Module 1: Composition & Structure Of Membranes Flashcards
Prokaryotic cell
Bacterial cell
Does not contain true nucleus
10x more of these cells than eukaryotic
Microbiome
Pop of microorganisms and microbes
Microorganisms
Organism not visible to naked eye, only under microscope
Streptococcus salivanus
Normal inhabitants of upper respiratory tract and oral cavity
Contributes to dental plaque
Staphylococcus haemolyticus
Resides on skin
Pathogen it gets inside body
Bacteriodes Thetaiotaomicron
Prédominant intestinal bacteria
Makes enzymes to breakdown plant material
Cell
Membrane bound structure containing:
Nucleic acids, proteins, carbohydrates, phospholipids
Membrane
Separate internal enviro from external
Phospholipids
Consists of glycerol molecule linked to phosphate and two fatty acids
Saturated
Single bonds
Unsaturated
Double bonds
Lipid micelles
Important for absorption of fat-soluble vitamins and complex lipids
Lipid raft
Region of lower fluidity
Holds macromolecules together in membrane
Gather proteins/collection of receptors on cell surface
Less fluid membrane with fewer unsaturated fatty acids & more cholesterol…
Lower permeability
More fluid membrane with more unsaturated fatty acids and less cholesterol
Higher permeability
Sélective permeability
Ability of cell membrane to control traffic of substances into and out of cell and its organelles
Fluid mosaic model
Membrane consists of proteins and carbohydrates embedded in fluid phospholipid bilayer
Passive/simple diffusion
Movement of small molecules in direction of conc. gradient
High to low conc.
No energy required
-lipid soluble molecules, gases, uncharged polar molecules
Passive transport
Movement of small molecules with conc. gradient (high to low) but involves embedded proteins in membrane
Does not require energy
-requires help if transmembrane proteins, Ions, hydrophilic molecules
Active transport
Movement of molecules against conc. gradient
Fuelled by energy from hydrolysis of ATP
Osmosis
Movement of water across membrane
Less concentrated to more concentrated
Aquaporin
Exclusively permeable to water
Channel water across membrane from high to low conc.
Isotonic environment
Cell in environment or has extracellular fluid concentration with same osmolarity as it’s interior
No net movement of water, cell retain shape and optimal activities
Hypotonic environment
Extracellular fluid has a lower solute concentration than inside cell
Results in excessive movement of water leading to sell swelling or bursting
Hypertonic environment
Environment with higher solute concentration on exteriors and interiors of cell
Net loss of water – quick membrane shrinking and shrivelling
Primary active transport
Transmembrane transport proteins directly affected by energy released from ATP hydrolysis and undergoes change to pump substances across membranes against concentration gradient
Secondary active transport
Neighbouring transmembrane proteins takes advantage of electrochemical gradient established in primary active transport pumps to move their own solutes against gradient
Sodium— potassium pump
Greater concentration of sodium in extracellular fluid relative to interior of cell
Greater concentration of potassium in interior than extracellular environment
Ratio: 3 sodium:2 potassium
