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Step 1 2019 First Aid Flashcards > Biochem FA - p46 - 56 Cellular/Labs > Flashcards

Biochem FA - p46 - 56 Cellular/Labs Flashcards

1
Q

Explain p53’s role in cell cycle?

A

p53 induces p21, which inhibits CDKs –>hypophosphorylation (activation) of Rb –> inhibition of G1-S progression

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2
Q

How do cyclin-cdk complexes affect other proteins to continue the cell cycle?

A

phosphorylation

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3
Q

Growth factors bind to ______ to move cell cycle from ____ –> _____ phase

A

Growth factors (eg, insulin, PDGF, EPO, EGF) bind tyrosine kinase receptors to transition the cell from G1 to S phase

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4
Q

What makes permanent cells unique?

A

Remain in G0

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5
Q

How to permanent cells regenerate?

A

from stem cells

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6
Q

Ex of permanent cells

A

neurons, sk musc, cardiac musc, RBCs

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7
Q

What is a stable cell?

A

Can enter G1 from G0 when stimulated

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8
Q

Ex of stable cells

A

hepatocytes, lymphocytes, PCT, periosteal cells

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9
Q

Ex of labile cells

A

Bone marrow, gut epithelium, skin, hair follicles, germ cells.

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10
Q

What does the RER add to lysosomal proteins?

A

N-linked oligosaccharide

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11
Q

Which cells are rich in RER?

A

Mucus-secreting goblet cells of the small intestine and antibody-secreting plasma cells are rich in RER.

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12
Q

What is a Nissl body and what is its function/

A

Nissl bodies (RER in neurons)—synthesize peptide neurotransmitters for secretion

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13
Q

Where are steroid hormones produced?

A

smooth ER

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14
Q

What is the other function of smooth ER

A

detox of drugs and poisons

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15
Q

What cells are rich in smooth ER?

A

Liver hepatocytes and steroid hormone– producing cells of the adrenal cortex and gonads are rich in SER

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16
Q

Function of Golgi apparatus?

A

distribution center for proteins and lipids from the ER to the vesicles and plasma membrane.

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17
Q

What are additions that the Golgi makes to proteins?

A

Modifies N-oligosaccharides on asparagine. Adds O-oligosaccharides on serine and threonine. Adds mannose-6-phosphate to proteins for trafficking to lysosomes.

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18
Q

Disease with defect in N-acetylglucosaminyl-1-phosphotransferase?

A

I-cell disease (inclusion cell disease/mucolipidosis type II)—inherited lysosomal storage disorder

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19
Q

What is the underlying issue of I cell disease?

A

failure of the Golgi to phosphorylate mannose residues (dec mannose-6-phosphate) on glycoproteins –>proteins are secreted extracellularly rather than delivered to lysosomes.

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20
Q

Sx/ of I cell disease

A 
coarse facial features, 
gingival hyperplasia, 
clouded corneas, 
restricted joint movements, 
claw hand deformities, 
kyphoscoliosis, and 
high plasma levels of lysosomal enzymes
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21
Q

Difference between COPI and COPII?

A

COPI: Golgi –> Golgi (retrograde); cis-Golgi –>ER. COPII: ER –>cis-Golgi (anterograde)

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22
Q

Function of peroxisomes

A

ƒ β-oxidation of very-long-chain fatty acids (VLCFA)
ƒ α-oxidation (strictly peroxisomal process)
ƒ Catabolism of branched-chain fatty acids, amino acids, and ethanol
ƒ Synthesis of cholesterol, bile acids, and plasmalogens (important membrane phospholipid, especially in white matter of brain)

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23
Q

Sx of Zellweger syndrome?

A

Hypotonia, seizures, hepatomegaly, early death.

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24
Q

Zellweger - what gene and mode of inheritance?

A

autosomal recessive disorder of peroxisome biogenesis due to mutated PEX genes.

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25
Q

Sx of Refsum disease

A

scaly skin, ataxia, cataracts/night blindness, short 4th toe, epiphyseal dysplasia

R - reptile (scaly) skin
E- epiphyseal dysplasia
F - fourth toe short
S - sight issues 
U - uh-taxia?
M - treat with PlasMAphoresis (A = alpha oxidation)
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26
Q

Underlying cause and MOI of Refsum?

