RBC cell structure and function, and Hemoglobin synthesis and function

Hemoglobin

• is the main component found in the cytoplasm of a red blood cell.

• It is the molecule responsible for the oxygen-carrying capacity of the red blood cell, delivering oxygen to the tissues and collecting carbon dioxide and bringing it to the lungs for expiration.

• Is responsible for the viscosity of the blood in the peripheral circulation.

Glucose

The main energy source of the red blood cell is?

biconcave disc configuration

allows the deformability or flexibility of the red blood cell

 integral protein

If the protein is embedded, such that it traverses the entire length of the plasma membrane by lipid layer, it is called an?

Peripheral protein

When the protein attaches itself to the phosphate head group, not traversing the lipid layer, or when it is just on sideways, it is called?

Cytoskeleton

responsible for the flexibility and deformability of eryhtrocytes

• Spectrin

• Actin

• Ankyrin

• Band Proteins

• Tropomodulin

• Tropomyosin

Proteins that make up the cytoskeleton of a red blood cell:

• Ankyrin (50%-60%)

• Spectrin (20%)

• Band 3 (15%-20%)

• Protein 4.2 (<5%)

• RhAG (<1%)

What protein is deficient in Hereditary spherocytosis?

• α-Spectrin (65%)

• β-Spectrin (30%)

• Protein 4.1 (5%)

What protein is deficient in hereditary elliptocytosis?

Band 3 (100%)

What protein is deficient in Southeast asian ovalocytosis?

Lipids

• comprises the tail of the phospholipid molecule

• are hydrophobic, non-polar fatty acid chains facing the leaflet interior of the bilayer, orienting themselves away from the fluid because they are water-fearing

Cholesterol molecules

maintain the surface area to volume ratio by regulating membrane fluidity and permeability to electrolytes and non-electrolytes

1. Alpha and Beta Spectrum

2. Actin and Ankyrin

3. Protein 4.1

These are the Skeletal Proteins:

1. Glycophorin A

2. Band 3

These are some of the Integral Proteins:

Glycophorin A

• bears the ABO blood group antigen

• has a role in the expression of the ABO blood group antigens.

Zeta potential

refers to the sum of all the charges of the molecules in the red cell membrane.

TRUE

TRUE OR FALSE: The presence of the integral and peripheral proteins and a molecule called sialic proteins (also called sialic acid), maintains the negative charge of RBC

Sodium-Potassium ATPase activity

it transports sodium out and potassium inside.

Sodium

is termed a major extracellular cation

Potassium

is termed a major intracellular cation

Calcium-Magnesium ATPase activity

• AKA calcium pump

• is involved in the regulation and stabilization of membrane phospholipid structure

1. Maintaining the shape of the membrane.

2. Maintaining the red blood cells' endoplasmic volume

3. Maintaining its shape and flexibility.

These are the red blood cell functions:

Embden-Meyerhof pathway

• ● Responsible for metabolizing 90 to 95% of glucose.

• The end product of this pathway is the production of ATP

Rapoport-Luebering shunt

Is involved in the formation of 2,3-DPG

2,3-DPG

is a very important determinant of whether a red cell is capable of binding to oxygen or not.

Erythropoietin

is produced primarily by the kidneys.

1. It carries oxygen from the lungs.

2. It carries oxygen to the tissues.

3. It delivers carbon dioxide from the tissue to the lungs.

These are the roles of red blood cells in the circulation:

increased affinity for O₂

A shift to the left of the oxyhemoglobin dissociation curve indicates that hemoglobin has?

reduced affinity to oxygen

A shift to the right of the oxyhemoglobin dissociation curve results in?

Aminolevulinic acid synthetase

Enzyme that converts Glycine and Succinyl-CoA to Aminolevulinate (ALA)

ALA hydratase deficiency porphyria

Deficiency in Aminolevulinic acid synthetase is associated with lead exposure and leads to what disease?

Uroporphyrinogen synthase

What enzyme converts porphobilinogen to hydroxymethylbilane?

Acute intermittent porphyria

Deficiency in uroporphyrinogen synthase

Uroporphyrinogen cosynthase

What enzyme converts Hydroxymethylbilane to Uroporphyrinogen (UPG)?

Congenital erythropoietic porphyria

Deficiency in uroporphyrinogen cosynthase

Uroporphyrinogen decarboxylase

What enzyme concerts uroporphyrinogen(UPG) to Coproporphyrinogen(CPG)?

Porphyria cutanea tarda

Deficiency in uroporphyrinogen decarboxylase

Coproporphyrinogen oxidase

What enzyme converts Coproporphyrinogen(CPG) to protoporphyrinogen?

Hereditary coproporphyria

Deficiency in coproporphyrinogen oxidase

Protoporphyrinogen oxidase

what enzyme converts protoporphyrinogen to protoporphyrin IX?

Variate porphyria

Deficiency in Protoporphyrinogen oxidase

Ferrochelatase

What enzyme converts protoporphyrin IX to Heme?

Erythropoietic protoporphyria

Deficiency in ferrochelatase

1. Alahydrate Deficiency Porphyria

2. Erythropoietic Protoporphyria

The two stages associated with lead poisoning are:

• Iron in the Reduced Form

• Ferrochelatase Enzyme

These are the two things needed for protoporphyrin conversion to heme:

apoferritin

Ferritin is a protein complex composed of iron stored within the protein shell called?

Prussian Blue Reaction

The reaction for estimating stored forms of iron is called the?

Inherited Porphyrias

• These diseases are much rarer than acquired porphyrias.

• They are caused by a failure to inherit the gene that produces an enzyme needed in the metabolic pathway

Acquired Porphyrias

These include lead poisoning, excessive alcohol intake, iron deficiency, chronic liver disease, and renal disease.

1. Erythrogenic Porphyrias

2. Hepatic Porphyria

These are the two accumulation or porphyrin precursors: