AAMC Science Material Flashcards
How much charge is stored in a Farady?
one mole of electric charge
What is true of valence electrons in insulators?
they are tightly bound
What does it mean when two atoms are isoelectric?
they have the same number of electrons
How can you increase the solubility of a substance with a basic anion?
add acid
the H+ ions will neutralize the anion, making solubility more likely
How can you find the number of possible gametes for a diploid organism?
2 raised to the haploid number
Haploid number
described a single set of chromosomes
the haploid number of humans is 23
Is the release of epinephrine and norepinephrine mediated by the pituitary gland?
no
What is bone made up of?
Calcium, phosphate and hydroxyl groups
How do Southern blots work?
they have to disrupt a palindromic sequence
Palindromic sequence
5’ to 3’ is identical on both ends
What type of molecule is a spingomyelin?
a phospholipid, specifically a phosphatide
What orbital has the highest energy in d-block elements
the 4s subshell has higher energy than the 3d subshelll
subshell energies switch in the d-block elements
What gives catalytic efficiency?
ratio of Kcat to Km
Where is phosphodiester bond?
between 3’ and 5’ carbons on ribose
Which end of DNA has a free phosphate group?
the 5’ end
What type of genomes do retroviruses have?
RNA
What is true of the mRNA transcribed from cDNA of a retrovirus?
it should be the same as the original RNA sequence from the retrovirus’s genome
Antisense strands
are read for RNA synthesis but are non-coding
How much does one amino acid weigh?
110 Da
Steps of a blotting procedure
prep
electrophoresis
transfer
stain
Hill coefficient
a measure of cooperativity
Hill > 1 indicates positive cooperativity
What do surfactants do?
decrease surface tension
What is the shape of a Michaelis-Menton curve?
hyperbolic
What is needed for a molecule to bind to an anion exchange column?
a net negative charge
Is the distribution of cytoplasm even in ova-producing cells?
no
make haploid polar bodies that are degraded
Isoforms
have different lengths of amino acid chains and can be formed by exons / splicing
What direction does the sense strand run?
in the 5’ to 3’ direction
Isoelectric focusing
a gel electrophoresis that requires a pH gradient
Does molecular geometry include lone pairs?
no, molecular geometry only looks at atoms
electron geometry looks at the arrangement of electron groups
How do boiling chips work?
they break the surface tension of the liquid being heated and prevent superheating
What allows for the color change of transition molecules?
unfilled d-orbitals
What type of ions are often used for affinity chromatography?
metal ions, specifically nickel
What do washes allow us to remove?
unbound substrates
What is the bouyant force?
pgV
Beta minus decay
electron is emitted
neutron is converted to a proton
Beta plus decay
positron is emitted
proton is converted to a neutron
How can you tell when an image is inverted?
m = -q/p
when m is negative, the image is inverted
What is the strength of a lens equal to?
1/f where f is measured in meters
What is the intensity of radiation proportional to?
the number of photons emitted
Can somatic mutations be inherited?
No, only germ line mutations can be inherited
Signal sequences
allow transmembrane and secreted proteins to enter the endomembrane system / the ER
chemiosmosis
movement of ions across a membrane down their electrochemical gradient
When does myosin bind actin?
after troponin binds calcium
What are lipid rafts composed of?
cholesterol and sphingomyelin
Telomeres
on the end of linear chromosomes to prevent shortening due to trouble replicating the lagging strand
Centromeres
in the middle of sister chromatids and made of heterochromatin
At a constant speed, what does work equal?
force times velocity
What must happen in order to measure the state of membranes?
the rate of the studied reaction must be faster than the time it takes a new membrane state to form
What rates are used when measuring kinetics?
initial rates
How to titrate a weak base?
dissolve in acid and neutralize with base
What do uncompetitive inhibitors bind to?
bind to the ES substrate which appears to decrease the Km
Km in noncompetitive inhibition
unaffected
Pull down assay
form of affinity ligand purification
Cytochrome c
an electron transporter that can transport one electron at a time
made of a heme group
What type of molecules determine cell differentiation?
nuclear factors since they determine protein transcription
When does Tm occur?
when 50% of molecules are denatured
What is the relationship between Vmax and Kcat?
