Download - Inside the Cell
Inside the Cell
Cell cytoskeleton
Overview Prokaryotic vs Eukaryotic Cells Cell organelles Endomembrane system• transport within a cell, molecular “zip
codes” Cytoskeleton• a structural framework• facilitates cell division, movement, and
transport
Key concepts
The structure is related to function Cells are dynamic and integrated
Why are cells small?
4 3
Magnification vs Resolution
Resolution – minimum distance 2 points can be apart and still distinguished as separate
Light Microsco
py Brightfield (unstained) Phase Contrast
Brightfield (stained) Nomarski
Fluorescence Confocal
Grouping of cells Morphology- 2 types:
1. Prokaryotes- lack nucleus2. Eukaryotes, have a nucleus
Phylogeny, or evolutionary history- three domains:1. Bacteria2. Archaea3. Eukarya – eukaryotic
All cells are surrounded by Plasma Membrane
Plasma membrane encloses the cell and separates its contents from its surroundings
Fluid Mosaic - Phospholipid bilayer, proteins
Transport proteins, receptor proteins, and markers
Plasma Membrane
All cells contain DNA and ribosomes
DNA in Prokaryotes – usually circular– Chromosome – in the nucleoid region
– Small, usually circular, extrachromosomal plasmid - contains independent genes; for adapting to new environments
DNA in Eukaryotes –in the membrane-bound nucleus
Ribosomes are the site of protein synthesis
Bacteria: Common Structures
Plasma membrane Stiff cell wall A single chromosome Ribosomes, which synthesize
proteins
Simple interior organization No true nucleus Few, if any compartments
Typical Bacterial Cell
Bacterial cell wall Cell wall contains peptidoglycan Gram-positive – thick, single-
layered cell wall Gram-negative – multilayered
cell wall Cell wall determines shapes,
and susceptibility to antibiotics Polysaccharides cover cell wall for adhering
to surfaces and form aggregates: biofilms
Additional Internal Structures in some prokaryotic cells
Recent discoveries
Internal photosynthetic membranes
Some cytoskeleton of long, thin protein filaments
Some membrane-enclosed organelles
Organelle: a membrane-bound compartment specialized for a particular function, common in eukaryotes
External Structure: Flagella- Aids Bacterial Movement
Tail-like structure, ROTATES to move the cellStructure unique to bacteria (flagellin component)One or more per cell or none depending on the species