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Uworld > Molecular/Cell Bio > Flashcards

Molecular/Cell Bio Flashcards

1
Q

What is alternative splicing?

A

Exons of a gene are reconnected multiple ways during post transcriptional processing, creates diff mRNA sequences and contributes to biodiversity

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2
Q

What elements are needed for PCR?

A

DNA template that includes target region, flanking sequences adjacent to target region ( the oligotide sequences of flanking must be known to make primers)

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3
Q

What happens to tRNA that is mischarged with the wrong amino acid and not corrected by aminoacyl-tRNA at the tase proofreading?

A

It will incorporate into the growing polypeptide chain

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4
Q

What Is DNA laddering a marker of?

A

Is a sensitive marker for apoptosis and refers to DNA fragments in multiples of 180 base pairs

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5
Q

In bacteria, what functions to remove RNA primers and replace them with DNA?

A

DNA polymerase I

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6
Q

What refers to gene exchange that occurs through the crossing over of 2 double stranded DNA molecules?

A

Recombination

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7
Q

Nonsense mutations tend to move ______ in electrophoresis due to their dec size

A

further

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8
Q

trinucleotide expansions tend to move ____ in electrophoresis due tot heir inc sezie

A

less

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9
Q

Speed of hemoglobin in gel electrophoresis between HbgA, HgbS, HgbC

A

Hgb A>HgbS>HgbC

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10
Q

Explain the intrinsic pathway mitochondrial pathway of apoptosis

A
  • mitochondria become more permeable and pro-apoptotic substances are released in the cytoplasm under stress/ cessation of survival signals
  • the anti-apoptotic proteins Bcl-2 and Bcl-x that reside in the mitochondrial membranes and cytoplasm are replaced with pro-apoptotic proteins such as Bax, Bak, and Bim
  • The proapoptotic proteins allow for the inc permeability of the mitochondria which results in release of caspase activating substances like cytochrome C (can see many shrunken eosinophilic cells in the tumor b/c nucleus condensed and made it all pink)
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11
Q

Explain the extrinsic receptor ligand pathway of apoptosis

A

This requires engagement of death receptors on the cell surface. These death receptors are in the tumor necrosis family (TNFR1 and Fas=CD95).

  • After cross linking of Fas with ligand, multiple molecules of Fas come together to form a binding site for a death domain containing adapter protein called FADD
  • FADD then binds an inactive caspase bringing multipole caspases together–> activates caspases
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12
Q

Caspases are a family of proteins that cause?

A

apoptosis

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13
Q

The _______ is the site of ribosomal subunit maturation and assembly. What enzyme functions exclusively in this area? Howdoes it stain?

A

nucleolus, RNA polymerase I, basophilic

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14
Q

What is the hallmark of initial phase of injury and is it reversible?

A 
cellular swelling (membrane blebbing,loss microvilli, swelling of RER), yes
-b/c build up of Na in cell-->water follows
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15
Q

When membrane damage occurs cell injury is

A

irreversible

  • ex: why we do troponin tests in MI is to basically see if enzymes leaked into the blood=irreversible myocyte damage
  • ex: ETC is in INNER mitochondrial membrane and once its damaged can’t go back and giving O2 wouldn’t help, cytochrome C can lead out–> apoptosis
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16
Q

Causes of damage for FiO2–>PAO2—>PaO2–>SaO2

A

FiO2: high altitude
PAO2: anything that inc PACO2= COPD, hypoventilation
PaO2: affected by previous
SaO2: CO poisoning, Methehemoglobinemia(Fe3+ binding Hgb) (normally FeTWO binds O2)

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17
Q

Morphologic sign of cell death is loss of _____

A

nucleus

-pyknosis(nucleus shrinks), karryohexis (nucleus breaks up into small pieces)< karyolysis

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18
Q

In ______ necrosis, tissue remains firm, cell shape/organ are preserved and the nucleus disappears. This is characteristic of ____infarction of any organ except the _______

A

coagulative necrosis, ischemic, brain

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19
Q

In _________necrosis, tissue becomes liquified through enzymatic lysis of cells. What 3 situations do you see it in?

