Tips for studying Glycolysis…

-By Melissa Reardon, chem content tutor

This is a piece of advice I commonly share with CHEM 240 students in study sessions, “Do not know something just to know it. Know why it is important.”

For example, if you were to merely memorize Glycolysis in preparation for your next quiz or exam you should not expect to do well. Therefore, as you learn the catabolic pathway for carbohydrates try to answer these questions to practice my philosophy of study.

1. What would happen to Gycolysis if the enzyme from step one was eliminated?

HINTS:

• Open up your book to the two-page spread of glycolysis.
  • What is the first step?
  • What enzyme performs this step? It’s name is immediately to the right of the reaction illustration. It’s italicized.
  • WHY IS THIS STEP IMPORTANT?

2. What would happen within Glycolysis if the enzyme from step three was eliminated? Would it effect subsequent pathways? Why/why not?

Good Luck! For answers, post back or make an appointment to discuss solutions!

Adolescent Sexuality

-by Casey Shaw, Psych tutor

To wrap up the discussion on Adolescent Sexuality, I found this article  about teenagers’ “virginity pledges.” Similar to what was discussed in class, this article mentions how those who pledge abstinence are at higher risk of pregnancy and STD’s. Research is also showing that these pledges are short lived – what does that say about adolescence and commitment? If they cannot commit to their own sexuality, how committed can they be to others? …to their own identity? Post any thoughts!

 

Virginity Pledges Don’t Change Sexual Behavior

By Psych Central News Editor
        Reviewed by John M. Grohol, Psy.D. on December 30, 2008

Tuesday, Dec 30 (Psych Central) —

While teenagers’ pledges to remain a virgin until marriage may make them feel good about their sexuality choices, it apparently does little in actually changing their sexual behavior. A new study just published suggests that such premarital abstinence pledges are simply ineffective. The analysis from researchers at the Johns Hopkins Bloomberg School of Public Health looked at data gathered from a nationwide survey of 11,000 teens, the National Longitudinal Study of Adolescent Health.

The study found more than half of youths surveyed engaged in sexual activity, regardless of whether they had made a pledge to remain sexually abstinent.

Researchers also discovered something not entirely unexpected — virginity pledgers were 10 percent less likely to use a form of birth control. Virginity pledges are often tied to a person’s religious beliefs, which may also teach against using birth control.

The researchers focused on 934 high school students from about 3,400 students who had never had sex or had taken a virginity pledge in 1995. Investigators compared students who had taken a virginity pledge with those who hadn’t.

After five years, those who had taken a pledge did not differ from teens who hadn’t taken a pledge in rates of premarital sex, oral or anal sex, or sexually transmitted diseases.

The study also found that, after 5 years, more than 80 percent of virginity pledgers had retracted their promises.

The findings suggest that “virginity pledges” do little to deter teenage sexuality. It also suggests that people who take such pledges are at a slightly increased risk for pregnancy or sexually transmitted diseases when they do have sex, due to their decreased use of condoms or other birth control.

The findings were published in the January issue of the journal Pediatrics.

Source: Johns Hopkins Bloomberg School of Public Health

 

http://psychcentral.com/news/2008/12/30/virginity-pledges-dont-change-sexual-behavior/3568.html

It’s a bird, it’s a plane, it’s an astroid!

Carl Nehm, Accounting and Management Tutor, is looking out for our safety. He found a story on CNN about an Astroid that, luckily, didn’t hit and destroy the Earth. Enjoy!

http://www.cnn.com/2009/TECH/science/03/03/asteroid.misses.earth/index.html

A New Way to Think About the Electron Transport Chain…

By Melissa Reardon, Chem Tutor

Last Friday, I spent about three hours of my day explaining the importance of oxygen to the functionality of aerobic respiration for  CHEM 240 students preparing for their exam. Students are often puzzled over its role since the molecule is not involved in the Kreb’s cycle, and is the very last reactant within the electron transport chain. By the end of my tutoring shift I came up with (what I think is a pretty clever) way to think about the concept-a metaphor.

Points to keep in mind:

• The Major Products of Krebs Cycle:
  1. 2 CO2
  2. ATP
  3. 3 NADH
  4. 1 FADH2
• The role NADH & FADH2 is to carry the protons and electrons to the electron transport chain. Protons will be pumped through complexes into the intermembrane space, while electrons will pass though the electron transport system to created the coupled reaction used to drive ATP synthesis.
• Oxygen is the final electron acceptor within the electron transport chain.

Think of NAD+ as a car. NAD+ takes a drive through the Kreb’s cycle to pick passengers, proton and electron (now exists in the form NADH). These passengers need to meet up with their friend H2O.  It is NAD+’s job to deliver H+ and e- to a series of escalators which will carry them to H2O. Once NAD+ delivers its passengers, it will return to the Krebs cycle to pick up another pair of H+ and e-, and repeat.

There are two sets of escalators leading to H2O connected by a bridge that over looks the Grand Canyon. One day, however, this bridge breaks. NAD+, unaware of this occurrence, continues to drop H+ and e-  off at the escalator where they fall (sadly) to their deaths. Eventually, people discover this reoccurring tragedy and shut the escalator down. Hence, the electron transport chain stops. Suddenly, NAD+ has no where to drop off its passengers. With a full passenger load, NAD+ (remember it is in the form of NADH) cannot go back to the Krebs cycle to pick up more H+ and e- so it can drop them off at the electron transport chain. Hence, if NAD+ cannot pick up its passengers, the Krebs cycle stops.

Therefore, the deprivation of oxygen stops both the Krebs and electron transport systems.

I hope that provided a visual (FADH2 also works as a car).

Snow Day & Glycolysis

A few thoughts from your friendly chem tutor, Melissa Reardon. . .

Mother Nature has awarded students with two additional days of studying-Use your time wisely CHEM 240 ladies! Good luck on you exam! One last piece of advice…..do not concentrate on merely knowing what things are, know why they are important.

I have new “brain teasers.”

A  few CHEM 240 students have asked why our bodies cannot survive on anerobic respiration when oxygen supply is shut off. I invite readers to open a discussion concerning this question (I hope you all realize that you can leave comments on this space!). We can also discuss it at this week’s study tables if you wish-Wednesday 2:00 & Friday 3:00, McD. 108.

Here are some more questions relating to this topic:

1. Where does anerobic respiration occur within our bodies? Why?
2. Compare our  anerobic respiration technique with other organisms.
3. What is the importance of phosphofructokinase? What would happen if it was removed? (HINT: When I took CHEM 240, this information was important to know)