FLE Missed Flashcards
(128 cards)
Which statement is NOT true of PRIONS?
- They can be inherited
- They convert normal proteins into pathogenic proteins
- They can cause pathology in nearly every organ of the body
- They can be acquired through consumption of contaminated food
4
The correct answer is 4 because pathology is only observed in the CNS of the infected person or animal
Although prion infections are usually associated with consumption of contaminated meat, they also can be inherited and encoded in a person’s DNA
Prions convert normal proteins of the brain into pathogenic ones
This conversion is exponential and does take years to decades to complete
Which of the following bacterial populations would have the greatest size after 24 hours?
A) 10 cells with a doubling time of 8 hours
B) 100 cells with a doubling time of 12 hours
C) 1 cell with a doubling time of 2 hour
D) 1000 cells with a doubling time of 24 hours
C
- C is the correct answer since in a 24 hour period it will have 12 doubling times if it doubles every 2 hours*
- Therefore 1 cell will grow exponentially to* 4096 cells
- Answer A will have 4 doubling times in 24 hours. 10 cells will grow to 20, then 40, then 80, and finally 160
- Answer B will only have 2 doubling times in its 24 hour period. 100 cells will double to 200 and then to 400 cells
- Lastly, answer D will only double once in a 24 hour period resulting in 2000 cells.
Which event is an example of bacterial conjugation?
- A) A virus transferring the DNA for a toxin from Shigella dysenteriae to Escherichia coli
- B) The lysing of Escherichia coli cells and the DNA being picked up by Shigella dysenteriae
- C) The passage of RNA from Staphylococcus aureus cells to another strain of Staphylococcus aureus through a pilus
- D) The passage of DNA from Escherichia coli to Shigella dysenteriae through a pilus
D
- D is the correct answer because the definition of bacterial conjugation is the passage of foreign DNA through a pilus*
- pilus =a hairlike appendage found on the surface of many bacteria*
- Answer A describes transduction, which is the movement of foreign DNA from one cell to another via a phage
- Answer B is describing transformation, which is the picking up of naked DNA from the environment
- Answer C is also describing the passage of nucleic acid through a pilus, but only DNA is passed and not RNA

An increase in CHOLESTEROL has what impact on the plasma membrane?
A) increased membrane fluidity
B) increased solute transport across the membrane
C) decreased membrane fluidity
D) decreased solute transport across the membrane
A

- This question is asking you to recall knowledge about the fluid mosaic model (see pic)*
- Cholesterol is an important part of plasma membranes*
- It adds vital fluidity by disrupting the stacking of the lipid tails forming the membrane*
- By disrupting the stacking, the lipids can move more freely, and other molecules, such as trans-membrane proteins, can move about*
- C is incorrect because cholesterol is adding fluidity, not decreasing it
- B and D are incorrect because cholesterol does not impact solute transport across membranes
- However, you can also reach the answer rationally by looking at the figure of cholesterol and imagining how it might look within the lipid bilayer*
- It is very hydrophobic, so it will interact with the lipid tails, but it is also made of multiple planar rings, so it will not stack neatly with the long carbon chains*
- Since it doesn’t fit neatly into the membrane, it will increase movement.*
Based on the data in Figure 2, what is a normal cellular progesterone level?

A) 0.19 ng/ml
B) 0.36 ng/ml
C) 38 ng/ml
D) 0.38 ng
B

- The “normal” cells for this experiment are tested in the first lane, without cAMP or CCCP added*
- From the information given in Experiment 1, you can see that progesterone is labeled P4, which tells you that the chart above the graph has the data about progesterone concentration*
- For lane 1, the progesterone level is 0.3 +/- 0.1 ng/ml, giving you a range of 0.2-0.4 ng/ml*
A is incorrect because 0.19 ng/ml is outside that range
C is incorrect because 38 ng/ml is too large
This might be distracting, however, if you assume that the bar graph is telling you the progesterone concentration, since the bar for lane 1 is at approximately 38
Make sure when looking at a figure that gives multiple types of data that you know which data is coming from where
D is incorrect because 0.38 ng is not a concentration, it is merely a mass
H2O2 vs O2
Bond STRENGTH roughly correlates with bond….?
ORDER!
O2 is (+2)
H2O2 is (+1)
Therefore O-O bond in O2 is stronger
“Chelation”=?
“Chelation” describes a particular way that
ions and molecules
bind METAL IONS
Specifically: involves the formation or presence of two or more separate coordinate bonds between a multiple-bonded ligand and a single central atom

WHAT is the primary type of attraction that:
facilitates complimentary base pair matching?
What other kind of attraction can occur if this primary type is present?
H-bonding
is the primary type of attraction that facilitates complimentary base pair matching
Van der Waals attraction will also occur if molecules are hydrogen bound.
What is the synthetic purpose of the thermal decomposition of azobisisobutyronitrile (AIBN) in Step 2a?
- A) two tertiary free radicals for the functionalization of CRGO in Step 2b
- B) radical cations for the nucleophilic attack of CRGO in Step 2b.
- C) a stable diatomic nitrogen molecule.
- D)heat, to increase reaction rate.

