Anatomy 1/23

Put the lymph nodes in order of the pathway that breast lymph usually takes through them. Proximal Apical Lateral (Humeral) Subscapular Central

1. Pectoral, humeral, or subscapular, but mostly (75%) pectoral 2. Central 3. Apical

Enzymes allow reactions that might not normally occur to occur readily in the cell because enzymes act as very efficient catalysts. Which of the following is an important characteristic of the active site of all enzymes? A. The substrate binds due to multiple weak non bonding interactions B. All residues in the active site are contiguous in the primary structure C. It is located at the N-terminal end of the enzyme protein D. The product is released very slowly

A The substrate binds to residues in the active site through non bonding interactions

he addition of compound X to an enzymatic reaction results in an inhibition of enzyme activity. One of the best ways to experimentally determine if compound X is a non competitive inhibitor is to determine: A. its binding affinity for the enzyme B. the effect of increasing [X] concentration on Vmax C. the ratio of enzyme to compound X D. the molecular weight of compound X E. if the enzyme is covalently modified.

A good way experimentally to determine if an inhibitor is a non competitive one is to run the reaction under saturating conditions and add 1X, 2X inhibitor and see if the velocity of the reaction decreases in direct proportion to [X] added.

A patient presents to your office complaining of excruciating pain in his left shoulder over the past couple days after sustaining a ski accident at Big Bear, California. Upon examination, the shoulder is tender. You ask your patient to abduct his left arm and find that he is only able to initiate abduction to about 15 degrees. As a knowledgable physician, you recall from your first semester anatomy course that the most likely damaged nerve is: A. Axillary nerve B. Suprascapular nerve C. Long thoracic nerve D. Infraspinatus nerve

A. Axillary nerve

Which group of lymph nodes will ultimately receive the majority of lymph drainage from the breast? A. Central axillary lymph nodes B. Subdiaphragmatic lymph nodes C. Humeral lymph nodes D. Parasternal lymph nodes E. Subscapular lymph nodes

A. Central axillary lymph nodes

Which muscle forms the superomedial border of the suboccipital triangle? A. Obliquus Capitis Superior B. Semispinalis Capitis C. Rectus Capitis Posterior Major D. Obliquus Capitis Inferior E. Rectus Capitis Posterior Minor

A. Forms the superolateral border. B. Forms the roof. C. Correct. D. Forms the inferolateral. E. Is medial to the rectus capitis posterior major and is not a border of the suboccipital triangle.

25. Which of the following statements is true regarding the axillary nerve? A. The axillary nerve is accompanied by the posterior circumflex humeral artery B. The axillary nerve innervates the deltoid and teres major muscles C. The axillary nerve is a branch of the medial cord of the brachial plexus D. The axillary nerve is seen in the triangular interval of the humerus

A. The axillary nerve is accompanied by the posterior circumflex humeral artery The axillary nerve and the posterior humeral artery are found together in the quadrangular space. The axillary nerve also innervates the deltoid and the teres minor, not major as listed in answer choice B. The axillary nerve is a branch of the posterior, not medial, cord of the brachial plexus.

In lymphatic drainage of the breast, the major portion (about 75%) enters eventually into which group of nodes? A. Central axillary B. Deltopectoral C. Lateral axilllary D. Parasternal E. Subscapular

A. The lymph FIRST moves to the pectoral lymph nodes, then to the central axillary lymph nodes, then to the apical axillary lymph nodes.

The prognosis in breast cancer is poorer as more proximal lymph nodes are found to have cancerous cells in them. Spread of cancer to which of the following axillary nodes would indicate the worst prognosis? A. apical B. central C. lateral D. pectoral E. subscapular

A. apical As lymph drains from the breast into the axillary system, it moves from pectoral, lateral, and subscapular nodes to the central nodes, and then to the apical nodes. If cancer is found in the apical axillary nodes, this is a sign that the cancer has spread through the regional lymphatic system and may have metastasized to the rest of the body.

Is amylose branched, or is amylopectin?

Amylopectin

The extent of DNA synthesis in a cell could most specifically be determined by measuring the incorporation of which of the following radiolabeled compounds? A. Leucine B. Phosphate C. Ribose D. Thymidine E. Uracil

Answer D) is correct. Thymidine is only incorporated into DNA, not RNA or protein. Ribose is incorporated into RNA or Reduced to deoxyribose and incorporated into DNA. Uracil is incorporated into RNA, not DNA. Phosphate is incorporated into DNA and RNA. Leucine is an amino acid and is not incorporated into DNA or RNA.

Which amino acids are negatively charged?

Aspartate & glutamate

During the planning of therapeutic intervention for a 54-year-old female patient with cancer of the right breast, a 3rd year medical student would need to first consider where most of the cancer cells would metastasize, which would be: Abdominal wall Anterior mediastinum Axillary lymph nodes Opposite breast Parasternal lymph nodes

Axillary lymph nodes About 75% of the lymph from the breast goes to the axillary lymph nodes via the pectoral lymph nodes. This is the most important place to check for metastasis of the cancer cells! The lymph from the axillary nodes eventually drains into the subclavian lymph trunk. Most of the rest of the lymph drains into the parasternal lymph nodes, while a small amount drains to the abdominal wall and the opposite breast. The anterior mediastinum is not an important place for lymphatic drainage from the breast.

What vein pierces the clavipectoral fascia? A. Axillary vein B. Cephalic vein C. Subclavian vein D. Brachial vein E. Basilic vein

B

DNA contains which one of the following components? A. Nitrogenous bases joined by phosphodiester bonds B. Negatively charged phosphate groups on the exterior of the molecule C. Base pairs stacked along the exterior of the axis of the molecule D. Two strands that run in the same direction E. The sugar ribose

B) is the correct. The exterior "backbone" of DNA is a sugar-phosphate-sugar-phosphate" complex. Nitrogenous bases are covalently linked to the sugar of the nucleotide by a glycolytic bond. The bases are stacked along the interior of the axis of DNA. The two strands run in the opposite direction. The sugar of DNA is deoxyribose. Ribose is the sugar of RNA.

