Biochem Exam 2: Glycolysis

Front 1

glucose --> G-6-P
is catalyzed by _________ or __________ in liver only.

Back 1

hexokinase (low km)

glucokinase in liver (high km)

(step 1) *irreversible step

Front 2

G-6-P ----> F-6-P
is catalyzed by ......

Back 2

phosphoglucose isomerase

(step 2)

Front 3

What is the rate limiting and irreversible step in glycolysis?

Back 3

when PFK-1 is used to convert fructose 6 phosphate to fructose 1,6 bisphosphate

(step 3)

Front 4

What inhibits the rate limiting step of glycolysis, effectively downregulating glycolysis?

Back 4

citrate accumulates from TCA cycle not being able to continue (due to high levels of ATP) and leaks into cytosol, inhibiting PFK-1. This stops glycolysis

Front 5

Cleavage of F-1,6-BP to DHAP and GAP is catalyzed by .....

Deficiency in the A form (in muscle and RBC's) of this enzyme leads to___________.

Back 5

Aldolase

nonspherocytic hemolytic anemia w/ episodes of rhabdomylosis followed by febrile illness

(step 4)

Front 6

Isomerization of DHAP---> GAP is catalyzed by...........

Deficiency in this enzyme leads to ___________.

Back 6

Triose-P isomerase (TPI)

neonatal-onset hemolytic anemia, progressive hypotonia and eventual cardiomyopathy

(step 5)

Front 7

Arsenate inhibits what step in glycolysis?

Back 7

GAP to 1,3-BPG using glyceraldehyde 3 phosphate dehydrogenase (G3PDH), NAD+ cofactor
(step 6)

*arsenate competes with Pi for the active site

Front 8

When is the only NADH produced in glycolysis?

Back 8

GAP to 1,3-BPG using glyceraldehyde 3 phosphate dehydrogenase. THINK DEHYDROGENASE

Front 9

When is the 1st ATP produced in glycolysis?

Back 9

1,3-BPG converted to 3-phosphoglycerate using phosphoglycerate kinase

(step 7)
*HbF has a lower affinity for BPG than HbA, thus a higher O2 affinity

Front 10

3-phosphoglycerate---> 2-phosphoglycerate
is catalyzed by

Back 10

phosphoglycerate mutase

(step 8)

Front 11

what converts 2-phosphoglycerate to PEP?

Back 11

enolase

(step 9)

Front 12

What inhibits enolase?

Back 12

fluoride

*blood sample for glucose quantification is collected in tubes containing flouride

Front 13

PEP is finally converted to pyruvate using ___________.

Deficiency in this enzyme causes a decrease in ATP production from glycolysis in RBC's leading to what?

Back 13

pyruvate kinase

(step 10) *irreversible step

pyruvate kinase deficiency leads to hemolytic anemia

Front 14

when is the second and last ATP produced?

Back 14

last step (10), pyruvate kinase making pyruvate

Front 15

What enzyme makes lactate from pyruvate and NADH?

Back 15

lactate dehydrogenase
*reversible, direction of rxn depends on pH
(oxidative fate of pyruvate in absence of oxygen)

Front 16

What are 2 functions of PFK-2?

Back 16

1. Activates PFK-1, which is the rate limiting step for glycolysis (activates glycolysis).

2. catalyzes F6P --> F2,6-BP

Front 17

What cells are restricted to anareobic degradation of glucose (glycolysis) and how do they produce ATP?

Back 17

-cells without mitochondria or with poor oxygen perfusion of tissues
- ATP results from substrate level phosphorylation or oxidative phosphorylation (from glucose degradation)

Front 18

Insulin stimulates __________ to transport glucose into _______ and ___________ cells.

Back 18

GLUT-4 (insulin dependent)

muscle and adipose

Front 19

Glucose enters the hepatic (liver) cells via?

Back 19

GLUT-2 (insulin independent)

Front 20

glucose enters the brain via _________ and __________?

Back 20

GLUT-1 (expressed by glial cells)
and
GLUT-3 (neuron specific NSGT, also found elsewhere)
*both insulin independent

Front 21

Glucose enters RBCs via _________. Hereditary deficiency of this glucose transport protein results in decreased glucose in the _______________, leading to intractable seizures in infancy and developmental delay.

Back 21

GLUT-1

cerebrospinal fluid

Front 22

Type 2 (MODY) diabetes is an autosomal dominant disorder caused by a mutation in __________ leading to nonprogressive hyperglycemia, which can be managed by ____________.

Back 22

glucokinase

diet

Front 23

Phosphofructokinase (PFK-1) deficiency causes an inefficient use of glucose stores by RBCs and muscle leading to _____________ and ____________.

Back 23

hemolytic anemia

muscle cramping
*all glycolytic enzyme deficiencies will lead to this result

Front 24

What steps of glycolysis are considered the preparative/investment phase?
What steps are considered the ATP generating/yielding phase?