A

liquefactive
-brain infarction(mediated by microglia), abscesses(neutrophils mediate), pancreatitis(enzymes in pancreas digest itself)

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20
Q

_______necrosis resembles mummified tissue, and is characteristic of lower limb and GI tract. Can be superimposed with what other necrosis

A

Gangrene, liquefactive

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21
Q

________ is a combo of liquefactive and coagulative necrosis, it has a ______ like appearance, and is characteristic of __________ inflammation

A

Caseous, cottage cheese, granulomatous (from fungal or TB infection)

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22
Q

______necrosis has adipose tissue with chalk white appearance due to deposition of ____?

A

fat, calcium (fatty acids bind to Ca=saponification)

  • ex: trauma to breast, damage of peripancreatic fat
  • see giant cells, fat, calcifications
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23
Q

saponification is an example of ________ calcification

A

dystrophic

-ex: psammoma bodies

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24
Q

_______ necrosis is from damage to the blood vessel walls and leads to ______ of proteins into vessel wall with a ______ stain.

A

Fibrinoid, leakage, bright pink

-malignant HTN, vasculitis, preeclampsia (fibrinoid necrosis of placenta)

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25
Q

Apoptotic bodies are removed by ______ and is there subsequent inflammation?

A

macrophages,no

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26
Q

In the _________ pathway, performs create pores in membrane of target cell. Granzyme enters pores and activates caspases

A

cytotoxic CD8+ T cell mediated pathway

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27
Q

Which 3 enzymes are important for the removal of free radicals?

A

superoxide dismutase, catalase, glutathione peroxidase

O2-, H2O2, OH-

OH is most damaging

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28
Q

CCl4 is metabolized to what by what organ? What happens to hepatocyte

A

CCl3 by liver

hepatocytes have dec protein synthesis from cellular damage and apolipoproteins can’t work–> fatty change in liver

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29
Q

Amyloid is a ______ protein that deposits in the _______ space. It tends to deposit around? How does ti stain?

A

misfolded, extracellular, blood vessels, congo red and apple bifringence

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30
Q

Primary amyloidosis is systemic deposition of __________ derived from ____ light chain. What is it associated with?

A

AL amyloid, Ig, plasma cell dycrasias: overproduce light chain that leaks out and deposits everywhere

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31
Q

Secondary amyloidosis results from systemic deposition of ________ derived from SAA. SAA is an _______ reactant that is increased in ________ inflammatory states, malignancy, familial Mediterranean fever

A

AA amyloid, acute phase, chronic

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32
Q

Familial Mediterranean fever is a dysfunction of _______ and presents with fever and acute ______ inflammation. High _____ during attacks deposits as __ amyloid

A

neutrophils, serosal, SAA, AA

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33
Q

Amyloid depositing in kidneys leads to _______ syndrome

A

nephrotic

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34
Q

Amyloid depositing in heart leads to ________ and _______

A

restrictive cardiomyopathy(heart becomes less compliant and bendable) and arrhythmia

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35
Q

Diagnose amyloidosis through _______. Damage organs must be ______ because amyloid can’t be removed

A

abdominal fat pad and rectum, transplanted

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36
Q

In senile cardiac amyloidosis, _____ deposits in heart. It’s typically asymptomatic

A

non-mutated transthyretin,

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37
Q

In familial amyloid cardiomyopathy, _________ deposits in the heart. This leads to _______

A

mutated serum transthyretin, restrictive cardiomyopathy

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38
Q

In type 2 diabetes, _______ deposits in islets of pancreas

A

amylin (derived from insulin)

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39
Q

Alzheimer’s disease has _____ amyloid deposits in brain. This is derived from Beta-amyloid precursor protein on what chromosome?

A

AB, 21

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40
Q

Dialysis associated amyloidosis has _____ deposits in joints. This provides structural support for which MHC molecule?

A

Beta2 microglobulin, MHC class 1

-in CKD, beta2 isn’t filtered well so builds up in blood and deposits

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41
Q

Tumor cells with an amyloid background in the thyroid suggests

A

medullary thyroid carcinoma

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42
Q

With acute inflammation, how are these all affected: endothelial intracellular cGMP, blood velocity, RBC concentration, arteriolar resistance, endothelial transcytosis

A

increased cGMP, decreased velocity(b/c as you dilate/inc cross section–> dec vel), increased concentration, decreased resistance, increased transcytosis (collects fluid from vascular side and releases it on interstitial side)

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43
Q

example of tertiary structure

A

disulfide bonds

44
Q

example of quartenary structure

A

alpha and gamma chains of Hgb (when 2/more polypeptides form a single protein)

45
Q

Periodic acid Schiff (PAS) stain detects what in cells?