With what mRNA codon would the tRNA in the diagram below be able to form a codon-anticodon base pairing interaction? A. 5'-AUG-3' B. 5'-GUA-3' C. 5'-UAC-3' D. 5'-CAU-3'

B). The codon of the mRNA must base-pair with the anti-codon of the tRNA in a complementary and antiparallel fashion.

A 35-year-old female was involved in a rear-ended collision when she stopped at a red light. She was transported to the emergency room. Imaging studies revealed an injured ligament. Which ligament was most likely injured and what is the associated type of injury? (Her car had no head rests) A. Ligamentum flavum strain B. Anterior longitudinal ligament sprain C. Anterior longitudinal ligament strain D. Posterior longitudinal ligament sprain E. Posterior longitudinal ligament strain F. Supraspinous ligament sprain G. Supraspinous ligament strain

B. Anterior longitudinal ligament sprain This women has experienced whiplash from the vehicle accident. When she was suddenly rear ended her head accelerated backwards (hyper-extension) causing the anterior longitudinal ligament to sprain. A strain involves the tearing of muscle fibers and not ligaments.

What is the difference between α-D-glucose and α-D-galactose? A. They are mirror images of each other B. They differ in the configuration of substituents at C-4 C. One is an aldose and the other is a ketose D. They are anomers E. One forms only O-glycosidic bonds, and the other forms only N-glycosidic bonds

B. D-Galactose is a C-4 epimer of glucose

The protein albumin is a major buffer of the pH of the blood, which is normally kept between 7.2 and 7.4. Which of the following is an amino acid side chain of albumin that participates in this buffering range? A. Aspartate B. Histidine C. Tryptophan D. Glutamate E. Cysteine

B. Histidine

33. What artery does the long thoracic nerve closely parallel to? A. Axillary artery B. Lateral thoracic artery C. Thoracoacromial artery D. Thyrocervical artery E. Thoracodorsal artery

B. Lateral thoracic artery The lateral thoracic artery runs with long thoracic nerve along the superficial surface of the serratus anterior muscle.

Which of the following muscles/structure(s) forms the roof of the suboccipital triangle? A. Splenius capitis B. Semispinalis capitis C. Posterior arch of C1 D. Trapezius

B. Semispinalis capitis forms the roof of the suboccipital triangle, above which lies splenius, above which lies trapezius.

16-year-old boy is brought to the doctor complaining of fever, chills, and a stiff neck. The doctor suspects a case of meningitis and requests a lumbar puncture to be performed. Which layers does the needle pass through? A. Skin, posterior longitudinal ligament, anterior longitudinal ligament, dura mater, arachnoid mater B. Skin, supraspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater C. Skin, supraspinous ligament, ligamentum flavum, dura mater, epidural space, arachnoid mater D. Skin, posterior longitudinal ligament, ligamentum flavum, dura mater, arachnoid mater, pia mater

B. Skin, supraspinous ligament, ligamentum flavum, epidural space, dura mater, arachnoid mater The needle passes through skin, supraspinous ligament, ligamentum flavum, epidural space, dura mater, and arachnoid mater to reach the subarachnoid space for CSF collection. Remember, lumbar punctures are performed at the L3/L4 level in adults.

As the attending anesthesiologist, you are called to the ER to perform a lumbar puncture on a 45-year old male exhibiting signs of meningitis. As you pass the aspiration needle through the skin, what layers, in order will you pass through to gain access to CSF? A. Skin; fat; muscle; pia; dura; arachnoid B. Skin; fat; muscle; dura; arachnoid C. Skin; fat; muscle; dura; arachnoid; pia D. Skin; fat; muscle; arachnoid; pia

B. Skin; fat; muscle; dura; arachnoid CSF is produced by the chroid plexus and contained in the subarachnoid space. Therefore the layers one would need to penetrate are skin -> fat -> muscle -> dura -> arachnoid in that order.

A patient presents to the ER after having tripped and fallen forward on an extended right hand. An X-ray of the patient's shoulder shows an avulsion fracture of the greater tubercle of the humerus. During physical examination of the patient, you notice the patient's upper limb is medially rotated. You think back to your Anatomy class and remember that this presentation makes sense because: A. The medial rotators of the arm attach to the greater tubercle and can no longer function effectively due to the avulsion fracture B. The lateral rotators of the arm attach to the greater tubercle and can no longer function effectively due to the avulsion fracture C. The axillary nerve is damaged due to the avulsion fracture D. Blood supply to the arm has been compromised due to the avulsion fracture E. Pectoralis major and infraspinatus are lateral rotators of the arm that attach to the greater tubercle and can no longer function effectively due to the avulsion fracture

B. The lateral rotators of the arm attach to the greater tubercle and can no longer function effectively due to the avulsion fracture Supraspinatus, Infraspinatus, and Teres minor attach to the greater tubercle. The latter 2 laterally rotate the arm; this function would be totally lost in an avulsion fracture of the greater tubercle, causing the patient's upper limb to lie in a medially rotated position due to lack of muscles opposing medial rotation.

A 10-carbon sugar has recently been isolated from the cell wall of a plant indigenous to the Dominican Rain Forest. It has been determined experimentally that this sugar does not exhibit the property of mutarotation. Which of the following is a reasonable explanation for this phenomenon? A. the sugar is a ketose B. the sugar is not a reducing sugar C. the sugar is an aldose D. the sugar is a monosaccharide E. the sugar does not rotate plane polarized light.

