BILD 1 EXAM 2

• Definition of Energy 


  the capacity to cause change, or to do work
• two classifications of energy 


  potential and kinetic
• thermal energy 


  kinetic energy that involves with random movement of atoms
• heat 


  the transfer of thermal energy from one object to another
• light energy 


  used by plants to perform work (photosynthesis)
• potential energy 


  an object that is not in motion
• chemical energy 


  potential energy available for release in a chemical reaction
• thermodynamics 


  the study of energy transformations in matter (potential --> kinetic)
• first law of thermodynamics

  energy cannot be created or destroyed, only converted from one form to another
• free energy

  energy available to do work in a cell
• exergonic

  change in free energy is negative, release of free energy
• phosphate or sulfur bonds 


  stores released energy
• ATP 


  adenosine triphosphate, high energy compound
• three main components of ATP

  ribose, adenine, three phosphate molecules
• endergonic 


  the change of free energy is positive, requires energy in order to proceed; energy is stored in products
• metabolism

  the process of converting food and drinks into energy
• two types of metabolism

  respiration and fermentation
• catabolic reaction 


  breaks down large molecules into smaller molecules, while releasing energy
• respiration 


  occurs in environments with or without oxygen
• fermentation 


  occurs without oxygen
• inorganic carbon 


  carbon extracted from rock
• organic carbon 


  found in living things
• heterotrophs 


  use organic carbon
• autotrophs

  obtain inorganic carbon
• different sources of energy to break down food

  chemoheterotrophs, chemoautotrophs, photoheterotrophs, photoautotrophs
• chemoheterotrophs 


  use energy from chemicals to break down organic substances
• chemoautotrophs 


  use energy from chemicals to break down inorganic substances
• photoheterotrophs 


  use light energy to break down organic substances
• photoautotrophs 


  use light energy to break down inorganic substances
• enzyme 


  a protein that speeds up a chemical reaction
• activation energy 


  initial investment of energy for starting a reaction
• how do enzymes speed up reactions?

  by lowering the activation energy needed for the reaction to occur
• substrate 


  reactant an enzyme acts on
• substrate specificity 


  active site will only bind the substrate or substrates they are adapted to bind
• cofactors 


  nonprotein helpers that assist enzymes with things like electron transfers
• coenzymes 


  cofactors that are organic molecules
• inhibitors 


  prevent substrates from binding the active site by binding irreversibly or reversibly to the active site
• how do cells signal information to each other?

  by sending signaling molecules (ligands) to one another
• secreting cell 


  the cell sending the signaling molecule
• target cell 


  receiving the signaling molecule