Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Nutritional Biochem 1 > Selenium > Flashcards

Selenium Flashcards

1
Q

Selenium is a nonmetal that exists in many oxidation states (Se2-, Se4+, Se6+) and has chemical properties similar to what element?

A

Sulfur

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

Selenium is in the same column as what element in the periodic table, and can therefore be substituted for this element in different amino acids…

A

Sulfur

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

What is the best source of selenium?

A

Seafood

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

Soil concentration of selenium is directly related to it’s concentration in plants, with this being true, where are cancer rates the highest?

A

Areas that have low soil Selenium concentrations

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

What kind of transporters do Selenomethionine and Selenocysteine use?

A

Amino acid transporters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the order of uptake efficiency from greatest to least?

A

Selenomethionine > selenocysteine > selenAte > selenIte > selenide

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

What are 4 substances that enhance selenium absorption? (Hint: 3 vitamins, antioxidant)

A

Vitamin A, C, E, and Glutathione

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

What are the inhibitors of selenium absorption, and how is it done? (Hint: 2 heavy metals, a cyclic acid)

A

Mercury, Cadmium, and Phytates (phytic acid) all do this through CHELATION

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

What carries 60% of the selenium into plasma?

A

Selenoprotein P as Selenocysteine

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

What carries another 30% of selenium into plasma?

A

Glutathione peroxidase 3 (GPX3)

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

The concentration of Selenoprotein P can be used as what?

A

An indicator of Selenium deficiency

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

What is the most important selenoprotein for cerebral function?

A

Selenoprotein P

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

What else does Selenoprotein P protect the human body from? (hint: related to cerebral functioning)

A

PRODUCTION OF FREE RADICALS, [note: slows the progression of the disease (significant cognitive decline is related to decrease selenium concentration)]

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

Selenide can be methylated and excreted in the urine as what?

A

Methyl selenide

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

Selenocysteine is synthesized with selenide and what two enzymes?

A

Selenophosphate synthetase, Selenocysteine synthase

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

Selenium is incorporated into selenoproteins as selenocysteine via…?

A

Selenocysteine tRNA

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

Selenocysteine tRNA reads this stop codon as an insertion site…

A

UGA stop codon

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

Selenocysteine is considered to be what in relation to amino acids?

A

The 21st AA

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

The unique recoding of the UGA codon requires 2 additional proteins to facilitate the recognition of the sec-tRNA by the UGA, what are they?

A
  1. SBP2 (selenocysteine insertion sequence binding protein)

2. EFsec (elongation factor for selenocysteine)

20
Q

SBP2 and EFsec are essential for the translational insertion of what?

A

Selenocysteine into selenoproteins

21
Q

If 1 or both of the proteins (SBP2 and EFsec) are absent, what will become of the codon?

A

The UGA is read as a stop codon

22
Q

How many selenoprotein genes have been identified in the human genome?

A

25 selenoprotein genes

23
Q

What are the 5 selenium containing isoenzymes?

A

GPX1, GPX2, GPX3, GPX4, GPX6

24
Q

What is the only isoenzyme found extracellularly?

25
GPX3 and Selenoprotein P account for what percentage of the selenium in the plasma?
90%
26
In a proportional manner, what does the availability of Selenium affect? (hint: 3 things)
1. GPX activity 2. Concentrations of Se 3. mRNA levels
27
What enzyme converts thyroxine (t4) to triiodothyronine (T3)?
Iodothyronine 5'-deiodinase (mem cue?.. T3-T4 --> IT5D)
28
What affect did Selenium supplementation have on patient with autoimmune thyroiditis? (2 things)
Decreased inflammation | Decreased thyroid autoantibody concentrations
29
Thioredoxin reductase contains what at it's active site?
Selenocysteine
30
There are 4 functions of Thioredoxin reductase, what are they?
1. Synthesis of deoxyribonucleotides for DNA synth 2. Regeneration of antioxidants 3. Intracellular maintenance of redox state 4. Regulate gene expression by reducing transcription factors (ex. NFkB), affecting DNA binding
31
What is the key component that is needed in the body to synthesize all the selenocysteine containing enzymes?
Selenophosphate [Selenophosphate synthetase 2 (SPS2)]
32
What does SPS1 (selenophosphate synthetase 1) use instead of selenocysteine?
Cysteine
33
What is the relationship between SPS1 and SPS2?
SPS1 catalyzes synth of selenophosphate for SPS2 -- SPS2 will then catalyze the selenophosphate production from all other selenoproteins.
34
Selenoprotein W is found where and what does it protect against?
Found in the cytosol of skeletal and cardiac muscle cells and protects against oxidative injury!
35
Low plasma selenium is independently associated with what issue in the elderly?
Poor skeletal muscle strength
36
Excretion of dimethylselenide has what kind of odor?
Garlicky odor
37
Selenium deficiency can be seen in two different diseases, what are they and generally what do they involve? (hint: usually involves children)
Keshan disease - cardiomyopathy | Kashin-beck disease - osteoarthropathy (epiphyseal plate)
38
A daily intake of 200 ug/day of Selenium may diminish the risk of what two diseases (hint: most common causes of death!)
Heart disease, Cancer
39
If one was to increase their intake of selenium by 50%, what would that do to their risk of developing CHD?
Reduce the risk by 25%!
40
Serum selenium concentrations have been seen to affect the incidence of some cancers such as prostate cancer, but only in men, why is this?
Women don't have a prostate.... but what is the homologue? :)
41
Suggested mechanisms of cancer prevention by Selenium include what? (hint: 3 ways)
1. Inhibit cancer cell growth - causes cell cycle arrest 2. Increase apoptosis 3. Increased DNA repair
42
Selenium has been shown to boost the immune system function by stimulating what cells?
Cytotoxic lymphocytes, NK cells, Macrophages
43
Selenosis is the term used for...
Selenium toxicity
44
What populations are seen to have Selenosis?
Miners and people who supplement with Selenium
45
The tolerable upper intake level is set at how many ug/day?
400 ug/day

Nutritional Biochem 1 (6 decks)

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