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KCU Comprehensive Exam > Dr. White-Molecular and Biochemical Basis of Disease > Flashcards

Dr. White-Molecular and Biochemical Basis of Disease Flashcards

1
Q

what are the functions of the cytoskeleton?

A

bones of the cell
important in organization of the cell
maintains correctly shipped cells
insures cells are properly structured internally

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2
Q

What are the three families of cytoskeletal proteins?

A

actin filaments
microtubules
intermediate filaments

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3
Q

What do actin filaments do?

A

(mardi gras beads)

determine the shape of cell’s surface and are necessary for whole cell locomotion, secretion, endocytosis

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4
Q

What do microtubules do?

A

(slinky of life)

forms tube like structure and determine the position of membrane enclosed organelles, directs intracellular transport

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5
Q

What do intermediate filaments do?

A

(like girders in building or highway)

provide mechanical strength, resists mechanical stress, allows formation of hair and fingernails

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6
Q

What are actin subunits used for?

A

assembly of actin filaments, form helical assembles of subunits

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7
Q

Actin filaments are arranged in ______ structure

A

head to toe

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8
Q

Actin monomers contains a binding site for ____

A

ATP (or ADP)

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9
Q

What are tubule subunits used for?

A

formation of microtubules

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10
Q

Tubulin is a heterodimer of _____ and _____ with noncovalent bonds

A

alpha tublin and beta tubulin

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11
Q

Both alpha and beta tubulin have binding sites for ____

A

GTP

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12
Q

If cytoskeleton of RBC is defective it can lead to the diseased called hereditary spherocytosis (HS) , which causes what?

A

RBCs spherical not bi concave, fragile red blood cells burst resulting in hemolytic anemia

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13
Q

What is spectrin?

A

part of the RBC cytoskeleton

attaches to membrane, and is defective in HS

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14
Q

What is the clinical presentation of HS?

A

hemolysis, anemia, splenomegaly

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15
Q

What is listeria?

A

pathogenic bacteria that invade your intestinal cells and can cause serious infection

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16
Q

What are the symptoms of listeria?

A

headache, stiff neck, confusion, loss of balance, and convulsions in addition to fevers and muscle aches

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17
Q

How does listeria cause illness?

A

attaches to receptors on enterocytes, enters and replicates in your intestinal cells. Unusual behavior is based on the actin cytoskeleton and accessory proteins

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18
Q

Describe Duchenne muscular dystrophy (DMD)

A

most common fatal neuromuscular disorder
severe, progressive muscle degeneration
loss of ability to walk (wheelchair bound by 12)
loss of lung and cardiac function, scoliosis
premature death in 20s and 30s due to respiratory failure or cardiomyopathy

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19
Q

What is the treatment for DMD?

A

no medical treatment to alter course of disease, but treatment for patients general health and quality of life
glucocorticoids (prednisone) slow the decline in muscle strength but he effect is relatively short and does not alter clinical course of disease

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20
Q

DMD is X linked ____ and caused by which gene mutation?

A

recessive, dystrophin gene mutation

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21
Q

What is the main function of the dystrophin protein?

A

provide structural stability to the muscle cell membrane during cycles of contraction and relaxation

22
Q

What are the functional domains of the dystrophin protein?

A
  • n-terminus (actin binding domain)
  • long spectrin like repeat domain: cytoskeletal portion of the dystrophin protein
  • cysteine rich and C-terminus domains
23
Q

What is the clinical presentation of DMD?

A

dystrophic myopathy: progressive muscle degeneration with loss of functional muscle tissue over time with resulting weakness
elevated creatine kinase in blood: 50 to 100 times normal (over 1,000 U/L)
slow walking, general weakness
mean age of diagnosis : 4 years, 10 months
wheelchair by age 12/13

24
Q

What is pseduohypertrophy?

A

replacement of muscle with adipose and fibrous connective tissue- enlarged calves

25
Q

What is lordosis?

A

excessive inward curvature

26
Q

what is kyphosis?

A

upward back curvature outward

27
Q

Describe Becker muscular dystrophy (BMD)

A

milder form
loss of walking after 16 years
muscle pain, dilated cardiomyopathy
increased workload on left ventricle leads to ventricular enlargement, severity results in heart failure and death

28
Q

DMD lacks what protein? What is the difference in this vs BMD?

A

DMD lacks dystrophin protein

BMD has some dystrophin protein but abnormal quantity and size

29
Q

What is the function of mitochondria?

A

provide cellular energy in the form of ATP for the cell

30
Q

What is mitochondrial myopathy?

A

muscle disease caused by mitochondrial dysfunctions

31
Q

Are mitochondria maternally or paternally inherited?

A

maternally

32
Q

What is heteroplasmy?

A

when there is a mtDNA mutation: there is a mixture of normal mitochondria and mutant mitochondria
there is a threshold–too much mutant mitochondria, disease will occur

33
Q

What tissues are affected by mitochondrial disease?

A

brain/CNS, heart, skeletal muscles

34
Q

Describe MERRF

A

-myoclonus: often the first symptom, involuntary muscle jerking
- myoclonic epilepsy
- ataxia
- ragged red fibers
- seizures, dementia
90% of mutations caused by 2 mutations of tRNAlys

35
Q

What are the main mutations of the tRNAlys in MERRF?

A

85% due to A to G mutation in the mtDNA tRNAlys gene at nucleotide portion 8344
5% due to G to C at position 8356 in tRNAlys mtDNA gene

36
Q

Describe MELAS

A

-seizures
-blindness
- headaches
-anorexia
- recurrent vomiting
- lactic acidosis
- ragged red fibers
age of onset : 2-10 years

37
Q

Describe Kearnes-Sayre Syndrome (KSS)

A

onset before age 20
-retinitis pigementosa
at least one of the following: cardiac conduction abnormality, cerebellar ataxia, cerebral spinal protein level above 100 mg/dL
ragged red fibers seen in skeletal muscle

38
Q

describe CPEO

A

mild to moderate mt myopathy- mtDNA rearrangments

ptosis

39
Q

describe LHON

A

mt mutation only affects optic nerve
no muscle involvement
acute or subacute, bilateral, central vision loss
degeneration of the retinal ganglion cell layer and optic nerve
age of onset: 20 to 30s
mtDNA mutatie in coding genes of complex I proteins

40
Q

What are the functions of erythrocytes?

A

transport oxygen forms the lungs to the tissues

41
Q

hemoglobin occupies ____ percent of the volume of erythrocytes and _____ percent of the cells dry weight

A

33, 90

42
Q

what is tissue switching?

A

switch phenomenon as to where red blood cells are made during development (around birth)

43
Q

What is the structure of hemoglobin?

A

2 alpha globin chains, 2 beta globin chains
one heme per subunit that has iron that carries O2
four protoporphyrin IX rings

44
Q

What are the three types of hemoglobin in humans?

A

embryonic, fetal and adult

45
Q

What are the four types of globin chain in adult hemoglobin?

A

alpha, beta, delta, gamma

46
Q

What is the predominant form of hemoglobin in adults?

A

HbA which has 2 alpha and 2 beta subunits

47
Q

What are the alpha like chains of hemoglobin?

A

zeta embryonic and alpha

48
Q

What are the beta like chains of hemoglobin?

A

epsilon embryonic, gamma fetal, delta, beta

49
Q

How does HbS (sickle cell anemia) occur?

A

aa switch in position 6 in Beta globin of valine for glutamic acid

50
Q

Why does O2 flow from mother to fetus?

A

HbF does not bind well to 2,3 BPG and therefore has higher affinity for O2

KCU Comprehensive Exam (13 decks)

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