Study Notes
The ultrastructure of cells involves understanding the detailed structures within prokaryotic and eukaryotic cells. Prokaryotes have a simple cell structure without compartmentalization, while eukaryotes have a compartmentalized cell structure.
- Prokaryotes — simple cell structure without compartmentalization Example: Bacteria
- Cytoplasm — internal fluid component of the cell Example: Contains enzymes and nutrients
- Nucleoid — region where the DNA is located Example: Circular DNA strand
- Plasmids — small, circular DNA molecules Example: Can be transferred between bacteria
- Ribosomes — complexes responsible for protein synthesis Example: 70S in prokaryotes
- Cell membrane — semi-permeable barrier surrounding the cell Example: Controls entry and exit of substances
- Cell wall — rigid outer covering made of peptidoglycan Example: Provides shape and protection
- Slime capsule — thick polysaccharide layer for protection Example: Protects against drying out
- Flagella — projections enabling movement Example: Bacterial flagellum
- Pili — hair-like extensions for adherence or conjugation Example: Attachment pili
- Eukaryotes — cells with compartmentalized structures Example: Animal and plant cells
- Lysosomes — membranous sacs with digestive enzymes Example: Break down macromolecules
- Mitochondria — site of aerobic respiration Example: ATP production
- Nucleus — stores genetic material as chromatin Example: Contains nucleolus for ribosome assembly
- Chloroplast — site of photosynthesis Example: Found in plant cells
- Cell wall — provides support and protection Example: Made of cellulose in plants
- Free ribosomes — synthesize proteins for use within the cell Example: Enzymes
- Rough Endoplasmic Reticulum (rER) — synthesizes proteins for export Example: Has ribosomes attached
- Golgi apparatus — modifies and packages proteins Example: Processes proteins from rER
- Vesicles — transport materials within the cell Example: Small membrane-bound sacs
- Centriole — involved in cell division Example: Forms spindle fibers
- Vacuole — maintains hydrostatic pressure Example: Large central vacuole in plant cells
- Flagellum — used for cell movement Example: Sperm cell tail
- Cilia — move fluids or the cell itself Example: Respiratory tract cilia
Exam Tips
Key Definitions to Remember
- Prokaryotes: Simple cell structure without compartmentalization
- Eukaryotes: Cells with compartmentalized structures
- Ribosomes: Complexes responsible for protein synthesis
- Mitochondria: Site of aerobic respiration
Common Confusions
- Confusing prokaryotic and eukaryotic cell structures
- Misunderstanding the function of organelles like lysosomes and mitochondria
Typical Exam Questions
- What is the main difference between prokaryotic and eukaryotic cells? Prokaryotic cells lack compartmentalization, while eukaryotic cells have it.
- How do ribosomes differ in prokaryotic and eukaryotic cells? Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S.
- What is the function of the Golgi apparatus? It modifies and packages proteins for secretion.
What Examiners Usually Test
- Ability to identify and describe functions of cell organelles
- Differences between prokaryotic and eukaryotic cells
- Understanding of cell compartmentalization and its advantages