Flashcards in AB1: The cell, basic structure Deck (11)
What are the differences between prokaryotes and eukaryotes?
1) Prokaryotes have no membrane bound organelles- eukaryotes do
2) Prokaryotes tend to be single celled, eukaryotes can be single and multi-cellular
3) In Prokaryotes all functions are carried out by the same cell, in eukaryotes most cells are specialised to a particular function
4) Eukaryotes have a "true nucleus", Prokaryotes do not have a nucleus
What are the typical features of a Prokaryotic cell?
Plasma membrane, cell wall, flagella, a nucleoid, ribosomes, a capsule, bacterial chromosomes and pili
What are the typical feature of a Eukaryotic cell?
Rough and smooth endoplasmic reticulum, nucleus, plasma membrane, ribosomes, Golgi apparatus, lysosomes, mitochondria, peroxisome, microvilli, cytoskeleton, centrioles and flagella
What are the typical features of a plant cell?
Rough and smooth endoplasmic reticulum, ribosomes, central vacuole, cytoskeleton, chloroplasts, plasmodesmata, cell wall, plasma membrane, peroxisome, mitochondria, Golgi apparatus, centrosome and nucleus
What is a nucleoid?
nuclear region within a prokaryotic cell where genetic material is found- is not membrane bound so is not a nucleus
What is the role of the pili?
plays an important role in allowing bacteria to adhere to surfaces such as cells to cause infection in humans
What are microvilli?
specialised structures in epithelial cells such as cell lining your gut, give surface of plasma membrane a large surface area over which nutrients, solutes and water can be absorbed across the membrane in kidneys (not found in all animal cells)
What are the differences between animal and plant cells?
Plants have a cellulose cell wall, chloroplasts, central vacuole and plasmodesmata, animal cells do not. Animals and some plant cell have flagella, animal cells have lysosomes, plants do not and animals have 2 centrioles within a centrosome- plants have centrosome but no centrioles
What are the limitations of schematic diagrams of cells and organelles in books?
1) Colour- most colours are false, problem of absence of colour and contract is overcome by histologist who use staining of fixed cell and tissue samples
2) Scale- Schematic cartoons do not show relative sizes of organelles and shouldn’t be taken literally
3) Fluidity and Dynamics- Cells are not static pieces of technology- their structures and their component molecules are in a constant state of flux
What methods are used to study cell structure ?
Microscopy- fixing and staining with coloured or fluorescent dyes or heavy metals for electron microscopy
Homogenisation- involves breaking them up and cell fractionation- spinning them in a centrifuge at many different speed