Unit 3 Flashcards
What is the importance of the active site in an enzyme?
Enzymes catalyze a specific reaction with a specific substrate which fits perfectly into the active site
What would happen if the enzyme’s active site changed?
The substrate would no longer fit in the active site, wouldn’t be able to catalyze the reaction
What does an enzyme do to catalyze a reaction? (what changes, what stays the same)
Changes:
- lower energy barrier (takes less energy for the reaction to occur)
Doesn’t change:
- reactants or products
- free energy
- whether the reaction releases or absorbs energy
What things can impact enzyme activity?
- enzyme concentration
- substrate concentration
- temperature
- pH
- enzyme inhibitors
How does enzyme concentration impact enzyme activity?
more enzymes = increase in enzyme reaction rate, substrates interact/collide with enzymes more often
How does substrate concentration impact enzyme activity?
more substrates = increase in reaction rate, enzymes and substrates interact/collide more often
How does temperature impact enzyme activity?
- enzymes have an optimal temp for maximum reaction rate
- low temps = slower rate
- high temps = denaturation if too high
How does pH impact enzyme activity?
- enzymes have an optimal pH for maximum reaction rate
- high pH = decreased enzyme activity
- low pH levels can cause denaturation of the enzyme
How do inhibitors impact enzyme activity?
General
- certain chemicals inhibit enzyme function
- covalent bonds = irreversible inhibition
- weak interactions = reversible
Competitive
- looks like substrate and binds to the active site, stops the real substrate
- increasing substrate concentrations can overcome bonds
Noncompetitive
- not bound to the active site
- change the shape of the enzyme making it less effective
Why do living things not defy the second law of thermodynamics?
???
- all reactions release a small amount of heat energy that contributes to entropy
- metabolism releases energy
- ordered structures deteriorate over time and need to be replaced
???
What are the inputs and outputs of a light dependent reaction?
Inputs:
Water (H2O), light energy, NADP+, ADP + phosphate ion
Outputs:
NADPH, ATP, oxygen
What are the inputs and outputs of a light independent reaction? (Calvin Cycle)
Inputs:
CO2, ATP, NADPH
Outputs:
G3P (a 3 carbon sugar) which will later be glucose, ADP + phosphate ion, NADP+
Where does the light dependent reaction take place?
Thylakoids of chloroplasts
Where does the light independent reaction take place? (Calvin Cycle)
Stroma of chloroplasts
What is the main purpose of the light dependent reaction?
Captures energy from the sun to create ATP and NADPH for use in the light independent reaction
What is the main purpose of the light independent reaction? (Calvin Cycle)
Uses ATP and NADPH to produce carbs/sugars from CO2 taken in
What are the photosystems and why are they important?
- they are proteins embedded in the thylakoid membranes
- chloropyll pigments absorb light to excite electrons
What would happen if the proton gradient in photosynthesis was not working?
If the proton gradient stops working then ATP will not longer be produced for the light independent reaction to occur
What is the importance of the proton gradient in photosynthesis and how is it created?
- As electrons are transferred down the ETC H+ ions are moved into the thylakoid
- the H+ ions then leave the thylakoid through ATP synthase from high to low concentration to create ATP
What is the origin of photosynthesis?
- First evolved in prokaryotic cells
- moved to eukaryotic cells due to endosymbiosis
What are the inputs and outputs of glycolysis?
Inputs:
Glucose
Outputs:
2 pyruvate, 2 ATP, 2 NADH
Where does glycolysis take place?
In the cytosol
What is the main purpose of glycolysis?
The first step for both cellular respiration and fermentation, extract electrons and move them to NADH And FADH2 which is used in the ETC
What are the inputs and outputs of the citric acid/krebs cycle?
Inputs:
Acetyl CoA
Outputs:
NADH, FADH2 and ATP, CO2
Where does the citric acid/krebs cycle take place?
The mitochondrial matrix
What is the main purpose of the citric acid/krebs cycle?
Extract electrons and move them to NADH and FADH2 which is used in the ETC
Where is the electron transport chain?
The inner membrane of the mitochondria
What is the main purpose of the electron transport chain?
- series of small reactions that release small amounts of energy to bring in H+ ions
- Oxygen accepts the electron at the end and forms water
What is oxidative phosporylation and what is it’s main purpose?
- As the electron goes down the ETC H+/protons pass across the membrane to reach equilibrium
- ATP synthase forms ATP from ADP + P
- Oxidation = NADH/FADH2 lose electrons
- Phosphorylation = ADP + P –> ATP
What are the inputs and outputs of fermentation?
Inputs:
glucose, 2 ATP
Outputs:
Lactic acid or alcohol and CO2
Aerobic vs anaerobic respiration
Anaerobic = needs oxygen (most of cellular respiration)
Aerobic = doesn’t need oxygen (fermentation)
What is the importance of the proton gradient and how is it created? (cellular respiration)
What can the proton gradient be used for other than the production of ATP?
Energy from the proton gradient can be used to generate heat/regulate body temp instead of going through ATP Synthase
What is unique about fermentation? Why is that important?
Doesn’t require oxygen, starts with glycolysis but doesn’t go through the Krebs cycle or the ETC
What is the main goal of cellular respiration and fermentation?
To make ATP for use in the cell from stored sugars and carbs
What is the main goal of photosynthesis?
Allows plants to make food using light energy which is converted into chemical energy
Why is ATP important?
When it is converted into ADP it releases energy for use within the cell
Endergonic vs exergonic
Endergonic
- releases energy (still requires a little energy input for the reaction to occur)
- spontaneous
- products have LESS free energy than reactants
Exergonic
- absorbs energy
- non-spontaneous
- products have MORE free energy than reactants
Oxidation vs reduction
Oxidation = losing electrons
reduction = gaining electrons