A
A correct; tertiary radicals are most easily formed
- B is incorrect; the radicals formed are neutral
- C the byproducts are irrelevant to the further reactions
- D Branched vs. unbranched carbon chains presents no strong advantage to subsequent steps nor to the function of the biosensor.
In which solvent is P4 LEAST soluble?

A) H2O
B) CH3CH2OH
C) CH3COCH3
D) C6H6
A
- P4 is nonpolar; all bond dipole moments “cancel” each other out
- Water should be immediately recognized as the most polar of all solvents in choices A-D, and hydrocarbons as the least polar
- Alcohols are of intermediate polarity
- Answer C is a ketone, which is relatively non-polar, but more polar than benzene, Answer D
Therefore, the most polar, and therefore LEAST likely to dissolve P4 among the choices listed is water, Answer A
What are the most likely sources of human dietary PHOSPHORUS?
A)protein and hydroxyappetite
B)protein and amino bisphosphonate
C)DNA and RNA
D)phosphoric acid and calcium
C
- Nucleic acids are dietary sources of phosphorus due to the presence of the phosphate backbone*
- RNA and DNA are nucleic acids*
- Although “Diets rich in protein and calcium” were mentioned as diets that would likely meet phosphorus requirements, protein and calcium do not themselves contain any phosphorus
- A is incorrect because proteins do not contain phosphorus
- there are no biological amino acids that incorporate protein
What is the EMPIRICAL formula for HYDROXYAPATITE?
Ca5(PO4)3OH
A) Pi electrons of the phenyl ring and the tertiary hydrogen
B) Pi electrons of the cyclohexenyl ring and the methyl group
C) Hydroxyl groups, epoxide oxygen lone pairs, and nitrogen lone pair
D) Only the lone pairs of the epoxide oxygen

C
- For complex formation between a molecule and an antigen binding fragment, or for almost any binding interaction described in biochemistry, the interactions are intermolecular in nature*
- In other words, the process is not breaking and forming new covalent bonds, but causing attractions between molecules to hold them into a binding site*
- Further, hydrogen bonding is the most widely used and strongest of the intermolecular forces
- There are four locations on morphine that can participate in H-bonds:
- the two hydroxyl groups (donors or acceptors)
- the lone pair on the epoxide oxygen (H-bond acceptor only)
- the lone pair on nitrogen (H-bond acceptor only)
In which concentration range would the paper-based lateral-flow test strip be most effective as a quantitative tool for predicting blood morphine levels based on test line intensity?
A) 1.0 – 100 ng/mL
- because the color intensity is highest over this range
B) 1.0 – 100 ng/mL
- because the difference between test and control line intensities is positive and has the greatest magnitude
C) 0.1 – 1.0 ng/mL
- because over this range the control test line color intensity is the most consistent
D) 0.1 – 1.0 ng/mL
- because over this range the intensity vs. morphine concentration plot has the greatest slope

D
- For a test to be a good candidate for quantitative measurements, (as opposed to qualitative test where the goal is to determine “morphine present” or “morphine absent”)
- the observable response must:*
_VARY SUBSTANTIALLY_ and in a CONSISTENT DIRECTION
In the 0.1 to 1.0 ng/mL region:
- the relative color intensity increases from about 1 to 25 in near-linear fashion
- ΔYaverage per ΔX can be estimated to see that this range has a large slope compared to the other regions.
- If a sample is analyzed and the line intensity registers a relative color intensity of 15, what is the approximate molarity of morphine in the sample?*
- The molecular formula of morphine is C17H19NO3*
- HINT: MW=285 g*
A) 2.4 × 10–12 M
B)2.5 × 10–9 M
C) 2.4 × 10–6 M
D) 1.1 × 10–9 M

B
- In Figure 4, a relative color intensity of 15 corresponds to a morphine concentration of 0.7 ng/mL*
- If one round 285 grams to 3 x 102 grams, the calculation becomes:
(7 x 10-1 ng/mL)
X (1 g/ 109 ng)
X (1 mol/3 x 102 g)
X (1 x 103 mL/L)
= 2.33 × 10–9 M
See picture

