Haemoglobin and rbcs Flashcards
Electrophoresis
Method of analysing molecules by measuring migration in electric field. Support used: agarose for DNA, polyacrylamide for proteins, which acts as sieve thru which molecules migrate.
Spectrophotometry
Analysing molecules based on spectral properties. Spectrophotometer measures absorbance
Haem component
Synthesised in mitochondria . ls contained in other proteins eg myoglobin cytochromes peroxydases catalases. Combo of protoporphyrin ring with central ferrous iron atom. Iron usefully in FE 2+ form. Able to combine reversibly with oxygen. Bound within pockets of globin proteins.
Globin component
Synthesised in rough endoplasmic reticulum. Eight functional globin chains arranged in two clusters - alpha cluster and beta cluster.
Where is Hb found and conc in body and conc of Fe in g of Hb
Found only in RBCs. Normal conc in adults 120-165 g. Each g of hb contains 3.4 mg Fe.
2ndary struc and quaternary struc
2 - 75% of alpha and beta chains in form or a-helices. 4 - approx sphere, hydrophilic surface, hydrophobic core, haem groups found within pockets.
Absorbance
Fraction of incident light absorbed by solution. A = log10
How many subunits in Hb
4 : 2 alpha and 2 beta
Binding of O2
Cooperative, meaning binding of 1 O molecule to haem grp results in change in conformation of other subunits, affecting their ability to bind to O. In Hb this is a positive cooperative effect so as O binds to 1 haem the affinity of others increase. Twice as much O can be delivered. Seen in sigmoidal nature of O association curve.
Myoglobin
O binding protein in muscle. 1 haem grp per molecule and greater affinity for O than haemoglobin saturating at lower pO2 values. Lack of cooperativity means its poor at releasing O under same conditions.
Pulse oximeter
A pulse oximeter is a non-invasive way of measuring oxygen saturation levels. It relies on the difference in absorbance of oxyhaemoglobin and deoxyhaemoglobin. Oxygenated haemoglobin absorbs more infrared light but less red light than deoxygenated haemoglobin.
Carboxyhaemoglobin (CoHb)
Generated by the binding of carbon monoxide to ferrous iron (Fe2+) in Hb. Since hb has a 200-fold greater affinity for CO than O, it can readily outcompete O for binding to the four haem groups of Hb.
Methaemoglobin (MetHb)
Generated when the Fe2+ ion is oxidised to the Fe3+ (ferric) state which results in greatly impaired oxygen binding. Relatively low levels of MetHb can cause the oxygen dissociation curves to shift leftwards, which can result in tissue anoxia, as oxygen is not readily released by MetHb.
What does enzyme methemoglobin reductase do
Reduces methaemoglobin back to haemoglobin. Disorder methaemaglobinaemia can be hereditary eg as a deficiency in methemoglobin reductase or production of a mutant form of haemoglobin known as haemoglobin M, which is resistant to reduction.
how can Methaemaglobinaemia be acquired
following exposure to chemicals including aniline dues such as p-chloroaniline, nitrates, and local anaesthetics such as benzocaine.
Normal Hb runs further towards positive electrode. Why is normal Hb (A) more negatively charged than Hbs (Sickle hb)
Difference in charge due to point mutation in one aa of B chain. Glutamate in normal protein (hydrophilic, - charged) replaced by valine (hydrophobic, uncharged)
What are rbcs (erythrocytes) wbcs (leukocytes) and platelets derived from
Pluripotent Haemopoietic stem cells (HSCs). The cells above are produced throughout life in bone marrow. Blood cells all originate in bone marrow.
HSCs distributed in …
Ordered fashion in bone marrow amongst mesenchymal cells, endothelial cells and the vasculature with which HSCs interact.
Haemolysis is regulated by …
Genes, transcription factors, growth factors such as micro environment
What is haemopoiesis
Production and differentiation of blood cells
2 essential characteristics of HSCs
Self renewal (so some remain HSCs so pool not depleted). Differentiation to mature progeny (other daughter cells follow this path). These cannot renew themselves.
Origins of blood cells

Sites of haemopoiesis in fetus
Derive from mesoderm. Initially formed in vasculature of Yolk sac.
Disruption of regulation of hp can disturb …
Balance between proliferation and differentiation and may lead to leukaemia or bone marrow failure.











