BIOL1102 Lecture Notes - Lecture 2: Cytoskeleton, Microtubule, Tubulin
4 Jun 2018
School
Department
Course
Professor
Biology
Cell structure
All cells:
-bounded by a plasma membrane
-contain a semifluid: cytosol
-contain chromosomes
-have ribosomes
2 types of cell organisation: (before = pro, true = eu) (nucleus / no nucleus)
-prokaryotic
-eukaryotic
Cell sizes:
-prokaryotes: ~ 1-10 micrometers
-plant/animal cells: ~10-100 micrometers
-nerve cells: ~ 0.1-1m
PROKARYOTES
Prokaryotic Cells
-NO NUCLEUS
-DNA located in nucleoid
-do not have membrane bound organelles
-Earth’s sole inhabitants, 2-3.5 billion years ago
-most prokaryotes are microscopic: but large in
numbers
-reproduce quickly by binary fission, evolves
quickly
-most prokaryotes are unicellular
-BUT some species form colonies
-prokaryotic cells have a variety of shapes
- spheres (cocci)
- rods (bacilli)
- spirals
-cell wall of many prokaryotes is covered by a capsule: sticky layer of
polysaccharide or protein
-most motile bacteria propel themselves by
flagella(structurally+functionally different from eukaryotic flagella).
Molecules come to their surface and the cells react
-prokaryotic cells usually lack complex compartmentalisation
Cell-surface structures
-their wall, which maintains cell shape, provides physical protection,
prevents cell from bursting in a hypotonic environment
-use technique called Gram stain: species classified into two groups
based on cell wall composition:
- Gram-positive: large amount of peptidoglycan, traps violet
dye in cytoplasm, alcohol rinse does not remove violet, masks red dye
- Gram-negative: less peptidoglycan, located between plasma
membrane and outer membrane, vile easily rinsed, cell appears pink/
red
find more resources at oneclass.com
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Document Summary
2 types of cell organisation: (before = pro, true = eu) (nucleus / no nucleus) Earth"s sole inhabitants, 2-3. 5 billion years ago. Most prokaryotes are microscopic: but large in numbers. Reproduce quickly by binary ssion, evolves quickly. Prokaryotic cells have a variety of shapes. Cell wall of many prokaryotes is covered by a capsule: sticky layer of polysaccharide or protein. Molecules come to their surface and the cells react. Their wall, which maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environment. Use technique called gram stain: species classi ed into two groups based on cell wall composition: Gram-positive: large amount of peptidoglycan, traps violet dye in cytoplasm, alcohol rinse does not remove violet, masks red dye. Gram-negative: less peptidoglycan, located between plasma membrane and outer membrane, vile easily rinsed, cell appears pink/ red. Contain true nucleus, bounded by a membranous nuclear envelope. Plasma membrane: a selective barrier, allows passage of nutrients and waste.
