Lecture 6 - module 2 Flashcards
What is respiration used for?
Organisms use cellular respiration to extract energy from organic molecules.
What are two categories of how organisms obtain energy?
- Autotrophs
- Heterotrophs
How do autotrophs obtain energy?
They produce their own organic molecules through photosynthesis to break down into energy
How do heterotrophs obtain energy?
They consume organic compounds produced by other organisms to break down into energy.
How do organisms extract energy from organic molecules?
Cellular respiration.
What is the basic formula for cellular respiration?
Sugar (glucose) + 6 Oxygen = 6 carbon dioxide + 6 water + energy
What is free energy?
Large amount of energy that must be released in small steps.
How much free energy can come from one mol of glucose?
-686 kcal/mol or more.
Why does cellular respiration occur in many steps instead of all at once?
Because it increases the amount of energy made and decreases the amount lost.
What do electron carriers do?
Catch energy.
What is an example of an electron carrier?
NAD+ which acquires 2 electrons and a proton to become NADH.
What do cells use ATP for?
To drive reactions.
What are 2 mechanisms for synthesis of ATP?
- Substrate-level phosphorylation
- Oxidative phosphorylation
What is the substrate-level phosphorylation?
It transfers the phosphate group directly to ADP.
What is the oxidative phosphorylation?
Indirect way of making ATP from a proton gradient.
What are 4 steps of cellular respiration?
- Glycolysis
- Pyruvate oxidation
- Citric acid cycle
- Electron transport chain and chemiosmosis
What is the input and output for glycolysis?
1 glucose (6 carbons) = 2 pyruvate (3 carbons)
Where does glycolysis occur?
In the cytoplasm.
What is produced in glycolysis?
Net of 2 ATP and 2 NADH.
What happens with pyruvate after glycolysis?
Oxidation:
1. Aerobic respiration - if there is oxygen
or
2. Fermentation - if there is no oxygen
What is aerobic respiration?
- When pyruvate is oxidized to acetyl coenzyme A (acetyl-CoA) which enters the citric acid cycle.
- oxygen is final electron receptor
- significant amount of ATP produced
What is fermentation?
- When pyruvate is reduced in order to oxidize NADH back to NAD.
- oxygen is not available
- organic molecule is the final electron acceptor
What must happen to NADH?
It must be recycled so the process can continue.
What is pyruvate oxidation?
When pyruvate is in the presence of oxygen, it is oxidized.
Where does pyruvate oxidation occur in prokaryotes and eukaryotes?
In eukaryotes it occurs in the mitochondria and in prokaryotes it occurs in the plasma membrane.
What are the products from the oxidation of one 3-carbon pyruvate?
1 CO2
1 NADH
1 acetyl-COA.
What is the citric acid cycle?
When the acetyl group from pyruvate is oxidized.
Where does the citric acid cycle occur?
The matrix of the mitochondria.
What are the steps of the citric acid cycle?
- Acetyl-CoA + oxaloacetate = citrate
- Citrate rearrangement of decarboxylation
- Regeneration of oxaloacetate
What is the product from one Acetyl-CoA in the citric acid cycle?
2 CO2r
3 NADH
1 FADH2
1 ATP
What is the electron transport chain (ETC)?
A series of membrane-bound electron carriers.
Where is the electron transport chain?
Embedded in the inner mitochondrial membrane.
What does the ETC do?
- Transfers electrons to complexes of ETC and passes them along
- Each complex operates as a protein pump, driving protons to the intermembrane space
What is chemiosmosis?
Accumulation of protons in the intermembrane space drives protons into the matrix via diffusion.
How do protons reenter the matrix?
ATP synthase.
How is ATP synthesis carried out?
By tiny rotary motor driven by protein gradient. Protons travel through the stalk and cause the head to rotate.
What is the theoretical energy yield of respiration?
30-32 ATP
How does anerobic respiration occur without oxygen?
The final electron acceptor is an inorganic molecule other than oxygen. Many prokaryotes use sulfur, nitrate, carbon dioxide.
What are the two oxidation processes that can occur without oxygen?
- Anaerobic respiration
- fermentation
What are 2 types of anaerobic respiration?
- methanogens
- sulfur prokaryotes
What is mathanogens?
When CO2 is reduced to CH4. Found in cows.
What is sulfur prokaryotes?
inorganic sulfate is reduced to hydrogen sulfide.
What is fermentation?
Reducing organic molecules in order to regenerate NAD
What are two types of fermentation?
- Ethanol fermentation - occurs in yeast
- Lactic acid fermentation - occurs in animal cells
What is catabolism of proteins?
When amino acids undergo deamination to remove the amino group and the remainder of the amino acid is converted toa molecule that enters glycolysis or the citric acid cycle.
What is catabolism of fat?
When fats are broken down to fatty acids and glycerol.
Which produces more energy: respiration of a 6-carbon fatty acid or a 6-carbon glucose?
6-carbon fatty acid produces 20% more energy.
What is the process of photosynthesis?