A

glycoprotein

46
Q

splicesomes remove introns containing __ at the 5’ splice site and __ at the 3’ splice site

A

GU, AG

47
Q

When is translated initiated in eukaryotes

A

when the small ribosomal subunit attached to the 5’ cap of mRNA and then scans for the AUG sequence within the Kozak sequence

48
Q

What are the 3 stop codons

A

UGA, UAG, UAA

49
Q

Receptors for thyroid hormone and vitamins A and D are located in the _______ at all times. Where is progesterone?

A

nucleus,

-progesterone is in cytosol and can go to nucleus

50
Q

Fas ligands mediate the extrinsic pathway of? The Fas receptor is expressed on which lymphocytes

A

apoptosis, T lymphocytes

51
Q

Kozak sequence indicate the start of ____________

A

translation, AUG sequence

52
Q

CD8+ cells use the _________ to target viral proteins for destruction

A

ubiquitin ligase

53
Q

The ______ has ribosomal RNA

A

nucleolus

54
Q

______ may be located upstream, downstream, or within a transcribed gene. These function to inc and dec the rate of __________

A

enhancers/silencers, transcription

55
Q

________ are typically located 25-75 bases upstream from their associated genes and function to initiate _________

A

promoters, transcription

56
Q

________ have one origin of replication while _______ have multiple origins of replication

A

prokaryotes, eukaryotes

57
Q

what would bind multiple deoxythymidines

A

poly A tail

58
Q

Patients with ___ have antibodies against snRNPs (anti-______) and these are an essential component of ________

A

lupus, Smith, spliceosomes=removal of introns from RNA transcripts

59
Q

_________ of RNA transcripts is performed by ____________. This process stabilizes mRNA helping it exit the nucleus

A

polyadenylation, polyadenylate polymerase

60
Q

______ bodies play an important role in mRNA translation regulation and degradation

A

P bodies

61
Q

________ recognize stop codons

A

releasing factors

62
Q

_________ facilitate tRNA binding and the translocation steps of protein synthesis

A

elongation factors

63
Q

Transcription factor 2 D binds the ________ to initiate transcription

A

TATA box

64
Q

Explain PI3K/Akt/mTOR pathway

A

bind growth factor—>autophosporylation of tyrosine residues—>activation of PI3K–>activation of protein kinase B–>translocation to nucleus and gene transcription

65
Q

________ functions for remove RNA primers (5’ to 3’ exonuclease activity) and replace them with DNA

A

DNA polymerase I

66
Q

The TATA and CAAT boxes serve as ________ for transcription and serve as binding sites for _________ and __________

A

promoters, transcription factors, RNA poly 2

67
Q

what stabilizes unwound template strands

A

single stranded DNA binding protein

68
Q

what removes the RNA primer and replaces it with DNA

A

DNA poly 1

69
Q

frameshift are caused by while missense/nonsense/silent are caused by

A

insertions/deletions, substitutions

70
Q

mitochondrial disorder that leads to bilateral vision loss

A

leber hereditary optic neuropathy

71
Q

myoclonic epilepsy

A

myoclonic seizures and myopathy with associated exercise, skeletal muscle biopsy shows red ragged fibers

72
Q

MELAS

A

mitochondrial encephalopathy with lactic acidosis and stroke like episodes

73
Q

nuclear fator kappa b is a transcription factor with a critical role in _________. Where is it normally present and what is it bound to?

A

immune réponse to infection

  • found in the cytoplasm in a late state and bound to it’s inhibitor protein: IkappaB
  • extracellular signals like toll like receptors or LPS can lead to IkappaB destruction and this allows NFkb to go to the nucleus and leads to production of numerous cytokines
74
Q

microsomal monooxygenase does what

A

its a cytochrome P450 enzyme that can convert pro-carcinogens into carcinogens

75
Q

lipoma v liposarcoma

A

lipoma: benign and soft rubbery subcutaneous nodules but have mature fat cells without scalloping
liposarcoma: have numerous lipoblasts (

76
Q

DNA polymerase can only add primers to the _____’ end

A

3’ so these pieces would lead to complementary DNA strands

77
Q

nonpathogenic and pathogenic influenza virus are both grown in culture and progeny of nonpathogenic virus is shown to have wild type enhanced infectivity

A

genetic shift=reassortment

78
Q

a host cell is connected with 2 viral strains and progeny viruses exhibit coat or envelope proteins not coded for by the genetic material packaged within them. Get additional traits but there is a change in genome

A

phenotypic mixing

79
Q

point mutations in viruses can lead to antigenic _______

A

dirft

80
Q

gene exchange that occurs through the crossing over of 2 double stranded DNA molecules, resulting progeny can have recombined genes not present simultaneously in either parent virus

A

recombination (occurs less frequently than reassortment)

81
Q

uptake of naked DNA by a prokaryotic or eukaryotic cells, alters the genetic composition of the host cell by typically causes no genomic change in progeny visions

A

transformation

82
Q

In a petri dish, a normal line of cells will show _________ and stop growing and this is mediated by _______ and ______. Malignant cells will continue to divide and even pile up like __________

A

contact inhibition, cadherins and catenins, mounds

83
Q

cells like hepatocytes and steroid producing cells of adrenal cortex are rich in what in the cell?

