Lecture 7A Flashcards
What is energy?
the capacity to cause change
what are the two kinds of energy?
1) potential energy: energy stored
2) Kinetic energy: energy in motion ( heat and thermal energy )
True or false
energy is constantly converted from one form to another
true
what type of energy is chemical energy?
potential energy also known as bond energy
chemical energy is released when a chemical reaction rearranges the atoms of molecules
what are the laws of thermodynamics?
first law: principle of conservation of energy (energy can be transferred and transformed but not created or destroyed)
second law: entropy is increasing ( every energy transformation increases entropy )
what is light energy and what is it converted to by plants?
light energy= used to create chemical energy
- chloroplasts convert light ( kinetic ) to chemical energy by creating bonds in sugar molecules (potential)
the mitochondria uses the chemical energy ( potential) in glucose, amino acids, and fatty acids to synthesize ATP (potential)
true or false
there is always some energy the escapes the system as heat
true
what is thermodynamics?
the study of energy transformations that occur in a collection of matter
how much percentage is energy taken in and used by each trophic level to create biomass?
10%
what is free energy?
the quantification of the potential energy of a reaction.
G= H - TS
enthalpy (H) = total amount of energy in the system
entropy (S)
Temperature (T)
the greater the free energy= greater potential
more free energy leads to what?
less stable, greater work capacity
less free energy leads to what?
more stable, less work capacity
what are the properties of a spontaneous reaction?
- negative delta G
- free energy decreases during spontaneous reactions
- spontaneous reactions can be harnessed to perform work
what are the two types of chemical reactions in cells that are based on free energy changes?
energonic & exergonic
what are endergonic reactions?
the gain for free energy, reactants contain less energy than the products
requires enzymes and an input of energy to occur
delta G is positive
what are exergonic reactions
the loss of free energy, reactants have higher potential energy than products
require enzymes even if it doesn’t need an input of energy
delta G is negative = spontaneous
what is metabolism?
- the totality of an organisms chemical reactions
- an emergent property of life that arises from orderly interactions between molecules
what are the two main types of metabolic pathways?
1) catabolic pathways = release energy by breaking down complex molecules into simple compounds, exergonic, cellular respiration
2) anabolic pathways = consume energy to build complex molecules from simpler ones, endergonic, synthesis of protein from amino acids
how is cellular respiration a catabolic pathway?
because it breaks the covalent bonds of glucose and other metabolites
how is the translation step of protein synthesis considered an anabolic pathway?
during the translation step of protein synthesis, amino acids are covalently bonded together through dehydration sythesis reactions which requires an energy investment from the cell.
what is energy coupling?
using the energy prduced during a catabolic/exergonic process to drive an anabolic/endergonic process
what is ATP?
adenosine triphosphate, a nucleotide
- ATP is the molecule that mediates the energy transfer between catabolic and anabolic pathways
ATP is shuttled around the cell to provide energy for endergonic reactions
where in an ATP molecule is energy stored?
energy is stored in the phosphate group
three phosphate groups is a key identifier for an ATP molecule
What is an ATP nucleotide made up of?
- Nitrogenous base ( adenine )
- pentose sugar ( ribose )
- phosphate groups:
- > adeline + ribose + 1 phosphate group = AMP
- > adeline + ribose + 2 phosphate groups = ADP
- > adeline + ribose + 3 phosphate groups = ATP
why does ATP have high energy bonds?
because the three phosphate groups are negatively charged therefore they repel eachother, increasing instability which increases the energy
what is phosphorylation?
the process by which ATP donates energy through the transfer of a phosphate group to another molecule
phosphorylation causes the molecule to be more reactive (less stable) than the original unphosphorylated molecule
going from ATP to ADP is what type of reaction?
exergonic reaction
Glucose + fructose -> Sucrose is what type of reaction?
endergonic reaction
is this reaction spontaneous?
no this reaction is not spontaneous
is this a coupled reaction?
yes
What are three things that ATP drives?
1) cellular transport (transporting molecules across membranes via transport proteins)
2) Cellular mechanical work ( work involving motor proteins )
3) Chemical work (involving chemical reactions
what is the hydrolysis of ATP?
ATP-> ADP + Pi + cellular work
this reaction is reversible
what is the healthy amount of ATP in the body?
1g
10 million molecules of ATP consumed and regenerated per second per cell
what are the two types of electron transfer?
1) oxidation = loss of electrons by a molecule
2) reduction = gain of electrons by a molecule
reduction reaction = redox reaction
**gives up an electron = releases energy
gains the electron = recieves energy **
what are four acceptor molecules in redox reactions?
1) Nicotinamide adenine dinucleotide (NAD+): when NAD becomes reduced, it temporarily stores a large amount of free energy. Used in the synthesis of ATP
2) NIcotinamide adenine dinucleotide phosphate (NADP+): used more directly to provide energy for certain reactions, like photosynthetic reactions
3) Flavin adenine dinucleotide (FAD): reduced form FADH2, similar in role function to NAD+ but donates relatively less energy per molecule than NAD+
4) Cytochromes: contains iron, the iron component accepts electrons from hydrogen atoms, which helps makes ATP
