Question 1

Which of the following best explains why unsaturated fatty acids are typically liquid at room temperature, while saturated fatty acids are solid?

Accepted Answer

Unsaturated fatty acids contain cis double bonds that introduce kinks, preventing tight packing and lowering melting point.

Question 2

During beta oxidation of a 16-carbon saturated fatty acid (palmitic acid), how many rounds of beta oxidation occur, and how many acetyl-CoA molecules are produced?

Accepted Answer

7 rounds; 8 acetyl-CoA molecules

Question 3

Which enzyme is responsible for the transport of fatty acids into the mitochondrial matrix for beta oxidation, and how is this process regulated?

Accepted Answer

Carnitine acyltransferase I; regulated by malonyl-CoA

Question 4

A patient with familial hypercholesterolemia has a deficiency in LDL receptors. What is the most likely consequence at the cellular and systemic level?

Accepted Answer

Impaired LDL uptake, increased plasma cholesterol, and elevated risk of atherosclerotic plaque formation

Question 5

Which hormone stimulates the uptake of glucose into muscle and adipose tissue by activating GLUT4, and what is its effect on PFK-1 activity?

Accepted Answer

Insulin; activates PFK-1

Question 6

In the context of fatty acid metabolism, what is the fate of propionyl-CoA produced from the oxidation of odd-chain fatty acids?

Accepted Answer

It is converted to succinyl-CoA via a pathway requiring vitamin B12 and biotin.

Question 7

Which of the following statements about cholesterol metabolism is TRUE?

Accepted Answer

Cholesterol is a precursor for steroid hormones and bile salts, but cannot be broken down for energy.

Question 8

Which signaling pathway is activated under nutrient-rich conditions to promote cell growth, and is often dysregulated in cancer?

Accepted Answer

mTOR pathway

Question 9

What is the primary function of HDL in cholesterol transport?

Accepted Answer

HDL returns excess cholesterol from peripheral tissues to the liver for excretion.

Question 10

Which molecule acts as a sensor of cellular energy status, being activated when AMP levels are high, and what is its effect on metabolic pathways?

Accepted Answer

AMPK; stimulates catabolic pathways and inhibits anabolic pathways

Question 11

A person is fasting and their blood glucose is low. Which metabolic processes are upregulated in the liver to maintain blood glucose levels?

Accepted Answer

Glycogenolysis and gluconeogenesis

Question 12

Which of the following best describes the role of SREBP in cholesterol homeostasis?

Accepted Answer

SREBP is a membrane-bound protein that, when cholesterol is low, is cleaved and enters the nucleus to activate genes for cholesterol synthesis.

Question 13

Which of the following is a consequence of inhibition of the enzyme aromatase by environmental endocrine disruptors?

Accepted Answer

Decreased conversion of testosterone to estrogen, leading to a male-biased population

Question 14

Which of the following statements about the structure and function of phospholipids is CORRECT?

Accepted Answer

Phospholipids are amphipathic, containing both hydrophobic fatty acid tails and a hydrophilic phosphate head, enabling membrane formation.

Question 15

Which process is responsible for the formation of ketone bodies during prolonged fasting or diabetes, and what is the key substrate?

Accepted Answer

Ketogenesis; acetyl-CoA

Question 16

Which of the following best describes the effect of trans fatty acids on human metabolism?

Accepted Answer

Trans fatty acids act like saturated fats, are poorly metabolized, and may accumulate in tissues, increasing cardiovascular risk.

Question 17

Which of the following is TRUE regarding the transport of glucose across the intestinal epithelium?

Accepted Answer

Glucose transport involves a sodium-glucose co-transporter and is coupled to sodium-potassium ATPase activity.

Question 18

Which molecule is the key precursor for cholesterol biosynthesis, and what is the first committed step in the pathway?

Accepted Answer

Acetyl-CoA; conversion to mevalonate

Question 19

Which of the following statements about fatty acid synthesis is CORRECT?

Accepted Answer

Fatty acid synthesis occurs in the cytosol, uses malonyl-CoA as the carbon donor, and requires NADPH.

Module 4 Lectures

Guida di studio - Domande di pratica

Study guide - Flashcard