Anatomy of a cell Flashcards
What term is used to describe a molecule with both polar and non-polar regions?
Amphipathic
What are the two components of a glycosphingolipid?
A glycolipid and the amino alcohol sphingosine
What type of molecule is the phosphate head of a phospholipid?
A polar, hydrophilic molecule
What type of molecule are the fatty acid tails of a phospholipid?
Non-polar, hydrophobic molecules
What is the cell membrane highly permeable to?
Water, Oxygen, Small hydrophobic molecules
What is the cell membrane virtually impermeable to?
Charged ions (e.g. Na+)
What is the function of the mitochondria?
energy production
What is the function of the Rough Endoplasmic Reticulum?
Protein Synthesis using surface mounted ribosomes
What is the function of the Smooth Endoplasmic Reticulum?
Synthesis/detoxification of Cholesterol and lipids
What is the function of the Golgi Apparatus
Modification and packaging of secretions
What is the function of a lysosome
Contain hydrolytic enzymes for intracellular digestion
What is the function of the nucleus?
Contains the cells genetic code
What is the function of the nucleolus?
Transcription of rRNA (ribosomal RNA)
What are examples of inclusions?
Inclusions are components that have been synthesised by the cell itself or taken up from the extracellular environment (e.g. pigment, glycogen stores, lipid droplets, pre secretion product and endocytotic vesicles)
What are microfilaments composed of?
The protein actin
What are intermediate filaments composed of?
6 main proteins which vary in different cell types
What are microtubules composed of?
2 Tubulin proteins (α and ß), MAPS (Microtubule Associated Proteins), a capping protein and γ tubulin
What makes microfilaments dynamic cytoskeletal elements?
Actin molecules can assemble into filaments and later dissociate
What is the function of the intermediate filaments?
Bind intracellular elements together and to the plasma membrane
What type of cells contain the intermediate filament ‘Neurofilaments’?
Nerve cells
What type of cells contain the intermediate filament ‘Glial Fibrillary Acidic Proteins’?
Glial cells of the nervous system
What type of cells contain the intermediate filament ‘Desmin’?
Muscle cells
What type of cells contain the intermediate filament ‘Cytokeratins’?
Epithelial cells
What type of cells contain the intermediate filament ‘Vimentin’?
Mesenchymal cells
What type of cells contain the intermediate filament ‘Filesin’?
Cells of the lens of the eye
Which organelle contains the intermediate filament ‘Lamin’?
The nuclei of all cells
What type of cells are astrocytes?
Glial cells of the CNS
What two proteins can move along the microtubules within the cytoskeleton?
Dynein and Kinesin
What is Dynein and in which direction does it travel within a cell?
Dynein is an ATPase that moves towards the cell centre
What is Kinesin and in which direction does it travel within a cell?
Kinesin is an ATPase that moves towards the cells periphery
What is the purpose of a nuclear pore?
To allow for the movement of substances from the nucleus, to the cytoplasm
What is Euchromatin?
DNA that is more dispersed and is actively undergoing transcription
What is Heterochromatin?
DNA that is highly condensed and is not undergoing transcription
Name the two components of a ribosome and their function
Ribosomes are made up of a small subunit which binds to RNA, and a large subunit, which catalyses the formation of peptide bonds
Give an example of a type of cell that would contain an extensive amount of SER
Cells synthesising steroid hormones
What is the golgi apparatus composed of?
A group of flattened, membrane bound cisternae
What is the function of the golgi apparatus?
Golgi cisterns function of the modification and packaging of macromolecules that were synthesised in the ER. They add sugars, cleave some proteins and sort macromolecules into vesicles
What is the cis face golgi?
The receiving face of the golgi apparatus
What is the trans face golgi?
The face from which vesicles are formed
What stain is used in histology to view the mitochondria?
Janus green
What are the main two components of a mitochondria?
The matrix and the Cristae
What are the 3 types of intercellular junctions?
Occluding junctions, anchoring junctions and communicating junctions
What is the purpose of an occluding junction?
To link cells and form a diffusion barrier
What is the purpose of an anchoring junction?
To provide mechanical strength
What is the purpose of a communicating junction?
To allow the movement of molecules between cells
What is the other name given to an occluding junction?
Zonula occludents
What is the other name given to an adherent junction?
Zonula adherens
What is the other name given to a desmosome?
Macula adherens
What are the two types of anchoring junction?
Adherent junctions and desmosomes
What proteins are found in an occluding junction?
occludin and claudin
How are adherent junctions formed?
Transmembrane Cadherin molecules bind to each other, and to actin filaments within the cells cytoskeleton, through link molecules
What molecules are found in an adherent junction?
E-cadherin, catenin, vinculin, actin, α-actinin and Ca2+ ions
How are desmosomes formed?
The submembrane intermediate filaments of adjacent cells link
What molecules are found in a desmosome?
An intracellular attachment plaque, desmocollin and desmoglein
Where are desmosomes most commonly found?
The skin, where they can provide mechanical stability
What is a communicating junction comprised of?
A circular patch studded with several hundred pores
What are the pores of a communicating junction formed from?
Connexon proteins
Where are communicating junctions most commonly found?
In epithelia, and also in some smooth muscle and in cardiac muscle where it is critical for the spread of excitation
What is a junctional complex?
The close association of several types of junction (zonula occludents, zonula adherens and macula adherens)
What are the stages of endocytosis?
The cell membrane invaginates, fuses and the newly made endocytotic vesicle (endosome) buds into the cell. This process is often receptor mediated
What is a phagosome?
A vesicle formed within a phagocyte, containing a bacterium or other pathogen
What is formed from the binding of a lysosome to a phagosome?
A phagolysosome
