Exam II-L7 (Glycolysis/Gluconeogenesis)

Question 1

What cell types does glycolysis primarily occur in? What organ does gluconeogenesis primarily occur in?

Answer 1

Glycolysis occurs in ALL cells

Gluconeogensis primarily occurs in LIVER cells

Question 2

____: the process by which glucose is broken down to release usable energy (energy is released)

____: the process by which glucose is SYNTHESIZED, requires energy input (energy is consumed)

Answer 2

Glycolysis: the process by which glucose is broken down to release usable energy (energy is released)

Gluconeogenesis: the process by which glucose is SYNTHESIZED, requires energy input (energy is consumed)

Question 3

True or False: A minimum level of glucose in the blood is required for survival

Answer 3

True

Question 4

What is the central pathway for breakdown of sugar?

Answer 4

Glycolysis

Question 5

Where does glycolysis occur within a cell?

Answer 5

Cytosol

Question 6

One molecule of glucose is split into two molecules of ____

Answer 6

pyruvate

Question 7

How many NADH molecules are produced during glycolysis?

Answer 7

2 NADH

Question 8

How many ATP are invested in the early phase of glycolysis?

How many ATP are gained in the energy generation phase?

Answer 8

2 ATP are invested in early phase
4 ATP are generated in later phase

Glycolysis = net gain of 2 ATP

Question 9

What are the two main purposes of glycolysis?

Answer 9

1) Energy production (NADH and ATP)
2) Cellular growth (biosynthesis)

Question 10

Intermediates of glycolysis are used as building blocks of biosynthesis, which is important for processes such as ______

Answer 10

cell division and growth

Question 11

True or False: Deficiencies in one or more glycolysis enzymes reduces energy output from glycolysis

Answer 11

True

Question 12

When glycolytic activity is reduced, most cells can utilize other fuels (fatty acids, amino acids) to make ATP, but this requires ____

Answer 12

mitochondria

Question 13

What cell types lack mitochondria and, therefore, are highly sensitive to decreases in glycolysis activity?

Answer 13

RBC’s!

Question 14

Glycolysis is the only source of energy for what cell type?

Answer 14

RBC’s

Question 15

When there is RBC’s loss, normal cellular functions are not maintained due to lack of ___

Answer 15

ATP

Question 16

True or False: Disorders of glycolysis can reduce RBC lifespan from 120 days to a few days to weeks

Answer 16

True

Question 17

Disorders of glycolysis can result in anemia. What are the clinical features of anemia?

Answer 17

1) Decreased RBC’s
2) SOB
3) Fatigue

Question 18

Under anaerobic (!!!) conditions, glucose will be converted to ____, which will be converted to ___

Answer 18

pyruvate; lactate

Question 19

Under aerobic (!!!) conditions, pyruvate is converted to ____ in the _____

Answer 19

acetyl-CoA in the mitochondria

Question 20

Conversion of ___ to ___ reoxidizes NADH to ____, allowing the next round of glycolysis to occur

Answer 20

pyruvate to lactate; NAD+

Question 21

What enzyme converts pyruvate to lactate?

Answer 21

Lactate dehydrogenase (LDH)

Question 22

What molecule is required during lactate dehydrogenase reaction?

Answer 22

NADH

Question 23

What cell types lack mitochondria?

Answer 23

RBC’s

Question 24

____ muscle favors anaerobic metabolism, as well as the ____of the eye

Answer 24

skeletal muscle; lens/cornea

Question 25

What two mechanisms are used by the liver to maintain blood glucose?

Answer 25

1) Glycogen 2) Gluconeogenesis

Question 26

Glycogen ___ glucose Gluconeogenesis ____ glucose

Answer 26

Glycogen stores glucose Gluconeogenesis creates glucose

Question 27

In gluconeogenesis, an equivalent of _ ATP are needed for each glucose made

Answer 27

6 ATP

Question 28

True or False: The liver has the ability to manufacture glucose from other molecules (e.g pyruvate)

Answer 28

True

Question 29

What process helps maintain and stabilize proper blood glucose levels in the absence of nutrients from the diet?

