Question

Prior to the work of Avery, MacLeod and McCarty (1933-44), the genetic material through to be
a. Protein
b. RNA
c. DNA
d. Carbohydrate

Answer 1

Hint: In humans, the genetic material is DNA that is deoxyribose nucleic acid. It is the blueprint that contains information to pass from one generation to another generation. The DNA replication helps to transmit the character from parents to offspring. It is an important step in reproduction.
In their experiment they showed that DNA acts as a transforming principle. When it is isolated from one strain of bacteria and introduced to another it gives the characteristic feature of one strain from which it was extracted to the other strain where it was injected .
The genetic material must be protein so that transformation occurs.

Complete answer:
> Protein:- It was shown that genetic material is something that transfers characteristics from parents to offspring and this is the nature of protein only. Hence this option is correct.
> RNA :- commonly known as ribose nucleic acid. It is a genetic material but present in simple organisms. Hence this option is wrong.
> DNA :- it is itself a genetic material but prior to their work it was thought that this material is made up of proteins. Thus this option is also wrong.
> Carbohydrate:- carbohydrates do not help in transformation. They themselves get converted to simple sugars. So, this option is incorrect.

Our required answer is a. protein.

Note: Griffith did an experiment and showed that bacteria transfer its genetic information by the process of transformation. He named this transforming principle as DNA. This process occurs when bacteria pick up DNA and get incorporated in it . Griffith injected two types of streptococcus pneumoniae, Type III-S and Type II-R, into mice. When he did the experiment he found that R-strain has taken up transforming principle from the heat killed S-strain and gets transformed to smooth coated virulent bacteria.