Part A Which organelle synthesizes proteins that are used in the cytoplasm? mitochondria ribosomes that are free within the cytoplasm Gough endoplasmic reticulum (RER)

To determine which organelle synthesizes proteins that are used in the cytoplasm, let's analyze the options provided: 1. **Mitochondria**: These organelles are primarily involved in energy production through the process of cellular respiration. They do have their own ribosomes and can synthesize some proteins, but they are not primarily responsible for synthesizing proteins used in the cytoplasm. 2. **Ribosomes that are free within the cytoplasm**: Free ribosomes are indeed responsible for synthesizing proteins that function within the cytoplasm. These proteins can include enzymes and other proteins that are necessary for various cellular functions. 3. **Rough Endoplasmic Reticulum (RER)**: The RER is involved in the synthesis of proteins that are typically secreted from the cell or incorporated into the cell membrane. While it does synthesize proteins, these are not primarily used in the cytoplasm. Based on this analysis, the correct answer is: **Ribosomes that are free within the cytoplasm**.