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USMLE Step 1 > Foundations/Cell Biology > Flashcards

Foundations/Cell Biology Flashcards

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USMLE® Step 1 flashcards
1
Q

What are the 3 different mechanisms cells employ to break down proteins?

A
  1. Ubiquitin protein ligase
  2. Lysosomes
  3. Calcium-dependent enzymes
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2
Q

Name the respective intermediate filament stains for the following tissues

  1. Connective tissue (sarcomas)
  2. Muscle (myosarcomas)
  3. Neuroglia (glioblastoma)
  4. Neurons – axons (neuroblastoma)
  5. Epithelium (carcinoma)
  6. Neurons
  7. Nuclear membrane/cytoskeleton
A
  1. Vimentin
  2. Desmin
  3. GFAP (glial fibrillary acid protein)
  4. Neurofilaments types 1, 2, and 3
  5. Cytokeratin
  6. Peripherin
  7. Nuclear lamins
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3
Q

What are the phases of the wound healing?

A

Inflammatory phase (Immediate)
0-3 hours ———————- Hemorrhage and clotting
12-24 hours ——————- Acute inflammation (infiltration of polymorphic neutrophils)

Proliferative phase (2-3 days after wound)
1-3 days ———————— Macrophage infiltration
———————— Granulation tissue (fibroblasts and vascular endothelium)
———————— Epithelialization

Remodeling (1 week after wound)
Weeks - months ————- Collagen profuction (Type III then Type I)

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4
Q

What substances do cytotosic T cells and NK cells use to indude apoptosis in the cells infected with virus?

A
  • Granzymes
  • Perforin
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5
Q

What highly damaging events can cause irreversible cell injury?

A
  • Calcium influx
  • Damage of the plasma membrane
  • Damage of the nucleus
  • Rupture of the lysosome
  • Mitochondrial permeability
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6
Q

What adult structures are derived from surface ectoderm?

A
  • Anterior hypothalamus (from Rathke pouch)
  • Lens of the eye
  • Sensory organs of the ear
  • Olfactory epithelium
  • Epithelial linings of the oral cavity
  • Epidermis
  • Anal canal below the pectinate line (which is skin)
  • Parotid, sweat and mammary glands
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7
Q

What adult structures are derived from the neuroectoderm?

A
  • Brain
    >> CNS neurons
    >> CNS glia: astrocytes, oligodendrocytes, ependymal cells
    >> Posterior hypothalamus
    >> Pineal gland
  • Retina and optic nerve
  • Spinal cord
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8
Q

What adult structures are derived from the neural crest?

A
  • PNS
    >> Autonomic nervous system
    >> Dorsal root ganglia
    >> Sensory nerves
    >> Celiac ganglia
    >> Cranial nerves
    >> Schwann cells
  • Pia and arachnoid mater
  • Eyes: cornea, sclera, ciliary muscle and iris pigment cells (anterior chamber)
  • Ears: ossicles of the middle ear
  • Mouth: odontoblasts
  • Thyroid: parafollicular C cells
  • Heart: aorticopulmonary septum (really an embryological structure)
  • Adrenal gland: chromaffin cells of the adrenal medulla
  • Digestive sytstem: enteric nervous system, enterochromaffin cells
  • Skin: melanocytes
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9
Q

What adult structures are derived from the mesoderm?

A
  • Muscle
  • Bone
  • Connective tissue
  • Serous linings of the body cavities: pleura, pericardium, peritoneum
  • Spleen
  • Blood, lymphatics and vessels
  • Other viscera:
    >> Wall of the gut tube
    >> Vagina
    >> Kidneys
    >> Adrenal cortex
    >> Testes and ovaries
  • Dermis
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10
Q

What adult structures are derived from the endoderm?

A
  • Gut tube epithelium all the way down to the anal canal above the pectinate line
  • Most of the urethra
  • Luminal epithelial derivates:
    >> Eustachian tube
    >> Thymus
    >> Thyroid follicular cells
    >> Parathyroid
    >> Lungs
    >> Liver
    >> Gallbladder
    >> Pancreas
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11
Q

What is the embryological origin of:

Olfactory epithelium?

A

Surface ectoderm

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12
Q

What is the embryological origin of:

Mammary glands?

A

Surface ectoderm

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13
Q

What is the embryological origin of:

Odontoblasts?

A

Neural crest

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14
Q

What is the embryological origin of:

Blood?

A

Mesoderm

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15
Q

What is the embryological orgin of:

Lens of the eyes?

A

Surface ectoderm

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16
Q

What is the embryological origin of:

Retina?

A

Neuroectoderm

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17
Q

What is the embryological origin of:

Anterior pituitary?

A

Surface ectoderm

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18
Q

What is the embryological origin of:

Cornea, sclera, ciliary muscles and iris pigment cells?

A

Neural crest

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19
Q

What is the embryological origin of:

Oligodendrocytes?

A

Neuroectoderm

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20
Q

What is the embryological origin of:

Liver?

A

Endoderm?

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21
Q

What is the embryological origin of:

Thyroid?

A

Endoderm

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22
Q

What is the embryological origin of:

Testes and ovaries?

A

Mesoderm

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23
Q

What is the embryological origin of:

Eustachian tube?

A

Endoderm

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24
Q

What is the embryological origin of:

Spleen?

A

Mesoderm

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25
Q

What is the embryological origin of:

Adrenal glands?

A

Mesoderm

26
Q

What is the embryological origin of:

Sweat glands?

A

Surface ectoderm

27
Q

What is the embryological origin of:

Thymus?