Back 24

Steps 1-5

Steps 6-10

Front 25

What is the energy yield of anaerobic glycolysis?

..aerobic glycolysis?

Back 25

2 ATP, 1 glucose

32 ATP, 1 glucose

Front 26

What intermediate of glycolysis feeds into the pentose phosphate pathway?

Back 26

Glucose 6-P

Front 27

Glycolytic intermediate 3-Phosphoglycerate and Pyruvate can be made into the amino acids ___________ and ___________, respectively.

Back 27

3-Phosphoglycerate ----> Serine
Pyruvate ----> Alanine

Front 28

Which two glycoloytic intermediates participate in the synthesis of 2,3-bis-Phosphoglycerate (2,3-BPG)?
What does 2,3-BPG regulate?

Back 28

1,3-BPG and 3-phosphoglycerate

regulates O2 release

Front 29

Acetyl CoA feeds into what other cycle?

Back 29

TCA

Front 30

Glycolysis leads to synthesis of FAs from Acetyl CoA, when carbohydrate intake is (higher/lower) than necessary for body energy?

Back 30

higher

Front 31

In the anaerobic degradation of glucose, ATP is synthesized via what process?

Back 31

oxidative phosphorylation

Front 32

Glycolysis is controlled allosterically via what 3 enzymes?

Back 32

Hexokinase
PFK-1
Pyruvate Kinase

Front 33

Hexokinase is inhibited by _____________
PFK-1 is inhibited by __________ and _________________
Pyruvate kinase is inhibited by __________

Back 33

Hexokinase is inhibited by G-6-P

PFK-1 is inhibited by ATP and low pH (high lactate)

Pyruvate kinase is inhibited by ATP

Front 34

PFK-1 is activated by ___________ and ____________
Pyruvate kinase is activated by __________

Back 34

PFK-1 is activated by high AMP and F2,6-BP

Pyruvate kinase is activated by F-1,6-BP

Front 35

In the liver, PFK-2 is activated by _________ and inhibited by ____________

In the muscle, it is activate by __________ and ____________

Back 35

liver;
activated by increased F6P
inhibited by PKA (which is activated by cAMP)
muscle:
activated by increased AMP and norepinephrine

Front 36

Isoenzymes of LDH are used in detecting the following diseases,
Cardiac: _________ and _____________
Hepatic: ________ and _______________
Skeletal muscle: _______ and _____________
Neoplastic disorders: _________ and ___________

Back 36

Cardiac: myocardial and pulmonary infarctions
Hepatic: hepatitis and cirrhosis
Skeletal muscle: hypoxia and muscle trauma
Neoplastic disorders: leukemias and large tumors

Front 37

why does aldolase b (liver) deficiency lead to fructose intolerance?

Back 37

F1P is not cleaved--> accumulation of F1P and AMP (from fructose synthesis)-->inhibition of fructokinase and uric acid formation--> accumulation of fructose and lactic acid --> fructose intolerance and metabolic acidemia

Front 38

why does aldolase b deficiency lead to hypoglycemia?

Back 38

aldolase also necessary in gluconeogenesis, no glucose is produced

Front 39

In respiratory acidosis (hypoventilation/hyperventilation) will occur, while in metabolic acidosis (hypoventilation/hyperventilation) will occur.

Back 39

Respiratory= hypoventilation causing acidosis
Metabolic= hyperventilation resulting from acidosis

Front 40

In what 2 reactions of glycolysis does substrate level phosphorylation (ATP production) take place?

Back 40

1,3-BPG -----> 3-phosphoglycerate (via phosphoglycerate kinase) (step 7)

PEP----> pyruvate (via pyruvate kinase)
(step 10)

Front 41

What are the consequences of lactic acid accumulation on the body's function?

Back 41

lactic acid breaks down into lactate and H+. H+ enters blood and drops pH leading to lactic acidosis

Front 42

Is glycolysis (inhibited/activated) during low cell energy?

Back 42

activated to make more ATP

Front 43

What is the connection btwn the rate of glycolysis and the size of a cancerous tumor?

Back 43

Cancerous tumors only use glycolysis for energy, therefore the rate of growth will be directly influenced by the rate of glycolysis

Front 44

Phosphofructokinase (PFK-1) deficiency causes an inefficient use of glucocose stores by __________ and ______, leading to hemolytic anemia and muscle cramping.

Back 44

RBCs and muscles

Front 45

Pyruvate from glycolysis can be made into what (4) substrates?

Back 45

alanine
OAA
lactate
Acetyl-CoA

Front 46

Pyruvate dehydrogenase (PDH) is activated by what and inhibited by what?

Back 46

activated: ADP, Ca2+
inhibited: NADH, acetyl CoA

Front 47

fructokinase deficiency leads to what?

Back 47

essential fructosuria
fructose cannot be phosphorylated into F-1-P