Cell Structures & Functions

All of the structures mentioned (chloroplast, cell wall, and vacuole) are found in plant cells but not in animal cells. Chloroplasts are responsible for photosynthesis, which is the process of converting sunlight into energy. Cell walls provide structural support and protection to plant cells. Vacuoles are large membrane-bound organelles that store water, nutrients, and waste materials. These structures are unique to plant cells and play important roles in their growth, development, and survival.

Mitochondria are responsible for providing the cell with energy through the process of cellular respiration. They are often referred to as the "powerhouses" of the cell because they produce the majority of the cell's energy in the form of ATP (adenosine triphosphate). Mitochondria have their own DNA and are capable of carrying out oxidative phosphorylation, a process that generates ATP by breaking down glucose and other molecules. Chloroplasts, on the other hand, are responsible for photosynthesis, not cellular respiration. Lysosomes contain enzymes for digestion, while vacuoles primarily store water and other substances.

Ribosomes are responsible for protein synthesis in the cell. They are small, spherical organelles found in the cytoplasm or attached to the endoplasmic reticulum. Ribosomes contain RNA and protein molecules and work together to read the genetic information stored in the DNA and produce proteins accordingly. They play a crucial role in the translation process, where the genetic code is converted into functional proteins. Mitochondria, Golgi Apparatus, and Chloroplasts have other important functions in the cell but are not directly responsible for protein synthesis.

The Golgi Apparatus is responsible for packaging proteins and other molecules into vesicles for transport out of the cell. It receives proteins from the rough endoplasmic reticulum and modifies them, adding sugars and other molecules to create functional proteins. These proteins are then sorted and packaged into vesicles that bud off from the Golgi Apparatus and are transported to the cell membrane for secretion or to other organelles within the cell. The Golgi Apparatus plays a crucial role in the intracellular transport and secretion of proteins.

Eukaryotic cells are characterized by having a true nucleus enclosed within a membrane, and they also possess membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes. These organelles have specific functions and are enclosed by their own membranes, which allows for compartmentalization and specialization within the cell. In contrast, prokaryotic cells lack a true nucleus and membrane-bound organelles, and their DNA is not enclosed within a membrane. Therefore, only eukaryotic cells have membrane-bound organelles.

Cytosol is the fluid inside the cell that acts as a site for chemical reactions. It is a clear, jelly-like substance that fills the cell and surrounds the organelles. It contains various enzymes and molecules that are necessary for metabolic reactions to occur. These reactions include protein synthesis, energy production, and the breakdown of waste products. Cytosol also helps in the transportation of molecules within the cell and provides support to the organelles.

The Golgi apparatus is responsible for processing and packaging cellular materials prior to export. It consists of smooth-sided channels that aid in the modification, sorting, and packaging of proteins and lipids into vesicles for transportation to other parts of the cell or for secretion outside of the cell. This activity is distinct from the other options listed, such as digestion, detoxification, and energy harvesting, which are performed by other organelles like lysosomes, peroxisomes, and mitochondria, respectively.

Mitochondria are known as the powerhouses of the cell, responsible for producing energy in the form of ATP through cellular respiration. Since an active cell requires more energy, it would require a higher number of mitochondria to meet its energy demands. Therefore, a particularly active cell would contain large numbers of mitochondria.

The rough endoplasmic reticulum (ER) is responsible for modifying and transporting proteins that will be sent outside of the cell. It is called "rough" because it has ribosomes attached to its surface, which are responsible for protein synthesis. The rough ER modifies and folds the newly synthesized proteins, adding necessary components such as carbohydrates or lipids. It then packages these proteins into vesicles for transport to the Golgi apparatus, where they will be further processed and eventually sent outside of the cell.

The nucleus is the correct answer because it contains the genetic material of the cell, which includes the instructions for making proteins. The DNA molecules in the nucleus provide the necessary information for protein synthesis.

The smooth endoplasmic reticulum is responsible for detoxification and assembling materials for use in the cell membrane. It plays a crucial role in lipid metabolism, including the synthesis of phospholipids and cholesterol, which are essential components of the cell membrane. Additionally, the smooth endoplasmic reticulum detoxifies harmful substances by breaking them down into less toxic compounds. It also stores and releases calcium ions, which are important for various cellular processes. Therefore, the smooth endoplasmic reticulum is the correct answer for this question.

The nucleolus is responsible for assembling ribosomes. It is a small, dense region within the nucleus of a cell. The nucleolus contains the DNA that codes for ribosomal RNA (rRNA), which is essential for ribosome assembly. It also contains proteins that are necessary for the formation and maturation of ribosomes. Ribosomes are the cellular structures responsible for protein synthesis, so the nucleolus plays a crucial role in protein production within the cell.

Cycloheximide is a protein synthesis inhibitor that specifically targets the ribosomes in cells. Ribosomes are responsible for the synthesis of proteins, and by inhibiting their function, cycloheximide prevents the completion of protein synthesis. This explains why Naomi observes short incomplete segments of proteins in the cells after adding cycloheximide. Therefore, the correct answer is Ribosome.

The nuclear membrane is responsible for regulating which materials can enter or leave the cell. It acts as a barrier, controlling the movement of molecules in and out of the nucleus. This selective permeability is crucial for maintaining the integrity and proper functioning of the cell. The nuclear membrane also helps in protecting the genetic material within the nucleus from potentially harmful substances present in the cytoplasm.

The presence of ribosomes indicates that cells are not photosynthetic bacteria because ribosomes are present in all types of cells, including both photosynthetic and non-photosynthetic bacteria. Therefore, the presence of ribosomes does not specifically indicate whether a cell is photosynthetic or not.