W35 L2 - Metabolism and the Pentose Phosphate Pathway

Flashcards on metabolism, focusing on the pentose phosphate pathway, its function, regulation, and significance in various cellular processes.

What is an evolutionary ancient pathway used by every single cell that uses glucose to generate NADPH plus ribose?

The pentose phosphate pathway (PPP)

According to lecture, what do we need NADPH for?

To make fatty acids

What structural feature indicates that NADPH is not meant to go into the electron transport chain to generate ATP?

It has an additional phosphate group in the two prime position of the sugar.

• This structural modification prevents NADPH from participating in oxidative phosphorylation, keeping it primarily for reductive biosynthetic reactions.

What happens to glucose when it enters the cell in the pentose phosphate pathway?

The molecule of glucose will be transported into the cell and immediately phosphorylated in the six position to create glucose six phosphate.

What are the two options for glucose-6-phosphate once it is created?

Glycolysis, to generate ATP, or the pentose phosphate pathway (PPP), to become oxidized.

What is the name of the enzyme that catalyzes the oxidation of glucose six phosphate to phosphogluconolactone in the pentose phosphate pathway?

Glucose six phosphate dehydrogenase (G6PD)

What inhibits G6PD?

NADPH

What activates G6PD?

ATP

Why is it called the pentose phosphate pathway?

Because it has five carbons and a phosphate. This is what lends the pathway its name.

What can we actually do with ribose?

RNA, or ATP

What is the first stage of the pentose phosphate pathway from glucose six phosphate to ribulose five phosphate called?

The oxidative pathway.

What is the second phase of the pentose phosphate pathway called where the sugars are modified?

The nonoxidative phase.

Where is the G6PD gene located?

It is X-linked, found on the X chromosome.

How many people worldwide suffer from a glucose six phosphate dehydrogenase deficiency?

Two to five hundred million people worldwide.

In what regions do you often see G6PD gene mutations?

They are typical malaria regions and this deficiency offers protection against the parasite, plasmodium, that causes malaria.

What three amino acids make up glutathione?

Glutamate, cysteine, which can form disulfide bonds, and glycine.

What is required to break the bond of oxidized glutathione?

NADPH

What ratio must we maintain in the cell related to glutathione?

In the cell, we need to maintain this ratio of oxidized to reduced glutathione to keep the cell in the correct redox environment.

Is the cytoplasm an oxidizing or reducing environment?

A reducing environment.

Is the mitochondria an oxidizing or reducing environment?

An oxidizing environment.

What substance can glutathione help to inactivate if you drink a lot of it?

Alcohol.

Why is the glutathione balance so important for the red blood cells?

The red blood cells transport oxygen, and oxygen is oxidating and can cause harm. If you don't have the right glutathione balance in the red blood cells, the red blood cells will suffer and die early.

Regarding, free radicals, what is the process that generates them that can be very toxic to cells?

Chemotherapy generates free radicals and, at the same time, inhibits the glucose six phosphate dehydrogenase so that it can't make more NADPH, potentially beating the cancer.