MMD Quiz 3

Digestive enzymes released into the small intestine by ducts

What does the exocrine portion of the Pancreas do?

Secrete glucagon and insulin

What does the endocrine portion of the Pancreas do?

Alpha cells

Which cells secrete glucagon in the Pancreas?

Beta cells

Which cells secrete insulin in the Pancreas?

Insulin

Stimulates cellular uptake of blood glucose and its storage as glycogen in the liver and muscle cells or as fat in fat cells

Glucagon

Promotes the hydrolysis of glycogen in the liver and fat in adipose tissue

Insulin secretion is increased and glucagon secretion is decreased. Causes cellular uptake of glucose

After a meal, what happens to insulin and glucagon secretion?

cellular respiration

The release of energy from molecules such as glucose accompanied by the use of this energy to synthesize ATP molecules

Aerobic respiration

Respiration that requires O2 and gives of CO2

C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy

chemical equation for cellular respiration

ATP

Energy from glucose break down is used to form _____

36-38 ATP

Breakdown of one glucose molecule results in _____ ATP molecules

NAD+ and FAD

Two coenzymes used in cellular respiration that each carry 2 electrons and 2 Hs

Pick up electrons at specific enzymatic reactions and carry these electrons to the electron transport chain

What is the role of NAD+ and FAD in cellular respiration?

Glycolysis and Krebs cycle

Which two processes of cellular respiration are NAD+ and FAD reduced in?

Reduction

FAD---->FADH2

NAD+---->NADH

This represents ____ of the coenzymes.

Glycolysis, Preparatory Reactions, Citric Acid Cycle, Electron Transport Chain

What are the phases of cellular respiration?

Cytoplasm

Glycolysis occurs in the _______.

Glycolysis

RBCs obtain energy exclusively from _____

Glycolysis

Converts 6-carbon glucose into 2 3-carbon pyruvates

2 ATP

How many ATP are used in glycolysis?

2 pyruvate

2 net ATP

2 NADH

What are the products of glycolysis?

substrate-level phosphorylation

The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.

oxidative phosphorylation

Energy released from transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP in the electron transport chain

Oxygen

Serves as the final electron acceptor in the electron transport chain

1 Glucose

2 NAD+

2 ATP

4ADP+P

Inputs of glycolysis

2 pyruvate

2 NADH

2 ADP

2 net ATP

Outputs of glycolysis

Hexokinase

The enzymes that catalyzes the phosphorylation of glucose to form glucose-6-phosphate in the first step of glycolysis. This is one of the ain regulatory steps of this pathway. Hexokinase is feedback-inhibited by glucose-6-P.

phosphoglucose isomerase

Enzyme in step 2 of glycolysis. Catalyzes the interconversion of glucose 6-phosphate and fructose 6-phosphate

Aldolase

Enzymes that converts fructose 1,6-biphosphate into glyceraldehyde 3-phosphate(G3P) and dihydroxyacetone phosphate

When phosphofructokinase-1 converts Fructose 6 phosphate ---> Fructose 1,6 biphosphate

What is the commitment step/point of no return in glycolysis?

Phosphofructokinase-1

converts fructose-6-phosphate to fructose-1,6-bisphosphate

PFK1

What is a good enzyme to control is you want to regulate glycolysis?

Hemolytic anemia and muscle breakdown following febrile illness

A deficiency of aldolase can lead to ____

Neonatal hemolytic anemia, causing neurologic abnormalities and cardiomyopathy

What can a deficiency in triose phosphate isomerase (TPI) lead to?

Hemolytic anemia

A deficiency in an enzyme involved in glycolysis can lead to ____, because RBCs rely solely on glycolysis for energy production.

Hexokinase

Phosphorylates glucose to G6P in the tissues

Glucokinase

Phosphorylates glucose to G6P in the liver

Inhibits

As G6P levels build up, what does this do to hexokinase?

Hexokinase phosphorylates glucose into G6P. As G6P builds up in the blood, it inhibits hexokinase

Explain the negative feedback between hexokinase and G6P.

Hexokinase is induced

What do high insulin levels do to hexokinase?

Induction of glycolysis

High insulin levels induce hexokinase. What does this cause?

High blood sugar induces insulin secretion. High insulin levels induce hexokinase and glucokinase resulting in start of glycolysis

Explain the relationship between blood sugar, insulin, and hexokinase/glucokinase.

Glycolysis is reduced and glucose levels remain elevated

Causes Maturity-onset diabetes of the Young(MODY)

What does a glucokinase deficiency cause?

ATP is low (low energy)

What do high levels of AMP indicate?

PFK1

____ is activated when AMP levels are high in cell.

High levels

PFK1 is inhibited when there are ___ (high or low) levels of ATP.

High ATP Levels

High Citrate levels

2 things that inhibit phosphofructokinase

PFK-2

Generates fructose 2,6-biphosphate from fructose 6 phosphate in the liver and after a meal

Activates PFK-1, stimulating glycolysis

What does fructose 2,6-biphosphate (from PFK-2) do to the activity of PFK-1?

Less

PFK-1 is ____(more or less) active when glucagon levels are high.

