#5 Take-home Exam Flashcards
Cell metabolism
The sum of all chemical reactions that occur in a cell
Activation energy (in regards to enzymes)
represents a strain on a cell’s resources and cell’s have evolved mechanisms to lower this energy bill
Stoma
A pore in a leaf for gas exchange
Mesophyll (in regards to leaf anatomy)
inner tissue of leaf containing many chloroplasts
Stroma
Fluid that fills space inside the chloroplast, where the Calvin Cycle occurs
Thylakoid
Flattened sac containing chlorophyll where light reactions occur
Chlorophyll
Green light-absorbing pigment
NADPH
used in anabolic reactions. It temporally stores the electrons and provides reducing “power” (electrons) to the Calvin Cycle.
NADH
delivers the two electrons to an electron transport chain in cellular respiration
FADH2
an electron carrier that helps NADH shuttle electrons for the electron transport chain in cellular respiration
What is the role of enzymes?
they function to speed up chemical reactions in the cell
What does it mean that an enzyme and its substrate
interact like a “lock and key.”
Enzymes use a ‘lock and key’ process that allows specific enzymes to catalyze very specific reactions. In this analogy, the lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme)
what is the role of the enzyme’s substrate, and the
enzyme’s active site
The substrateis a molecule upon which anenzymeacts and the enzymes active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction
Why is it important that an enzyme lowers the activation energy needed
to kick-start the reaction that enzyme catalyzes.
Because the lower the activation energy for a reaction the faster the rate.
Lowers cell’s energy bill
Explain how changing the temperature and pH effects the functionality (efficiency) of an enzyme
Each enzyme has an optimal temperature. If it gets too warm the enzyme loses its shape and can no longer function properly. If the temperature gets to cold then molecules move more slowly and enzyme activity decreases Enzymes also have an optimal pH for maximum efficiency if conditions are too basic or acidic the enzyme will denature
How does increasing the concentration of an enzyme’s substrate effect the ability (efficiency) of
an enzyme to convert its substrate into product?
Because the substrate concentration must be high enough to come into contact with the reactants
Where specifically do the light reactions of photosynthesis take
place?
in the thylakoid
what is the first step of light reactions
Chlorophyll molecule in photosystem II absorbs the energy from a photon exciting an electron. That energy is passed along until it reaches the reaction center where it provides energy to an electron of P680. That electron jumps to a higher energy level.
what is the second step of light reactions
- The electron from P680 is captured by the primary electron acceptor.
what is the third step of light reactions
- H2O is split and its electrons are supplied to the P680 as the P680 is giving up its electron to the primary electron acceptor. The resulting oxygen atoms from the split H2O form O2 and leave as waste.
what is the forth step of light reactions
- The excited electron held by the primary electron acceptor passes from photosystem II to photosystem I via an electron transport chain. The fall of the electron down the chain drives a H+ pump that forces hydrogen ions up a concentration gradient from outside the thylakoid to inside the thylakoid space. This establishes a concentration gradient of H+ ions which is a source of stored potential energy.
what is the fifth step of light reactions
- Meanwhile a chlorophyll molecule in photosystem I absorbs the energy in a photon and presents that energy to the P700 in the reaction center complex. The primary electron acceptor captures the electron from the P700 and the electron provided by photosystem II replaces the excited electron leaving the P700 that is captured by the primary electron acceptor.
what is the sixth step of light reactions
- The excited electron from the primary electron acceptor passes through a short electron+ transport chain to NADP , reducing it to NADPH.
what is the seventh step of light reactions
- Meanwhile the H+ ions flow down their concentration gradient through a special protein channel called ATP synthase which makes ATP.
Where specifically does the Calvin cycle take place?
In the stroma
What happens during the Calvin cycle
The Calvin Cycle takes the energy in NADPH and ATP and stores it in glucose and then produces sugar
What are the end products of the Calvin cycle?
Molecules of G3P
Where specifically does glycolysis take place?
in the cytoplasm of a cell
What are the end products of glycolysis?
harvests four electrons and makes two ATP molecules
Where specifically does the Krebs cycle take place?
in the matrix of a cell
What are the end products of the Krebs cycle?
for each molecule of pyruvate, the Krebs cycle harvests ten electrons and makes one one ATP molecules
Where specifically does oxidative phosphorylation take place?
in the inner membrane of the mitochondria
Briefly describe
what happens during oxidative phosphorylation
high energy electrons are being brought up to the top of the electron transport chain. they are then brought down the electron transport chain and drive hydrogen ion pumps. oxygen grabs electrons and grabs a hydrogen ion
oxygen + hydrogen = H20
H20 then goes away as a waste product
What are the end products of oxidative phosphorylation?
end products are H+ concentration gradient, lots of ATP, as well as H2O as a waist product
Compare and contrast the light reactions of photosynthesis and oxidative phosphorylation of cellular respiration explaining how they are “backward” images of one another.
Light reactions of photosynthesis and oxidative phosphorylation of cellular respiration are both redox reactions.
Photosynthesis is making food
while
cellular respiration consumes food and makes ATP.
Their chemical reactions are “backwards/flipped” in a sense.
