haemoglobin

Question 1

why is oxygen needed by all living cells?

Answer 1

all living cells respire

Question 2

equation for respiration

Answer 2

glucose + oxygen –> carbon dioxide + water + energy (ATP)

Question 3

function of red blood cells?

Answer 3

contains haemoglobin which binds with oxygen to deliver cells

Question 4

structure of haemoglobin?
each poly peptides contains a..?

Answer 4

quaternary structure - made up of 4 polypeptide chains - each of the polypeptides contains a heam group

Question 5

what does each heam group contain?
this is the part of Haemoglobin that..?

Answer 5

Fe2+ (iron) ions
going to binds to oxygen

Question 6

what is formed when haemoglobin binds with oxygen? what type of reaction is this?

Answer 6

oxyhaemoglobin
reversible reaction
oxygen + haemoglobin ⇌ oxyhaemoglobin
when oxygen unloads

Question 7

lungs have a …? concentration of oxygen

Answer 7

High

Question 8

tissues have a …? concentration of oxygen

Answer 8

Low

Question 9

why does haemoglobin have ahigh affinity for oxygen in the lungs?

Answer 9

in the lungs at the alveoli, oxygen has entered the capillaries and it’s going to load on haemoglobin because of the high concentration/partial pressures of oxygen

Question 10

in tissues oxygen is being used for?

Answer 10

respiration

Question 11

why does the tissues have a low affinity for oxygen?

Answer 11

because of the low concentration of ocygen (being used up respiring tissues) so oxygen unloads from haemoglobin for respiring tissues

Question 12

what are 4 key phrases associated with the Oxyhaemoglobin dissociation curve?

Answer 12

• Affinity of Hb to Oxygen - the ability of Hb to attract/bind to oxygen
• saturation of Hb with oxygen - when Hb is holding the maximum amount of oxygen it can bind
• loading/association of Hb - the binding of oxygen to Hb
• Unloading/ dissociation of Hb - when oxygen detaches/unbinds from Hb

Question 13

draw an oxyhaemoglobin disassociation curve

Question 14

what is the shape of the curve

Answer 14

s shape - sigmoid curve

Question 15

describe the graph

Answer 15

• at low partial pressure of oxygen, as we increase the oxygen, the percentage saturation of oxygen doesnt increase that much.
• but once we get a little higher, the percentage saturation of oxygen increases readily for a small increase in oxygen

Question 16

why is the graph S shaped?

Answer 16

• due to cooperative nature of oxygen binding. after the first oxygen molecule binds, shape of Haemoglobin changes, making it more easier for the 2nd haemoglobin then when this one binds it makes it easier for 3rd then 4th
• meaning that oxygen has a higher affinity for oxygen so on the graph the gradient get’s steeper
• the rate of increase in percentage saturation increases, as the oxygen further increases but after haemoglobin gets more saturated, it get’s harder for further molecules to bind and this is why it plateaus

Question 17

what is the Bohr shift?

Answer 17

when we increase carbon dioxide in our blood e.g when we are excercising, we lower the pH pf the blood, so reduces the affinity for oxygen, because HB changes shape, making it harder for molecules to bind

Question 18

explain why the Bohr shift is beneficial?

Answer 18

increases the amount of oxygen that’s being unloaded from haemoglobin at the tissues so the oxygen can be used for respiration

Question 19

explain how the curve shifts in less acidic conditions?

Answer 19

• low partial pressure of CO2 in the alveoli
• curve shifts left
• increased affinity for oxygen so loads more oxygen

Question 20

explain how the curve shifts in more acidic conditions?

Answer 20

• high partial pressure of carbon dioxide at respiring tissues
• curve shifts right
• decreased affinity for oxygen and unloads more oxygen

Question 21

why is haemoglobin different in different organisms?

Answer 21

haemoglobins is a protein made up of amino acids, so if we change the sequence of amino acids, haemoglobin structure changes and so changes the affinity is has for oxygen

Question 22

structure of haemoglobin differs depending on..?

Answer 22

the environment that the organism is adapted to live in

Question 23

when curve has shifted to the left, what does this mean?

Answer 23

• heamoglobin has a higher affinity for oxygen, means that it loads more readily in the lungs at a low partial pressures of oxygen

Question 24

this is useful for organisms living at..?

Answer 24

high altitudes - so low oxygen concentration- can load more oxygen into lungs

Question 25

explain how foetal haemoglobin is adapted?

Answer 25

• has a higher affinity for oxygen than in adult haemoglobin
• this is important as by the time the mothers blood reaches the placenta, if oxygen saturation decreased because some has been used up for the mother body
• therefore foetal haemoglobin needs to be better at absorbing oxygen than the mothers heamoglobin so the foetus can still get oxygen from its mothers blood across the placenta

Question 26

if in an organism the curve has shifted to the right..?

Answer 26

• they have alower affinity for oxygen
• so this is beneficial for our tissues
• at the same partial pressure of oxygen in the tissues, haemoglobin has a lower saturation for oxygen, this means that more oxygen has been unloaded into respiring tissues.

Question 27

this would occur in organisms with..?

Answer 27

a high metabolic rate -> small, active organism

Question 28

what does this do?

Answer 28

enables organism to survive better in their environments

Question 29

what is myoglobin able to do?

Answer 29

another type of haemoglobin in muscle tissue in vertebrates which is able to store and hold onto oxygen even at very low partial pressures of oxygen

Question 30

when partial pressures of myoglobin fall to very low levels, myoglobin…?

Answer 30

releases all of the oxygen it’s carrying

Question 31

FINISH