A

smooth ER because it plays a huge role in steroid synthesis and detoxification of drugs

84
Q

scaly skin, ataxia, anosmia, night blindness

A

refsum disease

-defect in alpha oxidation in peroxisomes

85
Q

hypotonia, seizures, hepatomegaly: auto recessive disorder of mutated PEX gene

A

Zellweger syndrome

86
Q

x linked recessive disorder of B oxidation of VLCFAs–> VLCFA build up in adrenal glands, white (leuko) matter of brain, testes–> adrenal crisis

A

adrenoleukodystrophy

87
Q

Bloom syndrome is from a defect in _____ and is characterized by?

A

helicase, photosensitivity, short stature, erythema, telangectasias
-predisposed to lymphoproliferative and GI malignancies

88
Q

In an agglutination inhibition test, the presence of agglutination is a ________ result and the absence of agglutination is a _________ result

A

negative, positive

89
Q

Characteristic of _______ receptors is that they have 7 transmembrane domain hydrophobic alpha helical domains

A

G protein

90
Q

Defective proline hydroxylation by prolyl hydroxylase inhibitor –> failure of __________ and stabilization by pro-alpha chains during collagen synthesis

A

triple helix formation

91
Q

As translation begins in the cytoplasm, a hydrophobic AA sign sequence at the N terminal of the _____ chain facilitates ribosomal binding to the _______ and the growing polypeptide chain to the ________. Absence of this single can leda to __________

A

alpha, rough ER, rough ER, polypeptide accumulation in the cytosol

92
Q

Inside the rough ER, the signal sequence is cleaved to yield the _______ chain, Next, many of the proline and lysine residues at the Y position are hydroxylated to hydroxyproline and hydroxylysine by ___________. This step requires what vitamin

A

pro-alpha, prolyl hydroxylase, vitamin C

93
Q

What is vitamin C necessary for in collagen synthesis. What further stabilizes this change

A

proper assembly of pro-alpha chains into tropical helical collagen, hydrogen bonding

94
Q

After pro collagen is formed, it is secreted from the cell and the N and C terminals are cleaved by ________ making less soluble collagen=_________

A

pro collagen peptidases, tropocollagen

95
Q

These collagen molecules spontaneously assemble into ________ which then cross link to form _________. Cross linking is facilitated by _______

A

fibrils, collagen fibers, lysyl oxidase

96
Q

the process by which bacterial DNA is transported from one bacterium to another by a virus (bacteriophage)

A

transduction

97
Q

Carbon dioxide/ carbon isotopes are used in the synthesis of __________ in the cytosol

A

pyrimidines

-uses carbamoyl phosphate synthetase 2

98
Q

urea cycle sues carbomyl phosphate synthetase ___ and takes place in the _______

A

1, mitochondria

99
Q

Which cell type is responsible for vibratory sense/pressure and diabetics often lose sense of these at their feet

A

Pacinian corpuscles

100
Q

What cell type are responsible for fine/light touch and position sense

A

Meissner corpuscles

101
Q

Which cell type is responsible for pressure, deeps static touch (sharps, edges), position sense

A

Merkel discs

102
Q

Which cell types are responsible for pressure, slippage of objects along surface of skin, joint angle change

A

Ruffini corpuscles

103
Q

Nonsilent mutations of an exon of the mRNA are translated into protein and lead to __________

A

abnormal/non functioning protein

104
Q

mutations in promoter region of mRNA that is from introns leads to ______

A

affect regulation of mRNA translation–>leading to higher or lower levels of the protein

105
Q

palindromic sequence of DNA

A

where reading 5’–>3’ one end is the same as the complementary strand so

5’TGTACA3’–>3’TGTACA5’

106
Q

________ is the need for cells to be attached to or in contact with another layer of cells

A 
anchorage dependence  (they can effectively grow floating unattached to a solid surface)
-is important when it comes to metastasis
107
Q

Find out HER2 positivity in breast cancer by what method

A

FISH

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