Lecture 2- cell structure and specialisation Flashcards
3 key features of cells
Exterior plasma membrane- separates cell from external medium
Nuclear region with DNA genetic material
Interior semifluid cytoplasm
Prokaryotes-overview
Bacteria
No nucleus
Little internal organisation- no membrane bound organelles
Size: 0.5-2.0 micrometers
Eukaryotes-overview
Distinct nucleus
Plasma membrane
Specialised internal organelles
Unicellular or multicellular
Size: 5-20 micrometers
Prokaryotes- overview
Most commonly eubacteria
Plasma membrane at edge of cytoplasm
Rigid peptidoglycan cell wall
Undifferentiated cytoplasm
Nucleoid region (containing DNA) not membrane enclosed
Prokaryotes cell wall
Made of peptidoglycan
2 classes:
Gram positive- only have outer cell wall
Gram negative- extra outer membrane external to cell wall with periplasmic space in between
Archea: overview
Similar features to bacteria
Some unique cell shapes
Distinct biochemistry of cell membranes
No peptidoglycan cell walls
Found in hostile environments
Eukaryote: cell diversity- model protist cell
Mainly unicellular
Flexible cell surface with supportive ‘pellicle’
Some have contractive vacuole
Eukaryote: cell diversity- model fungal cell
Unicellular yeasts or filamentous hyphae
Can contain multiple nuclei
Rigid chitin cell wall
Specialisation overview
Cell structure varies depending on cell function
Specialisation: movement
eg.Flagella and cilia allow propulsion
Also roles in airways/ ears
Specialisation: photosynthesis
eg.Chloroplasts in plants at high concentrations
Specialisation: metabolism
eg.Adipose cells for fat storage
eg.Brown fat cells for heat production
Specialisation: signalling
eg. Nerve cells have terminal dendrites and long axon
Specialisation: transport
eg. red blood cell for gas transport- no. nucleus or organelles, full of haemoglobin
small and flexible
Specialisation: reproduction
eg. sperm have flagellum
eg. mushroom spores produced on gills from basidia
