mcat science 4

We see d2sp3 hybridization in the transition metals and sp3d2 hybridization in the nonmetals.

Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids via _______ reactions

red cat    an ox

anode cathode on electrolytic cell
anode cathode on galvanic cell

In a synthesis reaction, two or more reactants (elements, molecules, or ions) combine to form a single product. Most commonly, these reactions involve two reactants, but more can be observed as well. A simple example is 3 H2 + N2 → 2 NH3. This category also includes reactions in which a functional group is added to a compound, such as phosphorylation (the addition of a PO32− group). Its opposite is decomposition or cleavage, in which a reactant is broken down into multiple smaller products.




In single displacement reactions, one element/group replaces another in a compound, while two elements/groups switch in double displacement reactions, as exemplified by: BaCl2(aq) + MgSO4(aq) → BaSO4(s) + MgCl2(aq). Conceptually similar are neutralization reactions, in which an acid and base react to create a salt and water, such as: HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l).




Combustion is a unique reaction in which a compound reacts, or burns, in the presence of elemental oxygen (O2). The fuel in most combustion reactions is a hydrocarbon, which produces carbon dioxide and water, as seen in the combustion of propane: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g).

If transmitted light rays refracted differently depending on their wavelengths, then the effective focal length of the lens would differ for each wavelength of light. As a result, for any light containing rays of multiple wavelengths, the rays would focus at multiple points, resulting in an unfocused image. This is known as a ______, in which optical instrument fails to converge light rays from a source to a single point.

enantiomers and diaesteriomers

_____ have similar chemical and physical properties

____ have similar chemical but different physical properties

In an isolated system, entropy is maximized when:

I. the system is at equilibrium. 

II. the system is far from equilibrium. 

III. the system is unable to perform work.

Gases behave most ideally under high temperatures and low pressures.

An organic synthesist seeks to identify an efficient stereoselective reagent with which to produce the enantiomer of the biologically active sphingosine molecule pictured in the passage. Which of the following would be the most logical choice to try? 

A. Tert-butoxide (achiral)

B. DMSO (achiral)

C. Diethyl tartrate (chiral, correct)

D. Propanol (achiral)

as temp increase volume increase 

as pressure increase temperature increase

as pressure increase volume decrease

pO2 = mol fraction O2 x Total pressure

mol fraction O2 = O2/ total

Km is an inverse measure of affinity

 FRα displays relatively high affinity for folic acid (to which it binds and imports into the cell via receptor-mediated endocytosis), relatively low affinity for 5MTHF

The Km for the binding of the FRα receptor to folic acid under physiological conditions is: 

A. greater than that for 5MTHF binding. 


B. smaller than that for 5MTHF binding. 


C. equal to that for 5MTHF binding. 


D. unable to be determined relative to that for 5MTHF binding.

p-nitrophenol has a pKa of 7.16, whereas ethanol has a pKa of 16. What best explains this difference?

Which of the following represents the net reaction for the electrolysis of water? 

2 H2O (l) → O2 (g) + 2 H2 (g) 

this option is properly balanced and lacks H+ and e-  in the net reaction.

Current units (Amphere)

A = C /s 
A = Coulumbs per second

Effusion refers to the movement of gas particles through a small hole. 

Rate of effusion increases with decreasing _____

Resting phase is also known as Gap 0 (G0). During this period, the cell just goes about its business; in fact, many fully-differentiated cells in the body remain in G0 for long periods of time. 

 interphase is broken into three stages: Gap 1 (G1), synthesis (S), and Gap 2 (G2). During G1 and G2, the cell grows, and during S, DNA is replicated. The fact that S is located between G1 and G2 allows checkpoints. The G1/S checkpoint, also known as the restriction point, is when a cell commits to division. The presence of DNA damage or other external factors can cause a cell to fail this checkpoint and not divide. The G2 checkpoint that takes place before cell division similarly checks for DNA damage after DNA replication, and if damage is detected, serves to “pause” cell division until the damage is repaired. Throughout interphase, chromatin is loosely packaged (euchromatin) to allow transcription and replication.

