Tissues 1 Flashcards
What is the single lipid bilayer that binds animal cells?
The plasma membrane
What is the nuclear envelope?
A double lipid bilayer that encloses the contents of the nucleus.
What is an organelle?
Membrane bound/membrane associated structure within a cell
What do eukaryotic cells have?
- Membrane bound organelles
2. A highly compartmentalised cytoplasm
What do the darker regions of a TEM nucleus show?
Heterochromatin
Why is heterochromatin in the darker regions less active?
It is more condensed
What is the nucleus?
- The site of the production of sub-units of ribosomes.
- An aggregate of clusters of rRNA genes
- Contains synthesised rRNA and proteins - assembled to make ribosomal subunits.
How many pairs of rRNA genes are there in humans?
5.
What structure is the nuclear envelope continuous with?
The endoplasmic reticulum
What are the 3 faces of the Golgi apparatus? Where do they face?
Cis - towards nucleus
Medial
Trans - towards plasma membrane
What are peroxisomes?
- Single membranes
2. Contain enzymes involved in lipid and oxygen metabolism.
What is the nuclear lamina?
- Specialised cytoskeleton
- Formed on internal surface of nuclear envelope
- Important in cell division - controls assembly/disassembly of nuclear envelope in cell division
Where are Ca ions stored in cells?
SER
What are the 3 main types of cytoskeleton?
- Microtubules
- Intermediate Filaments
- Microfilaments
What are microtubules made up of?
Alpha-tubulin and Beta-tubulin
What to microtubules do?
- Involved in cell shape
- Act as tracks for the movement of other organelles/components.
- 20nm
may involve other accessory proteins
What are microtubules the major component of?
Cilia and Flagellae
What is the centrosome
The central point of the cell from which the microtubule radiates out of (aka Microtubule Organising Centre, MTOC)
What forms the mitotic spindle?
Microtubules
What is the 9+2 arrangement?
9 MT doublets + 2 central MTs form the core of cilia and flagella
What are intermediate filaments?
- Group of filamentous protein polymers - form rope like filaments
- Cell type determines type of IF it has.
- Give mechanical strength to cells
- 10-15nm diameter
What connects desmosomes?
Cytokeratin
What are nuclear lamins?
- IFs that form a network on internal surface of nuclear envelope.
- IFs Involved in stabilising envelope
What are Microfilaments?
- Actin polymers
- Associated with adhesion belts in epithelia and endothelia.
- 5-9nm in diameter
- Involved in cell movement and shape
- Have accessory proteins (e.g. myosin) - acts with actin to control actin organisation and cell movement (by giving non-muscle cells contractile properties)
Where are actin MFs typically found in the cell?
Lining the peripheral regions of the cell.