Is this statement true or false? “Animal cells have mitochondria; plant cells have chloroplasts.” Explain your answer, and describe the functions of these organelles.
- Describe the structure of the plasma membrane of an animal cell. What would be found directly inside and outside the membrane?
The Correct Answer and Explanation is :
Question 1: Is this statement true or false? “Animal cells have mitochondria; plant cells have chloroplasts.”
Answer:
The statement is partially true, but incomplete. Here’s why:
- True: Animal cells do have mitochondria, which are the powerhouses of the cell, responsible for generating energy in the form of ATP through cellular respiration.
- Misleading/Inadequate: Plant cells have both chloroplasts and mitochondria. Chloroplasts are responsible for photosynthesis, a process that converts light energy into chemical energy (stored in glucose). However, plant cells also use mitochondria to break down this glucose during cellular respiration to produce ATP.
Functions of the Organelles:
- Mitochondria: Found in both animal and plant cells, these double-membraned organelles generate ATP by oxidizing glucose and oxygen in a process called cellular respiration. ATP serves as the primary energy currency of the cell.
- Chloroplasts: Found only in plant cells and some protists, chloroplasts capture light energy through chlorophyll and use it to convert carbon dioxide and water into glucose and oxygen (photosynthesis).
Question 2: Structure of the Plasma Membrane of an Animal Cell
The plasma membrane of an animal cell is a selectively permeable lipid bilayer made primarily of phospholipids, proteins, cholesterol, and carbohydrates.
- Phospholipid Bilayer:
- Composed of phospholipids with hydrophilic (water-attracting) heads facing outward and hydrophobic (water-repelling) tails facing inward.
- Provides structural integrity and creates a semi-permeable barrier.
- Proteins:
- Embedded within or attached to the bilayer.
- Include transport proteins, receptors, enzymes, and structural proteins.
- Facilitate specific functions like nutrient transport, signal reception, and structural support.
- Cholesterol:
- Embedded within the bilayer.
- Maintains membrane fluidity and stability, especially in varying temperatures.
- Carbohydrates:
- Found on the extracellular surface attached to proteins (glycoproteins) or lipids (glycolipids).
- Involved in cell recognition and signaling.
Directly Inside the Membrane:
- The cytoplasm, a jelly-like substance containing organelles, enzymes, and ions.
Directly Outside the Membrane:
- The extracellular matrix (ECM), consisting of proteins (e.g., collagen) and glycoproteins, and interstitial fluid. This space facilitates communication, support, and transport between cells.