B. The sugar is not a reducing sugar because the last chiral carbon atom does not have a free hydroxyl group which is necessary for cyclization to form a mixture of alpha- and beta-anomers

The breast receives blood supply from branches of which of the following arteries? A. Medial and lateral thoracic arteries B. Thoracic Aorta, Subclavian and Axillary artery C. Thoracic Aorta and axillary artery D. Axillary, subclavian and long thoracic artery

B. Thoracic Aorta, Subclavian and Axillary artery Lateral thoracic artery (axillary) Internal thoracic artery (Subclavian artery) Posterior intercostal artery (thoracic aorta)

You are in the emergency room when a patient is brought in, the loser in a street fight. He has received a stab wound about 1.5 cm long in the right side of the chest about 1.5 cm below and 1 cm medial to the coracoid process of the scapula. He has lost a lot of bright red blood from a large (~1.2 cm in diameter) severed artery found deep at this location. Intravenous fluids are immediately administered and a surgeon is called in to repair the artery. He begins by making an incision through the skin and subcutaneous tissue just below the clavicle, then cuts the clavicular head of the pectoralis major muscle and retracts it downward to obtain sufficient exposure of the area. He next encounters a partially severed muscle running downward and medially from the coracoid process. He divides the remaining fibers of the muscle and has you retract it downward. This exposes a bloody fat-filled space full of vessels and nerves. The muscle running downward and medially from the coracoid process which was partially severed was the: A. Coracobrachialis B. Pectoralis minor C. Long head of the biceps D. Subclavius E. Subscapularis

B. pectoralis minor Pectoralis minor inserts on the coracoid process of the scapula. Its origin is ribs 3-5, so it runs downward and medially from the coracoid process. Coracobrachialis is a muscle of the upper limb which takes origin from the coracoid process. However, it attaches to the shaft of the humerus and runs laterally. The long head of the biceps, subclavius, and subscapularis are not attached to the coracoid process.

What is the secondary structure of a prion?

Beta pleated sheet

Which of the following is characteristic for the active sites of enzymes? A. Nearly all amino acid side chains of the protein participate in catalysis B. The amino acid residues that form the active site are adjacent in the primary structure of the polypeptide C. The amino acid residues in the active site that bind the substrate are always the ones that catalyze the reaction D. In many cases the active site changes its conformation when the substrate binds E. In many cases, the initial binding of the substrate to the active site involves the formation of a covalent bond

C

Diane has a breast abscess. What is the most superior lymph node in her axilla which will drain the node? A. Supraclavicular lymph nodes B. Central lymph nodes C. Apical lymph nodes D. Superior mammary lymph nodes E. Superior pectoral lymph nodes

C. Apical lymph nodes

If the middle trunk was severed, which nerve would not be affected? A. Ulnar nerve B. Radial nerve C. Axillary nerve D. Median nerve E. Thoracodorsal nerve

C. Axillary nerve

Beta linkages are important in structural polysaccharides because: A. They are easily hydrolyzed by glycosidase enzymes B. They allow the chains to form compact coils C. They cause the chains to exist in an extended form thus allowing them to form fibers D. They cause the chains to absorb more water E. They can be formed by any hydroxy group in the monomer, whereas -linkages can only be formed by the anomeric cabon

C. Beta linkages such as those in cellulose are stabilized by hydrogen bonding and form extended fibers

The cephalic vein pierces what fascia to drain into which vein? A. Pectoral fascia, axillary vein B. Pectoral fascia, subclavian vein C. Clavipectoral fascia, axillary vein D. Clavipectoral fascia, subclavian vein

C. Clavipectoral fascia, axillary vein The cephalic vein runs along deltopectoral groove, pierces clavipectoral fascia, drains into axillary vein. (which becomes the subclavian vein at the first rib)

What is the major difference between glycogen and amylose? A. Glycogen contains only glucose, and amylose contains some fructose in addition to glucose B. Glycogen is a storage polysaccharide, and amylose is a structural polysaccharide of the extracellular matrix C. Glycogen is branched, and amylose is not. D. Glycogen contains some β-linkages, but amylose contains only α-linkages E. Glycogen is stored in the liver, and amylose is stored in skeletal muscle

C. Glycogen is branched, and amylose is not. Glycogen is similar to amylopectin not amylose and contains alpha-(1-6) gycosidic branches that join the chains together

A cricket player dislocated his shoulder during a game. The displaced humeral head came to rest anterior to the glenohumeral joint, inferior to the coracoid process. Given the most likely nerve injury with this type of dislocation, where would you expect paresthesia in this patient? A. Posterior shoulder B. Anterior shoulder C. Lateral shoulder D. Posterior arm and forearm E. Medial arm and forearm

C. Lateral shoulder An inferior dislocation (which results in the humeral head moving down then anteriorly from the joint) may injure the axillary nerve which provides sensation to the lateral shoulder.

A patient presents with peau d'orange sign on her left breast. The cancer has most likely invaded what structure/space? A. Suspensory ligaments B. Mammary glands C. Lymph vessels D. Retromammary space E. Lactiferous duct

C. Lymph vessels Lymphedema (swelling of lymph channels) causes peau d'orange (skin of an orange) appearance.

In the process of doing an axillary lymph node dissection in a 50 year-old patient, the surgery resident cleans the space between the pectoralis major and minor muscles, in an attempt to remove all of the lateral pectoral lymph nodes. Upon recovery it is noted that the patient's lower pectoralis major is paralyzed. The nerve most likely injured is the: A. axillary B. lateral pectoral C. medial pectoral D. suprascapular E. thoracodorsal

C. Since the medial pectoral nerve pierces pectoralis minor to reach pectoralis major, it seems likely for this nerve to be injured from trauma to the space between pectoralis minor and major. Also, remember that the medial pectoral nerve innervates the inferior part of pectoralis major, while the lateral pectoral nerve innervates the superior part of pectoralis major. The medial pectoral nerve innervates both pectoralis major and pectoralis minor, while the lateral pectoral nerve innervates pectoralis major only. These two nerves are named after their origin from two different cords of the brachial plexus. (This explains why their names and relative locations are reversed from what you might expect.) The thoracodorsal nerve (which is also derived from the brachial plexus) innervates latissimus dorsi, and is not involved with the pectoral muscles. The other two nerves, axillary and suprascapular, are also derived from the brachial plexus and will be studied along with the upper limb.

A 14-year old female is brought to the ER after falling from a horse. During surgery to repair a fractured vertebrae, the surgeon notices a severed dorsal scapular nerve. Which muscle will assist in retracting the scapula? A. Latissimus dorsi muscle B. Levator scapulae muscle C. Trapezius muscle D. Serratus posterior inferior muscle

C. Trapezius muscle The rhomboids and trapezius normally retract the scapula, but since the dorsal scapular nerve is severed, the rhomboids will not work.

