Lipid and Protein metabolism review session (Part 2)

Microbiome Metabolism

100

Define microbiota and microbiome 

Microbiota = the collection of bacteria from a site Microbiome = the collective gene content of these bacteria

200

What are the benefits of short chain fatty acids?

Enhanced gut barrier integrity

Increased insulin sensitivity

Lowered blood glucose

Release of GLP-1

300

What is the source of short chain fatty acids in the gut microbiota?

Dietary fiber

400

What receptor are activated by short chain fatty acids?

What cell types express these receptors?

 Gpr41 and Gpr43
• Enteroendocrine cells of intestine
• Adipose tissue
• Innate immune cells such as neutrophils and macrophages

500

Briefly describe the relationship between gut microbiota and inflammation

1
High-fat diet
Shifts the
community and
reduces mucus
2
Barrier weakens
Looser tight
junctions, thinner
mucus layer
3
LPS enters blood
Across the
epithelium and in
chylomicrons
4
TLR4 / CD14
Activated in adipose
tissue, liver and
muscle
5
Insulin resistance
Chronic low-grade
inflammation
impairs signaling

Pyrimidine Nucleotide metabolism

100

What are the purine nucleotides?

Adenine and Guanine

200

What are the three components of a nucleotides structure?

-Nitrogenous Base (purine or pyrimidine) 

-Pentose sugar (derived from glucose metabolism- Pentose phosphate pathway)

-Phosphate group

300

What is the rate limiting enzyme for purine and pyrimidine synthesis?

Phosphoribosyl pyrophosphate (PRPP) synthetase Catalyzes rate-limiting step in the synthesis of purines and pyrimidines

400

What is the rate limiting enzyme in pyrimidine synthesis?

Carbamoyl phosphate Regulated step of the pathway!

-Formed when glutamine and CO 2 combine in the presence of ATP and cytosolic Carbamoyl phosphate Synthase II (CPS II) 

-CPS II is inhibited by UTP and activated by PRPP. This is a crucial regulatory step in pyrimidine biosynthesis

500

Where is Dihydroorotate dehydrogenase (DHODH) located within the cell?

Dihydroorotate dehydrogenase (DHODH) catalyzes the conversion of dihydroorotate to orotate.

DHODH is located in the mitochondrial inner membrane.  

Purine Nucleotide metabolism

100

What are the pyrimidine nucleotides?

Cytosine, Thymine and Uracil

200

What is the difference between a nucleotide and a nucleoside?

The primary difference between a nucleoside and a nucleotide is that a nucleotide includes one or more phosphate groups, while a nucleoside does not.

• Nucleosides: Act as structural precursors for nucleotides and are sometimes modified into nucleoside analog drugs (such as antiviral or anticancer agents).
• Nucleotides: Serve as the building blocks (monomers) for DNA and RNA, function as cellular energy currencies (like ATP), and act as signaling molecules (like cAMP).

300

Briefly describe the pathology of Uric acid build up

-Possible causes

-Possible disorders

Uric acid build-up (medically called hyperuricemia) happens when your body has too much uric acid in the blood 

What Is Uric Acid?

• Waste Product: Uric acid is a normal waste product created when your body breaks down purines.
• Purines: These are natural chemicals found in your body’s cells and in certain foods (like red meat, organ meats, and some seafood) and drinks (like beer and sugary sodas).
• Normal Filtering: Usually, uric acid dissolves in your blood, travels to your Cleveland Clinic Hyperuricemia Guide, and leaves your body through your pee

Why Does It Build Up?

A high level happens because of one of two things—or both:

• Overproduction: Your body makes too much uric acid.
• Under-excretion: Your kidneys do not filter or remove enough uric acid from your blood.

400

Briefly describe why Inosine monophosphate (IMP) is an important molecule in purine synthesis

precursor for ATP and GTP (Parent nucleotide) precursor to AMP requires GTP and is inhibited by AMP precursor to GMP requires ATP and is inhibited by GMP

500

What enzyme catalyzes the first committed step in purine synthesis?

Glutamine PRPP amidotransferase  

Endocrine regulation of metabolism

100

Briefly describe the role of insulin in the body and what it tells us about metabolic resources

Insulin is the body’s notification that fuel sources
have arrived, and “everyone” (all tissues) should partake. 

Insulin is a hormone produced by your pancreas that moves glucose from your blood into your body's cells so they can use it for energy 

200

Are all tissues able to use glucose for energy production?

All Tissues Can Use Glucose as a
Fuel Source
- some are inhibited from using it under conditions of low availability of carbohydrates (CH

300

During starvation conditions, What metabolic process is stimulated to create glucose?

Gluconeogenesis from Amino Acids during fasting/starvation

 Transamination is used to convert amino acids into glucogenic amino acids alanine and glutamine, which
are used by the liver to synthesize glucose (gluconeogenesis)

400

What are the endocrine hormones that inhibit glucose uptake by peripheral tissues?

• Glucagon
• Cortisol
• Growth Hormone
• Epinephrine

500

Briefly explain why the body has glucose sparing hormones and what does this mean for metabolism in tissues around the body

The CHO-sparing hormones inhibit glucose uptake by peripheral tissues, saving the glucose for the brain. These tissues instead use fatty acids for fuel, so the CHO-sparing hormones promote lipolysis to release fatty acids. To ensure that glucose is not used up, the hormones promote gluconeogenesis, usually from amino acids (so most of these hormones induce protein breakdown) but also from glycerol released by lipolysis