 G2/M checkpoint is located after the S phase (during which DNA replication occurs) but before entry into mitosis. Specifically, this checkpoint ensures that DNA has been replicated properly before the cell begins to divide.

the protein component of microfilaments is ______

______ (along with _____) is found in muscle, but it is not found in microfilaments.

______ is the protein that composes prokaryotic flagella.

______ is the main constituent of microtubules, not microfilaments.

Capillaries are the smallest blood vessels in the body, with walls that are composed only of a single layer of ________ cells. 

Smooth muscle is found in arteries and (to a lesser extent) veins, as well as arterioles and large venules. Capillary walls do not contain smooth muscle.

Gluconeogenesis, which occurs in the liver during a period of fasting, produces glucose from non-carbohydrate carbon substrates such as pyruvate, glycerol, lactate, TCA cycle intermediates, and the carbon skeletons of glucogenic amino acids (either directly, or indirectly as intermediates of the TCA cycle).

However, acetyl-CoA cannot, when produced from the oxidation of even-chain fatty acids, serve as a substrate for gluconeogenesis. This is because the conversion of pyruvate to acetyl-CoA is irreversible; additionally, during the TCA cycle, the two carbons of acetyl-CoA are lost as two molecules of CO2 and are not integrated into the carbon skeletons of TCA cycle intermediates that can be directed into gluconeogenesis.

For what reason was 14CO2 production chosen to measure the rate of oxidation of labeled [1-14C] palmitate and TCA cycle flux?

match

sulfur phosphorous 

dna protein

The ______ is the site of protein modification. Proteins are made of amino acids, which don’t contain phosphate.

Cholecystokinin (CCK) acts in the small intestine upon the entry of food into the duodenum from the stomach.

Functions? (4)

what inhibits it?

The cerebellum receives information from sensory systems and then regulates fine motor movements. Thus, it coordinates posture, balance, fine motor coordination (like opening a bottle), and speech. It is located at the bottom back of the skull:







A: The pons is involved in sleeping and respiration.




B: The main function of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland.




D: The hippocampus is primarily involved in emotion and memory.

______ mutation is a point mutation and therefore does result from a single-nucleotide replacement, such a mutation replaces one amino acid with another

A _______ is the result of a mutation that substitutes a purine for a pyrimidine or a pyrimidine for a purine

A ______ mutation is an insertion or deletion of one or more nucleotides that results in a changed reading frame. 

The eukaryotic RNA stop codons are ? 

The introduction of a premature stop codon is a ________ mutation.

3 (hormone) (osteo) (effect on blood)
3 (hormone) (osteo) (effect on blood)

These bone marrow-derived cells are abundant in normal human and murine dermis and occupy the perivascular space, where they are closely associated with mast cells. They are a kind of dermal macrophage.

How parathyroid hormone increases blood calcium 

How calcitonin decrease blood calcium

In the Hardy-Weinberg equation, p and q represent the frequency of the dominant and recessive alleles, respectively, found in a population (p + q = 1). This equation is useful in determining the relative occurence of genotypes in a given population, but to determine phenotypes

As such, the phenotypic outcomes in a population can be calculated as p2 + 2pq + q2 = 1. The first term represents homozygous dominant individuals, the second term represents heterozygotes, and the third term refers to the homozygous recessive phenotypes in the population.

A cDNA library includes only the coding regions; therefore, it can be easily expressed in prokaryotes via their transcriptional machinery. However, expression of an entire genome in prokaryotes is hard for a number of reasons, including the fact that there is no splicing mechanism in prokaryotes to remove the non-coding regions.




A: A genomic library includes the entire genome of an organism. In contrast, a cDNA library is derived from the extracted mRNA. Thus, a genomic library is larger than a cDNA library.




B: Since the genomic library includes the entire genome, it includes both coding and non-coding regions. A cDNA library includes only the coding regions because the non-coding regions were spliced out during the post-transcriptional modification of mRNA.