6 carbon dioxide + water + light = glucose + water + oxygen
What is photosynthesis?
The process through which energy from the sun is captured.
What things carry out oxygenic photosynthesis?
- cyanobacteria
- 7 groups of algae
- all land plants
What are two types of photosynthesis?
- light dependent reactions
- carbon fixation reactions/light independent reactions/dark reactions
What are the steps of light dependent photosynthesis?
- capture energy from sunlight
- make ATP and reduce NADP to NADPH
What are steps for dark photosynthesis?
- use ATP and NADPH to synthesize organic molecules from CO2.
What are 4 parts of the chloroplast?
- Thylakoid membrane
- Grana
- Stroma lamella
- Stroma
What is the thylakoid membrane?
The internal membrane of a chloroplast that contains chlorophyll and other photosynthetic pigments.
What is grana?
Stacks of flattened sacs of thylakoid membrane in chloroplasts.
What is stroma lamella?
Connected grana in chloroplasts.
What is stroma?
Semiliquid surrounding thylakoid membranes in chloroplasts.
What are pigments?
Molecules that absorb light energy in the visible range.
What is light a form of?
Energy.
What is a photon?
A particle of light that acts as a discrete bundle of energy.
What is energy content of a photon inversely proportional to?
The wavelength of light.
What is the photoelectric effect?
Removal of an electron from a molecule by light.
What happens to energy when a photon strikes a molecule?
- It is lost as heat
or - It is absorbed by the electrons of the molecule
What is absorption spectrum?
The range of efficiency of photons a molecule is capable of absorbing.
What are 2 general types of pigments used in green plant photosynthesis?
- Chlorophylls
- Carotenoids
What are the main colors of light that plants absorb?
blue and red.
Why do plants look green?
Because they absorb the other wavelengths/colors of light and the green waves are what color is reflected to our eyes.
What is chlorophyll a?
It is the main pigment in plants and cyanobacteria and the only pigment that can directly convert light energy to chemical energy.
What light waves does chlorophyll a absorb?
violet-blue and red light.
What is chlorophyll b?
An accessory pigment/secondary pigment that absorbs wavelengths that chlorophyll a does not.
What are 2 types of accessory pigments?
- Carotenoids
- Phycobiloproteins - important in low-light ocean areas
What are 2 components of photosystems?
- Antenna complex
- Reaction center
What is the antenna complex?
It gathers photons and feeds the captured light energy to the reaction center. (made up of hundreds of accessory pigment molecules)
What is the reaction center?
It passes excited electrons out of the photosystem. (made up of 1 or more chlorophyll a molecules)
What are the steps of light dependent photosynthesis?
- Primary photo event
- Charge separation
- Electron transport
- Chemiosmosis
What is the primary photo event?
When the photon of light is captured by a pigment molecule.
What is the charge separation?
When energy is transferred to the reaction center.
What is the electron transport?
When electrons move through carriers to reduce NADP
What is chemiosmosis?
It produces ATP.
What is cyclic photphosphorylation?
A way of generating ATP via electron transport that only occurs in bacteria and is anoxygenic photosynthesis (oxygen is not a byproduct).
What is noncyclic photophosphorylation?
- Plants use both photystems 2 and 1 in series to produces both ATP and NADPH
- the path of the electrons is not a circle
- photosystems replenished with electrons obtained by splitting water
What is photosystem I?
Oxygenic photosynthesis functions like sulfur bacteria.
What is photosystem II?
It can generate an oxidation potential high enough to oxidize water to make oxygen.
What are photosystems I and II a part of?
noncyclic photosynthesis.
How does photosystem I and II work together?
Photosystem 2 replaces electrons from breaking apart H2O and Photosystem I receives electrons from Photosystem II.
What is generated through Photosystem I and II?
ATP and NADPH.
What is chemiosmosis?
An electromagnetic gradient that can be used to synthesize ATP.
What allows protons back into the stroma?
Chloroplast has ATP synthase enzymes in the thylakoid membrane.
What do stroma do in chemiosmosis?
It catalyzes the reactions of carbon fixation through enzymes. (Does Calvin cycle reactions)
What is the same as mitochondria in cellular respiration?
The stroma in chemisomosis.
How do cells build carbohydrates?
They use energy (ATP from light-dependent reactions) and reduction potential (NADPH from photosystem I).
Who is the Calvin cycle named after?
Melvin Calvin.
What are the three phases of the Calvin cycle?
- Carbon fixation
- Reduction
- Regeneration of RuBP
What does 3 turns of the Calvin cycle incorporate enough carbon to produce?
A new G3P.
What does 6 turns of the Calvin cycle incorporate enough carbon to produce?
1 glucose.
What is the direct output of the Calvin cycle?
G3P.
What is the indirect output of the Calvin cycle?
Glucose.
What is G3P?
A 3 carbon sugar used to form sucrose or starch.
What is the energy cycle?
Where photosynthesis uses the products of respiration as starting substrates and respiration uses the products of photosynthesis as starting substrates. Used to turn light into a more usable form of energy.
