Cells Flashcards
What are the three types of cell junctions?
Tight junctions, desmosomes and gap junctions
How do tight junctions work?
They fuse plasmalemma of adjacent cells to form a seal. In this way, they are a selective barrier. (found in intestinal epithelia)
How do desmosomes work?
They strengthen connections between adjacent cells. They are resistant to twisting and bending. (found in skin epithelia).
How do gap junctions work?
Allow cell to cell communication (connexions are channels).
How does the basement membrane attach to cells?
Hemidesmosomes and focal adhesions
What are integrins?
They are transmembrane proteins that attach cell cytoskeleton to extracellular matrix and sense whether adhesion has occurred. So they function as signal transducers as well as attachment.
What are some problems with cell culturing?
Cells demonstrate contact inhibition, they behave and look differently, they demonstrate senescence.
What is autocrine cell communication?
Cell releases substances that regulate it
What is paracrine communication?
Cell releases substances that affect nearby cells.
What is necrosis?
It is caused by cell injury and involves loss of functional control. Osmotic control lost, cell bursts. Tissue damage and inflammation is induced.
What is apoptosis?
It is genetically programmed. Bcl-2 protein on mitochondria deactivated and induces caspase activation. They target specific proteins in nucleus to cause chromatin to be repackaged into apoptotic bodies that are phagocytosed.
What is endocytosis?
Bulk transport into a cell. Vesicles formed once material is in the cell.
What is exocytosis?
Secretion out of the cell
What are some static cell types in the body?
- CNS
- Cardiac
- Skeletal Muscle
What are some stable cell types in the body?
- Fibroblasts
- Endothelium
- Smooth Muscle
What are some renewing cell types in the body?
- Blood
- Skin epithelium
- Gut epithelium
Outline some differences in prokaryotes and eukaryotes?
No nucleus they have a plasmid, no mitochondria, they have specialisations e.g. flagella, pili, cell wall
Describe mitochondrial DNA inheritance?
Circular, maternal lineage, no recombination (can be identical to siblings and mother).
What are the four basic types of tissue?
Epithelial, muscle, nerve, connective tissue.
Define epithelium and outline its functions
A tissue composed of cells that covers the external body surface and lines internal closed cavities and body tubes that communicate with the exterior. Epithelium also forms the secretory portions of glands and lines their ducts. In specialised epithelium functions as receptors for the special senses (smell, taste, hearing and vision).
What are microvilli, stereovilli, cilia? Give examples of where they are found
Microvilli = intestine, kidney tubules
Stereovilli= particularly long microvilli- epididymis, sensory hair of ear
Cilia= motile cytoplasmic processes can beat in synchrony- tracheobronchial tract, oviducts
What are the differences between rough and smooth ER?
Rough- ribosomes on flat cisternae
Smooth- no ribosomes and tubular shape (lipid biosynthesis and and steroid genesis function)
What is the function of the golgi apparatus?
modify, sort, package proteins synthesised on the RER
