Module one: Cells as the Basis of Life Flashcards
the cell membrane is…
a membrane that surrounds cells
the purpose of the cell membrane is to…
allow the cell to exchange material between the cells internal and external environment
the cell membrane is composed of a…
phospholipid bilayer made up of hydrophobic tails (lipids) and hydrophilic heads (phosphate group)
what are integral proteins?
integral proteins are specific proteins that water-soluble substances pass through. They can be permanent or temporary
what are peripheral proteins?
proteins with a carbohydrate group which allows for cells to communicate about what is requires and needs to remove. Individual cell types have their own proteins recognized by the immune system (flags).
what is diffusion?
a form of passive transport which involves the movement of any molecules from an area of high concentration to low concentration until equilibrium is reached.
If there is a greater difference in concentration of substances, there is a…
steeper concentration gradient, therefore faster diffusion
carrier proteins are…
a transport protein for specific solutes, moving them from one side of a membrane to the other
channel proteins are…
a type of transport protein which lets water molecules or small ions through (aquaporins)
osmosis is…
the net movement of solvent molecules form a region of high solvent concentration to a region of low solvent concentration through a semi-permeable membrane.
the cell swells if there is…
a high concentration of water outside the cell
the cell shrinks if there is…
a low concentration of water outside
isotonic
when fluids inside and outside the cell are of equal solute concentration
the external solution is hypertonic…
when a cell is surrounded by a solution that has lower solute concentration than their cytoplasm
the external solution is hypotonic…
when a cell is surrounded by a solution of higher solute concentration
active transport
the movement of molecules from a region of low concentration to high concentration which requires energy input, making it movement against the concentration gradient
endocytosis is…
the process by which large particles move into the cell with the help of the cell membrane
phagocytosis is…
when a particle is engulfed by membrane and material is digested (eating)
pinocytosis is…
when cell membrane engulfs liquid containing dissolved molecules
receptor-mediated endocytosis is…
pinocytosis which is manipulated by protein receptors on the cell membrane
when there is a high concentration gradient, substances diffuse _____
rapidly
when there is a low concentration gradient, substances diffuse _____
slowly
uncharged molecules penetrate the cell membrane ___
easily
charged molecules require ____, allowing for them to penetrate cell membrane
channel proteins specific the the ion as they can’t cross the hydrophobic centre of cell membrane
factors affecting diffusion include…
concentration gradient, characteristics of materials (chemical and physical), SA to volume ratio
small molecules ____ diffuse across cell membrane
easily
large molecules are transported across cell membrane by…
endocytosis or exocytosis
SA to volume ratio
It is an evolutionary advantage to have smaller cells, as they have a higher surface to volume ratio
high SA to volume ration means…
the distance a substance has to travel to reach the centre of a cell decreases, causing faster movement
enzymes
proteins that control all metabolic reactions in living cells. They are catalysts and control the rate of reaction in cells
metabolism
the sum of all chemical reactions occurring within a living organism which requires a specific enzyme
catalyst
a substance which speeds up a chemical reaction by lowering the active energy required
enzymes are composed of…
protein molecules that are highly folded to create a specific shape on the active site
substrate
the reactant with enzyme
active site
where the reactants (substrates) in a reaction bind
enzyme+substrate
substrate-enzymes complex
true or false: when a reaction is finished, energy is released from the active site
true
after a reaction, the enzyme…
remains unchanged and is available for the same process to occur
lock and key model
the way in which an enzyme functions where the active site is rigid and the substrate fits in exactly
induced fit model
the way in which an enzyme functions where the active site is flexible and binding of substrate induces enzyme to alter shape slightly
factors that influence enzyme activity include
temperature, pH and substrate concentration
high temperature and enzyme activity
enzymes best function at the body temperature of an organism. At high temperatures, the active site of enzyme changes shape (denatures)
low temperature and enzyme activity
at low temperatures, the enzyme changes shape and its functioning slows down or stops (often reversible)
pH and enzyme activity
enzymes have a limited range of pH in which they function optimally and anything outside of this will cause denaturing. Most will function at pH 7.
substrate concentration
the higher the substrate concentration, the higher efficiency until all available enzymes are used up AKA saturation point
embedded protein
help certain substances such as amino acids to cross the membrane
facilitated diffusion
the passive transport of molecules or ions across a membrane via specific proteins
