AAMC

Na+ & urea *reabsorption* in the nephron *creates osmotic pressure* within medullary interstitium of the kidney & draws *water: filtrate → surrounding tissue* (which was made hypertonic by increased OP)

& *excretion of nitrogenous* waste takes place due to the *urea transporter* (which removes *urea* from interstitium and transports it back *into → ascending LOH*.

Female ovum is analogous to male spermatozoon

(sperm maturation)Spermatogonium → 1 spermatocyte (1st meiotic to) → 2 spermatocyte (2nd meiotic to) → Spermatid (differentiation to) → Spermatozoa

A drug that inhibits microtubules formation can inhibit phagocytosis

*Microtubules* are cytoskeletal elements that help determine *cells shape*. Think leukocyte shape.

In human females, mitotic divisions of oogonia that lead to the formation of presumptive egg cells (primary oocyte) occur between: 1. Fertilization and birth only. 2. Fertilization and puberty only. 3. Birth and puberty only. 4. Puberty and menopause only.

*Mitotic* divisions all occur prior to birth. It means by the time the female is born, mitotic divisions of her oogonia are complete. First choice.

*LOH*

*Na+ reabsorption* is LOH's most important *function.* It is very dependent of Na+ pump for its function Thick ascending is the only part of the nephron that doesn't have aquaporins.

Sum of protons, neutrons & electrons in strontium-90? 90 126 128 218

1. Find neutrons number: 90-38 = 52 Sum: protons (38) + neutrons (52) + electrons (28) = 128

Which of the following is least directly affected by sympathetic nervous system? 1. Peristalsis. 2. Digestive enzymes secretion. 3. Food enzymatic breakdown. 4. Nutrients delivery to muscles & organs

1. SNP inhibits peristalsis. 2. Inhibits digestive enzymes 3. Doesn't affect enzymes directly, correct choice. 4. SNS delivers blood glucose (dilates vessels) to supply muscles & organs.

Compound 1 is a strong acid because its anion is better stabilized by? 1. Resonance 2. Inductive effect 3. H-bonding between OH & CO2- 4. Dehydration

1. There is no resonance. 2. No dehydration. 3. No inductive effect. 4. Carboxylate ion in 1 is stabilized by H-bonding with oxygen group. Compound 2's carboxylate is not in the right orientation for H-bonding to happen.

*Actin & myosin in muscular contractions* The bridges between them form, break, reform leading to sarcomere shortening. 1. Neuro impulse releases Ca++ from SR within the muscle cell. 2. Ca++ binds troponin (which along tropomyosin, blocks myosin binding site *on actin*).

3. Ca++ binding troponin causes a shift in troponin/tropomyosin complex revealing myosin binding site. 4. Myosin binds actin causing *a conformational change in myosin* that cocks the head of the myosin molecule and slides actin filament relative to myosin. 5. *ATP binds myosin* causing it to detach from actin and (recharge) or rebend again.

What is best to improve two liquids separation in a flask? 1. Heating at a slower rate. 2. Using a vacuum source to achieve a lower pressure inside the distillation apparatus. 3. Cooling condenser with iced water. 4. Using a short fractioning column.

4. This causes the liquids to vaporize & condense fewer times. 3. This has no effect on *separation* because this step occurs after the liquids have separated already. 2. Creating a lower pressure would decrease BP for *both* liquids, not helping in separating them. 1. Heating at a slower rate would allow both liquids more time in the column, allowing liquid and vapor to equilibrate) and improve their separation.

Kidney

Acid-base balance. BP regulation. Water balance Removal of nitrogen waste

Fatty acid salt *phobic←(Rn-CO2-Na+) → philic*

Acyl chain → phobic & polar head → philic (FA salts dissolve partially in polar & nonpolar media)

Alcohols require acid catalysis to undergo substitution by nucleophiles. The acid catalyst enhances the reaction by? 1. Increasing solvent polarity. 2. Creating a better LG 3. Neutralizing basic impurities. 4. Protecting the alcohol group

Alcohol substitution: getting rid of OH group. *Hydroxyl is one of the worst LGs in substitution rxns* Acidic conditions protonate OH, so LG is water (a better LG). A protecting group would hinder the reaction not make it happen.

