Tissues 1 Flashcards
What can be found in cytoplasm?
- Organelles
- Proteins and macromolecules
- Cytoskeleton filaments
What is found in the nucleoplasm?
Heterochromatin
What is the function of the nucleolus?
Ribosome synthesis.
What size ribosomes do prokaryotes have?
70S (50S and 30S)
What size ribosomes do eukaryotes have?
80S (60S and 40S)
What size ribosomes do mammalian mitochondrial have?
55S (39S and 28S)
What is the nuclear lamina?
A specialised cytoskeleton on the internal surface of the nuclear envelope.
What is the function of the nuclear lamina?
Controls the assembly and disassembly of the nuclear envelope in cell division.
Is rough ER granular or agranular?
Granular - smoothER is agranular
What is the function of the rough ER?
Synthesis of membrane proteins and proteins which are membrane-bound.
What is the function of the smooth ER?
Controls lipid metabolism and detoxification, as well as calcium storage.
What does a high presence of mitochondria indicate?
Highly metabolic activity.
What are peroxisomes?
Involved in lipid and oxygen metabolism. A by-product of their catalysis is peroxide.
What is the cytoskeleton?
A system of filaments formed by the polymerisation of protein monomers in three main forms.
What are the three forms of the cytoskeleton?
- Microfilaments
- Microtubules
- Intermediate filaments
What are microtubules made up of?
Polymers of alpha and beta tubulin heterodimers.
How thick are microtubules?
20nm
What is the function of microtubules?
Involved in cell shape and act as tracks for the movement of organelles around the cell.
Where are MTOCs normally found?
Near the nucleus of a cell
How think are intermediate filaments?
10-15nm
What is the function of intermediate filaments?
Mechanical strength
Example of microtubules in biology?
Flagella and cilia
Example of intermediate filaments in biology?
Nuclear lamina
What are microfilaments made up of?
Polymers of actin
What is the function of microfilaments?
Associated with cell shape and movement in muscle cells.
How thick are microfilaments?
5-9nm
What is the extracellular matrix?
Material deposited by cells which forms an insoluble part of the extracellular environment. Often poorly organised. Made up of fibrillar and reticular proteins.
Why are cell-cell junctions important?
Allow the formation of continuous and cohesive layers, giving mechanical strength and sealing the intracellular pathways.
What are zonulae?
Belts
What are maculae?
Spots
What are desmosomes?
Found throughout lateral membrane to provide mechanical continuity between cells. Linked to intermediate filaments.
What are gap junctions?
Clusters of pores that are continuous in the adjacent cell membrane. Allows the passage of ions and small molecules between cells.
What factors affect movement via gap junctions?
- pH
- Calcium concentration
- Voltage
- Signalling molecules
