Biochem Exam 1 Flashcards
What does Carnitine do?
Carries fatty acids into the mitochondria
What is sickle cell anemia?
a genetic disorder of the blood
In a conjugated protein, a prosthetic group is what?
a) a fibrous region of the globular protein
b) a nonidentical subunit of a protein with many identical subunits
c) a part of the protein that is not comprised of amino acids
d) a subunit of an oligomeric protein
e) synonymous with “protomer”
a part of the protein that is not composed of amino acids
The secondary structure of most fibrous proteins consists of:
a) beta sheet only
b) alpha helix only
c) beta sheet only or alpha helix only
d) beta sheet and alpha heliz in alternating arrangment
e) beta sheet and alpha helix randomly arranged
beta-sheet only or alpha helix only
How many water molecules are released when a pentapeptide is synthesized from a free amino acid?
4 (4 peptide bonds)
Fe2+ is protected from _________ by surrounding nitrogen atoms in the prrole ring strucutre of heme and a nitrogen atom of a histidine.
Oxidation
The interaction of ligands with proteins
a) results in the inactivation of proteins
b) is nonspecific
c) is rare in biological systems
d) is nonreversible
e) is temporary
is temporary
Which of the points (A-E) depicted below is Kd
C
The pKa values of the depicted amino acid are:
pK1 = 2.17
pK2 = 9.04
pKR = 12.48
The pI of the amino acid is:
10.76
The name of the depicted amino acid is:
CH2-CH2-CH2-CH2-NH3
a) lysine
b) arganine
c) asparagine
d) glutamine
e) phenylalanine
lysine
The heme part in myoglobin is the:
a) product
b) prosthetic group
c) substrate
d) ligand
e) allostatic effector
prosthetic group
The depicted formula shows a(n):
R1 - S - S - R2
disulfide
What functional groups are present on this molecule?
O
|| CH2 - CH2 - C - H | OH
hydroxyl and aldehyde
The depicted molecule is a(n):
R1 - C - O - C - R2
|| ||
O O
anhydride
A: Tyr.Lys.Met
B: Gly.Pro.Arg
C: Asp.Trp.Tyr
D: Asp.His.Glu
E Leu.Val.Phe
Which tripeptide has a tyrosine at its C terminus?
A
A: Tyr.Lys.Met
B: Gly.Pro.Arg
C: Asp.Trp.Tyr
D: Asp.His.Glu
E Leu.Val.Phe
Which one will have the greatest light absorbance at 280nm?
C
A: Tyr.Lys.Met
B: Gly.Pro.Arg
C: Asp.Trp.Tyr
D: Asp.His.Glu
E Leu.Val.Phe
Which one is best suited for hydrophobic interactions?
E
In sickle cell anemia, _________ is replaced by ________ in subunit beta
a) hydrophilic glu; hydrophobic val
b) hydrophilic val; hydrophobic glu
c) hydrophobic glu; hydrophobic val
d) hydrophobic val; hydrophilic glu
hydrophilic glu; hydrophobic val
What is the most likely weak interaction between the R groups of valine and alanine in an aqueous solution?
a) hydrolysis
b) hydrogen bonding
c) ionic interaction
d) hydrophobic interaction
e) condensation
hydrogen bonding
Which of the following statements is false?
1) Mb has one oxygen-binding site, whereas Hb has 4
2) Mb is a monomer and Hb is an oligomer
3) Mb oxygen binding curve is sigmoid while the one of Hb is hyperbolic
4) Mb is smaller than Hb
5) Mb and Hb have function of binding oxygen
Myoglobin’s oxygen binding curve is sigmoid while the one of hemoglobin is hyperbolic
Which of the following is not a pair of diastereomers?
A nd C
The main stabilizing force in alpha-helices is ___________________?
hydrogren bonding
Two amino acids of the standard 20 contain sulfur atoms, they are:
Methionine and cysteine
Changing the shape of a molecule by rotating functional groups around a single bond, without breaking it leads to:
conformation change
The formation of a peptide bond is a ____________
a) weak interaction
b) hydrolysis
c) condensation
d) non-covalent bond formation
e) none of the above
condensation
The graph below shows 3 oxygen-binding curves.
