Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biochem 2 - Final > Cysteine Article Takeaways > Flashcards

Cysteine Article Takeaways Flashcards

(100 cards)

Start Studying
0
Q

Tons of toxic industrial waste products, including heavy metals are being mixed with what, being dispersed across America’s farmland.

A

liquid agricultural fertilizers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

We are all vulnerable to what type of exposure to toxic metals?

A

Chronic, low level exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the heavy metals that are controversially put in fertilizers, soil, and pastures?

A

Aresenic, lead, cadmium, nickel, mercury, and uranium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can acute metal toxicities be diagnosed?

A

Patient history and overt symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Chronic, low-level exposure to heavy metals produces what type of symptoms? When do these symptoms tend to be expressed?

A

non-descript symptoms; overt expression of physiological aberrations are often not realized until later in life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Among the most insidious toxic metals are the sulfhydryl-reactive metals, which include which 4 metals?

A
  • mercury (Hg)
  • cadmium (Cd)
  • lead (Pb)
  • arsenic (As)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which two metals are heavily deposited in the kidney?

A

Mercury (Hg) and Cadmium (Cd)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the biological half-life of cadmium (Cd) in the kidney?

A

On the order of decades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which metal does not readily cross the BBB in adults, unlike mercury (Hg)?

A

Cadmium (Cd)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which metal is associated more with peripheral neuropathy than with disorders of the CNS?

A

Cadmium (Cd)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Which metal is deposited primarily in bone?

A

Lead (Pb)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which metal disrupts erythropoiesis?

A

Lead (Pb)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which chronic conditions are associated with heavy metal toxicity? (list of symptoms)

A

fatigue, musculoskeletal pain, neurological disorders, depression, poor cognitive function, poor memory, and allergic hypersensitivity.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which metal is the most volatile over the other sulfhydryl-reactive metals?

A

Mercury (Hg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the primary source of chronic, low levels of Mercury (Hg) exposure?

A

Dental amalgams and fish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are two ways in which mercury enters water to pollute fish?

A

Off-gassing from the earth’s crust and industrial pollution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does mercury make its way up the food chain?

A

It is methylated by algae and bacteria in water and moves up the food chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which fish contain the highest concentrations of mercury?

A

swordfish, shark, salmon, and tuna

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are other sources of mercury (aside from off-gassing and pollution)?

A

combustion of fossil fuels, production of chlorine, paper and pulp, fungicides/seed preservatives, and some paints
(in some parts of the world, large amounts of Hg enter the environment as a result of careless processing of gold from ore)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the two major, highly absorbed subspecies of mercury?

A

Elemental Hg and methylmercury (MeHg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What type and percentage of mercury is found in “silver” dental amalgams?

A

50% Elemental mercury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Elemental mercury is volatile and does what at room temperature?

A

vaporizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Mercury is poorly absorbed if ingested, but is efficiently absorbed through which organ and means? What important barrier is crossed?

A

Lungs/respiration; blood brain barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Due to its lipophilic nature, elemental mercury has a high affinity for which membranes?