D: A genomic library (which houses the entire genome) includes promoters, but a mature mRNA molecule does not. Therefore, a cDNA library doesn’t either.

pentose phosphate pathway

oxidative phase product
reversible or irreversible

non-oxidative phase product
r or irreversible

One way in which a ribosome can be seen to act as a ribozyme is that the ribosome can act as a scaffold that assists with the assembly of peptides from amino acids. 

The term "ribozyme" refers to something that acts as an enzyme - in other words, it catalyzes chemical reactions. Interestingly, while typical enzymes are only made of protein, ribozymes are made at least partially of RNA. In the cell, ribosomes play an assistive role in holding mRNA in a way that allows amino acids (also known as protein monomers) to bond to the mRNA one at a time during the process of synthesizing these amino acids into a peptide chain.

Promoters are regions of DNA that lie upstream to a given gene and initiate transcription by binding specific transcription factors that contribute to the binding of RNA polymerase. Additionally, expression is upregulated by enhancers, which are DNA sequences that can be located further from the gene of interest, and work by binding transcription factors that twist DNA into a hairpin loop, bringing distant regions into close proximity for transcription to begin. Silencers are the opposite of enhancers in eukaryotic cells; they are regions of DNA to which transcription factors known as repressors bind. Additionally, the methylation of C and A residues can reduce transcription. Methylation is associated with epigenetics, which refers to inheritable phenotypic changes involving mechanisms other than the alteration of the genome itself.

 

Gene expression can also be regulated on the level of nucleosomes (i.e. chromatin and histones). Acetylation promotes transcription by attaching acetyl groups to lysine residues on histones, making them less positively-charged and causing a looser wrapping pattern that allows transcription factors to access the genome more easily.

 

Finally, non-coding RNA plays a role in gene expression. MicroRNA (miRNA) strands are single-nucleotide strands incorporated into an RNA structure with a characteristic hairpin loop, while small interfering RNA (siRNA) molecules are short and double-stranded. Both tend to be approximately 22 nucleotides in length, and silence genes by interrupting expression between transcription and translation.

Which of the following does the complementary nature of the DNA sense strand and antisense strand encompass?

I. Every nucleotide base on the sense strand has a complementary base on the antisense strand.



II: The sense strand is never transcribed into RNA; only the antisense strand is.




III: Transcription of DNA to RNA always takes place by transcribing DNA onto an antiparallel RNA strand, not a parallel one.

Glycolysis , gluconeogenesis, and fermentation all take place in the ________

krebs takes place in the ______

ETC takes place in the ______

A _______ is an enzyme attached to its cofactor. 




 An  is an inactive enzyme without its cofactor.

which codon change would most likely result in an amino acid being unchanged? 

1st, 2nd, or 3rd base?

______ is a technique used to sequence proteins via successive cleaving of terminal amino acid residues.

The cytochrome c oxidase complex (complex IV) is the last enzyme of the electron transport chain. It receives one electron from each of four soluble cytochrome C molecules, transferring them to a single oxygen molecule and thus converting one O2 molecule into two molecules of water.

Which cytoskeletal component forms the majority of the outer layer of skin? 

A. Microfilaments 

B. Microtubules 

C. Intermediate filaments

D. Elastins

which trimester?

organ systems appear during _____

rapid brain growth occurs during _____

organ systems mature after birth and foramen ovale closes at birth

long bones include (4)

long bones contain _____marrow indicating low blood cell production

flat bones include (3)

flat bones contain ____ marrow

Low levels of carbs in ER and Golgi:

- Water leaves the ER and Golgi through osmosis

- carbs in ER and golgi act as a source for structural diversity and transport tags for glycoproteins without sugar tags proteins are secreted rather than delivered to cellular compartments like storage or lysosomal vesicles

- defect in post-translational processing

- glycogen breaks down to provide carb residues for structural and enzymatic activity for a cell