25. Which of the following enzymes are responsible for this chemical reaction? 5'-AACGGGATCCATTGCTA-3' 5'-AACGGGATCCATTGCTA-3' 3'-TTGCCGTAGGTAACGAT-5' 3'-TTGCCCTAGGTAACGAT-5' A. A restriction enzyme B. RNA polymerase C. DNA polymerase D. Ligase

Choice C) is the correct answer. The nucleotide sequence to the left of the arrow is identical to the nucleotide sequence to the right of the arrow. The two sequences contain thymine (T), which is only found in DNA. So, DNA polymerase is the enzyme that will replicate DNA into DNA. In order for RNA polymerase to be the correct answer, the T's in the top strand of the right sequence would have to be replaced by U's. In order for reverse transcriptase to be the correct answer, the top strand of the left sequence should be removed and the T's in the bottom sequence should be exchanged for U's.

The sequence of part of a DNA strand is the following -ATTCGATTGCCCACGT-. When this strand is used as a template for DNA synthesis, the product will be which one of the following? A. TAAGCTAACGGGTGCA B. UAAGCUAACGGGUGCA C. ACGUGGGCAAUCGAAU D. ACGTGGGCAATCGAAT E. TGCACCCGTTAGCTTA

Choice D) is the correct answer. The sequence of DNA shown in the question stem is written 5' to 3'. Each answer nucleotide sequence is also written 5' to 3'. Since DNA is "read" 3' to 5' and polymerized 5' to 3', the first nucleotide in the synthesized DNA should begin with an A. Only answers C) and D) begin with an A. Answer C contains U's which are only found in RNA.

24. Why is DNA synthesized only in a 5' to 3' direction? A. The 3' hydroxyl group of the DNA strand is the determining factor. B. The 5' triphosphate of the DNA strand is the determining factor. C. It really doesn't matter, things just evolved that way. D. It has to do with proof reading. E. The 2' hydroxyl group of the DNA strand is the determining factor.

Choice D) is the correct answer. When an incoming nucleotide has recently been added to the polymer by the creation of a phosphodiester bond with the previous nucleotide, the incoming nucleotide is cleaved so that a pyrophosphate is one of the products of the reaction. If that new nucleotide is inappropriately base paired, it must be removed. The removal of an incorrectly base paired nucleotide leaves behind a reactive 3' OH which can react with the new triphosphate of another nucleotide. A 3' hydroxyl group is necessary for polymerization but does not explain why DNA is synthesized only in a 5' to 3' direction. If DNA was synthesized in a 3' to 5' direction, a 5' triphosphate would be present as long as the DNA polymerase did not make a mistake and the nucleotide had to be removed and replace by another nucleotide. When a 5' nucleotide is removed for incorrect base pairing, the 5' nucleotide that remains after it is remove would only have a monophosphate which does not "carry" enough energy for polymerization to occur. The 2' hydroxyl group of the nucleotide will determine which polymerase will recognize it and used it for making nucleic acid.

Your friend just bought a new stethoscope, and asked if he could place it on your triangle of auscultation to try it out. Which nerves innervate the superficial back muscles that constitute the borders of the area he's talking about? A. Thoracodorsal nerve, and posterior rami of spinal nerves B. Spinal accessory nerve, greater occipital nerve, and thoracodorsal nerve C. Cranial nerve XI, dorsal scapular, and intercostal nerves D. Dorsal scapular, thoracodorsal, and spinal accessory nerves

D

What does a stop codon interact with that causes translation to cease? A. Initiation factors B. Elongation factors C. A tRNA that has an anticodon for a stop codon D. Release factors

D). Stop codons interact with proteins that are called release factors. The release factors' tertiary structure is similar to the tertiary structure of a tRNA. This allows release factors to fit into the "slot" that a tRNA would fit into. The release factors interact with the stop codon to cause all the translation components to "come apart" and thereby stop translation.

he codon UAA is referred to as a stop codon. What exactly is a stop codon? A. The stop codon instructs the transcription machinery to stop the process of transcription. B. The stop codon instructs the splicing machinery to stop the process of RNA splicing. C. The stop codon instructs the polyadenylation machinery to stop the process of adding As to the end of a transcript. D. The stop codon instructs the translation machinery to stop the process of translation. E. None of the above statements are true.

D). The stop codon interacts with release factors (proteins shaped like a tRNA that interacts with the stop codons) that cause translation of the mRNA to cease.

During your internal medicine rotation, your attendant asks you to auscultate your patient's lungs through the triangle of auscultation. You recall from your anatomy course that this triangle is bounded by: A. Medial border of latissimus dorsi, lateral border of trapezius, inferior border of rhomboid major B. Medial border of trapezius, lateral border of latissimus dorsi, inferior border of rhomboid major C. Medial border of scapula, lateral border of leavator scapulae, and superior latissimus dorsi D. Medial border of scapula, lateral border of trapezius, superior border of latissimus dorsi E. Medial border of trapezius, lateral border of latissimus dorsi, superior border of rhoimboid minor

D. In this question, the borders refer to the borders of the muscles, not the borders of the triangle.

During a drug screening program, a researcher finds a chemical compound that decreases the activity of the enzyme monamine oxidase. A fixed dose of the drug reduces the catalytic activity of the enzyme by the same percentage at all substrate concentrations, with a decrease in Vmax. Which of the following best describes this drug? A. Positive allosteric effector B. Competitive inhibitor C. Suicide inhibitor D. Non competitive inhibitor

D. Vmax decreases in both suicide inhibition and non-competitive inhibition, but suicide inhibition can be somewhat counteracted by a large concentration of substrate.

A 22 year-old man presents with a stab wound to the lateral chest beneath his left arm. Physical exam reveals that the medial border of the patient's left scapula projects posteriorly and closer to the midline. Which nerve is most likely damaged? A. Axillary nerve B. Medial pectoral nerve C. Radial nerve D. Long thoracic nerve E. Suprascapular nerve

D. Long thoracic nerve

The 3' UTR contains which of the following nucleotide sequences? A. The translational control element for ferritin B. The promoter sequence C. The mRNA cap nucleotides D. The polyadenylation sequence

D. The correct answer is D. Answer A is found in the 5' UTR. Answer B) is found before the 5' UTR. Answer C can be considered part of the 5'UTR. Answer E is encoded by nucleotides in the exon before the splice site and nucleotides in the intron after the splice site.