Answer 29

Gluconeogenesis

Question 30

When blood glucose levels are low (glucose stores are depleted) which organ makes glucose from other intermediates and then secretes it into the body for use?

Answer 30

The liver

Question 31

True or False: The brain does not requires a minimum level of glucose for proper function

Answer 31

False - The brain DOES requires a minimum level of glucose for proper function

Question 32

The brain uses ~25% of glucose pool daily. It does not readily use other sources of fuel, such as ___

Answer 32

fatty acids

Question 33

True or False: RBC's lack mitochondria and cannot release energy from amino acids/fatty acids

Answer 33

True

Question 34

What other molecules (besides pyruvate) can the liver use to make glucose via: gluconeogenesis?

Answer 34

1) Adipocytes = Glycerol 2) Skeletal muscle = Amino acids 3) Anaerobic Metabolism = Lactate

Question 35

How does long-term activity of gluconeogenesis in the liver, due to starvation and malnutrition, affect muscle tissue?

Answer 35

Leads to muscle tissue breakdown

Question 36

What does a baseline activity level of gluconeogenesis in the liver help prevent?

Answer 36

Lactate accumulation in the blood

Question 37

Describe the Cori Cycle

Answer 37

Question 38

In the Cori Cycle, the liver uses gluconeogenesis to convert lactate to ___

Answer 38

glucose

Question 39

In the Cori Cycle, lactate travels in the blood to the ___

Answer 39

liver

Question 40

True or False: Mutations in gluconeogenesis enzymes reduce body's ability to maintain blood glucose levels

Answer 40

True

Question 41

What are four clinical features of gluconeogenesis disorders?

Answer 41

1) Hypoglycemia 2) Fatigue 3) Lightheadedness 4) Fainiting

Question 42

Patients with disorders of ____ can have difficulty maintaining minimum glucose levels, especially in between meals or overnight

Answer 42

gluconeogenesis

Question 43

Defects in gluconeogenesis can lead to _______, a condition in which there is a build-up of acid

Answer 43

Lactic acidosis

Question 44

True or False: Defects in gluconeogenesis can lead to reduced ability of liver to convert lactate to glucose, leading to lactate accumulation in the blood

Answer 44

True

Question 45

True or False: Glycolysis and Gluconeogenesis are tightly controlled by a combination of mechanisms within the liver

Answer 45

True

Question 46

Insulin is released from ___ cells in response to ___ blood glucose, which acts on many cells Glucagon is release from ___cells in response to ___ blood glucose, which acts primarily in the ____

Answer 46

beta cells; high alpha cells; low; liver

Question 47

In a well fed state, the pancreas secretes ____, which promotes ____

Answer 47

insulin; glycolysis

Question 48

In fasting/starvation conditions, pancreas secretes ___, which promotes ____

Answer 48

glucagon, gluconeogenesis

Question 49

How many reversible and irreversible reactions does glycolysis contains?

Answer 49

7 reversible reactions 3 irreversible reactions

Question 50

Gluconeogenesis must "bypass" irreversible reactions of glycolysis using different ___

Answer 50

enzymes

Question 51

True or False: Both glycolysis and gluconeogenesis in a liver cell will be active at the same time

Answer 51

False - only glycolysis and gluconeogenesis in a liver cell will be active at the same time, to prevent futility

Question 52

What enzyme mediates the first irreversible reaction of glycolysis

Answer 52

Hexokinase - When blood glucose levels rise and glucose enters the cell, it is phosphorylated by hexokinase -Higher glucose outside the cell causes an inward flow of glucose

Question 53

In the first irreversible reaction of glycolysis, glucose is phosphorylated. What is the effect?

Answer 53

Glucose is trapped inside of the cell

Question 54

What is the last step of gluconeogenesis?

