Cell Biology 2 Flashcards
1
Q
Enzymes
A
- enzymes are protein catalysts that speed up reactions that otherwise would not occur in a watery environment often using ATP energy to build up complex organic molecules which the cell needs
2
Q
Cell membranes
A
- regulate the passage of substances into and out of cells and between cell organelles and cytosol
- detect chemical messengers arriving at the cell surface
- link adjacent cells together by membrane junctions
- anchor cells to the extracellular matrix
3
Q
Membrane Lipids
A
- water insoluble, oily compounds that are soluble in organic solvents.
- fatty acids and other compounds that are functionally or structurally related to membrane bilayers
- fatty acids form phospholipids which then aggregate non-covalently to form membrane bi-layers.
- membranes are therefore different from the other macromolecules in the cell which are made of covalently linked subunits.
4
Q
Phospholipids
A
- in animals = unbranched
- saturated or unsaturated
- phosphatidylcholine is the most common phospholipid in cell membranes
-phosphocholine headgroup is hydrophilic and fatty acid tail is hydrophobic
5
Q
Cholesterol
A
- present in eukaryotic cells but not prokaryotes
- plasma membrane is relatively thick and impermeable due to high cholesterol.
6
Q
What determines membrane fluidity ?
A
- amount of cholesterol
- number of double bonds in hydrocarbon tail
- length of hydrocarbon tail
- prokaryotes
- eukaryotes
7
Q
membrane protein
A
- carry out specific functions. e.g. transport of specific ions or nutrients
- highly variable depending on cell type
- may have carbohydrates attached
- some are anchored and do not move in the membrane
- transmembrane proteins extend through the bilayer.
- peripheral membrane proteins = non covalent or covalent attachment and are found on extracellular surface.
8
Q
The Cytoskeleton
A
- most proteins are not directly connected to membranes
- some cytoskeletal proteins provide mechanical strength of cell controls cell shape and forms mitotic spindle
- some guide the movement of vesicles
- not all cells have an extensive cytoskeleton
9
Q
key facts about cytoskeleton
A
- microtubules mediate vesicle motility.
- actin filaments are just under the plasma membrane and control cell shape and movement
- intermediate filaments help support the nucleus and give the cell mechanical strength.
