Hey student, In this lesson, we will cover

0:6a very important respiratory pigment,

0:9which is haemoglobin. Haemoglobin, it is a

0:13very, very important respiratory pigment,

0:15which is present in the RBC's. So, each

0:19molecule of RBC, it contains around 26

0:24crores of haemoglobin molecules in them.

0:27Now when we talk about haemoglobin, if we see its

0:30composition, we see that it has 2 parts.

0:33The first , in here, we can see is the

0:36haem.

0:38This is a haem and next to it, is the

0:43globin. So, these are the two parts of

0:48haemoglobin. Now, when we talk about

0:51haem, haem basically refers to the iron.

0:54So, haem is formed of again two

0:56components, which is iron and a

1:3porphyrin. So, porphyrine, it is a ring like

1:8structure in which the iron is present

1:11in here. Now, when we talk about the iron,

1:14we see that the iron which is present

1:16in the haemoglobin, it is present in the

1:19form of ferrous meaning fe2 plus but the

1:25haemoglobin which is present in the

1:27muscle cells, it is called myoglobin. And

1:30in myoglobin, this iron is present in

1:33the form of ferric which is Fe 3 plus. So

1:38myoglobin has fe 3 plus form of iron and

1:41haemoglobin has fe 2 plus form of iron. Now,

1:46when we are talking about the porphyrin

1:47ring, we say that, it is made up

1:50of two parts, the first is the acetic

1:56acid and it is also containing the

2:1glycine amino acid. So, we have seen

2:7that the haem part of haemoglobin, it

2:10contains iron and porphyrin. In the

2:13ring of porphyrin, iron is located in

2:15the center. So it contains this iron part

2:19and the porphyrin ring is made up of

2:22acetic acid and glycine amino acid.

2:25Now, coming to the globin part, in

2:29the globin part we see that it is the

2:31protein part. And each molecule of this

2:35protein, it is made up of four types of

2:38polypeptide chains. Now let's see what

2:42are these polypeptide chains? So, if I

2:45show you, in here, there are four types of

2:49polypeptide chain.

2:51The first one is called alpha

2:53polypeptide chain, the next is the beta

2:56polypeptide chain,

2:58next we see it is gamma and lastly is

3:2the delta. So, alpha, beta, gamma and delta

3:6polypeptide chains. They form a

3:9single molecule of protein. Now, in alpha

3:14polypeptide chain, basically, there are

3:16present 141 amino acids, whereas in

3:22all the rest three, there are present

3:25around 146 amino acid. So, this is the

3:32composition of these polypeptide chains.

3:35Now on the basis of, you know, these four

3:38polypeptide chains, there can be found

3:40three types of haemoglobin. Let's see what

3:44are they. So, the first one is the HbA

3:49meaning the adult haemoglobin.

3:53So this adult haemoglobin, it is found

3:56approximately like 95 to ninety-seven

3:59percent in a human adult and it is formed

4:3of two polypeptide chains of alpha

4:7plus two polypeptide chains of beta.

4:12So, this is the haemoglobin of an

4:15adult,

4:16okay? or we call it adult haemoglobin. So the next

4:19is HbA2, so this is the

4:25second type of a adult haemoglobin which is found

4:28to be like 2 to 3 percent only.

4:30Now, this is formed of two alpha

4:35polypeptide chains plus two Delta

4:39polypeptide chain. So this is the second

4:42type of adult haemoglobin. The third

4:45type is HbF, meaning the fetal haemoglobin.

4:49Now, this fetal haemoglobin, it is formed of

4:52two polypeptide chains of alpha plus two

4:58polypeptide chains of gamma. So we have

5:1seen, that the globins, these are the

5:4protein molecules and they can be formed

5:7of the four types of polypeptide chains.

5:9These can be HbA, HbA 2 and HbF, which

5:14are the three types of haemoglobin and

5:17these three types, we have seen that the

5:19composition is somewhat like this. Now

5:23moving forward if we talk about

5:24haemoglobin ,its function basically, so the

5:27basic function of haemoglobin is to, it

5:30carries the oxygen. So a single molecule

5:33of haemoglobin, it carries 4 molecules

5:36of oxygen and also if we see one gram of

5:42haemoglobin, we will write HB, it carries around 1.34

5:50ml of O2,

5:52okay? So one gram of haemoglobin, it carries

5:55around 1.3 ml of O2. Now, we see that

6:1hundred ml of blood, how much haemoglobin

6:7is present in hundred ml of blood ? It is

6:915 gram, approximately 15 gram, So, now

6:15can we find out that hundred of ml of

6:17blood will have how much amount of

6:19oxygen ?

6:20It will be simple, multiplying

6:251.34 into 15 grams, which

6:29will make it somewhere up to 20 ml of

6:33oxygen. So this way, we have found out

6:37that when one gram of haemoglobin carries

6:401.34 ml of oxygen, we see that hundred ml

6:45of blood carries 20ml of oxygen because

6:49hundred ml of blood has 15 gram of

6:52haemoglobin present in it . Now it is very,

6:55very important for you to note, that the

6:57haemoglobin F which is the fetal

6:59haemoglobin. It has higher affinity of

7:1oxygen towards itself as compared to

7:4the haemoglobin of an adult. So students,

7:8in this lesson you have learned that the

7:10haemoglobin has two parts, the haem and

7:13the globin. Haem is basically the iron

7:16and porphyrin and globin is the

7:18protein part. On the basis of the

7:21different polypeptide chains, there can

7:22be three types of haemoglobin and the

7:25major function of haemoglobin, as it acts

7:28like a respiratory pigment is to carry

7:31oxygen.

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