The clavipectoral fascia is penetrated by which artery? A. Anterior circumflex humeral B. Axillary C. Subscapular D. Thoracoacromial E. Thoracodorsal

D. The thoracoacromial artery pierces the clavipectoral fascia before giving off its four branches: pectoral, clavicular, deltoid, and acromial. It supplies pectoralis major, pectoralis minor, the deltoid muscle, and the acromioclavicular joint. It is a branch off of the axillary artery. The axillary artery and all its other branches, including the anterior circumflex humoral and subscapular arteries, run deep to the clavipectoral fascia. The thoracodorsal artery is a branch of the subscapular artery which also runs deep to the fascia.

he enzyme that catalyzes the following reaction belongs to which broad enzyme class? Protein + ATP--- Phosphoprotein + ADP A. Isomerase B. Lyase C. Oxidoreductase D. Transferase E. Ligase

D. Transferase Kinase

A twenty year old man is in the emergency room suffering a knife wound. He complains of weakness upon elevation of his shoulder. The main muscle responsible for this action is innervated by? A. Dorsal scapular nerve B. Dorsal primary rami C. Transverse cervical nerve D. Spinal accessory nerve

D. Trapezius is the main muscle responsible for elevating the shoulder. A. innervates Levator scapula, which elevates the scapula, and the rhomboids, which retract the scapula and fix it to the thoracic wall as well as rotating the glenohumeral joint. B. Innervates the deep back muscles. C. Provides cutaneous innervation to the neck, but is confusing because the trapezius (and Levator scapula) is supplied by the transverse cervical ARTERY.

A sailor walks into your clinic displaying early signs of scurvy (skin changes, bleeding gums). Why does a lack of Vitamin C result in the degeneration of collagen fibers? A. Vitamin C is necessary as an anti-oxidant, removing any reactive oxygen species from attacking the collagen and breaking apart its protein structure B. Vitamin C is required to convert proline to hydroxyproline, increasing the number of hydrogen bonds within alpha-helices of collagen, fortifying the collagen network within connective tissue C. Vitamin C is an anti-oxidant, preventing the oxidation of Cys residues to maintain the integrity of disulfide bridges. These bridges hold collagen molecules together and fortify the collagen network found in connective tissue D. Vitamin C is required to convert proline to hydroxyproline, increasing the number of hydrogen bonds between collagen beta-pleated sheets, fortifying the collagen network within connective tissue E. Vitamin C does not play a significant role in collagen formation or maintenance

D. Vitamin C is required to convert proline to hydroxyproline, increasing the number of hydrogen bonds between collagen beta-pleated sheets, fortifying the collagen network within connective tissue. Hydroxyproline and hydroxylysine are main components of the collagen protein. The extra H molecules in these amino acids allow for an increase in H-bonding between beta sheets of collagen. Answer A does describe Vitamin C as an anti-oxidant, but a lack of this function does not cause scurvy (it could cause cancer though!). Answer B is wrong because alpha-helices are not involved with Vitamin C. C is describing a component of keratin (NOT collagen), and vitamin C is not involved in disulfide bridge formation. E is wrong. D is the correct answer, describing how Vitamin C is crucial in the formation of hydroxyproline.

Postoperative examination revealed that the medial border and inferior angle of the left scapula became unusually prominent (projected posteriorly) when the arm was carried forward in the sagittal plane, especially if the patient pushed with outstretched arm against heavy resistance (e.g., a wall). What muscle must have been denervated during the axillary dissection? A Levator scapulae B Pectoralis major C Rhomboideus major D Serratus anterior E Subscapularis

D. serratus anterior Serratus anterior, innervated by the long thoracic nerve, draws the scapula forward. If it is denervated, there is no muscle to oppose the motion of the trapezius which is elevating and retracting the scapula. The medial border of the scapula falls away from the posterior chest wall and begins to look like an angel's wing. This is termed a "winged scapula." A winged scapula commonly occurs after an injury to the long thoracic nerve, which runs on the superficial surface of serratus anterior and is particularly vulnerable to trauma. The long thoracic nerve contains contributions from C5, 6, and 7, so remember the saying "C5, 6, and 7 keep the wings from heaven." This is a classic scenario to remember!

What is the net charge on glutamate at ph 13? A. +2 B. +1 C. 0 D. -1 E. -2

E.

A 61-year-old male presents to the ED following a traumatic injury to the right posterolateral neck. A stat C-spine X-ray reveals a fracture of the right transverse process of C1. Which of the following muscles is attached to the fractured site and is responsible for ipsilateral head rotation? A. Obliquus capitis superior B. Rectus capitis posterior major C. Rectus capitis posterior minor D. Semispinalis capitis E. Obliquus capitis inferior

E. Obliquus capitis superior and obliquus capitis inferior are the 2 muscles of the suboccipital triangle that attach to the transverse process of C1; OCI inserts here and thus rotates the head ipsilaterally. OCS inserts on the occipital bone and is responsible for head extension and lateral flexion. Rectus capitis minor attaches to the C1 posterior arch, not its transverse process. Semispinalis capitis attaches to the head and spinous processes of C4-T12 and inserts on the transverse processes, but it is not part of the suboccipital triangle.

During one of your clinical rotations, you hear about a patient who recently died (1-2 days) from Creutzfeld-Jacob disease. Curious, you saw physicians performing an autopsy within an isolated room and wearing heavy protection to prevent any infection. Why are the doctors afraid of an infection if the patient is already dead? A. The prion is not degraded, even after death, due to the change in the protein's tertiary structure (normal is an alpha-helix, abnormal is beta-pleated sheet B. The prion is not degraded, even after death, due to the change in the protein's secondary structure (normal is a beta-pleated sheet, abnormal an alpha-helix) C. A highly resistant virus is the cause of this disease, and can survive within the patient's body up to a week after death D. The prion is not degraded, even after death, due to the change in the protein's tertiary structure (normal is a beta-pleated sheet, abnormal an alpha-helix) E. The prion is not degraded, even after death, due to the change in the protein's secondary structure (normal is an alpha-helix, abnormal is beta-pleated sheet)

E. Prions are abnormal proteins due to a change in the SECONDARY structure. Normal proteins are easily degraded by proteases and soluble due to the alpha helices present in its secondary structure. Prions (abnormal proteins) are INSOLUBLE and RESISTANT to degradation (even after death) due to the change to a beta-pleated sheet as it's secondary structure. C is incorrect because this disease is not caused by a virus.