Salty meals (high NaCl intake) won't cause aldosterone release

Aldosterone causes Na+ reabsorption (not secretion)

Autosome

All chromosomes except the sex chromosome

Amines lone pairs

Amines act as: 1. Bases 2. Nucleophiles If nitrogen is sterically hindered, then amine won't be a good nucleophile anymore.

Blood pressure measurement

Arteries & arterioles > capillaries > veins

Geometry (shape)

Atoms position only (not e-s)

What would happen to the BP if leak develops to vacuum distillation apparatus of two liquids? 1. BP increases for both. 2. BP decreases for both. 3. Remains the same. 4. Becomes more similar to one another.

BP: vapor pressure = atm. Normal BP happens @ 1 atm. T ↑, BP ↑ If surface P ↓, liquid BP ↓ Leak means surface pressure ↑, both BPs ↑

*FA*s have general formula *Rn-CO2H*

Its corresponding *FA salt* has the general formula: *Rn-CO2-Na+*

RCO2

Carboxylate Carboxylate ion: RCO2-N+ (saponification product)

BP depends on: 1. Cardiac output 2. Blood flow resistance *BP = total peripheral resistance x cardiac output (Ohm's law)*

Cardiac output: stroke volume x HR Resistance: vessels size & pre-capillary sphincters

Negative pressure *pumping action*

Causes mammalian lung inflation

What could result after a venous clot? 1. Net fluid flow in the direction of interstitial spaces will increase. 2. Net flow in direction of interstitial will decrease. 3. Capillaries osmotic pressure will increase. 4. Capillary osmotic pressure will decrease.

Clot, blocks, increases hydrostatic pressure, fluid out, option one. (BP ↑ to push clot away) Additional note: more particles with less water → osmotic pressure ↑

HBr bond

Covalent, because H & Br are not metals.

Allosomes other names:

Sex chromosome Hetero*typical* chromosome *Hetero*chromosome *Idio*chromosome

Diaphragm in ventilation

Dome at rest (curving towards lungs & heart). Flat during contraction (inhale)

pH change or heat can change protein's 3D structure reducing its catalytic activity (if it was an enzyme for example)

Denaturation

mRNA turnover is MOST critical during *cell differentiation* during development.

Development is EXTREMELY time-sensitive of *mRNA turnover.*

G1 or G0

Diploid, nondividing cells, the cell remains metabolically active, but not replicating (S) or segregating (M). If it won't divide again, G0.

Glycine in water

Dipolar ion. Containing both EWD & EDGs makes it highly polar

Adaptive radiation 1 species → multiple (due to isolation)

Divergence of one species into multiple species over time. This occurs when subgroups of the original species are separated or *isolated in different environments* so these subgroups independently evolve.

Bile components

Hb breakdown products (i.e. bilirubin & bile salts "*amphipathic*")

Oxygen has the greatest attraction for electrons in the ETC

E- move to a slightly more electronegative carrier as the electrons pass through each ETC step. Oxygen is the final accept with the greatest e- attraction.

Boiling chips or ebulliators in the bottom of the flask break the surface tension of the heated liquid to preventing bumping or superheating

Ebulliators introduce bubbles to break the surface tension.

Postmenopausal women receiving estrogen & progesterone would experience resumed periodic menstruation.

Estrogen administration in men doesn't make a difference because estrogen-related osteoporosis is evident in women, not men.

Mitochondria origin hypothesis

Even that some mito proteins are made by cytoplasmic ribosomes from mRNA transcribed from nuclear genes, the transfer of genes from symbionts to euk nucleus could have occurred during evolution.