Vmax = Kcat*[Et]
If Vmax significantly drops what happens to Km?
Km drops because you don’t need as much substrate to reach 1/2Vmax
What does pyruvate kinase do?
converts PEP to pyruvate and adds a phosphate to ADP
Does urine production increase with high or low BP?
urine production increases w high BP
Relationship of BP to flow rate
BP = Q*R
Venturi effect
lower area = higher velocity = lower pressure
How does vasoconstriction effect BP?
vasoconstriction reduces the volume of vessels and increases the resistance
the increase in resistance makes BP go up
Glycogen phosphorylase
catalyzes the rate limiting step in glycogenlysis
Is sound speed dependent on temperature?
sound will travel faster in a warmer room
Through what material does sound travel the fastest?
through solid materials
How many molecules of ATP do FADH2 and NADH produce respectively?
FADH2 - 2 ATP
NADH - 3 ATP
How many electron carriers are produced during kreb’s cycle?
3 NADH and 1 FADH2
What does absorption of UV light always do?
excites bound electrons
What does the energy of a photon equal?
the energy gap between the ground and excited state
Venturi effect
when pipe narrows, the velocity increases and the pressure decreases
Why do C-G base pairs make more stable DNA?
they increase pi stacking
Lewis base
electron donor
Lewis acid
electron acceptor
Coordinate ion complex bond
cation metal interacts with EDGs to make a coordinate covalent bond
When is blood flow heard?
when pressure is above diastolic but below systolic number
Diastolic and systolic BP
Diastolic BP: pressure in arteries when heart at rest
Systolic BP: pressure in arteries when heart contracts
Hess’s law
can add individual changes in enthalpy to find the overall enthalpy change
What is secondary protein structure determined by?
backbone elements
What happens in phagocytosis?
the phagosome fuses to a lysosome
Which channels open during depolarization?
Na+ channels
Which channels are open in absolute refractory period?
K+ channels
Ubiquitination
tags protein for destruction by a proteasome, does not require a lysosome
Prion
abnormally folded protein that causes aggregation
Microglia
macrophages specifically for the CNS
Oligodendrocytes
myelination in the CNS
Schwann cells
myelination in the PNS
Astrocytes
nutrition for the CNS
What do frameshift mutations often alter?
often alter the C-terminus since they affect everything after the mutation
Cytotoxic T-cells
bind directly to viral antigens
Lactic acid fermentation
NADH is oxidized to NAD+
pyruvate is reduced to lactate
Do prokaryotic cell membranes have cholesterol?
NO
Do prokaryotes undergo mitosis?
NO
How can you measure purification yield?
compare units from specific activity
Ternary complex
three different molecules bound together
Is protein denaturing cooperative?
yes
Precursors for gluconeogensis
glycerol, lactate/pyruvate, certain amino acids, oxaloacetate and odd chain FAs
What molecule does lipid synthesis require?
acetyl-CoA
What does reverse transcriptase PCR allow us to study?
specific levels of RNA
What type of solvents are wanted for SN1 and SN2?
SN1: polar protic
SN2: polar aprotic
Example of polar aprotic solvent
DMSO, DMF and acetone
PCC
weak oxidizing agent
Inert gases
Helium and nitrogen
If you just ate a salty meal, would you want more or less aldosterone?
less
do not need more Na+ in bloodstream
Do prokaryotes and eukaryotes have different ribosomes?
yes
eukaryotes are slightly larger
Nucleosides
lack phosphate group and are precursors to nucleotides
What does adrenal failure lead to?
lack of steroid hormones
For a thermodynamic mixture, which is the more stable product?
the product with a greater amount produced
What is the energy stored on a capacitor?
