digestive and metabolism

What is the typical pH range of the human stomach?

$$1.5-3.5$$

The length of the human small intestine is approximately _____ meters.

$$6$$

The human large intestine measures approximately _____ meters in length.

$$1.5$$

What is the primary physiological role of bile salts in digestion?

Emulsification of fats.

Which enzyme is responsible for the initial breakdown of starch into maltose?

Amylase

Pepsin catalyzes the hydrolysis of proteins into _____.

Peptides

Lipase catalyzes the digestion of fats into glycerol and _____.

Fatty acids

Which two monosaccharides are produced by the action of lactase on lactose?

Glucose and galactose.

The absorption of Vitamin $B_{12}$ is dependent on which substance produced by the stomach?

Intrinsic factor

In which specific section of the small intestine does the majority of nutrient absorption occur?

Jejunum

The primary site for the absorption of water and electrolytes in the digestive tract is the _____.

Large intestine

Which organ produces bile but does not secrete any digestive enzymes?

The liver

The pancreas secretes _____ to neutralize acidic chyme entering the small intestine.

Bicarbonate ($HCO_3^-$)

Which enzyme complex links the glycolytic pathway to the Krebs cycle?

Pyruvate dehydrogenase

Where is the Krebs cycle (citric acid cycle) located within the cell?

Mitochondrial matrix

The Electron Transport Chain (ETC) is located on the _____.

Inner mitochondrial membrane

In which cellular compartment does $\beta$-oxidation of fatty acids occur?

Mitochondria

The Urea cycle takes place across which two cellular compartments?

Mitochondria and cytosol.

Name the first bypass enzyme of gluconeogenesis that converts pyruvate to oxaloacetate.

Pyruvate carboxylase

Which gluconeogenic enzyme converts oxaloacetate to phosphoenolpyruvate (PEP)?

PEP carboxykinase

Which enzyme bypasses phosphofructokinase-1 ($PFK-1$) in gluconeogenesis?

"Fructose-1

Name the final bypass enzyme of gluconeogenesis that allows glucose to be released into the blood.

Glucose-6-phosphatase ($G6Pase$)

Concept: Cori Cycle

Definition: The process by which lactate from muscles is converted back to glucose in the liver.

In which two primary tissues is glycogen stored in the human body?

Liver and muscle.

Why is muscle glycogen unavailable for maintaining blood glucose levels?

Muscle cells lack the enzyme Glucose-6-phosphatase ($G6Pase$).

What is the primary physiological function of liver glycogen?

Maintenance of blood glucose levels.

Which enzyme serves as the primary regulatory point for the Pentose Phosphate Pathway (PPP)?

Glucose-6-phosphate dehydrogenase ($G6PD$)

The Pentose Phosphate Pathway (PPP) is crucial for producing _____ for fatty acid and cholesterol synthesis.

$$NADPH$$

How much ATP is generated by the Pentose Phosphate Pathway (PPP)?

Zero ATP.

The liver detoxifies ammonia by converting it into _____.

Urea

Approximately how many grams of glycogen can be stored in the liver?

$100$ g

Where is bile stored and concentrated before being released into the duodenum?

Gallbladder

What is the primary chemical component of most gallstones?

Precipitated cholesterol

Pancreatic lipase digests triglycerides specifically into glycerol and _____.

Fatty acids

Which two pancreatic proteases break down proteins into smaller peptides?

Trypsin and chymotrypsin.

Peptidases complete protein digestion by breaking peptides into _____.

Amino acids

Lactose intolerance is caused by a deficiency in which enzyme?

Lactase

Which structural features of the small intestine maximize the surface area for absorption?

Villi and microvilli.

Gut microbiota are essential for the production of Vitamin $K$ and Vitamin _____.

$B_7$ (Biotin)

The appendix is primarily composed of which type of tissue?

Lymphoid tissue

What term describes the rhythmic muscular contractions that move food through the digestive tract?

Peristalsis

Which hormone stimulates the secretion of gastric acid in the stomach?

Gastrin

The hormone secretin triggers the release of _____ from the pancreas.

Bicarbonate

Which hormone stimulates the contraction of the gallbladder to release bile?

Cholecystokinin ($CCK$)

Which condition results from a lack of intrinsic factor leading to Vitamin $B_{12}$ malabsorption?

Pernicious anemia

Vitamin $B_{12}$ deficiency typically leads to _____ anemia and neurological symptoms.

Megaloblastic

Iron deficiency is the most common cause of _____ anemia.

Microcytic

What is the name of the primary protein used for intracellular iron storage?

Ferritin

Which protein is responsible for transporting iron through the blood plasma?

Transferrin

Hemochromatosis is a genetic disorder characterized by the pathological overload of _____.

Iron

What is the net ATP yield from the complete oxidation of one molecule of palmitic acid ($C_{16}$)?

$106$ ATP

The total aerobic respiration yield for one molecule of glucose is approximately _____ ATP.

$$30-32$$

What is the net gain of ATP and $NADH$ from one cycle of glycolysis?

$2$ ATP and $2$ $NADH$.

How many $NADH$ molecules are produced per molecule of glucose during the Krebs cycle?

$6$ $NADH$

How many $FADH_2$ molecules are produced per molecule of glucose during the Krebs cycle?

$2$ $FADH_2$

"In the Electron Transport Chain

each $NADH$ molecule yields approximately _____ ATP."

"In the Electron Transport Chain

each $FADH_2$ molecule yields approximately _____ ATP."

Which molecule acts as the final electron acceptor in the mitochondrial Electron Transport Chain?

Oxygen ($O_2$)

How do enzymes affect the activation energy of a chemical reaction?

They lower it.

True or False: Enzymes alter the $\Delta G$ (Gibbs free energy) of a reaction.

False

What is the optimal pH for the enzyme pepsin?

$$\% \approx 2$$

What is the optimal pH for the enzyme trypsin?

$$\% \approx 8$$

What is the optimal pH for salivary amylase?

$$\% \approx 7$$

Ubiquitin is used by the cell to tag proteins for degradation by the _____.

Proteasome

Which organelle contains catalase to detoxify $H_2O_2$?

Peroxisome

Lactase deficiency leads to which gastrointestinal condition?

Lactose intolerance

What is the maximum velocity of an enzyme-catalyzed reaction called?

$$V_{max}$$

What does the Michaelis constant ($K_m$) represent in enzyme kinetics?

The substrate concentration at $\frac{1}{2} V_{max}$.

How does competitive inhibition affect $K_m$ and $V_{max}$?

$K_m$ increases; $V_{max}$ remains unchanged.

How does noncompetitive inhibition affect $K_m$ and $V_{max}$?

$V_{max}$ decreases; $K_m$ remains unchanged.

"Besides proteins

what other biological molecules can function as enzymes?"

Which metabolic pathway produces $NADPH$ and ribose-5-phosphate?

Pentose Phosphate Pathway (PPP)

The process of generating ATP using a proton gradient across a membrane is called _____.

Chemiosmosis

Uncoupling proteins (UCP) in brown fat generate _____ instead of ATP.

Heat

"In humans

anaerobic respiration leads to the production of _____."

Which molecule is used as a rapid ATP buffer in muscle tissue?

Creatine phosphate

Which nitrogenous waste product is the most toxic and is excreted by fish?

Ammonia

Birds and reptiles excrete nitrogenous waste primarily as _____.

Uric acid

Gout is a clinical condition caused by the deposition of _____ crystals in joints.

Uric acid

Which enzyme is the most abundant on Earth and is involved in carbon fixation?

Rubisco