The isolation of nascent Okazaki fragments during DNA replication led to the surprising discovery of uracil in the fragment. The uracil is present due to which of the following? A. Deamination of cytosine B. Chemical modification of thymine C. An error in DNA polymerase D. Failure of mismatch repair E. The need for a primer

E. The presence of uracil in DNA is because of the need for a primer which can only be laid down by RNA polymerase.

A patient presents to the emergency department after an attempted suicide. The patient attempted to hang himself, but was found by his wife in time to save his life. What vertebrae is most likely to be fractured and what spinal nerve exits below this vertebrae? A. C1 vertebrae and spinal nerve C1 B. C2 vertebrae and spinal nerve C2 C. C3 vertebrae and spinal nerve C4 D. C1 vertebrae and spinal nerve C2 E. C2 vertebrae and spinal nerve C3

E. Hangman's Fracture is C2, Jefferson Fracture is C1 J1, H2

Which of the following is true about the tertiary structure of proteins? A. Disulfide bonds are part of the tertiary structure B. Only proteins with more than one polypeptide subunit have a tertiary structure C. Proteins with tertiary structure do not contain α-helix or β-pleated sheet D. van der Waals interactions play no role in the tertiary structure E. Interactions between hydrophobic amino acid side chains are the most important to hold the tertiary structure together

E. Hydrophobic interactions in the core of the folded protein are the most important stabilizing interactions for tertiary structure. Disulfide bonds are a post-translational modification that take place after the folded protein leaves the robosome

During his first game as running back, Andrew was running with the ball and was tackled from behind. In an effort to break his fall, he outstretched his right arm and felt an immediate snap and then a loss of sensation. Upon returning to the sideline, the trainer had him attempt to abduct his arm against resistance, but he could not initiate the abduction without feeling excruciating pain. Which muscle and nerve has Andrew most likely injured? A. Deltoid - axillary nerve B. Teres major - lower subscapular nerve C. Supraspinatus - upper subscapular nerve D. Deltoid - suprascapular nerve E. Supraspinatus - suprascapular nerve

E. Supraspinatus - suprascapular nerve

A woman with breast cancer subsequently develops metastases in her vertebral column. The most direct route for spread of the tumor to the vertebral column was via: A. branches of the cephalic vein B. branches of the lateral thoracic vein C. branches of the thoracoacromial veins D. lymphatic vessels draining into the axilla E. branches of the intercostal veins

E. The most likely route for the cancer to reach the vertebral column is through the intercostal veins, i.e. hematogenous spread. The cephalic vein and thoracoacromial vein would not be draining the breast, and the lateral thoracic vein would not be directing blood toward the vertebral column. Lymphatic vessels may carry some tumor cells to the axillary lymph nodes and may participate in the spread of the cancer, but this isn't the best answer for this question. The most direct way for the cancer to spread to the vertebral column is through the venous system.

Ethylene glycol, the major ingredient in antifreeze, is occaisionally consumed by alcoholics as a substitute for ethanol. Ethylene glycol is also a substrate for alcohol dehydrogenase (ADH) but the aldehyde product that is formed is highly toxic. Ethanol is often administered as a treatment in cases of ethylene glycol poisoning. What is the likely reason that ethanol is an effective treatment for ethylene glycol poisoning"? A. Ethanol is an allosteric effector of ADH in addition to being a substrate B. Ethanol combines with the toxic product formed by the reaction of ADH with ethylene glycol in a manner that renders it non toxic C. Acetaldehyde, which is produced by the reaction of ADH with ethanol, is of therapeutic value D. Ethanol induces another enzyme that is capable of metabolizing ethylene glycol E. ADH exhibits a much lower Km for ethanol than for ethylene glycol

Ethanol has a higher affinity (lower Km)for alcohol dehydrogenase and can displace ethylene glycol from the active site before it can be oxidized to toxic oxalyl dialdehyde. Thus it can be excreted by the kidneys before it is oxidized

A polypeptide has a primary structure of Lys-Ala-His-Asp-Val-Arg-Gly-Glu. What is the overall charge? A. +2 B. +1 C. 0 D. -1 E. +2

Focus on the charges of the amino acids and add them together. So for this particular polypeptide, Lys, Arg and His all have a +1 charge, Glu and Asp have a -1 charge, and Val, Ala and Gly are all neutral. The total charge would be 1+1+1-1-1 = +1.

What are the branches of the axillary artery?

H - Superior thoracic artery T - thoracoacromial artery -> acromial, pectoral, clavicular, deltoid artery L - Lateral thoracic artery S - subscapular artery -> thoracodorsal artery, circumflex scapular artery P - posterior circumflex humeral artery A - anterior circumflex humeral artery

Breast cancer cells can spread directly to the cranial cavity and brain via the vertebral venous plexus. Through which route can they reach this plexus? Axillary lymph nodes Internal thoracic vein Intercostal veins Parasternal lymph nodes Thoracoacromial artery

Intercostal veins. Hematogenous spread through the intercostal veins is the easiest way for breast cancer to reach the internal vertebral venous plexus. It is true that the axillary lymph nodes drain 75% of the lymph from the breast, and the parasternal lymph nodes drain most of the remaining lymph. However, these lymphatic channels are not the major way that cancer would be transmitted to the internal vertebral venous plexus. This plexus of veins would be most likely to receive cancer cells transmitted through the blood. The internal thoracic vein drains some blood from the breast, but it would not direct the blood toward the vertebral column. It directs blood more directly toward the vena cana.

