1.2 Comparing Prokaryotic and eukaryotic cells Flashcards
Common features
- plasma membrane
- Semifluid substance called cytosol
– Chromosomes (carry genes)
– Ribosomes (make proteins)
Exploring Eukaryotic cells
Animal cells
Fungal cells
Cells with chloroplasts
Plant cells
Protistan cells
Cell walls of plants
- The cell wall is an extracellular structure that distinguishes plant cells from animal cells
- Prokaryotes, fungi, and some protists also have cell walls
- The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water
- Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protei
Plant cell walls
• Primary cell wall:
thin and flexible
• Middle lamella:
thin layer between primary walls of adjacent cells
• Secondary cell wall (in some cells):
added between the plasma membrane and the primary cell wall
The Nucleus: Information central
- The nucleus contains most of the cell’s genes
- The most conspicuous organelle
• Nuclear envelope encloses the nucleus
– double membrane
– lipid bilayer
Ribosomes: Protein factories
• Ribosomes are particles made of ribosomal RNA and protein
• Ribosomes carry out protein synthesis
– In the cytosol
– On the outside of the endoplasmic reticulum or the nuclear envelope
The endomembrane system
- Golgi apparatus
* Endosomes, lysosomes, exosomes etc.
Vacuoles: Diverse maintenance compartments
Food vacuoles - formed by phagocytes
Contractile vacuoles - found in many freshwater protists, pump excess water out of cells
Central vacuoles - found in many nature plant cells, hold organic compounds and water.
Mitochondria and chloroplasts change energy from one form to another
Mitochondria:
are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP
Chloroplasts:
found in plants and algae, are the sites of photosynthesis
Peroxisomes:
oxidative organelles
The evolutionary origins of mitochondria and chloroplasts
have similarities with bacteria
- enveloped by double membrane
- contain free ribosomes + circular DNA molecules
- grow + reproduce somewhat independently in cells
The endosymbiont theory
- early ancestor of eukaryotic cells engulfed a nonphotosynthetic prokaryotic
- endosymbiont relationship with host
- merged into single organism, a eukaryotic cell with mitochondrion
- photosynthetic prokaryote was taken up, becoming the ancestor of cells that contain chloroplasts