What are the essential features of a cell?
- Exterior plasma membrane (phospholipid bilayer)
- Nuclear region w DNA
- Interior cytoplasm (semifluid matrix)
What are the 2 cell types?
- Prokaryotic
- Eukaryotic
What are prokaryotic cells like?
No nucleus, little defined internal structure & unicellular - v small ~5-2.0um diameter
What are eukaryotic cells like?
Contain nuclei, more complex w specialised organelles
May be unicellular or multicellular (animals, plants or fungi)
What are the 3 divisions in the tree of life?
- Eukaryotes
- Bacteria - prokaryotes
- Archaea - “”
What type of cells are eubacteria?
Prokaryotes
They are the most commonly encountered of the prokarya
What features are most commonly found in eubacteria?
- Plasma membrane (PM)
- Rigid cell wall - composed of peptidoglycan (carb/protein polymer) external to PM
Simple internal organisation & lack of differentiation
Genomic DNA presented in ‘nuclei’ region - not steerage for cytoplasm
What are the types of bacteria?
- Gram-positive
- Gram-negative
What is Gram+ bacteria like?
Has plasma membrane and cell wall
What is Gram- bacteria like?
Has extra periplasmic space outside of the plasma membrane & cell wall
Name a type of gram- bacteria
E.coli
What are the main ways that bacterial cells are diverse?
- Cell shape
- Cell appendages
- Some have infoldings of the plasma membrane
Why do some bacteria have infoldings in the plasma membrane?
(Give an example)
To allow photosynthesis
e.g. Cyanobacteria (blue green) with apparent internal membranes
What are the various cell shapes found in bacterial cells?
Round, oval, spiral, curved, rods, chains etc
Give some examples of bacterial cell appendages that allow for specialisation
- Some have rotating flagella on surface for motility
- Many Gram- have short ‘fimbriae’ for attachment to surfaces and ‘pili’ for attachment to bacteria
What are some features of archaea (prokaryote)?
- Have many similar features to bacterial cell structure
- Have some unique cell shapes - beached, flat & square
- Have distinct biochemistry - incl cell membranes, DNA molecular differences
- Lack peptidoglycan cell wall
- Found in hostile environments
How are bacterial and archaea cells similar?
Similar:
- Size range
- Shape (rods, round)
Have external flagella and pili
DNA present in nucleoid region, not sep. from cytoplasm
What do archaea cells have instead of the peptidoglycan wall which they lack?
They instead have very diverse outer surface layers
Archaea can be found in hostile environments, give some examples
- Hot volcanic springs
- Airless marine sediments
- Salt lakes
What are eukaryotes like?
Wide variety
Structurally more complex than Prokaryotic cells
What are the features of eukaryotic cell structure?
- Plasma membrane (PM)
- DNA cont in a nucleus, separated from cytoplasm by membrane - DNA present on chromosomes
- Cytoplasm is compartmentalised - features organelles
- Complex cytoskeletal system to maintain cell integrity e.g. microtubules & intermediate & acting filaments
What is the role of the plasma membrane in eukaryote cells?
It delineates the edge of cell cytoplasm
Give some examples of eukaryote cell diversity?
Animal, plant, protist, fungal cells
What are the main constituents in an animal cell?
- Nucleus
- Organelles: mitochondria, Golgi body, peroxisomes, RER & SER, small vacuoles
- Ribosomes
- CENTRIOLES
- Cytoskeleton
