Unit 3: Cellular Energetics Flashcards
metabolism
sum of all of an organism’s chemical reactions
catabolic reactions
chemical reactions that release energy by breaking down molecules
anabolic reactions
chemical reactions that consume energy by building larger molecules
spontaneous process
process that occurs on its own in an organism
free energy
energy of a system that is easily availiable work; denoted by G
endergonic reactions
nonspontaneous reactions that are not energetically favorable; consume energy; positive change in G
exergonic reactions
spontaneous reactions that are favorable; release energy; negative change in G
What are the three kinds of work that a cell does?
Chemical work
Transport work
Mechanical work
ATP
adenosine triphosphate; “energy currency” in the cell. When one of the phosphates is broken off, releases energy that can be used for work
What is ATP made of?
Adenine nucleotide
Ribose sugar
3 Phosphate groups
energy coupling
using energy from a exergonic reaction to power an energy-requiring endergonic reaction
phosphorylated intermediate
a molecule that has a phosphate attached to it from ATP and is unstable
catalyst
speeds up a chemical reaction without being consumed by the reaction
activation energy
the energy needed to weaken molecules enough so that their bonds can break
enzyme
protein that speeds up a chemical reaction by lowering the activation energy
substrate
reactants that enzyme will act on
active site
parts where the substrate binds
products
final substances formed from the substrates
induced fit
the idea that the enzyme active site will change its shape so that it fits the substrate
What mechanisms does an enzyme use to lower activation energy?
Stressing and bending the chemical bonds
Provides an optimal environment for chemical reactions to take place
The active site directly binds to substrates and binds the substrates together
What factors affect enzyme function?
The initial concentration of substrate
pH
Temperature
cofactor
nonorganic substance that help enzymes function
coenzymes
organic substances that help enzymes function
competitive inhibitors
mimic substrate and fight for active site to inhibit enzyme
noncompetitive inhibitors
bind to another place on enzyme other than the active site to inhibit enzyme
allosteric regulation
enzyme’s function is inhibited via the binding of a regulatory molecule to a separate site other than the active site
allosteric activator
increases activity of enzyme
allosteric inhibitor
decrease the activity of an enzyme
cooperativity
when one substrate binds to one subunit of an enzyme, all other substrates have an affinity for that substrate
feedback inhibition
when the product of a metabolic pathway inhibits the enzyme of the metabolic pathway
cellular respiration
the process by which eukaryotic organisms turn glucose into ATP energy
What is the equation for cellular respiration?
C6H12O6 + 6O2 —-> 6CO2 + 6H2O
redox reactions
chemical reactions where electrons are transferred between two substances
reduction
gaining of electrons
oxidation
loss of electrons
reducing agent
substance that gives off electrons
oxidizing agent
a substance that gains electrons
electron carrier
substance that can hold electrons
NAD+ and NADH
electron carrier in cellular respiration that holds one electron and one H+ proton
What is the final electron acceptor in cellular respiration?
Oxygen
oxidative phosphorylation
set of ATP producing processes involving the electron transport chain and chemiosmosis
substrate-level phosphorylation
ADP is phosphorylated into ATP
glycolysis
breakdown of glucose into two pyruvates in the cytosol
What are the two phases of glycolysis?
energy investment and energy payoff
What are the products of glycolysis?
2 pyruvate, 2 net ATP, and 2 NADH
How is pyruvate converted into acetyl COA?
CO2 is removed
pyruvate is oxidized by NAD+
pyruvate dehydrogenase complex
converts pyruvate into acetyl COA
citric acid cycle (Krebs cycle)
oxidizes acetyl COA into 3 NADH, 1 FADH2, ATP, and 2 CO2; runs twice per glucose, once per pyruvate
chemiosmosis
movement of H+ ions across the inner membrane of the mitochondria through ATP synthase to form ATP
electron transport chain
series of enzymes that break the transfer of electrons from NADH to Oxygen into several small steps, so that energy is not wasted in one explosive step and send H+ ions outside the matrix
What happens during oxidative phosphorylation?
NADH and FADH2 release their electrons and protons into the electrons transport chain to power the transfer of H+ protons into the intermembrane space of the mitochondria. The H+ protons flow back through ATP synthase producing ATP from ADP and organic Phosphate. The electrons then go to oxygen to form water using H+ ions as well. 30-32 ATP is produced per glucose
fermentation
anaerobic metabolic reactions that give energy
What is the electron acceptor in fermentation?
Pyruvate
Alcohol fermentation
glucose splits into pyruvate, and CO2 is removed from pyruvate to form acetaldehyde, which is reduced by NADH to form ethanol, recycling NAD+ to be used again. Produces 2 ATP every cycle
lactic acid fermentation
glucose split into 2 pyruvates, pyruvate reduced by NADH to form lactate, recycling NAD+ to be used again
photosynthesis
formation of glucose using sunlight, water, and carbon dioxide
What is the equation for photosynthesis?
6CO2 + 6H2O + sunlight energy —-> C6H12O6 + 6O2
What happens in the light reactions in photosynthesis?
- light as photons strike chlorophyll in photosystem 2 in the light-harvesting complex, which is passed around from chlorophyll to chlorophyll until reaches the central chlorophyll a and excites electrons there.
- The excited electrons from chlorophyll a are transferred to the primary electron acceptor, which becomes reduced.
- H2O is split into 2H+, 1/2 O2, and electrons, (O2 is released as a by-product). The H and O are released into the thylakoid space.
- The electrons travel from PS2 to PS1 via the electron transport chain, releasing the electrons’ energy to form an H+ gradient.
- The H+ gradient makes ATP in chemiosmosis
- photons strike chlorophyll in PS1 exciting electrons until they reach the central chlorophyll of PS1.
- electrons transfer to NADP+ reductase reduce NADP+ into NADPH for the Calvin cycle.
What happens in the calvin cycle?
ATP and NADPH energy are used in the process of fixing CO2 to a 5-carbon chain in a cycle to form glucose
absorption spectrum
measures how well different pigments absorb different wavelengths of light
action spectrum
measures how well photosynthesis works on different wavelengths of light
photosystem
protein complex with a reaction center complex surrounded by light-harvesting complexes; where conversion of solar energy to chemical energy occurs
light harvesting complex
harvests light using its numerous chlorophyll molecules. Photon light energy is passed from chlorophyll to chlorophyll until it reaches the central chlorophyll a
reaction center complex
holds chlorophyll-a molecules as well as a primary electron acceptor
primary electron acceptor
becomes reduced when receives electrons, completing the conversion of light energy to chemical energy
What happens in the Calvin cycle?
- 3 CO2 are fixed to 3 RuBP (5-C sugar) by an enzyme called rubisco to make 3 6-carbon chains
- the 3 6-Carbon chains are broken into 6 3 carbon chains, which are then “zapped” by NADPH with electrons as well as being phosphorylated by ATP to form 6 G3P. One of these G3P goes to become glucose by attaching to another one from a second cycle.
- The other 5 G3P are recycled into 3 RuBP to complete the cycle
C3 plant
direct organic product of carbon fixation is 3 carbon compound of G3P
photorespiration
rubisco fixes O2 to RuBP rather than CO2 to RuBP, which can kill plants
C4 plant
CO2 is first fixed to a 4-C sugar, which is broken down to 2 CO2 to then be used again in Calvin cycle
CAM plant
at night, collect CO2, at day, release it and use it with ATP and NADPH in the Calvin cycle normally
