PHAR 502 THYROID EXAM QUESTIONS WITH
VERIFIED ANSWERS
What is the functional unit of the thyroid?
thyroid follicle
Which molecule are T3 and T4 synthesized from?
L-tyrosine
What is the bond angle between the pheny and tyrosyl groups?
90 degrees (perpendicular
T3 pKa
8.47
T4 pKa
6.73
T3 % ionized at physiologic pH
10%
T4 % ionized at physiologic pH
80%
T or F T3 transports in the blood easier than T3 due to it's ionized form at physiological
pH
false. T4 is more ionized at physiological pH and thus is more easily bound to albumin and other
transport proteins
What characteristic of T3 makes binding at target sites easiest?
Ability to Hydrogen Bond
What is the preferred way to treat hypOthyroidism
T4 dosing
What is the function of thyroid peroxidase (TPO)?
Addition of Iodide onto tyrosine which is attached to thyroglobulin in the apical membrane
What is the most common form of Iodine?
Iodide (I-)
, Which two molecules can inhibit Iodide transport in thyroid cells
Perchlorate and Thiocyanate
What molecule regulates the Na/I symporter
Thyroid Stimulating Hormone
Where is the highest concentration of iodide found?
Follicular Colloid
Which molecule catalyzes the coupling reaction between two DIT molecules
Thyroid Peroxidase (TPO)
Which molecule helps to Transport T3 and T4 in the blood?
Thyroxine-binding globulin (prefer T4)
Which molecule converts T4 to T3 in the tissue?
Iodothyronine deiodinases
What is reverse T3?
Inactive form of T3 that is made from peripheral conversion of T4 to T3
What is the function of Type 1 5-deiodinase?
- Generates T3 for circulation
- inhibited by propylthiouracil
What is the function of Type 2 5-deiodinase?
Makes T3 from T4 for local use
What is the function of ubiquitination?
Regulates Type 2 deiodinase (T4 to T3)
What enzyme will always give you reverse T3?
5 Deiodinase (Type 3)
Which AA's are contained within TRH?
Proline, Histamine, Glutamate
Which enzyme cleaves amino groups off of TRH?
Carboxypeptidase
What kind of receptor is TRHR?
GPCR
VERIFIED ANSWERS
What is the functional unit of the thyroid?
thyroid follicle
Which molecule are T3 and T4 synthesized from?
L-tyrosine
What is the bond angle between the pheny and tyrosyl groups?
90 degrees (perpendicular
T3 pKa
8.47
T4 pKa
6.73
T3 % ionized at physiologic pH
10%
T4 % ionized at physiologic pH
80%
T or F T3 transports in the blood easier than T3 due to it's ionized form at physiological
pH
false. T4 is more ionized at physiological pH and thus is more easily bound to albumin and other
transport proteins
What characteristic of T3 makes binding at target sites easiest?
Ability to Hydrogen Bond
What is the preferred way to treat hypOthyroidism
T4 dosing
What is the function of thyroid peroxidase (TPO)?
Addition of Iodide onto tyrosine which is attached to thyroglobulin in the apical membrane
What is the most common form of Iodine?
Iodide (I-)
, Which two molecules can inhibit Iodide transport in thyroid cells
Perchlorate and Thiocyanate
What molecule regulates the Na/I symporter
Thyroid Stimulating Hormone
Where is the highest concentration of iodide found?
Follicular Colloid
Which molecule catalyzes the coupling reaction between two DIT molecules
Thyroid Peroxidase (TPO)
Which molecule helps to Transport T3 and T4 in the blood?
Thyroxine-binding globulin (prefer T4)
Which molecule converts T4 to T3 in the tissue?
Iodothyronine deiodinases
What is reverse T3?
Inactive form of T3 that is made from peripheral conversion of T4 to T3
What is the function of Type 1 5-deiodinase?
- Generates T3 for circulation
- inhibited by propylthiouracil
What is the function of Type 2 5-deiodinase?
Makes T3 from T4 for local use
What is the function of ubiquitination?
Regulates Type 2 deiodinase (T4 to T3)
What enzyme will always give you reverse T3?
5 Deiodinase (Type 3)
Which AA's are contained within TRH?
Proline, Histamine, Glutamate
Which enzyme cleaves amino groups off of TRH?
Carboxypeptidase
What kind of receptor is TRHR?
GPCR