Electron acceptors → high electron affinity

Examples: oxygen & sulfur

Testosterone → (-) GnRF of hypothalamus

Excess testosterone reduces FSH (to act on Sertoli) & may cause infertility

At high altitude, HR & RR ↑ due to hypoxia (not reduced body temperature)

Excitement and anxiety → BP ↑ → Urine ↑

Filtration formation

Fluid → glomerular capillaries (thru glomerular membrane) → Bowman's capsule This collectively is known as the glomerulus

CH2O

Formaldehyde

Bile structure

Hydrophilic and hydrophobic sides

What happens in the kidney if heart stops?

Hydrostatic pressure = 0 Fluid in the space around the glomerulus goes back to (protein-rich) hypertonic bloodstream (compared to the hypotonic, protein-poor capsular space). → fluid moves down osmotic gradient into the blood

If an artery supplying blood to a lung lobe was blocked but ventilation to the lobe was unaffected, how would alveolar gas partial pressures change? 1. PO2 ↑, PCO2 ↓ 2. PO2 ↓, PCO2 ↑

If blood flow to an alveolus was blocked, no flow of Hb-rich RBCs would be available to take away O2 and give away, CO2. This would make air inside the lung similar to atm (Higher O2 & lower CO2)

Synthesized gene sequences can be from DNA or RNA

If the question stem asked about gene sequences & the option included DNA only, then it may not be correct.

Question: To be an effective therapy, an antisense gene that is incorporated into a genome that contains the target gene must be: On the same chromosome as the target gene but not necessarily be physically adjacent. On the same chromosome as the target gene and must be physically adjacent. Regulated in a similar manner as the target gene. Coded on the same strand of DNA as the target gene.

It should be regulated in the same manner so they get produced together to ensure that the antisense RNA is available to bind the sense and prevent translation.

Endochondral ossification

Long bones grow by EO. Cartilage growth plate at the ends of long bones, thicken and solidify to bone.

Golgi & sER look similar under microscope

Membranes with many folds.

A drug that binds tubulin molecules of plant cells and prevents the cell from assembling spindle microtubules would most likely cause the resulting plant cells to? *1. *Greater genetic variability than parents. *2.* 2+ sets of chromosomes. *3.* A stronger cell wall *4.* Independent movement because of excess tubulin.

Microtubules are fibers that attach chromosomes in mitosis and form mitotic spindles. Disruption of mitotic spindles by drugs prevents proper segregation of chromosomes into daughter cells and results in an unequal number of daughter cells. 2 is the right answer. There is no tubulin in cell wall (3 incorrect). Tubulin has a minor role in motility (4 is wrong).

*Endosymbiotic theory* The inner membrane is the plasma membrane of the endosymbiotic prokaryotes (see pic)

Mito is descendent of prokaryotes that were engulfed by endocytosis into a vesicle lined with a membrane borrowed from a eukaryotic host's cell membrane.

H-bonding

Molecule w/ a H on an high electronegative atom (NOF) & a H-bond acceptor. O on C=O is usually an acceptor. H on NH is usually the donor

Histones

Most abundant proteins in eukaryotic cells

Bacterial conjugation (G-negative)

Sex pilus is needed to be produced by one bacterium to transfer DNA to another. Requires special genes to be present on a plasmid (fertility factor, F) Plasmid is able to move from one bacterium to another (*sexual reproduction*)

Most viral proteins are produced directly by *translating viral nucleic acids*

Not host nucleic acids translation

How would saponification of a TAG result in 4 FAs instead of 3 FAs?

One of the R groups of the TAG would contain a C=C. If the double bonds gets *partially* isomerized during saponification reaction, an extra FA may be obtained.