A

Myelin and lipid membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Once inside the cell, elemental mercury undergoes which reaction to become reactive Hg2+?
Elemental Hg is oxidized by catalase
25
MeHg, derived from fish and dimethylmercury is readily absorbed in what area?
gastrointestinal tract
26
MeHg can be de-methylated and oxidized into which form?
Hg2+
27
Once assimilated in the cell, Hg2+ and MeHg+ form covalent bonds with which two residues of proteins?
glutathione and cysteine
28
Once absorbed, Hg has a _____ excretion rate.
Low
29
A significant proportion of assimilated Hg is retained and continually accumulates in which 3 areas?
kidneys, neurological tissue, and the liver
30
Upon autopsy, high levels of mercury have been found in which tissues of dentists?
cardiac, thyroid, pituitary
31
The sulfhydryl-reactive metals have three major properties: the first is that transition metals promote what?
hydrogen peroxide and enhance the subsequent iron- and copper-induced production of lipid peroxides and the highly reactive hydroxylradical.
32
Which products alter membrane structure and are highly disruptive of mitochondrial function?
lipid peroxides
33
The pro-oxidant properties of the sulfhydryl-reactive metals is exacerbated by what effects on antioxidant processes?
inhibitory
34
Which two metals have a high affinity for glutathione (GSH)?
Mercury (Hg) and Cadmium (Cd)
35
A single atom of CD or Hg can bind to and cause irreversible excretion of what?
up to two GSH tripeptides
36
The metal-GSH conjugation process is desirable because of which result?
excretion of the toxic metal into the bile
37
The metal-GSH conjugation process is detrimental because it...
depletes the cell of GSH and thus decreases antioxidant capacity
38
Which two enzymes, related to GSH are inhibited by mercury?
GSH synthetase and GSH reductase
39
Mercury also inhibits the activities of the free radical quenching enzymes:
Catalase, superoxide dismutase, and GSH peroxidase
40
Inhibition of GSH peroxidase has been attributed to the formation of which complex?
mercury-selenide complex
41
In addition to promoting lipid peroxidation, depleting GSH and inhibiting antioxidative processes the sulfhydryl-reactive-metals disrupt the structure and function of numerous important protein through which means?
direct binding to free sulfhydryl groups.
42
Metal induced inhibition of Na/K/ATPase can result in what problems with astrocytes?
Swelling and destruction
43
What are the primary functions of astrocytes in the CNS?
homeostatic regulation of synaptic pH, Na/K and glutamate and metal sequestration
44
Mercury inhibits the polymerization of _________ causing the depolymerization of existing microtubules.
tubulin
45
Based on the study, short term and long term exposure to MeHg in drinking water resulted in a two- to three-fold up-regulation of what?
mRNA encoding for y-glutamyclcysteine synthetase (which is the rate limiting enzyme in GSH synthesis)
46
Which 3 metal toxicities cause fatigue?
Mercury, Lead, and Cadmium
47
Which metal toxicity does not cause fatigue?
Arsenic
48
Which metal toxicity causes depression?
Mercury
49
Which 2 metal toxicities lead to poor memory?
Mercury and lead
50
Which metal toxicity has negative effects on cognitive function?
Mercury
51
Which metal toxicity leads to emotional instability?
Mercury
52
Which metal toxicity leads to peripheral numbness or tingling?
Mercury
53
Which metal toxicity decreases senses of touch?
Mercury
54
Which metal toxicity causes hearing or vision loss?
Mercury
55
Which metal toxicity is responsible for hypersensitivities and allergies?
Mercury
56
Which heavy metal toxicity causes persistent infections, including chronic yeast overgrowth?
Mercury
57
Which heavy metal causes compromised immune function?
Mercury
58
Which metal toxicity causes cardiovascular disease?
Mercury
59
Which metal toxicity causes loss of apetite?
Lead
60
Which metal toxicity causes headaches?
Lead
61
Which metal toxicity leads to an inability to concentrate?
Lead
62
Which metal toxicity causes ADD/ADHD?
Lead
63
Which metal toxicity causes aberrant behavior?
Lead
64
Which metal toxicity causes decreased coordination?
Lead
65
Which metal toxicity causes irritability?
Lead
66
Which metal toxicity causes pain in the abdomen?
Lead
67
Which metal toxicity causes pain in the bones and muscles?
Lead
68
Which metal toxicity causes gout?
Lead
69
Which 2 metal toxicities causes anemia?
Lead and Cadmium
70
Which metal toxicity causes hypertension?
Cadmium
71
Which metal toxicity causes muscle and joint pain?
Cadmium
72
Which metal toxicity causes osteomalacia?
Cadmium
73
Which metal toxicity causes lumbar pain?
Cadmium
74
Which metal toxicity causes atherosclerosis?
Cadmium
75
Which metal toxicity causes kidney damage with associated urinary loss of essential minerals, amino acids, and protein?
Cadmium
76
Which metal toxicity causes malaise?
Arsenic
77
Which metal toxicity causes muscle weakness?
Arsenic
78
Which metal toxicity causes eczema?
Arsenic
79
Which metal toxicity causes dermatitis?
Arsenic
80
Which metal toxicity causes increased salivation and strong "garlic" breath?
Arsenic
81
Why is Hg relative more neurotoxic than nephrotoxic?
Activities of GSSH reductase and GSH peroxidase increase in steady state levels producing a protective and adaptive response in the renal epithelial cells, whereas neurons do not have this adaptive capacity.
82
Metallothioneins are a group of low molecular weight, intracellular proteins that serve as a storage depot for which 2 metals? What do they do?
Copper and zinc; "scavenge" sulfhydryl-reactive metals that enter the cell.
83
Metallothioneins are rich in which amino acid? (~30%) Which heavy metal do they have a higher affinity for than zinc?
Cysteine; Hg and Cd
84
Which amino acid inhibits transport of the MeHg-cysteine complex across the blood brain barrier?
L-Leucine
85
Which other amino acids (aside from leucine) compete for the L-amino acid transport system?
valine, isoleucine, phenylalanine, tyrosine, and tryptophan
86
Why would treatment with whey protein be helpful for heavy metal toxicity? (Whey protein contains 2.5 - 3% cysteine and 22-25% BCAAs)
Cysteine supports intracellular GSH production and metallothionein synthesis, yet provides adequate leucine to minimize the transport of metals into the CNS.
87
True/False: Pharmacological doses of cysteine/NAC (in the range of 1500mg/daily) can potentially exacerbate the adverse neurological effects of toxic materials.
True
88
Exposure to what metal directly affects uptake and release of dopamine, norepinephrine, and serotonin.
Mercury
89
What is the indirect effect of Hg regarding neurotransmitters?
depletion or poor assimilation of specific amino acids which are precursors of neurotransmitters.
90
Persistant candidiasis/dysbiosis associated with which metal burden can compromise the absorption of aromatic amino acids (phenylalanine/tyrosine/tryptophan) which are the precursors to dopamine/norepinephrine/serotonin respectively.
Mercury
91
Metal-induced inhibition of the 5'deiodinase enzyme is related to general peroxidative effects through the inhibition of which metal?
Mercury
92
HG is known to irreversibly bind to and "waste" which metal? Why does this matter?
selenium; 5'deiodinase is a selenium-dependent enzyme
93
Which metal may inhibit the conversion of prohormone T4 to T3 by interfering with selenium availability?
Mercury
94
How does mercury interfere with progesterone?
Hg binds to a free sulfhydryl group on the progesterone receptor and may thereby diminish progesterone binding and cellular response.
95
What are the 2 links of Hg to chronic fatigue?
- disruption in hormone metabolism (progesterone) | - binding to lipoic acid making lipoic acid unavailable for its vital role in the energy producing tricarboxylic acid
96
Which two metals are readily displaced from metallothionein by Hg and Cd? For what are they co-factors?
Copper and zinc; superoxide dismutase and copper is required for the synthesis of the catecholamines
97
Which metal is critical for wound healing, immune function, and metabolism of protein and nucleic acids?
Zinc
98
Ethylenediamine tetraacetic acid (EDTA) and the dithiol complexing agents have affinities for which metals?
Cu, Zn, Mn, Cr, and Mo, and can indirectly result in Mg depletion
99
What percentage of DMSA (a metal detoxification agent) absorbed is excreted in the urine as a cysteine-DMSA-cysteine disulfide complex?
90%; it would therefore be important to replace cysteine if using oral DMSA

Biochem 2 - Final (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions