Much of the intracellular structure of a eukaryote cell is involved in protein synthesis. The figure shows the amounts of protein in cells at different parts of the cell cycle between two cell divisions. G₁ is a stage just after the cell has divided, and G₂ is the stage just before the cell divides again. S is a stage when the cell is synthesizing material such as DNA, mitochondria, and other organelles.
-Most of the protein measured in the cells was likely synthesized by
A)mitochondria.
B)nucleolus.
C)smooth endoplasmic reticulum.
D)ribosomes.

Question

Much of the intracellular structure of a eukaryote cell is involved in protein synthesis. The figure shows the amounts of protein in cells at different parts of the cell cycle between two cell divisions. G₁ is a stage just after the cell has divided, and G₂ is the stage just before the cell divides again. S is a stage when the cell is synthesizing material such as DNA, mitochondria, and other organelles.
-Most of the protein measured in the cells was likely synthesized by
A)mitochondria. 
B)nucleolus. 
C)smooth endoplasmic reticulum. 
D)ribosomes.

Quizplus · Accepted Answer

Ribosomes are the organelles responsible for protein synthesis, therefore the protein measured in the cells is likely synthesized by ribosomes. Choice A is incorrect as mitochondria are involved in ATP production, not protein synthesis. Choice B is incorrect as the nucleolus is involved in ribosome production, not protein synthesis. Choice C is incorrect as the smooth endoplasmic reticulum is involved in lipid metabolism and detoxification, not protein synthesis.

Much of the Intracellular Structure of a Eukaryote Cell Is