a*H-bond*donor*and*acceptor*
-The*hydrogen*bond*is*about*5-10%*as*strong*as*a*covalent*bond,*enough*to*
make*molecule*R1*stick*loosely*to*R2*but*not*to*form*a*permanent*link*
-Positively*charged*side*chains*
-His,*Lys*and*Arg*
-These*side*chains*contain*weak*bases*that*gain*H+*(become*protanated)*and*
so*are*positively*charged*in*aqueous*solution*at*neutral*pH*
-Charge*makes*them*very*polar,*overriding*the*non-polar*hydrocarbon*chain*
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Myoglobin is a protein that stores o2 in muscle tissue. 1 dalton (da) = 1 g/mol (mass of h atom) Amino acids are joined with amide bonds to from a protein. Linked by peptide bonds (type of amide bond. Each amino acid has an amino group (nh3+) and a carboxylate acid group (coo-) Each amino acid has a different side chain [r] Formed by reaction between the amino group of one amino acid and the carboxylate group of another amino acid. Condensation involves removal of h2o from the units being linked. Hydrolysis regenerates the original carboxylic acid and amino group. The c=o group of the amide is the point of weakness allowing h2o attack. Large numbers of amino acids can be linked together to form a peptide chain. The combination of different side chains r are what gives each protein its unigue properties. There are 153 amino acids in myoglobin (16. 5 kda)