E = 1/2 CV^2
What can heat of combustion tell us?
relative thermodynamic stability
less heat = more stable
In order to use Michaelis-Menton what do you flood the system with?
flood the system with [S]
Relationship between resistivity and conductivity
inverses
pK
the pH where half of a protein is denatured
similar to the Tm
When pH is less than pI?
the species is positively charged
What do you want for aerobic respiration?
increased capillary density, mitochondria, and O2 affinity
Convergent evolution
two unrelated species develop similar traits in similar habitat
Divergent evolution
development of dissimilar traits in related species
diverging from a common ancestor
What type of enzymes are proteases?
hydrolases
use water to break peptide bonds
Lyases
break bonds by other means than hydrolysis or oxidation/reduction
Histone acetylation effects
loosens chromatin and increases transcription
Succinnate dehydrogenase
another name for complex II
Imprinted genes
genes are expressed in a parent specific manner
Where are striated muscles?
skeletal and cardiac muscles
Where are mononucleated muscles?
smooth and cardiac muscles
What does LH hormone trigger?
ovulation
What does estrogen do?
thickens endometrium and triggers the release of LH
What does hCG block?
LH in order to block ovulation
Electric force formula
F= qE
Why can you not continuously charge capacitors?
as more charge arrives it becomes harder and harder to fill the plates
Which species are capable of hydrogen bonding?
N, O and F
Why is water often omitted from equilibrium expressions?
it is essentially constant throughout the reaction
What is the standard temperature and pressure?
0ºC and 1 atm
How can you determine the volume of a gas?
need to look at the number of moles
the identity of the gas does not matter
Ionization constant
another name for Ka/Kb/Ksp
How can a blood clot affect pressure?
blood clots can increase hydrostatic pressure in the vessels and subsequently cause water to exit the vesselts
Would gamma rays be affected by a magnetic or electric field?
no since they do not possess charge
Formula for an electric field
E = kQ/r^2
Difference between primary and secondary oocytes
Primary oocytes are created through mitotic divisions and all present at birth
Secondary oocytes are created at puberty through meiosis
Antidueritic hormone
the same as ADH / vassopression
increases water retention
What can an increased glomerular filtration rate lead to?
increased urine output
What happens when glomerular BP drops?
the RAAS system is activated to increase BP
Paritoneal cavity
space within abdomen
Adaptive radiation
one species develops into multiple due to different environments
If you stir something and it gets hot what is true of the reaction?
it is exothermic
-OH group oxidation number
-1
What is 1atm equal to?
760 mmHg, 760 torr, 1*10^5 Pa
Do acid-base reactions change oxidation numbers?
no
How can you lower absorbance?
dilute the sample or decrease the path length
Relationship between a sensitization agent and drug
The sensitization agent should be administered before the drug
Where is a critical point on a pressure-temperature phase change diagram?
the critical point is at the end of the graph
What happens at critical point of pressure-temperature phase change diagram?
the liquid and gaseous phases blend into one
Lactone versus lactam
Lactone is an embedded ester
Lactam is an embedded amide
Lactonization
intramolecular esterfication that forms a lactone
What should you consider when a reducing agent or oxidizing agent is present in a reaction?
how they will effect carbonyl/alcohol groups before the reaction begins
Saponification
uses a strong base to break ester bonds and transform them into a salt
Carbamate
carbonyl with an oxygen and nitrogen attached
Random order enzyme
either substrate can bind first, the order does not matter
Ordered enzyme
one substrate binds before the other can
forms a ternary complex
Ping pong enzyme
one substrate binds and finishes its reaction before the other does
no ternary complex ever forms
Where do graded potentials happen?
graded potentials happen at cell body / dendrites
Where are Na+ and K+ voltage gated channels located?
the axon hillock
Cytochrome P450
oxidizes drugs to neutralize them
found in liver cells
Henry’s law
relates solubility to partial pressure
S = Kh * Pg
How do tRNAs move?
from A to P to E sites
Which amino acids can be phosphorylated?
S, T and Y
Gel filtration chromatography
separates molecules on size only
uses small beads with pores
Why do phosphate groups lower pI?
they are likely to donate H+ groups and make solution more acidic
Amber codon
a stop codon
Time for round trip of ball thrown vertically
t = 2v/g
Apoptosis
involves cell shrinkage not lysis
cells don’t want to lyse because it can damage nearby cells
Amino acid with lowest pI
arginine because it is the most acidic
Amino acid with highest pI
aspartate because it is the most basic
Slop of Lineweaver-Burke plot
Km/Vmax
