Glycolysis

Question 1

General Results for Glycolysis

Answer 1

6 carbon glucose molecule to two 3 carbon molecules (each called pyruvate) Needs 2 ATPS to make 4 ATPs = 2 net ATPs produced Anaerobic, does not need oxygen

Question 2

First irreversible rxn

Answer 2

take glucose, and using hexokinase we take a phosphate from that ATP to make it ADP and use that phosphate to make Glucose 6 Phosphate

Question 3

Second irreversible rxn

Answer 3

It happens after we use Phosphoglucose isomerase to turn our Glucose-6-phosphate to Fructose 6-Phosphate. We take another phosphate from another ATP (this is our second ATP for investment) and do the above step again to make the complex have 2 phosphates. This time it is done via PK-1 or Phosphofructokinase-1.

Question 4

Final Irreversible rxn

Answer 4

Phosphoglycerate mutase followed by Enolase turn our 3-PGs to phosphoenolpyruvates (PP), which are acted on by Pyruvate Kinase to turn our PPs into Pyruvates (the last irreversible rxn of glycolysis), in the process generating 2 ATPs from 2 ADPs (remember everything is X2)

Question 5

Draw out the iireversible tautomerization reaction that turns our enol pyruvate to a pyruvate in keto form

Question 6

Draw glycerol

Answer 6

Question 7

Draw glyceraldehyde

Answer 7

Question 8

Draw glyceric acid

Answer 8

Question 9

Draw glycerate

Answer 9

Question 10

Draw Acetone

Answer 10

Question 11

Draw Hydroxy-Acetone

Answer 11

Question 12

Draw di-hydroxy acetone

Answer 12

Question 13

Why are certain glycolysis steps irreversible?

Answer 13

Making these irreversible is great for fast energy production, but these steps must be bypassed during gluconeogenesis in the liver.

Question 14

How does glucose enter the cell?

Answer 14

Passive transport via GLUT4

Question 15

What are the 3 irreversible steps in glycolysis

Answer 15

Step 1: Glucose to G6P

Step 3: F6P to F16BP

Step 10: PEP to pyruvate

Question 16

What steps produce ATP

Answer 16

Step 7: 13BPG to 3-phosphoglycerate

Step 10: PEP to pyruvate

Question 17

What does glucokinase have a high Km

Answer 17

A high Km (aka low affinity) means that glucose uptake in the liver is restricted to when blood glucose is very high

Unlike hexokinase, glucokinase is not inhibited by its products and continues to function until blood glucose levels drop to normal level

Question 18

What is the major product of digestion of carbohydrates?

Answer 18

Glucose, but some galactose and fructose are also produced

Question 19

Pentose Phosphate Pathway

Answer 19

G6P used to make NADPH (which is used in the biosynthesis of fatty acids) and ribose-5-phosphate (nucleotide production)

Question 20

What is a carbohydrate?

Answer 20

Compounds that contain at least three carbons, a number of hydroxyl groups, and usually an aldehyde or ketone group

Question 21

Where can glucose and fructiose be phosphorylated?

Answer 21

On carbons 1 and 6

Question 22

Common dissarcharides

Answer 22

Maltose, Lactose, and Sucrose

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Question 23

What happens to RBCs when they are exposed to high levels of blood glucose?

Answer 23

The glycosylated fraction of hemoglobin (normally 4-6%) increases

Measuring this is helpful when determining glycemic control for individuals with diabetes

Question 24

Proteoglycans

Answer 24

Found in the EM or ground substance of connective tissue, synovial fluid, virteous humor, secretions of mucus-producing cells, and in cartilage

Question 25

Glycoproteins

Answer 25

Serve as enzymes, hormones, antibodies, and structural proteins Found in the extracellular fluid and in lysosomes Involved in cell-cell interactions

Question 26

What are the major dietary carbohydrates?

Answer 26

Strach, sucrose, and lactose

Question 27

What is glycogen?

Answer 27

The major storage form of carbohydrate in animals

Question 28

What does glycogen degradation produce?

Answer 28

glucose-1-phosphate, but free glucose is also formed

Question 29

What controls glycogen breakdown in the liver?

Answer 29

Glucagon and epinephrine via cAMP

Question 30

What controls muscle glycogen breakdown?

Answer 30

Epinephrine via cAMP

Question 31

Glycogen synthesis

Answer 31

Glucose enters the cell and is phosphorylated to G6P Phosphoglucomutase converts G6P to G1P G1P reacts with UTP, forming UDP-glucose (catalyzed by UDP-glucose pyrophosphorylase)

Question 32

What is the key regulatory enzyme for glycogen synthesis

Answer 32

Glycogen synthase (transfers glucose residues from UDP-glucose to the nonreducing ends of a glycogen primer)

Question 33

What is the key regulatory enzyme for glycogen degradation?

Answer 33

Glycogen phosphorylase: removes glucose residues, one at a time, from the nonreducing ends of glycogen molecules Produces G1P

Question 34

Regulation of glycogen degradation

Answer 34

Glucagon (liver cells) and epinephrine (live and muscle) activate adenylate cyclase, which converts ATP to cAMP cAMP activates protein kinase A protein kinase A phosphorylates glycogen synthase (less active) and phorphorylase kinase Phosphorylase kinase phsophorylates phosphorylase b, converting it to its active from, phosphorylase a (good luck) phosphorylase a cleaves glusose residues, producing G1P

Question 35

What activates phosphorylase b?

Answer 35

AMP (occurs during muscle contraction)

Question 36

What activates phosphorylase kinase?

Answer 36

Calcium (released from SR)

Question 37

Insulinomas

Answer 37

Leads to hypoglycemia Stimulaion of glucose transport into the muscle and fat cells

Question 38

Glucagonomas

Answer 38

Leads to hyperglycemia, as the liver is instructed to release glucose via glycogenolysis and gluconeogenesis in the presence of glucagon

Question 39

GLUT1 deficiency

Answer 39

The GLUT1 transporter translocates glucose across the blood-brain barrier When one allele is defective, the rate of glucose entry into the nervous system is insufficent for the cells' needs, leading to seizures, developmental delays, and microcephaly

Question 40

Deficiency of pyruvate kinase

Answer 40

Leads to decreased production of ATP from glycolysis RBCs have insufficient ATP for their membrane pumps, and a hemolytic anemia results (oxygen delivery to tissues is not necessarily affected)

Question 41

Why does pyruvate kinase deficiency not necessarily lead to decreased oxygen delivery?

Answer 41

As phosphoenolpyruvate accumulates, it is converted to 2PG, which leads to increased levels of 2,3BPG in the RBCs Elevated levels of 2,3BPG promote oxygen release from hemoglobin

Question 42

Major sites of regulation in skeletal muscle

Answer 42

Hexokinase and PFK1

Question 43

Major sites of regulation in the liver

Answer 43

Glucokinase, PFK1, and pyruvate kinase

Question 44

What determines if pyruvate is converted to lactate or acetyl-CoA

Answer 44

The activity of pyruvate dehydrogenase