James is making models of plant and animal cells using objects supplied by his teacher to represent organelles. for one cell, he will place the objects in a shoebox. first he fills a balloon with water and places it in the shoe box. he also drops a handful of marbles into the box.

which statement most likely describes the structures he has represented so far?
he is making an animal cell. the box is the cell membrane, and the balloon represents the large vacuole. the marbles are the endoplasmic reticulum.
he is making a plant cell. the box is the cell wall, and the balloon represents the large vacuole. the marbles are the tiny ribosomes.
he is making a plant cell. the box is the cell wall, and the balloon represents the nucleus. the marbles are the centrioles.
he could be making either a plant or animal cell. the box is the cell wall, and the balloon represents the large vacuole. the marbles are the centrioles.

The best answer is "He is making a plant cell. The box is the cell wall, and the balloon represents the large vacuole. The marbles are the tiny ribosomes." 

The box is the cell wall because it is rigid in shape. The balloon with water represents the vacuole since it is the water storage of the plant cell. The marbles are ribosomes since they are scattered throughout the cytoplasm as energy generating organelles.

Proteins are the workhorses of the cell, controlling virtually every reaction within as well as providing structure and serving as signals to other cells. proteins are long chains of  amino acids  , and the exact sequence of the amino acids determines the final structure and function of the protein. instructions for that sequence are encoded in  genes  . to make a particular protein, a messenger ribonucleic acid (mrna) copy is made from the gene (in the process called  transcription  ), and the mrna is transported to the  ribosome  . protein synthesis, also called  translation  , begins when the two ribosomal subunits link onto the mrna. this step, called initiation, is followed by elongation, in which successive amino acids are added to the growing chain, brought in by transfer rnas (trnas). in this step, the ribosome reads the  nucleotides  of mrna three by three, in units called  codons  , and matches each to three nucleotides on the trna, called the anticodon. finally, during termination, the ribosome unbinds from the mrna, and the  amino acid  chain goes on to be processed and folded to make the final, functional protein