12.11 - Haemoglobin Flashcards
Oxygen solubility in water/aqueous solutions is _____, so a more efficient method of transport is required, rather than trying to dissolve oxygen into blood.
ANSWER: ____________
To be efficient in transporting oxygen, Hb must readily __________ with oxygen at the gas exchange surface (e.g lungs) and ___________ oxygen at the respiring cells / tissue.
Low
Haemoglobin
associate (load)
dissociate (unload)
a) Haemoglobin is a complex protein with a __________ structure
b) composed of ______ polypeptide subunits
c) each of which containing a _____ group
d) 2 types of polypeptide chains, _______________ and ___________________
e) Each ____ (Fe2+) group can combine with one molecule of oxygen,
f) so each Hb molecule can combine with ____ molecules of oxygen (O2).
a) quartenary
b) four
c) haem
d) alpha helices and beta pleated sheets
e) haem
f) four
The uptake of oxygen by haemoglobin is a _____________ reaction.
The formula:
When oxygen combines with Hb, it forms:
REVERSIBLE
Hb + 4O2 = HbO8
oxyhaemoglobin
Explain a property of iron ions that enables these ions to carry out their role in red blood cells. (2)
1) Iron ions are charged/polar
2) So binds/associates with oxygen to form oxyhaemoglobin to transport oxygen.
PERCENTAGE SATURATION
1) What is % saturation? (in terms of Hb)
2) Higher saturation means that more… Lower…
3) What is the formula for calculating the % saturation of Hb with oxygen?
4) The maximum amount of oxygen uptake by haemoglobin is… so….
5) % saturation doesn’t just apply to just one haemoglobin molecule, can be a combination of many. E.g. 7 oxygen molecules over 2 haemoglobin molecules =
1) The amount of oxygen combined with haemoglobin (how much of the haemoglobin is bound to oxygen)
2)…oxygen is bound. …less oxygen is bound.
3) % saturation of Hb w/ oxygen = oxygenated haemoglobin
————————————- x 100
maximum saturation
4) 4 oxygen molecules… 4/4 = 100% , 3/4 = 75% , 2/4 = 50% , 1/4 = 25%
5) 7/8 x 100 = 87.5%
OXYGEN DISSOCIATION CURVE
1) What does the partial pressure of oxygen (pO2) mean? What are the units?
2) The more oxygen there is in the blood, the more the oxygen is…
3) Lower pO2 means…
4) Initially, as the pO2 of oxygen increases, the % saturation of Hb with oxygen…
5) This is due to…
6) An oxygen dissociation curve is always ‘_’ shaped and is described as a…
7) What is meant by the cooperative nature of oxygen loading?
1) The proportion of oxygen in a mixture of gases or a solution. (kPa)
2) loaded onto haemoglobin, so the haemoglobin becomes more saturated.
3) Less haemoglobin is saturated.
4) Increases
5) Cooperative loading
6) S shaped, sigmoid curve.
7) The first O2 molecule alters the tertiary structure of the Hb molecule. This EXPOSES the second and third O2 binding sites, making it easier for the 2nd and 3rd O2 molecules to bind + load. As the first oxygen molecule binds to haemoglobin, it increases the affinity for the second molecule of oxygen to bind. And subsequenttly, Hb attracts more oxygen.
LOADING AND UNLOADING
1) What is loading?
2) What is unloading?
3) What is affinity?
4) When there is HIGH O2 CONC (high pO2), then…
5) When there is LOW O2 CONC (low pO2), then…
6) Oxyhaemoglobin must also be able to ______ oxygen so the ______ around the body can use it. If oxyhaemoglobin moves to an area of LOW O2 CONC, then oxygen will be…
1) When oxygen is taken up by haemoglobin. (binding of O2 to Hb)
2) When oxygen is released/given up by haemoglobin (release of O2 from Hb)
3) “a natural attraction to something” Hb has a chemical attraction to O2 which is why it loads oxygen.
4) …more oxygen is loaded onto Hb.
5)…less oxygen is loaded onto Hb.
6) unload oxygen so the tissues around the body can use it.
unloaded to the surroundings.
pO2 in LUNGS AND RESPIRING TISSUES
1) The partial pressure of O2 is high in the…
2) Hb has a higher affinity for O2 at…
3) Haemoglobin becomes almost fully saturated as the red blood cells pass through the…
4) The pO2 in the tissue capillaries is…
5) Haemoglobin now has a lower affinity for O2 at a…
6) So the oxyhaemoglobin starts to break down and…
7) The oxygen released is then available to the…………to be used in……………
1)…capillaries
2)…a high pO2
3)…pulmonary capillaries (lungs)
4)…lower
5)…lower pO2
6)…unloads oxygen.
