THE WORKING CELL. Why do living organisms need energy?. To be able to carry out life’s functions such as growth, repair, movement, transport. Living cells need a constant supply of energy for breaking and making molecules such as proteins. What Can Cells Do with Energy?.
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Usually in the form of HEAT because all forms ofenergycan be converted to heat.
The Unit is : Calorie or Kilocalories (1000 calories).
Unit of work is: Joule or Kilojoule
Consumers are those that eat the producers
A closed systemis isolated from its surroundings.
The total energy in a closed system remains constant. Living organisms are open systems. Organisms can only convert energy from one form to another.
Energy for cellular work
ATP shuttles chemical energy and drives cellular work
Ex: cellular respiration and wood burning
Amount of energyrequired
Potential energy of molecules
Chemical reactions either store or release energy
Amount of energyreleased
Potential energy of molecules
products with less energy
Chloroplasts and mitochondria make energy available for cellular work
In other words enzymes work by lowering the activation energy, which means lowering the amount of energy needed to get a reaction going.
E cellular workA barrier
1 cellular work
Enzyme availablewith empty activesite
Substrate binds to enzyme with induced fit
Substrate is converted to products
ENZYMES ARE HYGHLY SPECIFIC cellular work
that determine which chemical reactions occur in a cell
Small molecules that help enzymes catalyze reactions.
Usually binds to the active site. Many are vitamins (called coenzymes) and others are inorganic metals such as zinc, iron or copper. All are “enzyme helpers”.
Active site cellular work
Normal binding of substrate
Diffusion and Osmosis
Embedded in the lipid bilayer they are able to open to both sides and play roles in active and passive transport
Molecules of dye rid of wastes, controls secretions and maintain its volume?
Brownian movement. The molecules are bumping against each other because they have kinetic energy.
Solute rid of wastes, controls secretions and maintain its volume?molecule
Molecules are in constant motion. This random motion is called Brownian movement.
The degree to which molecules are in motion determines their temperature.
Absolute zero is the point at which all molecular movement stops.
What drives this movement?
It is in dynamic equilibrium when as many molecules pass one way as cross in the other direction.
Osmosis is a special kind of diffusion involving water.
Osmosis is diffusion of water molecules across a selectively permeable membrane
Is diffusion of water across a membrane or “movement of water across a selectively permeable membrane following the concentration gradient”.
Water moves into an area of higher solute concentration.
Water moves across a membrane from an area of lower solute concentration to an area of higher solute concentration. This is the same as saying from where there is more water to where there is less water.
SOLUTE: any dissolved substance.
SOLVENT:substance in which the solute is dissolved, in cells usually water.
Equal called concentrationof solute
Solute molecule with
cluster of water molecules
Net flow of water
Tonicity refers to relative solute concentrationof two fluidson either side of the membrane
Hypertonic - have more solutes
Isotonic - have same amount of solutes
Hypotonic - have fewer solutes
Hypertonic solution called
(6) Shriveled (plasmolyzed)
Imagine that two sugar solutions with different concentrations are separated by a membrane that will allow water to pass through, but not sugar.
More of the water molecules in the hypertonic solution are bound up in hydration spheres around the sugar molecules, leaving fewer unbound water molecules.
Binding of ATP changes protein shape and affinity for solute
Transport concentrations are separated by a membrane that will allow water to pass through, but not sugar.protein
Vesicle forming concentrations are separated by a membrane that will allow water to pass through, but not sugar.
Fluid outside cell concentrations are separated by a membrane that will allow water to pass through, but not sugar.
Plasma membrane concentrations are separated by a membrane that will allow water to pass through, but not sugar.
Food being ingested
Pseudopodium of amoeba
Material bound to receptor proteins