CARBOHYDRATES Flashcards Preview

#‼️BIOCHEMISTRY - PLE TOPNOTCH 2020 > CARBOHYDRATES > Flashcards

Flashcards in CARBOHYDRATES Deck (91)
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1

Rapoport-Luebering shunt pathway

  •  Found in RBCs where the reaction catalyzed by phosphoglycerate kinase is bypassed
  • 1,3-BPG → 2,3-BPG
    • Enzyme: Bisphosphoglycerate mutase

 

2

Lysosomal acid maltase deficiency

Pompe disease (Type II)

• ↑ Glycogen in lysosomes

• Juvenile onset: hypotonia, death from heart failure by age 2

• Adult onset: muscle dystrophy

3

Essential fructosuria

Fructokinase deficiency

• Fructose → Fructose-1-P

• Enzyme: Fructokinase or hexokinase

4

What is the substrate of PPP?

Glucose-6-phosphate

5

Liver phosphorylase deficiency

Hers disease (Type VI)

• Hepatomegaly, mild hypoglycemia

* No liver Glycogen Phosphorylase, so no liver glycogen breakdown = glycogen accumulates there = hepatomegaly

6

Discuss this graph

7

most common enzyme defect in glycolysis?

Pyruvate kinase

  • converts PEP to pyruvate 
  • presents as hemolytic anemia

8

2 steps in glycolysis produce ATP via substrate-level phosphorylation

  • 1,3-Bisphosphoglycerate → 3-Phosphoglycerate
    • Enzyme: Phosphoglycerate kinase
  • Phosphoenolpyruvate → Pyruvate
    • Enzyme: Pyruvate kinase

9

Differentiate PFK-1 and PFK 2 

10

non-reducing sugar

Sucrose

 

11

Discuss the process of GLUCONEOGENESIS

12

Rate-limiting step of glycogenolysis

Shortening of glycogen chains

Enzyme: Glycogen phosphorylase

13

What type of glycolysis is utilized by:

• Cells with mitochondria

• Cells with adequate supply

AEROBIC GLYCOLYSIS AKA Embden-Meyerhof-Parnas Pathway​

End product: Pyruvate

14

Heinz bodies and bite cells are found in what disorder?

G6PD deficiency

 

15

Second Phase of PPP

Nonoxidative and  Reversible

  • Enzymes:
    • Transketolases (Cofactor: Thiamine)
    • Transaldolases
  • Products:
    • Ribose-5 phosphate
    • Fructose-6phosphate
    • Glyceraldehyde-3phosphate

16

NADPH functions

o Reductive biosynthesis of fatty acids and steroids

o Glutathione reduction inside RBCs

o Cytochrome P450 monooxygenase system

o Oxygen-dependent bactericidal mechanism of WBCs

o Synthesis of nitric oxide

17

• Flatulence and diarrhea after ingestion of dairy products

• Seen in up to 90% of adults of African or Asian descent are lactase-deficient

Lactose intolerance

Lactase deficiency

18

GLUT 1 is found in ___

Brain, kidney, colon, placenta, RBC

19

Mono-saccharides

(Hexoses)

Glucose, Fructose, Galactose and mannose

20

• Isomers that differ in configuration around only one specific carbon atom (except the carbonyl carbon)

• Examples: glucose and galactose (differ only in position of –OH in C4), glucose and mannose (differ only in position of –OH in C2)

EPIMERS

21

Mono-saccharides

(Pentoses)

Ribose, Ribulose and Xylulose 

22

What type of glycolysis is utilized by:

• Cells without mitochondria

• Cells without sufficient O2

 

ANAEROBIC GLYCOLYSIS

End product: Lactate

23

Muscle phosphorylase deficiency

McArdle syndrome (Type V)

Poor exercise tolerance, muscle cramps and myoglobinuria but no lactic acidosis, high muscle glycogen

* because muscle lacks the phosphorylase enzyme, it cannot retrive glucose residues from glycogen, leading to cramps. 

* No GP in the muscle, (GP is the rate-limiting enzyme in

glycogenolysis), so no GP, no muscle glycogen breakdown

24

GLut 4 is found in ___

Heart and skeletal muscle, adipose tissue

"FHM" fat, heart, muscle

25

Purpose of PENTOSE PHOSPHATE PATHWAY Also known as the Hexose MonoPhosphate shunt

o Produces NADPH

o Produces ribose 5-phosphate required for biosynthesis of nucleotides

o Provides a mechanism for the metabolic use of 5-carbon sugars

o Take Note: Neither produces nor consumes ATP

26

  • Characterized by Deficiency in NADPH oxidase
    • Converts molecular oxygen into superoxide in leukocytes (especially neutrophils and macrophages) and used in the respiratory burst that kills bacteria
  • Severe, persistent, and chronic pyogenic infections caused by catalase-positive bacteria

CHRONIC GRANULOMATOUS DISEASE

*In the absence of NADPH oxidase, neutrophils will not be able to convert oxygen to superoxide, which is used to kill bacteria that they’ve engulfed.

27

Insulin is needed in ___

GLUT 4 transporter ("FHM" - fat, heart, muscle)

28

Important products of PPP

NADPH and Ribose-5-phosphate

29

Most common cause of congenital lactic acidosis

Pyruvate dehydrogenase deficiency

  • X-linked dominant
  • ↑ lactate (anaerobic glycolysis) + ↓ acetyl CoA (citric acid cycle) leads to brain deprived of acetyl CoA leading to psychomotor
  • retardation and death
  • Treat with ketogenic diet

 

30

Where does TCA occur?

  • In all cells with mitochondria
  • Mitochondrial matrix
    • Except: succinate dehydrogenase (inner mitochondrial membrane)