In this unit you learned about the parts and pieces of individual cells.
- Some cellular components such as ribosomes and flagella/cilia are present in both prokaryotic and eukaryotic organisms
- Membrane-bound organelles are a hallmark of eukaryotic cells.
- Some organelles are specific to a type of eukaryotic cell, such as chloroplasts which are found only in photosynthetic organisms
- Each organelle has a distinct and important function.
- Some cellular components found a ‘system’ such as the endomembrane system or the cytoskeleton.
|Table 1. Components of Prokaryotic and Eukaryotic Cells|
|Cell Component||Function||Present in Prokaryotes?||Present in Animal Cells?||Present in Plant Cells?|
|Plasma membrane||Separates cell from external environment; controls passage of organic molecules, ions, water, oxygen, and wastes into and out of cell||Yes||Yes||Yes|
|Cytoplasm||Provides turgor pressure to plant cells as fluid inside the central vacuole; site of many metabolic reactions; medium in which organelles are found||Yes||Yes||Yes|
|Nucleolus||Darkened area within the nucleus where ribosomal subunits are synthesized.||No||Yes||Yes|
|Nucleus||Cell organelle that houses DNA and directs synthesis of ribosomes and proteins||No||Yes||Yes|
|Mitochondria||ATP production/cellular respiration||No||Yes||Yes|
|Peroxisomes||Oxidizes and thus breaks down fatty acids and amino acids, and detoxifies poisons||No||Yes||Yes|
|Vesicles and vacuoles||Storage and transport; digestive function in plant cells||No||Yes||Yes|
|Centrosome||Unspecified role in cell division in animal cells; source of microtubules in animal cells||No||Yes||No|
|Lysosomes||Digestion of macromolecules; recycling of worn-out organelles||No||Yes||No|
|Cell wall||Protection, structural support and maintenance of cell shape||Yes, primarily peptidoglycan||No||Yes, primarily cellulose|
|Endoplasmic reticulum||Modifies proteins and synthesizes lipids||No||Yes||Yes|
|Golgi apparatus||Modifies, sorts, tags, packages, and distributes lipids and proteins||No||Yes||Yes|
|Cytoskeleton||Maintains cell’s shape, secures organelles in specific positions, allows cytoplasm and vesicles to move within cell, and enables unicellular organisms to move independently||Yes||Yes||Yes|
|Flagella||Cellular locomotion||Some||Some||No, except for some plant sperm cells.|
|Cilia||Cellular locomotion, movement of particles along extracellular surface of plasma membrane, and filtration||Some||Some||No|
Let’s match our earlier disease list with the right organelle. Think about how the function of these organelles directly relates to the disease symptoms.
- Cystic Fibrosis: plasma membrane
- Pompe disease: lysosomes
- Leigh’s Disease: mitochondria
- Emery-Dreifuss muscular dystrophy: nuclear envelope
We’ll come back to cystic fibrosis in the next section, where we will focus in greater detail on the cell membrane.