Flashcards
Lecture 7- Plasma Membrane and Transport
Flashcards do conjunto (39)
- 1What model best explains the plasma membrane?Fluid mosaic model
- 2What is the phospholipid bilayer composed of?Phospholipids, cholesterol and glycolipids
- 3Is cholesterol polar?Weakly amphipathic- OH group is polar and the rest is non polar
- 4How does cholesterol attach to phospholipids?It forms a hydrogen bond with the polar heads of the phospholipids
- 5Roles of membrane proteinsForm the glycocalyx, required for the detection of 'self' in immunity, aids in cell-cell adhesion
- 6What are the functions on the plasma membrane?Regulates what enters and exists the cell which controls pH and charge, cell recognition, cell signalling from hormones, enzymatic functions and aids in cell linking and cross talk
- 7What determines the fluidity of the membrane?The double bonds within lipids
- 8What effect does cholesterol have on the first few hydrocarbon groups of the phospholipids?It immobilises them which makes the bilayer less deformable and decreases its permeability to small water soluble molecules.
- 9What is a feature of intracellular membranes?They contain less cholestrol
- 10Why is it necessary for the membrane to be fluid?Allows interactions to occur within the plasma membrane and allows the movement of membrane components required for cell movement, growth, division, secretion and the formation of cellular junctions
- 11What is the purpose of selective permeability of plasma membranes?It allows the cell to build concentration gradients, pH can be regulated and electrical gradients are built (inside of cell is more -ve) creating membranes potentials
- 12What molecules are permeable to the lipid bilayer?Non-polar molecules such as oxygen, carbon dioxide and hormones
- 13What molecules are impermeable to the lipid bilayer?Ions such as NA+ and large molecules such as glucose
- 14Which types of transport across the plasma membrane are passive?Diffusion, osmosis and facilitated diffusion
- 15Which types of transport across the plasma membrane are active?Primary active transport and secondary active transport
- 16Which types of transport across the plasma membrane are vesicular?Endocytosis, phagocytosis, pinocytosis, trancytosis
- 17What is diffusion?The movement of substances down their own concentration gradient either through the lipid bilayer or through membrane channels.
- 18What is facilitated diffusion?The movement of substances down their own concentration gradient via channel or carrier proteins.
- 19What is osmosis?The diffusion of water through a semi-permeable membrane
- 20What are the transmembrane proteins channels that osmosis occurs through called?Aquaporins
- 21What are the two types of pressures present in osmosis called?Hydrostatic pressure and osmotic pressure
- 22What happens to red blood cells if they are placed in a hypertonic solution?They will shrivel because more water will leave the red blood cells than enter via osmosis
- 23What happens if red blood cells are placed in a isotonic solution?They will remain the same because the same amount of water will be entering and leaving the cells via osmosis
- 24What happens if red blood cells are placed in a hypotonic solutionThe red blood cells will burst because more water will enter the cells than leave via osmosis
- 25How can you relive cerebral edema (water on the brain)?Infusion of hypertonic solution
- 26What is primary active transport?Movement of a substance against its concentration gradient. ATP is required to change the shape of the carrier protein, pumping the substance across
- 27What is secondary active transport (co-transport)?Energy stored in a Na+ or H+ gradient is used to drive other substances across
- 28Who is given the drug digitalis?Patients with heart failure
- 29How does digitalis work?It slows the sodium potassium pump, allowing Na+ accumulation. This slows the Ca2+/Na+ antiporters causing Ca2+ levels to increase in the heart. This increases the strength of heart contractions.
- 30What is vesicular transport used for?Endocytosis (bringing substances into the cell) and Exocytosis (expelling from the cell).
- 31What are the three types of endocytosis?Phagocytosis, receptor mediated endocytosis and pinocytosis
- 32In which cells is exocytosis important?Nerve cells (neurotransmitters) and secretory cells (digestive enzymes and hormones)
- 33What is trancytosis?A combination of endocytosis and exocytosis. It is common in endothelial cells.
- 34What are tight junctions?Formed by the fusion of integral proteins of adjacent cells and prevent anything passing through the extracellular space between them
- 35What are adherens junctions?Plaque which attaches to membrane proteins and microfilaments of the cytoskeleton . Often form adhesion belts. Resists separation in contractile activities such as peristalsis
- 36What are desmosomes and hemidesmosomes?They are anchoring junctions held together by linker protein filaments called cadherins or integrins extending from plaques. They distribute tension and prevent tearing.
- 37Where are desmosomes and hemidesmosomes usually found?Skin and heart muscle
- 38What are gap junctions?The adjacent cells are connected by hollow cylinders called connexons made of transmembrane proteins
- 39Where are gap junctions found?In electrically excitable tissues for synchronisation such as heart and smooth muscle
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- Biology- Semester 1 (Lecture 7- Plasma Membrane and Transport) FlashCards sobre Lecture 7- Plasma Membrane and Transport , criado por emma_moran em 28-12-2013.
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