Endocrine System Project - Thyroid (Podcast)

Karina Martin

Mr. Quick

A Block - 2/24/14

Hello, today I am going to talk about the endocrine system. More specifically, I am going to talk about the T3 and T4 hormones located in the thyroid gland. TSH, otherwise known as thyroid-stimulating hormone, is released from the pituitary, an endocrine gland that sits just beneath the base of the brain. From the pituitary, TSH goes into the bloodstream and travels to the thyroid gland. Here, TSH causes cells within the thyroid to produce more T3 and T4 hormones.

This whole process of producing T3 and T4 hormones starts in the portal capillaries where thyrotropin-releasing hormone or TRH is secreted and then sent to the anterior pituitary, the endocrine gland I mentioned before located beneath the brain. There, TRH stimulates thyrotropes (hormones produced by the anterior lobe of the pituitary) to synthesize and release TSH. You already know what happens next. The TSH makes its way to the thyroid gland and then (TADA!) we have T3 and T4 hormones.

T3 and T4 hormones have a negative feedback loop that regulates the secretion of TSH. If TSH is not secreted, thyroid function becomes depressed and the thyroid gland wastes away. Control of TSH stimulates the thyroid gland and increases circulating levels of thyroid hormones. In other words, no TSH equals no thyroid gland which equals short life which equals BAD! You see, the thyroid plays a very important role in a human’s metabolism. Hormones T3 and T4 have an effect on every cell in the body. They control the rate in which the cells in your body use energy and oxygen. Because thyroid hormones play such an important role in the function of the brain, a deficiency of thyroid hormone can cause depression, memory problems, and even psychosis. Thyroid hormones are also important when it comes to human growth and development; therefore, hormone deficiency can also cause severe mental retardation and serious growth delays.

Now, remember when I talked about TSH? Well, when in the process of making its way from the pituitary to the thyroid gland, TSH is given  instructions by a gene receptor called TSHR. This receptor extends itself throughout the membrane of follicular cells in the thyroid gland. It serves as a customized binding site for the TSH hormone. TSH attaches itself to the extracellular portion of the receptor, activating a series of reactions that control the development of the thyroid gland and its functions.

Thyroid hormones are poorly soluble in water. They are lipid soluble, however, and diffuse into the cell, where they, as I mentioned before, attach themselves to receptors, migrate to the nucleus, and activate specific target sequences of DNA. On the other hand, water soluble hormones use their effects through an intracellular second messenger that is activated when a hormone attaches itself to a membrane receptor.

The thyroid gland is an important part of your body. As I mentioned before, it is very difficult to survive without one. Some people don’t have thyroid glands however. And if you are, don’t freak out! While the hormones a thyroid produce are essential to life, people can live without a thyroid gland as long as the hormones are replaced. A thyroid hormone can be replaced with a synthetic one. Interesting, right? Well, that’s all I have to say about thyroid hormones. Thanks for listening!

Here is the link to my podcast: https://drive.google.com/file/d/0BwtzLZZCgHBqekludWlzWndFYTQ/edit?usp=sharing

Works Cited

• http://voices.yahoo.com/can-live-without-thyroid-gland-6993008.html?cat=5
• http://classes.midlandstech.edu/carterp/Courses/bio211/chap16/chap16.htm
• http://ghr.nlm.nih.gov/gene/TSHR
• http://mcb.berkeley.edu/courses/mcb135e/thyroid.html

WHY PINEAPPLE NO LIKE JELLO?

Karina Martin

Mr. Quick

A Block

2/16/14

                             The Effects of Enzyme Bromelain on Collagen (protein) Bonds

ABSTRACT:

    The objective of this lab was to observe how fresh pineapple and canned pineapple react when mixed with jello. In other words, my partner and I wanted to see the effects of pineapple enzymes on jello. We designed an experiment where we made three plates of jello, two of which contained either fresh pineapple or canned pineapple. After leaving the three plates of jello alone for a couple of days, we observed that the jello containing fresh pineapple was still in a liquid state. The jello containing canned pineapple, however, became set (jello state), as did the jello mix containing nothing extra (obviously). 

INTRODUCTION:

   Jello packets usually has a note or warning saying not to add fresh or frozen fruit because the gelatin will not set. This is because many fruits, including pineapple, contain a chemical called bromelain, which can affect the hardening or setting of the jello. Bromelain contains two enzymes that have the capability of breaking down proteins called proteases. Many gelatin, like jello, get their shape/structure from links formed between chains of collagen. Bromelain cuts these chains of collagen and keeps the gelatin from jelling properly (becoming set). Fresh pineapple does this as a defense mechanism. Canned pineapple, on the other hand, is heated during the canning process. This means that the enzymes in bromelain in the pineapple are inactivated once they have been heated to about 158° F (70° Celsius).  Therefore, the jello mixed with canned pineapple (or any other canned fruit) will become set. 

HYPOTHESIS: 

    If we fill three plates with jello mix, with fresh pineapple in one and canned pineapple in another, then the only jello not to become set/gel will be the one containing fresh pineapple due to the fact that fresh pineapple has not been heated while canned pineapple has. 

MATERIALS:

• 26 grams of fresh and canned pineapple chunks
• 6.6 grams of jello powder 
• 3 plates (petri dishes)
• a beaker
• 39.4 grams of hot water 
• 39.4 grams of cold water
• tape and marker (for labels)

PROCEDURE:

1. Pour 6.6 grams of jello powder into a beaker
2. Add 39.4 ml of hot water to jello powder
3. Stir the water and powder until dissolved 
4. Add 39.4 ml of cold water to jello mix
5. Stir the jello again
6. Pour jello mix into beaker
7. Pour equal amount of jello mix from beaker into 3 plates
8. Add 26 grams of fresh pineapple chunks into one plate
9. Add 26 grams of canned pineapple chunks into another plate
10. Leave one plate with only jello
11. Wait for results and check next class.

RESULTS:

PLATES	SET	LIQUID
JELLO w/ FRESH PINEAPPLE	NO	YES
JELLO w/ CANNED PINEAPPLE	YES	NO
JELLO (alone)	YES	NO

CONCLUSION:

    In conclusion, the jello containing fresh pineapple did not become set, while the jello containing canned pineapple did, proving our hypothesis. Therefore, when pineapple still containing bromelain mixes with jello (which contains collagen), the jello will not set properly due to the breaking of collagen bonds. However, when heated pineapple mixes with jello, the jello does set properly due to the reformation of the collagen bonds' shapes and active site. The bromelain is inactivated and the jello can become set. Throughout this experiment, my partner and I kept the plate with only jello constant. Measuring the fruit, water, or jello incorrectly are possible errors that could have occurred along the way.  My partner and I also could have done more trials to get more accurate results. We also could have tested other fruits or had the plates of jello and fruit in different temperatures and/or environments. 

CITATIONS:

"Pineapple and Jell-O." About.com Chemistry. N.p., n.d. Web. 17 Feb. 2014.

"UCSB Science Line Sqtest." UCSB Science Line Sqtest. N.p., n.d. Web. 17 Feb. 2014.

"Why Can't You Put Pineapple Chunks in Jello?" General Chemistry Online: FAQ: Chemistry of 

      Everyday Life:. N.p., n.d. Web. 17 Feb. 2014.