Be able to identify each of the following cell structures on the model or diagram and know the functions of each: cell (plasma) membrane, cytoskeleton, nucleus, nucleolus, nuclear membrane, rough endoplasmic reticulum (ER), smooth endoplasmic reticulum, ribosomes, mitochondria, Golgi body, vesicles, lysosomes, centrioles, peroxisomes, cytoplasm, cytosol, cilia, flagella (Figure 2.5) (note – peroxisomes and lysosomes cannot be distinguished visually)
The Correct Answer and Explanation is :
In the provided diagram of the cell, the following structures are key components with specific functions:
- Cell (Plasma) Membrane: This structure is a semi-permeable barrier surrounding the cell, made of phospholipids and proteins. It controls the movement of substances in and out of the cell, maintaining homeostasis.
- Cytoskeleton: Composed of protein filaments, it provides structural support to the cell, maintains its shape, and aids in cell movement. It also plays a role in intracellular transport.
- Nucleus: This is the cell’s control center, containing the cell’s genetic material (DNA). It regulates gene expression and coordinates cell activities like growth, metabolism, and reproduction.
- Nucleolus: Located inside the nucleus, the nucleolus is responsible for ribosomal RNA (rRNA) synthesis and assembly of ribosomal subunits.
- Nuclear Membrane: The double-layered membrane surrounding the nucleus, which separates the contents of the nucleus from the cytoplasm. It has pores that regulate the exchange of materials between the nucleus and cytoplasm.
- Rough Endoplasmic Reticulum (ER): The rough ER has ribosomes on its surface and is involved in protein synthesis and modification, especially for proteins that are secreted, embedded in membranes, or sent to lysosomes.
- Smooth Endoplasmic Reticulum: Lacking ribosomes, the smooth ER is involved in lipid synthesis, detoxification, and carbohydrate metabolism.
- Ribosomes: These are the sites of protein synthesis. They can be found freely in the cytoplasm or attached to the rough ER.
- Mitochondria: Known as the powerhouse of the cell, mitochondria generate ATP through cellular respiration, providing energy for various cellular processes.
- Golgi Body: This structure processes, sorts, and ships proteins and lipids from the ER to their destinations inside or outside the cell.
- Vesicles: These small membrane-bound sacs transport materials within the cell or to the cell membrane for secretion.
- Lysosomes: Containing digestive enzymes, lysosomes break down waste materials and cellular debris. They are essential for recycling cellular components.
- Centrioles: These cylindrical structures are involved in cell division, organizing the microtubules that separate chromosomes during mitosis.
- Peroxisomes: These organelles contain enzymes for breaking down fatty acids and detoxifying harmful substances, especially hydrogen peroxide.
- Cytoplasm: The gel-like substance inside the cell, excluding the nucleus, that houses all organelles and provides the medium for chemical reactions.
- Cytosol: This is the liquid component of the cytoplasm, mainly composed of water and dissolved substances, where cellular processes take place.
- Cilia: These short, hair-like structures are involved in movement or sensing the environment, such as moving fluids or particles along the surface of the cell.
- Flagella: Similar to cilia but longer, flagella are used for locomotion in some cells (e.g., sperm cells).
Peroxisomes and lysosomes cannot be distinguished visually, as they appear similar under a microscope and both play roles in digestion and waste processing. However, their contents and specific enzymes differ.