carrying oxygen

Question 1

how is oxygen transported

Answer 1

• in the erythrocytes (red blood cells)
• red blood cells contain a protein called haemoglobin

Question 2

why is haemoglobin adapted to carry oxygen

Answer 2

• a complex protein with a quaternary structure
• it contains 4 subunits each containing a polypeptide chain and a haem group

Question 3

how many oxygen molecules can fit on a haemoglobin protein and why

Answer 3

• 4
• each haem group has 1 iron molecule that has an affinity to oxygen (binding attraction)

Question 4

how is oxygen carried

Answer 4

• oxygen binds (associates) with haemoglobin in the lungs
• oxygen unbinds (dissociates) with the haemoglobin in the respiring tissues
• the ability for oxygen to associate with the haemoglobin depends on the partial pressure of oxygen
• the partial pressure of oxygen is a measure of the concentration

Question 5

what is cooperative binding

Answer 5

• haem groups are at the centre of the haemoglobin molecule which means its difficult for the oxygen to bind to it
• as the partial pressure of oxygen increases, the concentration gradient increases
• when the first oxygen molecule binds to the haemoglobin, it changes the shape slightly meaning that its easier for the second molecule to bind to the haemoglobin

Question 6

how is carrying oxygen represented

Answer 6

• an oxygen dissociation curve
• its the relationship between the levels of oxygen in the tissue and the saturation of haemoglobin with oxygen in the blood

Question 7

what is the bohr effect / shift

Answer 7

• as blood enters the respiring tissue oxygen saturation in the haemoglobin is high
• the partial pressure of oxygen in the tissues is low
• oxyhaemoglobin releases more oxygen to the tissue
• more oxygen is available when carbon dioxide is released
• shift to the right

Question 8

explain the shift to the left in foetal haemoglobin

Answer 8

• the mother and the fetuses blood never mix
• materials can easily be exchanged via diffusion
• fetal haemoglobin has a higher affinity for oxygen meaning that it has a slightly different structure than adult haemoglobin
• the percentage saturation of oxygen is higher in the fetal haemoglobin than in the adult haemoglobin

Question 9

explain the shift to the left in myoglobin

Answer 9

• is an oxygen binding protein
• it has intracellular oxygen storage
• it allows organisms to hold their breath for extended periods of time
• it has a much higher affinity for oxygen than haemoglobin
• it has a higher percentage saturation than haemoglobin at the same partial pressures

Question 10

why do llamas have a shift to the left

Answer 10

• they live at high altitudes
• the number of red blood cells increases
• the haemoglobin has a higher affinity for oxygen which means it can load the oxygen more readily and release it at low partial pressures

Question 11

what are the adaptations of a lugworm

Answer 11

• a low metabolic rate
• pumps seawater through its burrow which gives it access to the limited amount of oxygen available
• the oxygen dissociation curve is very much to the left of a human one
• haemoglobin loads oxygen very readily but only releases it at low partial pressures