7)…tissue cells to be used in aerobic respiration.
THE EFFECT OF INCREASED RESPIRATION RATE ON OXYGEN DISSOCIATION
1) Tissue cells respire ____________
2) Quickly reducing the dissolved ________
3) This reduces the pO2 to a _________
4) The oxygenated blood arriving with fully saturated Hb will begin to…
5) And more oxygen will be…
6) This is because the surrounding pO2 is lower, and so the Hb will have…
1) aerobically (use oxygen)
2) O2 in the surrounding tissue fluid.
3) Lower level than normal.
4)…unload more oxygen (become less saturated)
5) released from the Hb to the tissue cells.
6) an even lower affinity to oxygen.
EFFECT OF CO2 CONCENTRATION - BOHR SHIFT
1) In higher than normal partial pressure of CO2…
2) If pCO2 increases….
3) This causes the haemoglobin oxygen dissociation curve to…
WHY?
4) When CO2 dissolves in the blood, it makes the blood…
5) As Hb is a protein, a change in the pH…
6) That’s why it has a lower affinity to O2 at..
MORE…
7) The more that tissue cells respire….
8) Hb now has a lower affinity to oxygen at…
9) So, more oxygen is….
10) More oxygen is now available to…
1)…haemoglobin’s affinity for oxygen is even lower.
2)…the saturation of Hb decreases.
3)..shift to the right. (boh_R_ shift)
4)…more acidic (lowering the pH)
5) slightly alters its tertiary structure (R group interactions and bonds)
6) Higher levels of CO2
7)…the more the CO2 conc. will increase (as CO2 is a product) + cause a shift to the right in the curve.
8)…the respiring cells
9)…unloaded from the haemoglobin, at the same pO2 as it becomes less saturated
10)…meet the oxygen demands of the respiring cells/tissues (for aerobic respiration)
ADAPTATION TO ENVIRONMENT
1) Different species and different populations of the same species, live in different environments with….
2) Genetic differences between species leads to…
3) Mutations causes the variation in Hb affinity…
4) As mutations accumulate, the more the…
1)…varying pO2
2)…different haemoglobin affinities.
3)…based on alterations to the tertiary structure of Hb - this alters the position of their dissociation curve.
4) primary, secondary and tertiary structures are altered, so different Hb molecules are produced. Different Hb have different affinities to oxygen.
HIGH ALTITUDE / LUGWORM / BOTTOM OF LAKES / FOETUS
1) Partial pressure of O2 in the environment…
2) So haemoglobin has a…
3) More O2 is loaded…
4) It becomes fully saturated at lower pO2 and….
5)This is then transported to the….. for use in….
CURVE SHIFTS TO THE LEFT
1)..is low. (hard to get O2)
2)…higher affinity for oxygen (needs to cling onto every bit of O2 it can get)
3)…at lower partial pressures of oxygen.
4)…rapidly unloads its oxygen when the haemoglobin passes into the tissues.
5) the tissues for use in aerobic respiration.
BOHR SHIFT
1) Increase in partial pressure of…
2) oxygen dissociation curve shifts to the…
3) Haemoglobin has a….
4) More oxygen is…
5) for use in….
CURVE SHIFTS TO THE RIGHT
1)…CO2 in the blood.
2)…right
3)…lower affinity for oxygen
4) unloaded at the tissues
5) aerobic respiration
SMALL MAMMALS AND BIRDS
1) They have a _______ SA:V ratio - a higher ________ rate.
2) must increase rate of respiration to…
3) Haemoglobin has a…
4) More oxygen is…
5) For use in…
CURVE SHIFTS TO THE RIGHT
1) Large SA:V ratio - a higher metabolic rate
2)..maintain body temperature.
3) lower affinity to oxygen.
4)…unloaded at the tissues
5)…aerobic respiration.
Heat from respiration helps mammals to maintain a constant body temperature. Use this information to explain the relationship between SA:V ratio of mammals and the oxygen dissociation curves of their haemoglobins. (5)
1) Smaller mammals have a greater SA:V ratio.
2) So more heat loss
3) And a greater rate of respiration
4) Oxygen is required for aerobic respiration
5) So Hb releases (unloads) more oxygen more readily / Hb has a lower affinity.
