Cell organelles

Match each organelle with its basic function: mitochondrion, chloroplast, ribosome, Golgi apparatus, lysosome, endoplasmic reticulum, vacuole, and nucleus.

Classify the organelles and structures of the eukaryotic cell into two groups: membrane-bound and non-membrane-bound. Give at least two examples of each group.

Indicate which organelles and structures are characteristic of the plant cell and absent in the animal cell, and which are shared by both cell types.

In a cross-section of an animal eukaryotic cell, six characteristic organelles or structures can be distinguished: 1) mitochondrion, 2) rough endoplasmic reticulum, 3) Golgi apparatus, 4) lysosome, 5) nucleus, and 6) centrosome. Describe the basic function of each of them in one sentence.

Observe the image of a sectioned eukaryotic plant cell. Identify the structures marked with numbers 1 to 6 and explain, comparing it with the animal cell, what role the cell wall and the large vacuole play in the shape and rigidity of plant cells.

Unit challenge. As a future biomedical researcher, you must analyze real cell samples from electron micrographs. Your objective is to prepare a comparative technical datasheet demonstrating cell diversity and organelle function.

1. Data collection: Access the public scientific repository Cell Image Library (cellimagelibrary.org) and select two micrographs with a visible scale bar: one bacterium and one eukaryotic cell (animal or plant) where its organelles are clearly distinguishable.

2. Measurement and calibration: Measure the scale bar and cellular dimensions with a ruler. Using the relationship $\text{Magnification} = \frac{\text{Observed size}}{\text{Actual size}}$, calculate the actual size of both cells and of two representative organelles (such as a mitochondrion or chloroplast), expressing the values in $\mu\text{m}$ (e.g., $1.5\ \mu\text{m}$).

3. Reasoned report: Design a comparative table contrasting prokaryotes and eukaryotes, discussing the function of the measured organelles and explaining how they support the modern tenets of cell theory and the endosymbiotic hypothesis.

Evaluation criteria:

• Accuracy in calculating actual cell sizes and correct use of scale in $\mu\text{m}$.

• Morphological identification and appropriate functional justification of the organelles.

• Conceptual rigor in linking observations to cell theory and organizational models.

Locate in which organelle or cellular structure each of these processes occurs and briefly justify your answer: aerobic respiration, photosynthesis, synthesis of proteins destined for secretion and intracellular digestion of aged materials.

Morphometric electron microscopy analysis of three unknown human cell lines (A, B, and C) provides the following data regarding the percentage of cell volume occupied by each organelle:

• Type A: Mitochondria: 38 %; Smooth endoplasmic reticulum: 17 %; RER: 5 %; Golgi apparatus: 2 %; Secretory granules: < 1 %.

• Type B: Mitochondria: 6 %; Smooth endoplasmic reticulum: 2 %; RER: 34 %; Golgi apparatus: 20 %; Secretory granules: 15 %.

• Type C: Mitochondria: 5 %; Smooth endoplasmic reticulum: 2 %; RER: 4 %; Golgi apparatus: 3 %; Lysosomes and phagosomes: 26 %.

Reasonably assign to each cell type one of the following physiological functions: mechanical contraction and calcium homeostasis (skeletal muscle fiber), massive protein secretion (pancreatic acinar cell), or destruction of phagocytosed pathogens (macrophage). Justify each assignment by relating the assigned function to the abundance of the corresponding organelles.