Question

70S type of ribosomes are found in
A. Prokaryotic cells
B. Prokaryotic cells and chloroplast
C. Mitochondria
D. Nucleus, mitochondria

Answer 1

Hint: The macromolecular compound that is located within both the prokaryotic cells and the eukaryotic cells, takes part in protein synthesis is known as ribosomes. There are mainly two types of ribosomes found, these are 70S ribosomes and 80S ribosomes.

Complete answer: 70S ribosomes are found in prokaryotic cells and the chloroplast. 70S ribosomes are smaller in size that comprises two units. These are the large unit and small units. The large unit is the 50S and the small unit is 30S. S is the svedbergs unit that measures the centrifuge rate during centrifugation. Ribosomes are responsible for producing protein according to the codon present on the mRNA. The protein synthesis process involves three steps, named initiation, elongation, and termination. Initiation involves the assembly of the ribosome to the start codon of mRNA. In elongation, the ribosome moves along the mRNA with the help of tRNA, and the synthesis of the amino acid chain starts. When the ribosome reaches a termination codon on the mRNA protein synthesis stops. It is called the termination of protein synthesis.
So, the correct answer is “Option B”.

Additional Information: Eukaryotic cells comprise comparatively larger ribosomes that are 80S ribosomes. The two units of the 80S ribosomes are 60S and 40S. The molecular weight of the 80S ribosome is 4-4.5 million Dalton. The larger subunit of 80S ribosomes possess 40 proteins and a smaller subunit comprises 33 proteins. It is assumed that chloroplast was an individual organism that was feely found in nature that comprised some organelles like ribosomes in the beginning but due to survival problems it takes place into another organism like plants and algae. Thus it possesses an endosymbiotic origin. Due to the condition chloroplast involves their protein synthesis and genome mechanism.

Note: 70S ribosomes possess a length that varies between 200-290 A and the diameter varies between 170-210 A. The molecular weight of the 70S ribosomes is 2.7-3 million Dalton. The larger unit (50S unit) of70S ribosomes contains 34 proteins and a smaller unit that is 30S unit comprises 21 proteins.