Which one is the fetal hemoglobin O2-binding curve
Curve A: Kb=21
Curve B: Kb=27
Curve C: Kb=35
B - Curve B
The chirality of an amino acid results from the fact that its alpha-carbon:
is bonded to four different chemical groups
_________ is/are (a) covalent stabilizing force(s) in the tertiary/ quaternary structure of many proteins.
a) hydrogen bonding
b) disulfide bonds
c) hydrophobic interactions
d) ionic interactions
disulfide bonds
Oxygen is a(n) ______ of hemoglobin
ligand
The functional group between R1 and R2 in the depicted compound is a(n) ___________
R1 - C - O - R2
||
O
Ester
The charge of aspartate (pK1= 1.88, pK2= 9.6, pKR= 3.65) at pH 12 is _____.
-1
The name of the amino acid #1 in the depicted oligopeptide is ______________
Tyrosine
The depicted amino acid has a(n) ______________ R-group
uncharged polar
Some of the typical symptoms of sickle cell anemia are signs of ________
lack of oxygen supply to the body
Which of the following is NOT a fibrous protein?
a) alpha-Keratin
b) Silk fibroin
c) Collagen
d) Insulin
Insulin
Which of the following involve a double bond?
a) cis/ trans isomers
b) Enantiomers
c) Diastereomers
d) Anomers
cis/ trans isomers
Which of the following makes the oxygen-binding curve of hemoglobin less sigmoid and this increases hemoglobins affinity for oxygen
a) more protons
b) climbing the matterhorn
c) carbon monoxide
d) iron deficiency
Climbing the Matterhorn
Which modification step of tropocollagen synthesis is dependent on vitamin C?
a) hydroxylation
b) glycosylation
c) disulfide bond formation
d) removal of C- and N- termini
Hydroxlation
Which of the following are considered ligands and have an allosteric effect on hemoglobin, which leads to a change in affinity for O2?
1) O2
2) BPG
3) CO
4) Heme
1,2,3
In titration curves, pKa values are determined by finding the pH values that correspond with _______ and the label of the y-axis is _________
a) endpoints; pH
b) endpoints; equivalents (or mL) OH-
c) midpoints; pH
d) midpoints; equivalents (or mL) OH-
midpoints; pH
Name the two covalent (enzyme-catalyzed) modification steps that occur in the rough endoplasmic reticulum and briefly explain why these modifications lead to better/ stronger collagen.
Hydroxylation: additional -OH –> increased H bonding
Glycosylation: Increase in -OH for increase H-bonding
How does the body adjust to high altitudes (low oxy supply)? Give what occurs in the given timeframe, as well as the effect of what occurs.
Short term (24hrs):
Long term (few weeks):
Short term: Increase in BPG, result is lowering of O2 affinity of Hb, results in increase in O2 available to tissues
Long term: Increase in RBCs, results in increase of # of O2-binding sites, leads to delivery of needed amount of O2, even with lower saturation in lungs
Draw the general strucutre of alpha-L-amino acids (Fischer Projection) under physiological conditions
COO-
|
H3N+ – C – H
|
R
Graph showing Lung and Tissue Titration Curves
The pH in the blood affects Hb affinity for O2
a) In the graph, label the oxygen-binding curve of the pH in the lungs and the pH in the tissues (use ‘lungs’ and ‘tissue’ as labels)
Lungs are top curve
Tissue is bottom curve
Graph showing Lung and Tissue Titration Curves
The pH in the blood affects Hb affinity for O2
b) Explain what the cause for the pH change is between the lungs and the tissue (this is not dependent of the function of Hb).
It is caused by cellular respiration: the production of CO2 in the tissue.
Graph showing Lung and Tissue Titration Curves
The pH in the blood affects Hb affinity for O2
c) The pH affects the function of Hb. Explain how that happens (hint: since the function is changing, the structure must be changing).
Changes in pH affect O2s affinity for Hb, structural changes occur due to protonation and deprotonation.
When pH lowers deprotonation occurs and O2 affinity for Hb goes down.
When pH rises protonation occurs and O2 affinity for Hb goes up.
Graph showing Lung and Tissue Titration Curves
The pH in the blood affects Hb affinity for O2
d) Explain how the effects of the pH changes allow for the tissue to receive more oxygen compared to if the pH was steady throughout the body.
The lungs have a higher pH which means the O2 affinity in the lung tissue is very high. This means almost full O2 saturation in lung tissue.
The tissues have a lower pH which means the O2 affinity in the tissues is lower. So, Hb binds less O2 and that makes more O2 available for use in the tissues.
