Selenium and Iodine

Question 1

3 a.a. in GPx?

Answer 1

Gly-Cys-Glu

Question 2

what is the 21st amino acid?

Answer 2

selenocysteine (SEC), where Se replaces S

Question 3

adding microminerals to soil is referred to as:

Answer 3

biofortification

Question 4

things that prevent absorption of selenium

Answer 4

other metals, phytate

Question 5

How to make protein containing SEC?

Answer 5

enzyme converts seryl-tRNA to SEC-tRNA during translation

Question 6

examples of selenoenzymes?

Answer 6

glutathione peroxidase, 5’-deiodinase

Question 7

how is SEC diff from GLA and OHPro?

Answer 7

added as a.a. during translation, whereas latter are post-translational changes

Question 8

good food sources of selenium?

Answer 8

fish, brazil nuts, soil levels (esp. affect meat amount)

Question 9

RDA fro selenium is ___mcg, and EAR is based on:

Answer 9

55; amount needed to maximize synth of GPx

Question 10

In a region of China, this disease is Se deficiency and viral prob causing fibrosis of heart

Answer 10

Keshan disease

Question 11

disease involving degeneration of joints, implicating Se deficiency

Answer 11

Kashin-Beck

Question 12

high Se protects from high ___

Answer 12

arsenic (Bangladesh)

Question 13

UL for Se is ___mcg from ___ sources

Answer 13

400; all

Question 14

UL set based on:

Answer 14

hair/nail brittleness (selenosis) in area in China with high Se

Question 15

UF is set at __ because symptoms are ___

Answer 15

2; irreversible

Question 16

what does IDD stand for?

Answer 16

iodine deficiency disorders

Question 17

particular food sources of iodine are referred to as:

Answer 17

goitrogens

Question 18

active form of thyroid hormones is ____, transport form is ___

Answer 18

T3 (triiodothyronine); T4 (thyroxine)

Question 19

I binds to ring of ____

Answer 19

tyrosine

Question 20

where do we store iodide?

Answer 20

in thyroid gland

Question 21

how is iodide diff from most microminerals?

Answer 21

significant urinary excretion

Question 22

absorption of I is almost ____%, and in ____

Answer 22

100; stomach and small intestine

Question 23

why can’t insulin be taken orally?

Answer 23

it is a protein so it would be digested

Question 24

steps of thyroid hormone synth?

Answer 24

1) I enter thyroid cell by active transport 2) I added to thyroglobin at Tyr (Fe dependent) to make Thg-MIT 3) another I is added to Thg-MIT to make Thg-DIT 4) 2 Thg-DIT make T4, DIT + MIT = T3 5) T3/4 remove from Thg and release to plasma

Question 25

low T3 triggers this hormone:

Answer 25

thyroid stimulating hormone (thyrotropin)

Question 26

hyperplasia of thyroid gland because of TSH stim in I-deficiency

Answer 26

goitre

Question 27

goitre in western countries is possibly cause by:

Answer 27

surgery on nodules, use of radioactive iodide (gamma rays), sometimes cancer

Question 28

T3 is found in these tissues

Answer 28

liver, brain, pit., brown adipose

Question 29

T3 influences:

Answer 29

transcription, ^ BMR, heat production, ^ O2 consumption–>CNS development, linear growth

Question 30

EAR is set to meet requirement for____

Answer 30

uptake by thyroid gland (95mcg)

Question 31

RDA is SD of EAR ____%

Answer 31

20

Question 32

the child of mother deficient during pregnancy

Answer 32

cretin

Question 33

symptoms of cretinism?

Answer 33

mental retardation, neuro defects, growth abnormalities

Question 34

examples of goitrogens?

Answer 34

thiocyanate-generators: cabbage and cassava species

Question 35

when these nutrients are low, problem of I deficiency is worse

Answer 35

Se, Vit A, Fe

Question 36

people living in ____ regions more likely have IDD prevalence

Answer 36

mountainous

Question 37

In Canada, mandatory to add ___mcg I per gram of table salt

Answer 37

76

Question 38

goiter is endemic in these regions

Answer 38

Andes, Eastern Europe, Nepal, Ethiopia

Question 39

UL for I is ___mcg from __ sources

Answer 39

1100; all

Question 40

UL for I is based on____

Answer 40

elevated serum TSH and goitre-like symptoms (hyperthyroidism)