A

—autosomal recessive disorder of α-oxidation –> phytanic acid not metabolized to pristanic acid.

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27
Q

XLR disorder of B-oxidation is? mutation?

A

Adrenoleukodystrophy due to mutation in ABCD1 gene - leads to VLCFA build up in adrenals and white matter of brain and testes

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28
Q

Defects in the ubiquitin-proteasome system is assoc with what disease?

A

Parkinsons

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29
Q

ex of micro filaments and function?

A

Muscle contraction, cytokinesis ex/ Actin, microvilli.

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30
Q

Fxn and ex of intermed filaments

A

Maintain cell structure

ex/ Vimentin, desmin, cytokeratin, lamins, glial fibrillary acidic protein (GFAP), neurofilaments.

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31
Q

Fxn and ex of microtubules

A

Movement, cell division

ex/ Cilia, flagella, mitotic spindle, axonal trafficking, centrioles.

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32
Q

Structure of microtubules

A

Cylindrical outer structure composed of a helical array of polymerized heterodimers of α- and β-tubulin

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33
Q

Each dimer of microtubules has what energy molecule attached to it?

A

GTP

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34
Q

Drugs that work on microtubules?

A 
s (Microtubules Get Constructed Very Poorly):
 ƒ Mebendazole (antihelminthic) 
ƒ Griseofulvin (antifungal) 
ƒ Colchicine (antigout) 
ƒ Vincristine/Vinblastine (anticancer) 
ƒ Paclitaxel (anticancer)
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35
Q

Molecular motor proteins - what direction?

A

ƒ Dynein—retrograde to microtubule (+ Ž −).

ƒ Kinesin—anterograde to microtubule (− Ž +).

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36
Q

Cilia structure?

A

9 doublet + 2 singlet arrangement of microtubules

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37
Q

What does axonemal dynein?

A

ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets

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38
Q

What is the basal body, what’s the structure?

A

Base of cilium below cell membrane - consists of 9 microtubule triplets B with no central microtubules

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39
Q

What disease involves an issue in embryologic heart looping?

A

Primary heart tube loops to establish left-right polarity; begins in week 4 of gestation.
Defect in left-right Dynein (involved in L/R asymmetry) can lead to Dextrocardia, seen in Kartagener syndrome

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40
Q

What is the primary malfunction in Kartagener syndrome? Mode of inheritence?

A

immotile cilia due to a dynein arm defect; AR

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41
Q

Why are there fertility issues in Kartageners?

A

Results in DEC male and female fertility due to immotile sperm and dysfunctional fallopian tube cilia, respectively; inc risk of ectopic pregnancy

42
Q

Sx of Kartagener?

A

Can cause bronchiectasis, recurrent sinusitis, chronic ear infections, conductive hearing loss, and situs inversus (eg, dextrocardia on CXR

43
Q

Dx screening test of Kartagener?

A

Dec nasal nitric oxide (used as screening test).

44
Q

How does Na/K pump work?

A

Na+-K+ ATPase is located in the plasma membrane with ATP site on cytosolic side. For each ATP consumed, 3Na+ go out of the cell (pump phosphorylated) and 2K+ come into the cell (pump dephosphorylated).

45
Q

Drugs that work on Na/K pump?

A 
Ouabain (a cardiac glycoside) inhibits by binding to K+ site. 
Cardiac glycosides (digoxin and digitoxin) directly inhibit the Na+-K+ ATPase, which leads to indirect inhibition of Na+/Ca2+ exchange --> Inc[Ca2+]i --> inc cardiac contractility.
46
Q

Collagen type I is found where?

A

Bone (made by osteoblasts), Skin, Tendon, dentin, fascia, cornea, late wound repair.

47
Q

Collagen type II is found where?

A

Cartilage (including hyaline), vitreous body, nucleus pulposus.

48
Q

Collagen type III is found where?

A

Reticulin—skin, blood vessels, uterus, fetal tissue, granulation tissue.

49
Q

Collagen type III is deficient in what disease?

A

Type III: deficient in the uncommon, vascular type of Ehlers-Danlos syndrome (ThreE D).

50
Q

Collagen type IV is found where?

