EduNinjaWhich explains why haemoglobin is suitable as an oxygen carrier?
1 The haem group combines with oxygen.
2 The iron combines with oxygen reversibly.
3 Haemoglobin changes shape as oxygen loads.
1 only
1 and 2 only
2 and 3 only
1, 2 and 3
Which set of statements correctly describes haemoglobin?
iron ions can associate with oxygen forming oxyhaemoglobin
in each chain, hydrophobic R groups of amino acids point towards the centre of the molecule
at 50 \% saturation, two oxygen molecules are transported by the molecule
each chain contains a haem group of amino acids surrounding an iron ion
consists of two identical alpha chains and two identical beta chains
each chain can transport an oxygen molecule
an iron ion is present within each haem group
quaternary structure has two alpha chains and two beta chains
each molecule can transport a total of four oxygen atoms
iron ions in the molecule can bind reversibly with oxygen
in each chain, hydrophobic R groups of amino acids surround the iron ion
each molecule can transport a total of eight oxygen atoms
The masses of the parts of haemoglobin are shown in the table.
There are 1000 Da in 1 kDa .
What is the mass of a haemoglobin molecule in kDa ?
31.6
33.5
62.6
64.5
When red cells leave the lungs, haemoglobin is 98 % saturated.
How many molecules of oxygen will be carried by the majority of haemoglobin molecules?
2
4
6
8
During one cardiac cycle:
- blood enters the heart from the lungs and from the rest of the body
- blood leaves the heart to be transported to the lungs and to the rest of the body.
The cause of the differences between sickle cell haemoglobin and normal haemoglobin is a mutation in the gene that codes for one of the two types of polypeptide found in a haemoglobin molecule. This mutation leads to a change in the mRNA produced during transcription, causing a change in the primary structure of the polypeptide formed.
Fig. 3.1 shows some of the changes that occur as a result of this gene mutation.
Name the type of polypeptide in a haemoglobin molecule that is different in sickle cell haemoglobin compared to normal haemoglobin.
Why is haemoglobin stated to have a quaternary structure?
It has four haem groups.
It has two or more polypeptide chains.
It is coiled into a precise shape.
It is held together by four types of bonds.
Haemoglobin, a globular protein, consists of four polypeptide chains, two alpha chains and two beta chains. In normal individuals, in the DNA which codes for each beta chain, the sixth triplet has a code for glutamic acid.
In individuals with sickle cell anaemia this base triplet mutates and codes for valine.
What does this mutation change in the haemoglobin molecule?
the iron content
the primary structure
the quaternary structure
the secondary structure
Which molecules contain at least two double bonds?
saturated fatty acid, collagen and haemoglobin
collagen and saturated fatty acid only
haemoglobin and collagen only
saturated fatty acid and haemoglobin only