While observing a mastectomy on a 60-year-old female patient, a medical student was asked by the surgeon to help tie off the arteries that supply the medial side of the breast. The artery that gives origin to these small branches is the: Internal thoracic Musculophrenic Posterior intercostal Superior epigastric Thoracoacromial

Internal thoracic Small branches from the internal thoracic artery, known as medial mammary branches, supply the medial side of the mammary gland. The lateral side of the mammary gland is supplied by the lateral thoracic artery. The musculophrenic artery is a branch of the internal thoracic artery--it travels laterally and supplies blood to the 7th through 9th intercostal spaces. The posterior intercostal arteries are branches from the descending aorta--they supply the lateral and posterior portions of the intercostal space. The superior epigastric artery is a branch of the internal thoracic artery--it supplies the upper rectus abdominis muscle and the upper abdominal wall. The thoracoacromial artery supplies blood to the pectoral muscles, deltoid, subclavius, and the shoulder joint.

What is necessary for a sugar to exhibit the property of mutarotation?

It must be a reducing sugar The last chiral carbon atom must have a free hydroxyl group for it to cyclize.

Th half maximal velocity of an enzyme reaction is defined as

Km

Which arteries supply the breasts?

Lateral thoracic artery Internal thoracic artery Posterior intercostal artery

During a motorcycle accident, an 18-year-old male landed on the right lateral side of his rib cage with his right upper limb abducted. In the hospital he was found to have "winging" of the right scapula. Which nerve was likely damaged in the accident? Accessory Lateral pectoral Long thoracic Phrenic Vagus

Long thoracic nerve An injury to the long thoracic nerve denervates serratus anterior, meaning that there will be no muscle protracting the scapula and counteracting trapezius and the rhomboids, powerful retractors of the scapula. This means that the scapula will be winged backwards, which is this patient's main symptom. The long thoracic nerve is derived from the nerve roots of C5-7. This nerve is particularly vulnerable to iatrogenic injury during surgical procedures, such as mastectomies, because it is located on the superficial side of serratus anterior. The accessory nerve innervates trapezius--an injury to this nerve might lead to an inability to raise the acromion of the shoulder. The lateral pectoral nerve is a small nerve that provides innervation to pectoralis major.

Which amino acids are positively charged?

Lysine, Arginine, sometimes hisitidine

ilpivirine is a new NonNucleoside Reverse Transcriptase Inhibitor( NNRTI) approved by the FDA in 2011 to treat HIV infection.. It binds to a hydrophobic pocket proximal to the active site. What effect would Rilpivirine have on Vmax and Km ? A. No effect on Vmax and Km B. An increase in both Vmax and Km C. A decrease in both Vmax and Km D. A decrease in Km and an increase in Vmax E. A decrease in Vmax and no effect on Km

Non competitive inhibitors decrease Vmax with no effect on Km. Km is the concentration of E+S over concentration of ES, and since the inhibitor will bind equally well to the E and the ES, Km will not appear to change.

A post-fixed brachial plexus increases the risk for which brachial neuropathy? A. Wrist drop B. Hand of benediction C. Klumpke's palsy D. Erb's palsy E. Ape hand

Post-fixed brachial plexus means T2 and/or T3 contribute to the brachial plexus. This increases the risk of inferior trunk compression - Klumpke's palsy - due to increased risk of compression or stretching of the inferior trunk/roots in the superior thoracic aperture.

While dissecting out the suboccipital triangle, a group of 1st semester medical students is attempting to identify the 4 muscles found in that region. A professor comes by and asks which muscle exclusively extends the neck and which one exclusively rotates the neck to the same side? A. Rectus Capitus Posterior Major; Rectus capitus posterior inferior B. Rectus capitus posterior Major; Obliquus capitus inferior C. Rectus capitus posterior minor; Obliquus capitus superior D. Rectus capitus posterior minor; Obliquus capitus inferior E. Rectus capitus posterior Major; Obliquus capitus inferior

Rectus capitus posterior minor from origin-->insertion is almost vertical, limiting it's potential actions to Extension of the neck. Obliquus capitis inferior from origin-->insertion is almost horizontal, limiting it's potential action to rotation of the neck. Rotation is ipsilateral. Rectus posterior major extends and rotates. Obliquus capitis superior extends and flexes the head.

Alone in the alley, a man gets stabbed on the back of his neck and the knife nicks the vertebral artery within the suboccipital triangle. The knife pierced which two muscles that form the immediate roof of the triangle?

Semispinalis, Splenius

34. Sucrase is an intestinal enzyme that cleaves sucrose into it's constituents. What glycosidic bond is cleaved to release the glucopyranose and fructofuranose molecules? A. Beta 1 - Beta 4 linkage B. Alpha 1 - Alpha 4 linkage C. Alpha 1 - Beta 2 linkage D. Alpha 2 - Beta 1 linkage E. Alpha 1 - Alpha 6 linkage

Sucrose is a disaccharide formed by glucose and fructose cyclic monomers connected via an alpha 1 - beta 2 glycosidic linkage. Sucrase would cleave that bond to free each pyranose and furanose molecule. 53% of students answered this question correctly. This question's difficulty has been rated as 'moderate' compared to other questions in biochemistry.

A patient presents to the emergency room with a gunshot wound immediately inferior to the right clavicle. A CT scan shows that the bullet did not damage the axillary artery, but it did lacerate a branch of this artery. This branch typically arises immediately lateral to the first rib, well medial to the pectoralis minor muscle. Which artery is most likely damaged in this patient? A. Subscapular artery B. Suprascaular artery C. Superior thoracic artery D. Thoracoacromial trunk E. Lateral thoracic artery

Superior thoracic artery is the only branch of the first part of the axillary artery.

The arrangement of sugars into D- and L- configurations is based upon their resemblance to D- and L- A. glycine B. glucose C. fructose D. glyceraldehyde E. histidine

The absolute configuration of D- and L-glyceraldehyde are known from X-ray crystallography and used to assign configurations to sugars and amino acids

Which of the following nucleotide sequences is never found in an exon? A. 5' UTR B. 3' UTR C. Promoter D. Introns E. Codons for amino acids

The correct answer is C). The nucleotides that remain in final processed mRNA are called exons. The transcribed nucleotides that are removed to make the final processed mRNA are called introns. When the removed "intronic" nucleotides are included in the final processed mRNA, the process of including them is called "alternative splicing". These "intronic" nucleotides are now considered exonic nucleotides. So, there are times when "introns" are included in "exons". Codons for amino acids are always include in "exons". However, the nucleotides that are used to bind transcription factors and RNA polymerase are not transcribed in producing the transcript that will become mRNA.