A

basement membrane , lens

51
Q

What kidney disease shows issues with collagen type IV?

A

Targeted by auto antibodies in Goodpasture syndrome

Defective in Alport syndrome;

52
Q

HLA type of Goodpasture?

A

HLA DR2

53
Q

What type of hypersensitivity reaction in Goodpasture?

A

HS - II

54
Q

How does Goodpasture look microscopically?

A

LM—crescent moon shape Crescents consist of fibrin and plasma proteins (eg, C3b) with glomerular parietal cells, monocytes, macrophages
ƒ Linear IF due to antibodies to GBM and alveolar basement membrane

55
Q

What is the pattern of amino acids in precollagen?

A

usually Gly-X-Y (X and Y are proline or lysine). Glycine content best reflects collagen synthesis (collagen is 1⁄3 glycine).

56
Q

What residues are hydroxylated in collagen? Req which vitamin?

A

Proline, Lysine. Req vitamin C

57
Q

What is the next step after hydroxylation in collagen synthesis?

A

glycosylation of pro-α-chain hydroxylysine residues and formation of procollagen via hydrogen and disulfide bonds (triple helix of 3 collagen α chains).

58
Q

What disease has issues forming collagen triple helix?

A

osteogenesis imperfecta

59
Q

What converts procollagen into insoluble tropcollagen?

A

cleavage of disulfide-rich terminal regions of procollagen –>insoluble tropocollagen.

60
Q

What disease shows issues with procollagen cleavage?

A

Ehlers Danlos syndrome

61
Q

What vascular issue is seen with EDS?

A

berry and aortic aneurysms

62
Q

How does tropocollagen become collagen fibrils?

A

reinforcement of many staggered tropocollagen molecules by covalent lysine-hydroxylysine cross-linkage (by copper-containing lysyl oxidase) to make collagen fibrils

63
Q

Disease with issues with cross linking of collagen?

A

Problems with cross-linking –>Ehlers-Danlos syndrome, Menkes disease.

64
Q

Disease caused by defect in COL1A1 and COL1A?

A

Osteogenesis imperfecta

65
Q

What type of collagen is affected in osteogenesis imperfecta most commonly?

A

Most common is AD dec production of collagen type I

66
Q

Why is the sclera blue in osteogenesis imperfecta?

A

due to the translucent connective tissue over choroidal veins

67
Q

How to reduce fracture risk in OI?

A

treat with bisphosphonates

68
Q

Sx of OI?

A 
Patients can’t BITE: 
Bones = multiple fractures
 I (eye) = blue sclerae
 Teeth = dental imperfections 
Ear = hearing loss
69
Q

List the 3 types of EDS - incl. which is most common, which genes.

A 
Hypermobility type (joint instability): most common type.
 Classical type (joint and skin symptoms): caused by a mutation in type V collagen (eg, COL5A1, COL5A2).

Vascular type (fragile tissues including vessels [eg, aorta], muscles, and organs that are prone to rupture [eg, gravid uterus]): type III procollagen (eg, COL3A1).

70
Q

Mode of Inheritence of Menkes disease?

A

XLR

71
Q

Which enzyme has dec activity in Menkes? why?

A

Leads to dec activity of lysyl oxidase (copper is a necessary cofactor)

72
Q

Underlying issue in Menkes?

A

caused by impaired copper absorption and transport due to defective Menkes protein

73
Q

Genes in Menkes vs Wilsons

A

ATP7A, vs ATP7B in Wilson disease

74
Q

sx of Menkes

A

Results in brittle, “kinky” hair, growth retardation, and hypotonia.

75
Q

What makes elastin different from collagen?

A

Rich in nonhydroxylated proline, glycine, and lysine residues, vs the hydroxylated residues of collagen.

76
Q

What inhibits the breakdown of elastin?

A

alpha 1 antitrypsin , which normally inhibits elastase

77
Q

Changes in elastin with aging?

A

Changes with aging: decdermal collagen and elastin, dec synthesis of collagen fibrils; crosslinking remains normal.

78
Q

Genetic issue in Marfan?

A

AD FBN1 gene mutation on chromosome 15 (fifteen) results in defective fibrillin, a glycoprotein that forms a sheath around elastin

79
Q

Sx/ of Marfan?