Finding oxidizing & reducing agents in an equation: 2HCL + H2O2 + MnO2 → O2 + MnCl2 + 2H2O

Oxidizing agent: increasing in oxidation number Mn: from +4 to +2 (reduced), so MnO2 is the oxidizing agent (got reduced). O in H2O2 is -1 & 0 in O2, so H2O2 is the reducing agent (got oxidized)

*Sympathetic* NS has a rapid response because its *ganglia are interconnected*. It produces a rapid whole-body (systemic) response to a stimulus

Para isn't interconnected.

Lacking sweat glands in the tropics

People may die of heat stroke because the human body may gain, rather than lose, heat through radiation.

Nephron

Reabsorption of protons & bicarbonate from the filtrate contributes to acid-base balance.

Renin secretion (juxtaglomerular)

Regulates aldosterone secretion from adrenal cortex (BP regulation & Na+ nephron reabsorption).

What nitrogenous base would promote uric acid crystals formation in grout (related to purines) C G U T

Remember, purines are A & G

Heart ventricles & pressures

Right V (to lungs): 25 mmHg max Left V (to system): 120 mmHg max. Left ventricle: thicker & generates MORE pressure.

Polarity in neutral molecules results from uneven e- density distribution

Separation of unlike charges (i.e. zwitterions & ylides)

If an enzyme with increased activity is being studied for having a higher rate of function in vivo vs vitro, what could have resulted in this change?

Since the enzyme works normally in vivo, it means its active site hasn't been altered. It is more likely that an allosteric site on it increased its function in vivo.

Skeletal & cardiac muscles are striated

Smooth muscles aren't

Kidney responds to decreased blood volume entering it by activating the renin system

So if the kidney gets little flow, it'll increase renin which results in Na+ & water reabsorption causing increased BP

Which are directly required for spermatogenesis? I LH II FSH III Inhibin IV testosterone

Spermatocytes are nourished by Sertoli cells (can't grow without it) Sertoli are stimulated by: I FSH II testosterone

Normally the immune system avoids attacking the tissues of its own body because? A special intracellular process recognizes only foreign antigens. 2. The body does not make any antigens that the immune system could recognize. 3. It changes its antibodies to be specific only to foreign antigens. 4. It suppresses cells specific to the body's own antigens.

The immune system attacks foreign material. It avoids attacking by *suppressing cells that are specific to its own body's antigens* (surface molecules that would otherwise initiate an immune response).

Any mito disruption decreases ATP production

The influx of K+ or (any cation) into the mitochondrial matrix would disrupt electrochemical gradient responsible for protons flow into the intermembrane space.

Sweat glands secrete sweat through channels continuous with the epidermis

The sweat channels prevent water loss by isolating water-permeable, sweat-secreting cells from dry air. There are pores at skin surface. The epidermis is impermeable.

ROH is more polar than C=O

There are two Os in C=O and may share e- density.

ADH (vasopressin) responds to high osmotic pressure due to water loss. Stressed → thirst (high osmotic pressure) → ADH release

This happens in times of stress according to AAMC.

Na+ movement in neuron occurs in nodes of Ranvier

This movement does NOT cause AP or affect the NaK pump

Glomerular filtration rate (GFR) ↑ → tubules reabsorption might max, then fluid moves too quickly thru tubules until kidney tubules capacity to reabsorb is exceeded. ↓ BP (GFR↓): urine output ↓: tubule reabsorption ↑

Too fast → tubular reabsorption maxes, but there might be little time to reabsorb Slower → more time to reabsorb.

Translation inhibitor would involve inhibited protein production.

Transcription inhibitor involves transcription production inhibition.

# of possible peptides: n! (factorial) n: AA

Tripeptide: 3 x 2 x 1 = 6 ABC tripeptide: ABC, ACB, BAC, BCA, CAB, CBA.

Radiation

Vasodilation

Estrogen & progesterone are actively secreted in pre-menopausal women and maintain uterine cycle

With age, ovary becomes less responsive to pituitary gonadotropins and cyclical changes in the endometrium of uterus disappear.