_______- different manifestations of the same genotype in a population (different individuals)

_______ multiple alleles of the same gene being expressed

two types of mutations that cause defect in protein function

liver converts acetylCoA to ketone bodies and they are reconverted to acetylCoA in extrahepatic cells/tissues

so when the brain uses ketone bodies instead of glucose those ketone bodies are converted to acetylCoA

Ketone bodies: Acetone Acetoacetate β - Hydroxybutyrate.

in the liver acetylCoA is made by beta oxidation of fatty acids and is converted to ketone bodies when carbs are scarce. this occurs in the mitochondrial matrix of liver

________ remove introns in mRNA after they're synthesize so this is involved in transcription

Gastrin ---> _____ ------> HCL

greater than normal amount of chyme means more acidic which isnt good for pancreas because it requires an alkaline environment to function properly so no pancreatic enzymes to digest lipids

hormone secreted by stomach when hungry

hormone secreted by adipocytes when full

cathode or anode?

lower reduction potential =
higher reduction potential = 

electrons flow from ____ to ____



Li+(aq) + e–   --> Li(s) -3.045 V



I2(s) + 2 e– ---->   2 I–(aq) +0.535 V

which is the anode? which cathode?

increase diffusion of electrolytes down their neuronal concentration gradient by

increasing temp
increase surface area of axon (scavenging remaining myelin can do this)
increase concentration gradient
increase KE

neurotransmitter migration is mediated by the _____

action potentials are generated at the _____

SDS is a detergent that denatures proteins and is used in electrophoresis bcuz electrophoreisis separates proteins based off size . SDS is used in electrophoresis to make sure all proteins have a uniform size-charge ratio so the only factor determining their motion is size. 

It is not used in isoelectric focusing bcuz that depends on charges on protein surface

changing the first nucleotide in a codon almost always results in a _____ mutation

gastric ulcer results from failure to neutralize acid in stomach and the _____ secrete bicarbonate to neutralize acid

gall bladder- stores and secretes _____ which emulsify fat to absorb fat from digestive tract so you won't have large amount of fat in stool like you would in gall bladder removal

____ virus are unlikely to carry transcription factors

log (1/10) =

the standard cell potential for a concentration cell is always zero

the thin limb of the ascending loop of henle is impermeable to water but permeable to Na+ and Cl-

closed mitosis occurs in the _____

open mitosis occurs in the _____

______ is a technique which involves the application of centrifugal force to separate particles from a solution according to their molecular weight,  size, shape, density, viscosity of the medium and rotor speed.

PCR = Number of strands x (2^#of replication cycles)

example: If you have 100 strands and 5 replication cycles

100 (2^5)
2^5 = 32
100 (32) = 3200

______ hormone promotes fatty acid breakdown and inhibits glucose uptake by liver

Ribosomes are assembled in the _____ from _____ and proteins imported from the cytoplasm so a defect in the structure of a ribosome most likely occurs in the _____

when a fatty acid undergoes beta oxidation it turns to acetyl CoA and loses 2 carbons.

How many carbons are lost by a 16carbon fatty acid undergoing 3 cycles of beta oxidation?

2 x 3 = 6

so it would be a 10 carbon molecule

a-tubulin is a major component of _____ and is found in _____ and _____

Galvanic cell
-also called a voltaic cell
-positive cell potential
-spontaneous (delta G < 0)
*I like to remember that "gals (females) are spontaneous"
-cathode is positive
-anode is negative

Electrolytic cell
-negative cell potential
-requires energy input to induce a reaction
-not spontaneous (delta G > 0)
-cathode is negative
-anode is positive

paramagnetic vs diamagnetic

unpaired e- =
all paired e- =

____ are repelled by magnetic field
_____ are attracted to magnetic field

Only a few materials found in nature – iron, nickel, cobalt and gadolinium* – are ferromagnetic (attracted strongly), meaning they exhibit a strong response to a magnetic field by aligning with it.

reducing the width of aperture in optical microscope will result in worsened resolution because diffraction is more pronounced with smaller aperture

inappropriate folding of proteins cause aggregates to form by:

having more hydrophobic residues (tyrosine, valine, isoleucine, phenylalanine, alanine, leucine) on the outer surface of protein since most of the time they're in the hydrophobic core

having more beta sheets in the secondary structure

principle quantum # = size of orbital

azimuthal/ angular momentum quantum # = shape of the orbital

if a molecule exhibits a certain color that means it is reflecting that color, so any other wavelength range color is actually being absorbed.

