513 AAMC exam wrong answers Flashcards
The relative thermodynamic stability of isomeric organic compounds can be inferred from which of the following types of experimental data?
A.Boiling points
B.UV–visible absorption spectra
C.Mass spectroscopic fragmentation patterns
D.Heats of combustion
D- because the relative thermodynamic stability of isomers can be determined based on the amount of heat produced when the compounds are combusted; less heat, greater stability
- this is more accurate than BP
Radioactive tritium (3H) labelled guanine has been used to measure the rate of biochemical processes that involve its binding or incorporation.
Guanine
Given that water is the solvent for this type of experiment, what is the best site for tritium labelling?
A.I
B.II
C.III
D.IV
The answer to this question is A because the best site for tritium labelling would not exchange the tritium ions for protons in water. All of the N−H sites (II−IV) would readily exchange tritium protons due to their lone pair-facilitating protonation and subsequent tritium exchange with water, but the C−H site (I), lacking a lone pair, would retain its tritium label.
iodine vs iodide
iodine –> 2 together - naturally occurring state
iodide–> in the ion form (I-)
I-
iodide
I2
iodine
The pH of a 1 L phosphate buffer solution was measured as 7.6, but the experimental procedure calls for a pH 7.2 buffer. Which method will adjust the solution to the proper pH? (Note: The pKa values for phosphoric acid are 2.2, 7.2, and 12.3.)
A.Add enough 1 M Na2HPO3 to increase the phosphate anion concentration ten-fold.
B.Add 1 M NaOH to neutralize a portion of the hydronium ions found in the solution.
C.Alter the ratio of monosodium/disodium phosphate added to favor the monosodium species.
D.Add 100 mL distilled, deionized water to dilute the basicity of the buffer.
The answer to this question is C because, in order to lower the pH of a buffer, the proportion of acidic buffer component must be increased. Adding strong base, diluting with water, or adding a different basic salt will not lower the pH. It is a Reasoning about the Design and Execution of Research question because you reason about the appropriateness of a specific experimental change in order to conduct research in the natural sciences.
Which experimental condition is NOT necessary to achieve reliable data for Michaelis–Menten enzyme kinetics?
A.Initial velocity is measured under steady state conditions.
B.Solution pH remains constant at all substrate concentrations.
C.The concentration of enzyme is lower than that of substrate.
D.The reaction is allowed to reach equilibrium before measurements are taken.
D, because once the reaction reaches equilibrium, measurement of Vo will be impossible and the kinetic data will look the same regardless of substrate concentration. Hence, response D is not necessary (nor desirable) to achieve reliable data for Michaelis−Menten enzyme kinetics. In contrast, Distractors A−C are essential to obtain reliable Vo versus substrate concentration data to calculate KM and Vmax using Michaelis−Menten enzyme kinetics
“what should you do to achieve undesirable results”
heme structure
heme is a porphyrin
- the basic unit of a porphyrin is a pyyrole ring (5 sided ring with one N
hydroxylation
hydroxylation is (organic chemistry) the introduction of a hydroxyl group into a molecule, especially by the replacement of a hydrogen atom
- oxidation
hydrolase
break apart with water
ligase
a ligase is an enzyme that can catalyze the joining of two large molecules by forming a new chemical bond, usually with accompanying hydrolysis of a small pendant chemical group on one of the larger molecules or the enzyme catalyzing the linking together of two compounds
volume flow rate
Q= A x Velocity
list periodic groups from left to right
alkaloid metals, alkaline earth metals, transition metals, halogens, noble gases
fluid pressure formula (NEED TO KNOW THIS)
pgh
density - g - h
if specific gravity is given and i need its desity what do I do?
specific gravity means it is that many times larger then the density of water
so if sg= 13.6
then density of that fluid is 13.6 x density of water (1000kg/m^3)
density of water
1g/cm^3
1g/ml
1000g/L
1000 kg/m^3
rote memorization
Rote memory generally entails memory for material without much reference to the meaning, emotions, or to the context to which it is associated. The major practice in rote memorization is learning by repetition or routine, without full comprehension or attention to what is being memorized.
rote memorization
Rote memory generally entails memory for material without much reference to the meaning, emotions, or to the context to which it is associated. The major practice in rote memorization is learning by repetition or routine, without full comprehension or attention to what is being memorized.
imprinted gene
Imprinted genes are genes whose expression is determined by the parent that contributed them.
Imprinted genes violate the usual rule of inheritance that both alleles in a heterozygote are equally expressed.
Examples of the usual rule:
If a child inherits the gene for blood group A from either parent and the gene for group B from the other parent, the child’s blood group will be AB.