A

Endoderm

28
Q

What is the embryological origin of:

Kidneys?

A

Mesoderm

29
Q

What is the embryological origin of:

Schwann cells?

A

Neural crest

30
Q

What is the embryological origin of:

Pancreas?

A

Endoderm

31
Q

What is the embryological origin of:

Parathyroid?

A

Endoderm

32
Q

What is the embryological origin of:

Epidermis?

A

Surface ectoderm

33
Q

What is the embryological origin of:

Urethra?

A

Endoderm

34
Q

What is the embryological origin of:

Middle ear ossicles

A

Neural crest

35
Q

What is the embryological origin of:

Mammary glands?

A

Surface ectoderm

36
Q

What is the embryological origin of:

Lungs?

A

Endoderm

37
Q

What is the embryological origin of:

Optic nerve?

A

Neuroectoderm

38
Q

What is the embryological origin of:

Sensory organs of the ear?

A

Surface ectoderm

39
Q

What is the embryological origin of:

Salivary glands?

A

Surface ectoderm

40
Q

What is the embryological origin of:

Pineal gland?

A

Neuroectoderm

41
Q

Which cyclin-CDK complexes assist in the progression from G1 phase to the S phase?

A

Cyclin D + CDK 4

Cyclin E + CDK 2

42
Q

Which cyclin-CDK complexes assist in the progression from G2 phase to M phase?

A

Cyclin A + CDK 2

Cyclin B + CDK 1

43
Q

Which amino acids are nuclear localization signals rich in?

A
  • Proline
  • Lysine
  • Arginine

>> Nuclear localization signals are amino acid sequences 4-8 amino acids long, and are signals nuclear pores recognize and allow access to the nucleus

44
Q

What amino acids are modified by the Golgi apparatus?

A
  • Asparagine – N-oligosaccharides
  • Threonine and Serine – O-oligosaccharides
  • Tyrosine – sulfate
45
Q

What molecule does the Golgi apparatus add to proteins in order to direct the proteins to the lysosomes?

A

Mannose-6-phosphate

46
Q

What are the presenting features of a patient with I-cell disease?

A
  • Intellectual disability
  • Corneal clouding
  • Coarse facies
  • Hepatosplenomegaly
  • Skeletal abnormalities
  • Restricted joint movements

>> Inherited lysosomal storage disorder
>> Defect in phosphotransferase
>> Often fatal in childhood

47
Q

What structures are derived from the first branchial arch?

A

The Ms and Ts

Cartilage

  • Meckel cartilage
  • Mandible
  • Malleus and incus
  • Spheno-mandibular ligament

Muscles

  • Muscles of Mastication
  • Mylohyoid
  • Tensor veli palatini
  • Tensor tympani

Nerves

  • Maxillary nerve (CNV2)
  • Mandibular nerve (CNV3)
48
Q

What structures are derived from the first branchial cleft?

A

External auditory meatus

49
Q

What structures are derived from the second branchial arch?

A

The Ses for the Second pharyngeal/branchial arch

Cartilage

  • Stapes
  • Styloid process
  • Lesser horn of hyoid
  • Stylohyoid ligament

Muscles

  • Muscles of facial expression
  • Stapedius
  • Stylohyoid
  • PlatySma
  • DigaStric muscle

Nerve
- Facial nerve (the nerve that makes you Smile)

50
Q

What structures are derived from the third pharyngeal/brachial arch?

A

Think pharynx.

Cartilage
- Greater horn of the hyoid

Muscles
- Stylopharyngeus

Nerves
- CNIX Glossopharyngeal nerve

51
Q

What structures are derived from the 4th and 6th pharyngeal arches?

A

Think larynx.

Cartilage

  • Thyroid
  • Cricoid
  • Arytenoids
  • Corniculate
  • Cuneiform

Muscles
- 4th arch:
>> Pharyngeal constrictors
>> Cricothyroid
- 6th arch:
>> All intrinsic laryngeal muscles except the cricothyroid muscle

Nerves

  • 4th arch: superior laryngeal nerve of the CNX
  • 6th arch: recurrent laryngeal nerve of the CNX
52
Q

What structures are derived from the 2nd-4th pharyngeal clefts?

A

Temporary cervical sinuses: eventually obliterated

53
Q

What structures are derived from the first branchial/pharyngeal pouch?

A
  • Middle ear cavity
  • Eustachian tube
  • Mastoid air cells
54
Q

What structures are derived from the second pouch?

A

Epithelial lining of the palatine tonsil

55
Q

What structures are derived from the third pharyngeal/branchial pouch?

A
  • Inferior parathyroids (dorsal wing)
  • Thymus (ventral wing)
56
Q

What structures are derived from the fourth pharyngeal/branchial pouch?

A

Superior parathyroids

57
Q

Which amino acids is collagen rich in?

A
  • Glycine
  • Proline
  • Lysine
  • Hydroxyproline
  • Hydroxylysine
58
Q

Which amino acids is elastin rich in?

A
  • Glycine
  • Proline
    >> NON-hydroxylated
59
Q

What is elastin made of?

A

Tropoelastin with fibrillin scaffolding

60
Q

Name the main 3 types of Ehlers Danlos syndrome. What are their respective clinical features?

A
  • Classical type (Collagen types I and V)
    >> Skin tenting
    >> Hypermobile joints
  • Hypermobility type (Collagen type I mainly)
    >> Hypermobile joints
  • Vascular type (Collagen type III)
    >> Aneurysm rupture
    >> Hemorrhages
    >> Easy bruising
    >> Berry aneurysms

USMLE Step 1 (14 decks)

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