∆G’ = ∆G°’ + RTln [Products]/[Reactants]
=0.4 + (8.31)(310)(ln[0.01])
A PEPTIDE BOND differs from
most OTHER chemical bonds in that it features….?
What does this feature PREVENT?
RESONANCE between the C-O and C-N bonds

PREVENTING
FREE
ROTATION!!!
When a SPRINTER is running:
What is the SOURCE of the work done to accelerate Sprinter?
The GROUND is doing work on the SPRINTER
By definition, the force doing work on an object must be a force ON the object
- The GROUND is exerting a force ⇒ runner*
- Runner’s LEGS are exerting a force ⇒ ground*
A certain medical device converts the KE of high-velocity metal beads into HEAT energy
If 100% conversion efficiency were possible:
What MAXIMUM theoretical heat energy can be produced by a single chromium bead with:
- a VOLUME of 1.0 x 10-4 cm3
- a VELOCITY of 2.0 x 104 m/s?
(Density of Cr = 7,140 kg/m3)
1.4 x 102 J
Begin with the formula KE = 1/2mv2
- Density = mass/volume
- so mass = density*volume
- Substituting mass into the first equation we get:
KE = (0.5)(density)(volume)(velocity)2
However!!
- Volume is given in cm3
- and must be converted to m3
Using dimensional analysis:
1x10-4 cm3 x (1m/100cm)3
= 1.0 x 10-10 m3
Now one can simply solve:
=½(7.1 x 103 kg/m3)(1.0 x 10-10 m3)(2.0 x 104m/s)2
This simplifies to:
= (3.5 x 103)(1 x 10-10)(4.0 x 108)
- = (3.5 x 10-7)(4.0 x 108)
- = 14 x 101
- = 1.4 x 102 Joules
- = 14 x 101
For an acid-base equilibrium at
CONSTANT TEMPERATURE:
which of the values listed is CONSTANT?
A) pH
B) Concentration of the conjugate base
C) Concentration of the weak acid
D) pKa
D
pKa is the ONLY constant among the answers
The acid-base equilibrium constant, Ka, is a constant for a GIVEN REACTION at a GIVEN TEMPERATURE
…Therefore the negative log of that constant would ALSO be a constant!
The pH of the solution is dependent on the concentration of acid and base in the equilibrium
- making Answer A incorrect
The concentration of both the acid and the conjugate base can VARY depending on the reaction
- making both Answer B and C incorrect
Titrating aqueous AMMONIA with HCl
would produce a titration curve that looks like WHAT?
- Hydrochloric acid is a STRONG acid,*
- while ammonia is a WEAK base*
Because the titration starts out with
just the weak base present:
we need a plot that starts out basic, but not strongly basic

In the synthesis of tri-substituted oxazolidines the ACETYLENE acts as a:

A) Bronsted acid
B) Bronsted base
C) Lewis acid
D) Lewis base
C
The acetylenes contain an electron-deficient pi-systems making the double bond ELECTROPHILIC and susceptible to nucleophilic attack
“During normal growth, SOS pathway genes are repressed by LexA, which binds to the SOS box in the operator on either the coding strand or the template strand of the gene”
Q: The nucleotide sequence of the SOS box is most likely:
A) GAACGTTC
B) TATAAA
C) TAGTTGAT
D) GCGCCC
A
- In the passage, it was stated that LexA can bind to either the coding strand or the template strand of the SOS box
This tells you that the SOS box must be a PALINDROME!
- Remember that DNA sequence palindromes read the same 5’-3’ on BOTH sides
In answer A, 5’- GAACGTTC- 3’
the compliment strand is 3’ –CTTGCAAG- 5’
…which is IDENTICAL when read 5’-3’
- Suppose a person holds a mass m in their hand*
- with their elbow bent and their forearm*
- in a neutral horizontal position*
- If both muscle groups are flexed simultaneously, the system will be in equilibrium when the triceps muscle group exerts a force equal to:*
A) exactly 80m
B) one-half the force exerted by the biceps muscle group.
C) twice the force exerted by the biceps muscle group.
D) less than twice the force exerted by the biceps muscle group

D
When a person holds a mass steady with a bent elbow, the forearm is PREVENTED from moving either up or down
The MASS also acts DOWN on the forearm
at a lever arm of 40cm
The forearm itself has mass!
which can be assumed to act downward at approximately the center of the forearm
Therefore the bicep must counteract:
- the torque due to the weight of the mass
- torque due to the weight of the forearm itself
- whatever force/torque the tricep is exerting
- Therefore, when in equilibrium the tricep must be exerting LESS than twice the force of the bicep—
due to the co-directional torque resulting from mass m