77. In a bar fight, a guy gets a cut in his arm, at the deltopectoral groove, his bleeding is most likely from which of these vessels? A. Axillary artery B. Basilic vein C. Cephalic vein D. Brachial profunda artery

The course of the cephalic vein is in the deltopectoral groove.

ou are assisting in a childbirth during your clinical rotations. While preparing to give the mother an epidural anesthetic for the pain, the Chief Resident turns to you and asks what two layers is the epidural space found between. A. Dura mater & arachnoid mater B. Arachnoid mater & pia mater C. Vertebral canal & dura mater D. Pia mater & spinal cord E. Vertebral body & posterior longitudinal ligament

The epidural space is a fatty filled space located outside the dura mater but within the vertebral canal. Between the Arachnoid mater & Pia Mater (choice B) you will find the Subarachnoid space. This is normally filled with cerebrospinal fluid (CSF.) The pia mater & spinal cord have no space, real or potential between them and you can not separate the two without damaging the spinal cord. (Choice D)

Why does denervation of the serratus anterior cause winged scapula?

The trapezius and rhomboids retract the scapula and the serratus anterior protracts it. The serratus anterior is innervated by the long thoracic nerve.

Serum proteins have a very specific optimal pH and some will become denatured if there are slight deviations from it. After consuming a particular dipeptide, it becomes denatured upon contact with the extremely acidic gastric juices within the stomach. What would be the overall charge on this dipeptide containing Lys and Leu amino acids at normal and within a very acidic environment respectively? A. +1/ +1 B. +1/ 0 C. +1/ +2 D. -1/ 0 E. -2/ -1

This question is about amino acid isoelectric points. At physiological pH all amino acids exist as zwitterions (a protonated amine group and de-protonated carboxyl group). This specific dipeptide, at physiological pH would have an overall charge of +1, due to the pronated amino group (+1), neutral Leu R group, protonated Lys R group (+1), and de-protonated carboxyl group (-1). At an acidic pH, the carboxyl group becomes protonated, REMOVING the -1 charge from the dipeptide, resulting in an OVERALL charge of +2.

Which vitamain is crucial in formation of hydroxyproline?

Vitamin C

The rate of a Michaelis-Menton enzyme-catalyzed reaction was measured at several concentrations that produced much less than the half maximal velocity. Which of the following best describes the effect on reaction rate? A. The reaction rate increases exponentially as substrate concentration increases B. The reaction rate is gradually reduced by product inhibition C. Denaturation of the enzyme reduces the reaction rate D. The rate is linearly proportional to the substrate concentration E. The reaction rate shows zero order kinetics

When the substrate concentration is much less than Km, the reaction is directly proportional to the substrate concentration and linear

Is galactose an aldose or a ketose?

aldose

Is glucose an aldose or a ketose?

aldose

Is ribose an aldose or a ketose?

aldose

In the axilla the pectoralis minor is a landmark, being closely related to all of the following structures except: cephalic vein cords of the brachial plexus lateral thoracic artery medial pectoral nerve second part of the axillary artery

cephalic vein The cephalic vein is the only structure listed that does not have a special relationship to pectoralis minor. The cords of the brachial plexus are found deep to pectoralis minor. The second part of the axillary artery is defined as the segment of the axillary artery which is covered by the pectoralis minor muscle. So, branches of the second part of the axillary artery, including the lateral thoracic artery, lie deep to pectoralis minor. The medial pectoral nerve pierces pectoralis minor to reach pectoralis major.

What are the branches of the Subclavian artery?

dorsal scapular artery-> circumflex scapular artery-> suprascapular artery thyrocervical trunk ->suprascapular artery, transverse cervical artery

Which comes first superficial to deep, the dura mater or the epidural space?

epidural space (epi means above)

What are the main components of collagen?

hydroxyproline & hydroxylysine

Is fructose an aldose or a ketose?

ketose

Upon finding a malignant tumor in the medial portion of the breast of a 40-year-old female, the surgeon began to search for the lymph nodes that would be the first ones reached by metastatic spread of cancer cells from this site. Which group(s) would have to be examined to determine whether metastasis had occurred? Central only Parasternal only Parasternal and apical Parasternal and lateral Parasternal and pectoral

parasternal and pectoral As lymph drains from the breast, the majority of fluid travels to two groups of lymph nodes: the axillary and the parasternal. 75% of the lymph goes to the axillary lymph nodes, with the pectoral nodes being the first axillary nodes to receive the drainage. So, the pectoral nodes would need to be inspected to determine whether cancer had spread to the axillary system. Central and apical nodes are also part of the axillary system. These nodes might receive cancerous cells, but they are more distal sites of drainage. Cancer would be most likely to metastasize to the pectoral nodes first. The parasternal nodes receive most of the lymph that does not drain into the axillary nodes. They are an especially important route of drainage from the medial side of the breast. So, it is also important to survey these nodes to determine whether cancer has spread into the lymphatics.

After a jarring blow to the left anterior shoulder region, a young field hockey player was told by an examining physician that she had a muscle tear that resulted directly from the superolateral distraction of a fractured coracoid process. Which muscle was torn? Deltoid Pectoralis major Pectoralis minor Serratus anterior Subclavius

pectoralis minor Of the muscles listed, pectoralis minor is the only one which is attached to the coracoid process. The deltoid originates from the clavicle, acromion and scapular spine and inserts on the deltoid process of the humerus. Pectoralis major originates from the clavicle, sternum, and ribs and inserts on the crest of the greater tubercle of the humerus. Serratus anterior originates on the ribs and inserts on the medial border of the costal surface of the scapula. Subclavius originates on the first rib and inserts on the clavicle. So, none of these other muscles would be detached by a fracture of the coracoid process. What other muscles are attached to the coracoid process? Coracobrachialis and the short head of the biceps.

What muscles retract the scapula?

rhomboids + trapezius

Which two structures most immediately supply the suprascapular artery?

thyrocervical trunk, circumflex scapular artery