Lipids and Membranes Flashcards
What is a plasma memebrane?
The bounday that seperates the living cell from its surroundings
What does the plasma membrane serve as?
A selective barrier that allows chemical reactions to ocur effectively.
What is the most abundant lipid in the plasma membrane?
Phospholipiods
What is the structure of a phospholipid?
The hydrophilic head, which is “attracted” to water and the hydrophobic head, which “hides” from water
What do phospholipids self asmenble to form?
Bubbles or micelle to form phosphlipid layers
What building block moves less than phospholipids within the bilayer?
Proteins
What kind of movement do unsaturated hydrocarbon tails have?
Fluid/rougher
What kind of movement does saturated hydrocarbon tails have?
Viscous movement
What is used in place of cholesterol for plants?
Sterols
What is cholesterol used for?
It provides stability and acts as a temperature buffer quality for the membranee. Sterols for plants
What model does the plasma membrane have?
The fluid-mosaic model
What is the fluid phospholipid layer?
It is a layer where transmembrane proteins are partially or completely embedded, creating semi-permeable channels.
What are the classes of membrane proteins?
Peripheral proteins and integral proteins
What are peripheral proteins?
Proteins loosely bound to the surface of the membrane
What are integral proteins?
Proteins that penetrate the lipid bilayer across the whole membrane
What is another name for integral proteins?
Transmembrane proteins
What type of protein is antigen?
A peripheral protein
What type of protein are transport proteins?
Intergral Proteins
What is the function of channel proteins?
Wide open passages
What is the function of ion channels?
Gated passges
What is the function of aquaporins?
Only lets water
What is the function of carrier proteins?
Changes shape
What is the function of transport proteins?
Requires ATP
What are glycoproteins?
Recognition proteins
What are hormones?
Receptor proteins
What is the function of adhesion proteins?
Anchors
Who discovered aquaporins?
Peter Agre (1991) and Roderick McKinnon (2003)
Why are proteins the perfect molecule to build structures?
They alter structure and function
What does a plasma membrane have to do to be a selectively permeable barrier?
A plasma membrane needs to import ions and molecules necessary for life while excluding ions and moleales that might damage it.
What can be found inside the plasma membrane that anchors proteins?
Hydrophobic non polar amino acids
What is found on the outer surfaces of membrane in fluid?
Hydrophobic polar amino acids
What are the molecules that can get through the plasma membrane?
Hydrophobic molecules eg oxygen, carbon dioxide, nitrogen, steroids and small uncharged polar molecules eg water, glycerol, urea
What are molecules that can’t get through the plasma membrane directly?
Large uncharged polar molecules eg glucose, sucrose and ions (positive or negative)
What are the ways of getting through the cell membrane?
Passive transport, facilitated transport and active transport
What are the two ways of going from high to low concentration?
Passive and facilitated transport
What is passive transport?
The diffusion of hydrophobic molecules (lipids)
What is facilitated transport?
The diffusion of hydrophilic molecules through a protein channel
What is the difference between passive transport and facilitated transport?
Passive transport is done on its own and facilitated transport is done with help.
What is active transport?
The diffusion against the concentration gradient from low concentration to high concentration. Uses a protein pump and requires ATP
What law is diffusion applied to?
The 2nd law of thermodynamics
What helps facilitated diffusion?
Channels for ions/water and carriers for sugars/amino acids
How do proteins open in the gated channels?
They only open in the presence of stimulus.
’ How are large molecules usually moved in and out of cells?
Through vesicles and vacuoles and endocytosis or exocytosis
What is phagocytosis?
Cellular eating
What is pinocytosis?
Cellular drinking
What is osmosis?
The diffusion of water from high concentration to low concentration that occurs only when solutions are separated by a membrane that permits wate to cross but holds back some or all solutes
What is the solute concentration for hypertonic solutions?
More solute, less water
What is the solute concentration for hypotonic solutions?
Less solute more water
What is the solute concentration for isotonic solutions?
Equal amount of solute and water.
What does cell survival depend on?
Balancing water uptake and loss
How are plant cells and animal cells in hypotonic solutions?
Animal cells- Lysed and burst while plants were turgid and normal
How are plants and animals in isotonic solutions?
Animal cells are normal and plant cells are flaccid
How are plants and animals in hypertonic solutions?
Animal cells are shriveled while plant cells are plasmolyzed
What are salt water organisms compared to their environment?
Hypotonic
Where are transmembrane proteins embedded?
In the fluid phospholipid layer
What creates semi-permeable channels?
The embedding of transmembrane proteins in the phospholipid layer