Pyruvate Kinase

Enzyme at the end of glycolysis that dephosphorylates phosphoenolpyruvate to pyruvate

Activated

After a meal, pyruvate kinase is _______

Upregulates pyruvate kinase activity

What does high fructose 1,6-biphosphate (the committed molecule) do to pyruvate kinase activity?

Deactivates it. High glucagon levels mean BGL is low, so you do not want to break down glucose

What does glucagon do to pyruvate kinase activity?

Low production of ATP in RBC; hemolytic anemia

What happens with pyruvate kinase deficiency?

Upregulates; Downregulates

Insulin ______ glycolysis, while glucagon ______ glycolysis

Goes into the TCA cycle

What happens to pyruvate at the end of glycolysis with an abundance of O2?

It enters lactic acid fermentation

What happens to pyruvate at the end of glycolysis with depletion of O2?

Lactate dehydrogenase (LDH)

Converts pyruvate to lactate during an anaerobic state

Reduced, Oxidized

In an anaerobic state, pyruvate will be ____ (reduced or oxidized) to lactic acid and NADH is ___ (reduced or oxidized) to NAD+.

Arrhythmia

What can a build of of lactic acid cause?

pyruvate carboxylase

converts pyruvate to oxaloacetate

Replenishes intermediates in the TCA cycle

What is the importance of pyruvate being converted to OAA via pyruvate carboxylase?

Alanine down regulates glycolysis by inhibiting pyruvate kinase; alanine is used as substrate material in gluconeogenesis during fasting and prolonged starvation

Pyruvate can be transaminated and turned into alanine. What does alanine do to glycolysis?

Pyruvate translocase

pyruvate is transported into the mitochondria by _____

aerobic respiration

In ____ (aerobic or anaerobic) respiration, pyruvate is oxidized to Acetyl CoA.

Pyruvate dehydrogenase complex (PDHC)

catalyzes oxidative decarboxylation of pyruvate, to form acetyl-CoA

Lost as carbon dioxide

What happens to the carbon atom when 3-carbon pyruvate is converted to 2-carbon acetyl CoA?

Produces the molecules that will enter the TCA cycle

What is the importance of the preparatory reaction that precedes the TCA cycle?

cristae of mitochondria

Where does the preparatory reaction of the TCA cycle occur?

Twice

The preparatory reaction occurs ____ per glucose

Causes the buildup of lactate, because the TCA cycle is not functioning, so the cell will generate ATP by hydrolysis and fermentation

This causes lactic acidosis

What does pyruvate dehydrogenase deficiency cause?

Krebs cycle

Citric Acid Cycle

Alternate names for the tricarboxylic acid cycle (TCA cycle).

mitochondrial matrix

Where does the Krebs cycle occur?

A two carbon acetyl CoA combines with a 4 carbon oxaloacetate molecule, forming a 6 carbon citrate molecule

What is the first step of the TCA cycle?

Amphibolic

The TCA cycle is _____, meaning it has both a catabolic component and an anabolic component

2 acetyl groups

6 NAD+

2 FAD

2 ADP+2P

Inputs of the TCA Cycle

4 CO2

6 NADH

2 FADH

2 ATP

Products of TCA cycle

Citrate Synthase

Catalyzes the condensation of 2 carbon acetyl CoA and 4 carbon oxaloacetate to form 6 carbon citrate

Aconitase

Isomerizes citrate to isocitrate in the TCA cycle

Isocitrate

Removes CO2 and produces NADH from NAD+ in the TCA cycle

Increase TCA cycle activity

What does a high level of ADP/AMP in the cell do to the activity of the TCA cycle?

Decrease TCA cycle activity

What does a high level of ATP in the cell do to the activity of the TCA cycle?

isocitrate dehydrogenase

What enzyme catalyzes the rate-limiting step in the TCA cycle?

Allosterically activates isocitrate dehydrogenase. This enhances the activity of the TCA cycle

What do high ADP levels do to isocitrate dehydrogenase? What does this do to the TCA cycle?

NADH

Allosteric inhibitor of isocitrate dehydrogenase

Allosterically inhibits isocitrate dehydrogenase, slowing down the activity of the TCA cycle

What does high NADH levels do to the isocitrate dehydrogenase? What does this do to the TCA cycle?

Causes NADH levels to build up

High ATP levels slow down the ETC, which causes ______ to build up

3

How many ATPs does NADH yield per NADH molecule?

1.5-2

How many ATPs does FADH2 yield per FADH2 molecule?

4 ATP

10 NADH

2 FADH2

What is the total production of energy molecules (ATP, NADH, FADH2) in glycolysis, pyruvate oxidation, and the citric acid cycle?

Used by the liver to make glucose

In the fasting state, what are TCA intermediates used for?

Used by the liver to make fatty acids

In the fed state, what are the TCA intermediates used for?

cristae of mitochondria

Where does the ETC occur?

Energy is used to create a H+ gradient

H+ ions are pumped from the mitochondrial matrix from the inter membrane space, creating an electrochemical gradient

What happens to the energy that is lost as electrons are passed from one electron carrier to the next in the ETC?

Proton motive force

The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across biological membranes during chemiosmosis.

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

As the H+ passes through the ATP synthase complex (from the inter membrane space back into the matrix), energy is released to form ATP from ADP

Explain what happens during the synthesis of ATP (chemiosmosis) after the ETC

NADH dehydrogenase

What is complex I in the ETC?