A

tall with long extremities; pectus carinatum (more specific) or pectus excavatum; hypermobile joints; long, tapering fingers and toes (arachnodactyly); cystic medial necrosis of aorta; aortic incompetence and dissecting aortic aneurysms; mitral valve prolapse.

80
Q

Difference between subluxation of lens in Marfan vs homocystinuria?

A

Subluxation of lenses, typically upward and temporally (vs downward and medially in homocystinuria).

81
Q

murmur in Marfan sounds like what?

A

holosystolic murmur with mid systolic click

82
Q

How does squatting and standing up affect the murmur in Marfan?

A

Squatting delays mid systolic click, standing is opposite (dec preload)

83
Q

What other genetic diseases we went over has the same cardiac issue as Marfans

A

Fragile X or EDS

84
Q

What does PCR amplify?

A

DNA

85
Q

3 steps to PCR, temp for each one

A
  1. Denaturation - heated to 95* C
  2. Annealing - cooled to 55*C
  3. Elongation - temp inc to 72*C
86
Q

What is added at the annealing stage

A

. DNA primers, a heat-stable DNA polymerase (Taq), and deoxynucleotide triphosphates (dNTPs) are added

87
Q

Fxn of RT-PCR?

A

Detects and quantifies mRNA levels in a sample. Uses reverse transcription to create a complementary DNA template that is amplified via standard PCR procedure

88
Q

What is CRISPR/cas9?

A

A genome editing tool derived from bacteria

89
Q

Parts of CRISPR?

A

Consists of a guide RNA (gRNA) , which is complementary to a target DNA sequence, and an endonuclease (Cas9), which makes a single- or double-strand break at the target site

90
Q

Potential fxn of CRISPR?

A

Break imperfectly repaired by nonhomologous end joining (NHEJ) –> accidental frameshift mutations (“knock-out”) , or a donor DNA sequence can be added to fill in the gap using homology-directed repair (HDR) .

91
Q

Fxn of Southern vs Northern vs Western vs SW blot

A

Southern - DNA
Northern - RNA
Western - protein
SW - DNA binding proteins

92
Q

Fxn of flow cytometry?

A

Laboratory technique to assess size, granularity, and protein expression (immunophenotype) of individual cells in a sample.

93
Q

How does flow cytometry work?

A

Cells are tagged with antibodies specific to surface or intracellular proteins. Antibodies are then tagged with a unique fluorescent dye. Sample is analyzed one cell at a time by focusing a laser on the cell and measuring light scatter and intensity of fluorescence

94
Q

Microarrays can detect?

A

Able to detect single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) for a variety of applications including genotyping, clinical genetic testing, forensic analysis, cancer mutations, and genetic linkage analysis.

95
Q

ELIZA used for?

A

used to detect the presence of either a specific antigen or antibody in a patient’s blood sample.

96
Q

Detection in ELIZA

A

Detection involves the use of an antibody linked to an enzyme. Added substrate reacts with enzyme, producing a detectable signal.

97
Q

In Karyotyping, _______ is added to cultured cells to halt chromosomes in ____ (what phase of cell cycle)?

A

Colchicine is added to cultured cells to halt chromosomes in metaphase.

98
Q

Gene issues that could be detected with FISH?

A

microdeletion, translocation, duplication

99
Q

Steps of molecular cloning of recombinant DNA molecule in bact host?

A
  1. Isolate eukaryotic mRNA (post-RNA processing) of interest. 2. Add reverse transcriptase (an RNA-dependent DNA polymerase) to produce complementary DNA (cDNA, lacks introns). 3. Insert cDNA fragments into bacterial plasmids containing antibiotic resistance genes. 4. Transform (insert) recombinant plasmid into bacteria. 5. Surviving bacteria on antibiotic medium produce cloned DNA (copies of cDNA).
100
Q

What does the Cre-lox system do?

A

Can inducibly manipulate genes at specific developmental points

101
Q

RNA interference?

A

dsRNA is synthesized that is complementary to the mRNA sequence of interest. When transfected into human cells, dsRNA separates and promotes degradation of target mRNA, “knocking down” gene expression.

Step 1 2019 First Aid Flashcards (63 decks)

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