If a child inherits the gene encoding hemoglobin A from either parent and the gene encoding hemoglobin S from the other parent, the child’s red blood cells will contain roughly equal amounts of the two types of hemoglobin.
But there are a few exceptions to this rule. A small number of genes in mammals (~100 of them at a recent count) and in angiosperms have been found to be imprinted. Because most imprinted genes are repressed, either
the maternal (inherited from the mother) allele is expressed exclusively because the paternal (inherited from the father) allele is imprinted or vice versa.
example of an imprinted gene
- IGF2
— the gene encoding the insulin-like growth factor-2 In humans (and other mammals like mice and pigs) the IGF2 allele inherited from the father (paternal) is expressed; the allele inherited from the mother is not.
If both alleles should begin to be expressed in a cell, that cell may develop into a cancer.
Barr body
Human females inherit two copies of every gene on the X chromosome, whereas males inherit only one (with some exceptions: the 9 pseudoautosomal genes and the small number of “housekeeping” genes found on the Y). But for the hundreds of other genes on the X, are males at a disadvantage in the amount of gene product their cells produce? With some exceptions (see below), the answer is no. This is because females have only a single active X chromosome in each cell.
During interphase, chromosomes are too tenuous to be stained and seen by light microscopy. However, a dense, stainable structure, called a Barr body (after its discoverer) is seen in the interphase nuclei of female mammals. The Barr body is one of the X chromosomes. Its compact appearance reflects its inactivity. So, the cells of females have only one functioning copy of most (see below) of the X-linked gene — the same as males.
X-chromosome inactivation occurs early in embryonic development. In a given cell, which of a female’s X chromosomes becomes inactivated and converted into a Barr body is a matter of chance (except in marsupials like the kangaroo, where it is always the father’s X chromosome that is inactivated). After inactivation has occurred, all the descendants of that cell will have the same chromosome inactivated. Thus X-chromosome inactivation creates clones with differing effective gene content. An organism whose cells vary in effective gene content and hence in the expression of a trait, is called a genetic mosaic.
What is meant by maternal imprinting or paternal imprinting
Maternal imprinting means that the allele of a particular gene inherited from the mother is transcriptionally silent and the paternally- inherited allele is active. Paternal imprinting is the opposite; the paternally-inherited allele is silenced and the maternally-inherited allele is active.
imprinted gene = silenced
flashbulb memory
subjectively vivid, compelling memories of details associated with reception of news about emotionally arousing events were referred to as flashbulb memories
highly detailed, exceptionally vivid ‘snapshot’ of the moment and circumstances in which a piece of surprising and consequential (or emotionally arousing) news was learned about.
what causes flashbulb memory
highly emotional state or arousal
reproductive memory
- recall that is hypothesized to work by storing the original stimulus input and reproducing it during recall
- accurate
- stores encoded information to be retrieved at a later time.
However, this type of memory is subject to errors of constructive memory or reconstructive memory.
reconstructive memory- is a theory of memory recall, in which the act of remembering is influenced by various other cognitive processes including perception, imagination, semantic memory and beliefs, amongst others.
recall is influenced by that persons beleifs, culture, cognition and during recall person may fill in the gaps using their knowledge, goals, logic
prospective memory
is a form of memory that involves remembering to perform a planned action or recall a planned intention at some future point in time. Prospective memory tasks are common in daily life and range from the relatively simple to extreme life-or-death situation
reconstructive memory
refers to the idea that remembering the past reflects our attempts to reconstruct the events experienced previously.
refers to a class of memory theories that claim that the experience of remembering an event involves processes that make use of partial fragmentary information as well as a set of rules for combining that information into a coherent view of the past event.
remember to tell dad to take his pain meds tmrw is an example of what type of memory
prospective memory
episodic memory
is a category of long-term memory that involves the recollection of specific events, situations, and experiences. Your memories of your first day of school, your first kiss, attending a friend’s birthday party, and your brother’s graduation are all examples of episodic memories.
semantic memory
recall of general facts
Semantic memory is recall of general facts, while episodic memory is recall of personal facts. Remembering the capital of France and the rules for playing football uses semantic memory. Remembering what happened in the last game of the World Series uses episodic memory.
procedural memory
long-term memory that is responsible for knowing how to do things, also known as motor skills. As the name implies, procedural memory stores information on how to perform certain procedures, such as walking, talking and riding a bike.
iconic memory
is part of the visual memory system which also includes long-term memory and visual short-term memory. Iconic memory is a type of sensory memory that lasts just milliseconds before fading. The word iconic refers to an icon, which is a pictorial representation or image.
shorter than echoic memory