Answer 54

G6P is converted to glucose via: G6P - Blood glucose is low - Higher glucose inside cell causes outward flow of glucose

Question 55

True or False: G6Phosphatase is a gluconeogenesis bypass enzyme that is highly expressed in the liver

Answer 55

True

Question 56

Low cellular levels (low ATP, high ADP and high AMP) activate ____ and inhibit _____

Answer 56

Activate glycolysis Inhibit gluconeogenesis

Question 57

What two glycolytic enzymes are activated under low cellular level energy conditions? (low ATP, high ADP, and high AMP)

Answer 57

PFK1 and Pyruvate kinase

Question 58

High ATP inhibits ___ and activates ___

Answer 58

glycolysis; gluconeogenesis

Question 59

Which glycolytic enzymes are inhibited when there is high cellular energy levels (high ATP)?

Answer 59

PFK1 and Pyruvate Kinase

Question 60

True or False: Bypass enzymes are no longer inhibited under high cellular energy conditions, since gluconeogenesis requires sufficient ATP

Answer 60

True

Question 61

Under high glucose conditions, the pancreas will secrete insulin, promoting ___ in the liver and activation of _____ (enzyme) Covalent regulation !!!

Answer 61

Under high glucose conditions, the pancreas will secrete insulin, promoting glycolysis in the liver and activation of Protein Phosphatase-1 (enzyme)

Question 62

Under low glucose conditions, the pancreas will secrete glucagon, promoting ___ in the liver and activation of _____ (enzyme)

Answer 62

Under low glucose conditions, the pancreas will secrete glucagon, promoting gluconeogenesis in the liver and activation of Protein Kinase A (enzyme)

Question 63

What enzyme mediates the final step of glycolysis?

Answer 63

Pyruvate kinase

Question 64

Insulin activates Protein Phosphatase 1, which removes phosphate from pyruvate kinase, activating it and promoting ___

Answer 64

glycolysis

Question 65

Glucagon activates PKA, which adds a phosphate to pyruvate kinase, thereby inhibiting ____

Answer 65

glycolysis

Question 66

How does F2,6BP exert its effects?

Answer 66

Allosteric Regulation

Question 67

P2,6BP is a potent activator of ____ and inhibitor of ____

Answer 67

P2,6BP is a potent activator of glycolysis and inhibitor of gluconeogenesis

Question 68

How does insulin activation of PP1 affect F2, 6BP?

Answer 68

Insulin activation of PP1 leads to an increase in F2,6BP

Question 69

Does glucagon activation of PKA lead to an increase or decrease in F2,6BP levels?

Answer 69

Glucagon activation of PKA lead to a DECREASE in F2,6BP levels

Question 70

Insulin increases G2,6BP, thereby activating which irreversible glycolysis enzyme?

Answer 70

PFK1 note: bypass enzyme is inactivated

Question 71

High F2,6BP activates ___ and inhibits ____ Low F2,6B6 reduces activation of which enzyme? And removes inhibition of which enzymes?

Answer 71

High F2,6BP activates glycolysis and inhibits gluconeogenesis Low F2,6BP reduces activation of PFK1 and removes inhibition of bypass enzymes

Question 72

A person who has been in a well-fed state for a long time will have elevated ___ enzymes and decrease in ___ enzymes

Answer 72

increase glycolysis enzymes decreases gluconeogenesis enzymes

Question 73

How will epinephrine increase blood glucose?

Answer 73

Promoting gluconeogeneis in liver by activating PKA

Question 74

Low blood glucose stimuli activates glucagon, which activates PKA and increases gluconeogenesis and blood glucose. What stimuli activates this pathway, but with epinephrine?

Answer 74

Stress and fear

Question 75

Insulin will increase glycolysis in liver and skeletal muscles. However, glucagon will only increase gluconeogenesis in the liver and will have no effect in ____

Answer 75

skeletal muscles

Question 76

How does epinephrine affect skeletal muscle and liver?

Answer 76

Epinephrine will INCREASE glycolysis in the skeletal muscle Epinephrine will INCREASE gluconeogenesis in the liver