R - 750-620 (High wave/LOWER frequency)
O - 620-590
Y - 590-570
G - 570-490
B - 490-450
V - 450-380 (low wave/ HIGHER frequency)

Ronald
Mcdonald
is
visiting
ur
x
girlfriend 

Radio wave (highest wave length)
Microwaves
Infrared
Visible
UV
X-ray
Gamma (lowest wavelength)

RED/GREEN
ORANGE/BLUE
YELLOW/PURPLE

NAD+/NADH only undergo 2 e- transfers and so they don't need to be tightly bound to enzyme and don't react as quick with O2 to form free radicals

FAD/FADH2 undergo 1e- and 2e- transfers and therefore can react quickly with O2 to form free radicals that are stable called ______ and must be bound tightly to enzymes to keep from reacting with O2

what is the only amino acid that doesn't exist as a beta-amino acid?

If a ray of light travelling through the air strikes a glass slab at 90°, what will the angle of refraction be?

HYDROPHILIC OR hydorphobic side chain?

tyrosine
cysteine

glucose molar mass ______

dissacharride molar mass ______

ozone

- lewis base (donate e-)
- polar
- permanent dipole moment

equilibrium

- more moles gas in reactants means more entropy in reactants

enthalpy - = exothermic
enthalpy + = endothermic

exo: increase temp = increase products or reactants?

endo: increase temp =

odd number of e- in compound means its paramagnetic

even number of e- in compound means its diamagnetic 

look at periodic table and look at protons and its same amount of e- so add e- and you know

NO2 para or dia
N2O4 para or dia

ideal fluid- forces and acceleration remain constant

carboxylic acid --> add acid and alcohol and you get

an ionizable group would present one evquivalence point

So the 2 electron configuration tricks are: lose outer s before outer d, and look out for d5 / d10 stability.

energy released as electron falls from infinitte distance to ground state is given by A so any other transition is less than or equal to A

to a n=3 to n=2 jump .14A is plausible and above 1A isn;t and 0A isn't because energy was released going from higher to lower

emitted light has a lower energy than absorbed light

light with longer wavelengths defract more (at a greater angle) than light with shorter wavelengths so if diffraction and issue decrease wavelength to increase resolution

increase size of aperture on objective lens improves resolution when diffraction an issue

changing resolution on ocular lense wont make difference on resolution

disulfide bonds are formed through oxidation of sulfhydryl groups

hydrophobic amino acids more likely to be clustered around disulfide bonds in protein

a lactone ring results from the condensation of a _____ and _____ in the same molecule

a diver decelerates after complete submerge in water means water boyant force is more than diver weight

KE via drag is reason he decelerates 

once completely submerged buoyant force is constant

hydrogen on sulfuric acid attacks carbonyl oxygen allowing nucleophilic group to attack carbonyl carbon

why diastolic pressure lower than systolic?

when filling subshells fill one e- in each subshell first before pairing them

order of increasing melting point (higher mw)

urea > glucose > lactose

somatic mutation

most mutations occur while DNA is being replicated in ____ phase and it would not occur in meiosis because it is somatic mutation

the antigen binding site of an antibody is determined by its ______

oxygen flows from alveolus to alveolar caplillaries so PO2 in air must be higher in the alveoli than capillaries

a male child with disease has healthy parents so the disease cant be dominant with healthy parents

autosomal recessive both parents carriers and x-linked recessive mom carrier

lymphatic system functions

- remove excess fluid from interstitial space
- absorb fats from gi tract - lacteals
- remove and destroy foreign particles